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Newbie's Guide to Modding the RX-8
Autor Wiadomość

Auto: Mazda Rx-8
kW / HP: 231
Pomógł: 5 razy
Wiek: 28
Dołączył: 07 Gru 2012
Skąd: GOP
Wysłany: Czw 28 Mar, 2013 18:42   Newbie's Guide to Modding the RX-8

Now we start tonight with the naughty problem of modifications. If you get into it, you get very little benefit for quite a lot of money. So all you're really buying are the looks.

This one though, is a little bit different.

Now the first thing you need to know is that it is not mind reading. You have to be willing to read. If you are not willing to read these opening posts in their entirety, rereading as needed until you grasp the concepts, then the short story of how to mod is this:

It's really that simple. If you are only willing to read the short story, you have no business making any modifications. To any car.

The second thing you need to know is that this is not a cheap car to modify. "Cheap" is of course relative to your financial situation in life. But for some perspective:

You can buy a 2004 RX-8 for about the same amount of money as a 2005 Civic Coupe, about $7,000. A catback exhaust for the Civic will run you about $500, and give you about 5% power gain. A catback exhaust for the RX-8 will run you about $800-$1,000, and give you about 0% power gain. A cold air intake for the Civic will run you about $250 and give you about a 3-4% power gain. A cold air intake for the RX-8 will run you about $400 to $600, and give you between +0.5% to -10% power (depending on which one you go with, yes, NEGATIVE 10% power). "Chipping" a Civic will run you $50 to $100, depending on how much you do yourself and what maps you buy, and can get you between 3% and 8% power gain. The only ECU modifications you can do to the RX-8 will run you $500 to $800, and give you about a 2% to 3% power gain.

Power Modifications

Putting power at the top, because that is what everyone goes for first.

Estimated power 'caps' are ~230whp NA and ~400whp turbocharged. That being said, getting past ~215whp NA will require a >$5,000 engine rebuild and/or drivetrain friction reduction treatments. Both if you want over ~220whp. Exceptions are possible, but don't expect it. Getting past ~300whp with FI will usually also involve an engine rebuild, either because you want to do it properly in the first place, or the engine you have shattered while trying. Crossing the 300whp mark also means that you can't expect that your engine will last more than ~10,000 miles. More is possible, but you can't EXPECT it. To get to 400whp you will require a complete top notch engine rebuild with significant changes to increase the strength of the engine, including the block itself. Don't expect your engine to last long.

If you can't find a dyno to prove the gains, assume that claims of power gains are 'Willful misrepresentation of the truth in order to bilk gullible customers out of their money'. Also known as 'lying'. The sole exception to this is if it's an actual race team making the claim as they typically don't sell their developed products, and won't share their exact results. But then, they aren't trying to scam you either at that point. Any company that is trying to sell to the public has every interest in showing their product in the best possible light. So if they can't produce actual dyno sheets (not just photoshopped ones), then it's either because they have them and it proves their product is useless or they don't have them because they never tested. And if they never tested, how can it be trusted to produce the results advertised? It can't.
Also, remember that unless the dyno comparison is done on the same car at the same dyno in the same environmental conditions, comparing the numbers is meaningless. Comparing PEAK numbers is also largely meaningless, as it's worthless to gain 10hp in a 200rpm band by dropping 10hp across the rest of our 5-6,000 rpm band.

The relative "high power" limitations to the Renesis are largely due to the exhaust ports. They can not be increased in size by much since they are run through the side plates, between the oil and coolant passages, and the studs, etc... Prior RX-7s had the entire end of the rotor housing to work with for exhaust dumping. Adding exhaust ports to the housing is viable, though imperfect and makes the engine no longer a Renesis, rendering this point moot. Any high power goals will have to take this fact into account with some serious consideration. There are some methods of increased exhaust porting, though none known have performed flawlessly, usually introducing different issues that have to be addressed. There are also other points that produce capping effects on power, but the exhaust port size is the the one that people run into first and is the hardest to get around.

The more power you are making, the more heat you are pushing through the exhaust ports. Consistently high EGTs (exhaust gas temperature) have been shown to cause problems with the side seals and side seal springs. There are resolutions to this, if you are having the engine rebuilt. High power cars with a reliable and stable tune and fueling will likely have their side seals fail before the apex seals, however when a side seal fails, it's because of the spring deforming, pushing the seal out until it clips the exhaust port, shattering it and the seal fragments then destroy the apex seals, so most people might assume apex seal failure when it's actually the side seals that went first. High power with an unstable tune or fueling moves the likely failure point to a detonation that destroys the apex seals first. As far as the engine is concerned, the results are the same between these.

(can cause warranty hassle)
The OEM intake is really VERY good. The only 2 aftermarket intakes that can boast a power improvement are the Mazdaspeed and AEM. Which happen to be the exact same thing, just with different logos. That intake can give you a very slight bump in power. And I mean very slight. Within the 2% error margin of modern dynos. (2% of 180rwhp = 3.6hp). The only other viable intake for power reasons is the Racing Beat intake. There are a few other intakes that are net equal to the OEM intake, but not many. Every single other intake than this handful, from K&N to ebay kits, cold air and ram air, complicated and simple, every single one will cause you to lose power. This is because they do not have the proper R&D into how the air flows into our engine. They just fabricated a tube, made a port for the MAF, and jammed an air filter on the end. The air becomes heavily disrupted, the MAF can't read it right, and the ECU believes what the MAF is incorrectly telling it, causing the ECU to over and/or underfuel the engine all over the rev range. Even removing the OEM screens can cause power loss, since those screens are very well designed to straighten the air flow and smooth it down considerably. They aren't there to 'catch rocks'. Just to straighten the air flow.
The filter isn't even bad. There is FAR more breathable surface area on the OEM air filter than nearly every intake kit out there. The OEM filter is NOT a restriction on the air flow. The K&N drop-in panel was dyno'ed by Speedsource to show a consistent 1HP increase vs OEM. However, the K&N's filtering is substandard, and in Daytona races (Grand-Am ST class), they were losing engines to sand ingestion. (Reference: K&N air filter) 1HP is not worth that risk, especially if you are paying for it. Stick with OEM. The only solid reasons to go after market are:
- the subjective reason of "I like the sound"
- the cooling reason of removing the OEM air box to improve air flow from the radiator
- or the improvement in how easy it is to get to any items under the OEM air box.

(can cause warranty hassle, and can fail emissions depending on regulation requirements)
The header is one of the few areas where clear power gains can be had. Unfortunately, it's very hard to find isolated dyno charts of just the header gains. Pretty much every good header out there CAN make more power than stock. But it needs to be mated to the right combination of midpipe and catback. You need the entire system working together for the best gains. The header itself likely only has better power gains from OTHER power modifications. The OEM header is sufficient for OEM power levels, but can be quite terrible for higher power levels. Just replacing the header itself will give you a slight bump, but nothing really great. With more power comes more exhaust though, so at some point, the header DOES become a restriction and you can free up that restriction with most of the aftermarket headers out there. The exhaust theme will be "no restrictions" as you will see. We don't want or need 'backpressure'. As open as possible. "Long tube" headers are better than shorter ones, that attempt to mate up to the OEM compatible parts, but are relatively rare at the moment (that should change soon!)

Note: Using a header without a heat shield will dramatically increase underhood temperatures, and it is strongly recommended that you use a heat shield. We have enough heat problems already, don't add to it.

(can cause warranty hassle, and can fail emissions depending on regulation requirements)
If you take the admittedly illegal (for any country that has emissions regulations) step of removing the cat entirely, (which is also removing a dangerous failure point as well as giving you back some power) you have quite a few options.

There are a variety of other midpipes you can buy, including the RX7Store midpipe, Agency Power, Rotary Performance, BHR, Racing Beat, some rarer race developed midpipes, and a host of nameless ebay brands. What you need to know is that the OEM cat kills a TON of noise from the exhaust. Removing the cat introduces this noise back into the exhaust stream. Note that I said "noise", not "sound." An uncorked rotary is a beautiful thing to hear. From a distance. With ear plugs. Rotaries are inherently raspy at full throttle and partial throttle. The kind of raspy that makes your brain bleed as if it was being sandblasted. As one owner put it: "It's like attacking a tin shed with a chain saw, from inside the shed." Rotaries also have a much different pitch of exhaust note than piston engines. It's higher, more piercing. Rotaries are also much much louder. This is a side effect of how much energy (heat) we have getting dumped into our exhaust. The 787B 4 rotor being tested and measured for inclusion into Forza 4 was described as being "the loudest thing ever heard" by the sound guys. So loud that they had to use special equipment buffered and layered multiple times to try to dampen down the volume to prevent severe distortion. A 2-rotor isn't quite that loud, but it's certainly loud enough to cause physical pain. Perhaps you don't care, but the local cops, friends, family, and other enthusiasts will NOT share your opinion and cause you much trouble.

In order to combat the noise and tame it down, these midpipes use a variety of methods trying to accomplish the sound reduction. Only 3 midpipes out there use resonators that are easily accessible by consumers. These resonators are physical welded obstructions in the exhaust stream to chance, dampen, or muffle the sound. The rest use some sort of packing. Glass or steel wool are the two more common ones. Steel wool can melt/burn if you hold a match to it. Glass has a melting point between 1,400F and 1,600F We can produce upwards of 2,000F exhaust temps. See where this is going? Midpipes that use steel wool or glass as packing material to dampen the noise WILL fail. The packing will melt and blow out, leaving you with an unresonated, uncorked, and unrestricted straight pipe, full of rasp, drone, and pain. It doesn't matter how cheap it was, you wasted your money. An exception to this is Coast Fabrication. They produces work mostly for race teams, but their midpipes are accessible to the public as well, and their packing is a stainless steel mesh that does not melt or blow out.

The key point to remember here is to investigate the type of packing that is used. It has to be able to withstand our exhaust temperatures, otherwise it's a waste of money.

The three resonated midpipes are the BHR single resonated, the Agency Power dual resonated, and the Racing Beat dual resonated. Don't automatically assume that more resonators is better. Agency Power and Racing beat added the 2nd resonator because using only one resonator of a more conventional design was simply too loud. So they added a second one. Racing beat also has a bit of a hybrid, as they use packing as well. (Anyone know the material?). It helped enough to make it viable. But there is little R&D into the resonator as it relates to the rotary. As a result, they can still gets raspy, can increase how much a catback drones, and can play havok with the tone you wanted out of your catback. And it can still fail under our heat as our exhaust temps weaken the metal of the resonators, increasing rasp. It just takes longer than any packing. However, these pipes are often more cheaply obtained and so are still popular.

The BHR midpipe is the ONLY consumer midpipe out there specifically designed to work with a rotary engine. It's single resonator is not only capable of eliminating the drone, the rasp, and the excessive volume, it does it without power loss, it does it without structural weaknesses that can fail due to heat or rust, and it does not mess with the tone created by your selected catback. No other marketed consumer midpipe can meet all of these points. None. Some "race" products made by race teams may as well, but they won't be streetable. If you don't want BHR's full pipe, they will sell you the resonator itself for you to put in whatever pipe you want.

Removing the cat will probably cause a CEL. (P0420 Catalyst system efficiency below threshold ON 2 Catalyst) However, it might not cause it continually, or at all. Our ECU isn't always consistent in detecting when the cat is missing. If you get the CEL for no-cat, then there is only 1 way of clearing it permanently, and that is to block it in a custom ECU flash. The most common way is using an AccessPORT map, however any flashing tool or service should be able to accomplish it as well once the flash has been properly edited.

Alternate Catalytic Converter
(Probably voids emissions warranty )
The OEM cat is quite expensive, but if you must have a cat, there are a few other options. Most of the cheap cats out there will melt and blow out in short order. A Davesport cat installed in a BHR midpipe failed in 1 day of autocrossing, as an example. Largely how fast they fail depends on how much heat and fuel you are pushing through them. Your tune will certainly impact this. One of the only long-term cheap cats that hasn't seemed to fail yet is on HiFlight's car, a metallic-substrate Magnaflow #59959. It has survived daily driving and auto-cross, but has not yet been tested on the track. Other metallic substrate cats might fair a bit better than most as well. You are largely on your own when trying cats though, so I recommend researching properties and limitations, and not just picking at random. A cat option that is expensive, but not OEM, is HJS. They have a cat that can survive our exhaust temps about equally as the OEM cat, but the price is comparable.

(No impact on warranty)
Catbacks are largely personal preference on tone and note. Do your research, listen to sound clips. Some will drone badly under cruise, but you might be willing to deal with it. If you increase the size of the tips to 2.5" or higher, expect to have trouble with melting your exhaust shrouds. The only real power difference from one to the next is single tip vs dual. The single tip catbacks tend to slightly edge out the dual tip catbacks on the dyno, usually because the single tip catbacks streamline the exhaust flow a bit better, creating a bit less pressure buildup.

ECU Tune
(will void the warranty if found)
There is no known ECU tuning method for Series 2 (2009 - 2012) RX-8s. The ECU changed in critical ways and no company has yet been willing to spend the time to hack the ECU to determine how to flash it. These ECU points all relate only to the Series 1 RX-8 (2004 - 2008)

ECU tuning is often recommended, as it can improve a wide range of dynamics about our car, including throttle response, overall power, ECU triggered safety items such as OMP injection rate and fan trigger temp, etc... Power gains are limited to about 10hp maximum, though your gains are largely dependent on how bad the OEM tune is for your particular combination of engine and sensors.

Other debatable items such as increasing the rev limit are possible, though should be thoroughly understood before pursuing.

As for HOW to modify the ECU, there isn't much for options. There are some aftermarket full ECU replacements out there, but they are expensive and quite a bit of work. ECU tuning has some options, with the best option being through the COBB AccessPORT. A few companies put the effort into hacking the Series 1 ECU and were successful, though only COBB actively marketed a product for it full scale. They did not hack the Series 2 ECU however, and Mazda changed it enough that a full hack was needed. Too few cars were sold, too small of a possible customer base, for COBB to see the pay off in doing the work. The AccessPORT was also discontinued for all naturally aspirated cars (not factory T/C or S/C) in 2010(?). Mazdamaniac was able to negociate a deal with them where he would become the sole dealer for the RX-8's AccessPORT, COBB just needed to supply the hardware and he handled everything else. Unfortunately, even this route has come under trouble, as Mazdamaniac was banned from in March of 2012 due to vendor related complaints. Whether or not he will leave the community entirely and shut down his sales/tuning of the RX-8 is still unknown. The tuning through the AccessPORT does not require his tuning services however, as there are other tuners that are successful at producing viable tunes for our car, and the AccessPORT is just a tool. The only exclusivity he had was his remote tuning service (no one else decided to offer it), and after the discontinue, the dealer sales of the AccessPORT itself. Be very wary of tuners that claim to be able to tune "because they can tune piston engines" or "because they can tune RX-7s". There are differences between older MAP based and MAF based tuning, as well as dramatic differences between piston and rotary engine tunes. Make sure that they know MAF based tuning AND rotary tuning.

The Racing Beat reflash is also a viable option, and follows a similar concept as the AcccessPORT, only you send your ECU to them, no hardware to purchase (but you don't get the benefit of the extra hardware either).

Piggyback ECUs are problematic and unreliable, but possible as alternatives.

Every single "ECU chip" is a complete scam for our car. At best it's the same as taping a couple $100 dollar bills to your ECU, at worst it can fry your $1,800 ECU. Our ECU is too smart to be fooled into doing anything more than a few miles, and the OEM tune is already close enough to perfect that the ham-fisted approach of trying to fool it in a narrow set of circumstances while crippling it in the rest is a recipe for engine destruction.


COBB AccessPORT, or any other kind of flashing device for tuning
(will void the warranty if found)
This is more of a sub-topic of the ECU tune, but it seems that it needs it's own section, as it really isn't clearly spelled out anywhere.

The COBB AccessPORT is a tool, much like a wrench. To us, you are asking: "Can I remove my engine with this wrench?" Well, kinda. It's part of what is involved. You won't be able to make any progress without it, but even if you have that wrench, if all you do is hit yourself in the face with it, you won't get anywhere toward your goal. It has to be used appropriately, and it is simply one of many pieces that you will need to get there.

In more practical terms, the AP is nothing more than a communication device, a phone if you will. It can communicate with the OEM ECU. What it tells the ECU is entirely dependant on what information you are pushing through. If all you are pushing through is requests to clear codes, then that is all it's going to do. In order to increase the rev limit, you need to have the AP "flash" a map to the ECU.

But you have to get this map first.

Well, what is a map? A map is basically a digital copy of the ECU's parameters and tables that it uses to manage the car. Much like if you right click on a picture on the web and click "save-as" and save it to your computer. Just like that. You can upload that picture to the web if you want, and everything is exactly like it was.

But, you want a change. Lets say that the picture was of a girl with a big mole on her face. You wanted to touch that up and remove it. Well, you will use some other software to make those edits. Then you have to upload the new picture to replace the original. That's all the AP is doing when you flash a map. It's uploading the digital copy of the ECU's data files.

What tuners do, is they make edits to the data files to adjust fueling, timing, CEL blocks, rev limit changes, etc... as needed. Then they load them into the AP via USB and use the AP via ODB2 to load the flash to the ECU, applying the changes.

So you can get the AP to help you toward your goal, but you will also either need the software to make the edits AND the knowledge of what you are doing (because it's not a simple process of point and click), or you will also need the services of someone that does have the software and does know what they are doing. If you pick the 2nd option you will also need to pay them a fee of some sort, and probably work within their scheduling.

Lightweight Flywheel
(no impact to warranty)
This doesn't "Add power", but rather "changes the intertia dynamics of the drivetrain." Two cars that are otherwise identical will dyno the same numbers (on the same dyno at the same time) with a difference in flywheel weight. However, the engine will spin up, and down, faster in the car with the lighter flywheel, which translates to a more responsive engine and (potentially) quicker acceleration. Quicker acceleration means "more power" to most people, but this is an exception to that. The engine isn't making any more power, it's just having a bit less difficulty in reaching redline, so it gets there faster on the same amount of power.

Just having "a lightweight flywheel" isn't going to mean much though. Not all 11lb flywheels are the same in their overall effect. The lightweight 11lb flywheel with the weight removed from the outter edge of the flywheel will spin up and down faster than the lightweight 11lb flywheel with the weight removed from the center of the flywheel. Most companies know this, and go as far toward the outside edge as possible, but they all succeed in different ways that are bound to create differences between the flywheels, even if they have the same end weight.

The normal drawbacks are the expected drawbacks of when higher inertia is beneficial, such as how quickly the car tries to slow down when moving to an uphill, or starting from a stop. These are usually non-issues to most people, though if your manual transmission skill is lacking, you may want to consider postponing the change until your skill improves, as you will be more prone to stalling when coming to a stop or starting from a stop.

More technical reading here: http://www.stephenmason.c...nalinertia.html

(can cause warranty hassle, and justly void warranty if the issue is electronics related)
Don't. You might ask "why?", so here is an explanation:

There are 2 "benefit" points to changing to aftermarket pulleys.
The 1st "benefit" is a reduction in the weight of the pulley. This is a similar concept to going with a lightweight flywheel to assist with a more responsive engine. The problem is, the weight you are saving is very very very small, and it's close to the center of rotation, so there is very little gain by reducing it. It takes roughly 10lbs of weight saved at inch from the center of rotation to equal the interia savings of 1lb of weight saved at 10 inches from the center of rotation. Lightweight flywheels are still rather large in diameter (almost larger than the core engine block), and much of the weight stripped is near the outside of the flywheel. Pulleys have only a few inches and at most maybe a pound, and most of the weight to remove is near the center.
The 2nd "benefit" is to underdrive one or more accessories. The problem with this is that under driving your alternator is bad for your electronics and battery, and underdriving your water pump can have significant penalties to your ability to keep the engine cool. And all it takes is 1 overheating, or even undetected localized hot spotting, and your housings can warp and your engine is done. Underdriving your A/C is without penalty, but removing the AC system completely would accomplish the same AC effectiveness as underdriving it, and leave your car lighter and without the AC compressor drag at all, so it's the better choice (and cheaper).

Even the large main pulley should be left alone, as it needs to act like a stabilizing influence on the e-shaft, like the flywheel does to the other end. You can lighten the flywheel without adverse affect on the e-shaft, because it is still the heavier end. A greater difference between the two ends increases instability and flex. Adding weight with a pulley that is also a proper harmonic damper is common for high power piston engines, though a rotary is compact enough with lower lateral stresses (lateral in relation to the e-shaft rotational axis), that this hasn't been seen as necessary.

Auto: Mazda Rx-8
kW / HP: 231
Pomógł: 5 razy
Wiek: 28
Dołączył: 07 Gru 2012
Skąd: GOP
Wysłany: Czw 28 Mar, 2013 18:43   


(will void engine and drivetrain warranties, and likely bumper to bumper as well)
Nitrous is a cheap way of getting bursts of power, though if you pursue nitrous as a power adder, make sure you do your homework on the considerations. It's still easily possible to destroy your engine with it and it has continuing costs over time.

(will void engine and drivetrain warranties, and likely bumper to bumper as well)
There is really only 1 supercharging option, and that is the Pettit supercharger. The kit is relatively well put together, but has a high initial cost ($7k+) and still requires some changes for smooth and reliable operation. Used kits are exceedingly rare. You should have a spare engine on hand, or at least the cash for another engine or an engine rebuild, if you are considering any FI option. You are directly reducing the lifespan of your engine, perhaps to only a few miles.

There is only 1 'acceptable' reason for the belief of "superchargers are easier on the engine" vs a correctly tuned and set up turbocharger, and that is the nature of the turbo manifold and how it extracts energy from the exhaust stream means that there is more localized heat buildup on the exhaust ports, meaning side seal failure is accelerated faster compared to an equal power supercharger. Power = heat, so it's still relative. More power from a supercharger can mean shorter side seal life than a lower power turbocharger. Exact setup can make this statement move around quite a bit.

(will void engine and drivetrain warranties, and likely bumper to bumper as well)
There are no complete "kits" for turbocharging. Some kits get closer than others, but all require modifications. The most popular is variations on the GReddy kit using a 3071R turbine. These kits are for sale regularly and often cheaply. Even if the kit is cheap, you should expect to have a cash pool on hand of $10,000 before you start buying parts, and if you can get a 2nd engine as well, it's recommended, since you will probably be using it.

Engine Rebuild
(will void engine warranty)
Proper engine rebuilds can be a source of significant power gains. Not as dramatic as you can achieve with a piston engine rebuild, but there are certainly benefits that can be realized. This can get quite expensive, to the tune of $5,000 or more (a "basic" engine rebuild would be more like $2,500 to $4,000). Most of the advantages over a factory engine or a Mazda reman are simply in the quality of the build. The basic points are:
- Seal clearance / tolerances
The Mazda remans, and to a lesser degree the factory engines, have quite a bit of improvement available in the seal clearances. Too great of a clearance and it allows combustion blow-by that greatly reduces compression and greatly accelerates seal, housing, and/or side plate wear. Properly clearanced seals is critical to making good power AND having longer engine life.

- Intake porting
The OEM intake ports are good, but there are areas of improvement, and the rebuilders are learning more on a regular basis

- Exhaust porting
There isn't as much available to do here as you might expect, due to the need to keep the exhaust ports from breaking into the oil or coolant passages or having to remove studs. It's possible to use RX-7 housings or peripheral port the Renesis housings, which would open up a new world of possibilities for your engines. This is not something that a street driven RX-8 with a factory ECU can really deal with however, so it's development is largely relegated to race teams. Although race regs usually keep many teams from pursuing this. Bridgeporting has only been done successfully a few times, and the long term penalties are still largely unknown.

- Taller Apex seals
You will find much debate around this. Some people swear by the benefits, others point out the trouble to get them to fit and how the apex seals aren't really our problem. There is no direct power gain to be had from taller seals, but the theory behind the practice is that it will allow you more safety zone when pushing for more power. Do not blindly jump into this if you are getting your engine rebuild. Do your research and homework first (as always)

- FD side seal springs
This has been suggested as a "solution" for the side seal spring overheating problem seen by track and race cars. The incidental information is that this will improve this point of failure, though it's a bit shy of being "hard proven fact".

- E-shaft and rotor balancing
Balancing is another point of debate and contention. All rebuilders seem to agree that picking rotors that are approximately the same weight is important, however they differ on the recommendations of how far to go to balance the assembly. There is also known fact that at least SOME factory and reman engines are out of balance enough that the rotor tips can contact the housing as low was 8,500rpm (below our rev limit), however it's also fairly clear that not all factory and reman engines have this problem. There is largely a void of information on the balance requirements for a given RPM to be safe, and usually discussion about balancing so as to allow a higher RPM is met with scorn and ridicule about why you would want to be going higher anyway, rather than actually discussing the balance requirements. A better balanced assembly should be easier on the e-shaft and certainly smoother/freer reving as well as a benefit to engine lifespan. Many rebuilders find the basic balance "sufficient" while others disagree and go much farther.

"Adding" a rotor to make it a 3-rotor:
(will void all warranties)

4port engine to 6port engine swap (covers AT to MT as well):
(will void all warranties)

RX-7 13b-REW / FD swap:
(will void all warranties)
This is probably the most common engine swap there is, and it's still not very common. This swap has the advantage of having an engine that is pretty close to ours physically, and can be adapted to work with the RX-8's ECU, which means that much of the fabrication and wiring headache is a non-issue. It's still a long process and not cheap, as the engine is "pretty close", which means still not exact. The Renesis sits lower and farther back than the REW, and even a few inches can mean a surprising number of additional issues. Cooling is already a problem for the RX-8, so you need a completely new cooling system designed to take the REW's higher power (everyone that swaps pumps up the power). Expect that it will cost a minimum of $12,000 from a shop that is competent with both the RX-8 and the FD RX-7, and expect that it will still take 3-6 months to complete. Costs will likely climb higher however, with $15,000 to $18,000 more typical.

20b / 3-rotor swap:
(will void all warranties)
Similar to the REW swap above, although more-so in most dimensions. It can not run on the OEM ECU, so all the wiring must be completely re-done. The engine bay has to have significant fabrication changes to accommodate the engine in the correct location, and the parts themselves are rare, which means sourcing stuff (like the manifolds) can be a long and expensive process. Expect a minimum of $20,000 to start from a competent shop. If you go NA instead of Turbo, you can usually knock some money off that.

LS Swap:
(will void all warranties)
Often talked about, very very very rarely completed. The financial cost of failure is about as high as the financial cost of succeeding, and has been easily north of $30,000. There is nothing existing today that will make an LS swap easier. Every single last bit is custom. Even cars like the Miata where there are shops that do the swaps regularly STILL have a turn-key price of $30,000. For an RX-8 you can expect a healthy amount higher. As to who does them, the short, and nice, answer is that ZERO shops that can do this kind of swap advertise for it. None. Period. End of story.

Someone once asked what parts he needs to buy for an LS swap...
- engine
- stronger and compatible transmission
- stronger rear end
- stronger rear axles
- custom created driveshaft to the measurements in your car
- ECU to run the engine
- Several thousand feet of wiring
- An entirely new front subframe
- gauge cluster that works with the ECU
- a steering rack that you can get to work (stock one won't be able to fit there any more)
- entirely custom created cooling system for the coolant
- entirely custom created cooling system for the oil
- Completely custom exhaust built on your car after the engine is installed
- lots and lots of fabrication work by SKILLED fabricators to modify every single structural part of the engine bay
- lots of labor by someone that knows what they are doing with electrical work to re-wire every part of the car into the new ECU
- If you want AC, your AC will have to be completely custom

Literally nothing in the engine bay that is there in a stock RX-8 can stay where it is with such a swap. Including things like re-locating the brake master cylinder, which means re-running hardlines for the brakes.

Set aside about $25,000 to start, and expect to need another $10,000 to $20,000 more. Expect to not have your car for a minimum of a year. Expect that the best price you can get won't be able to finish within a year and will have stuff wrong and jacked up. Expect that the 2nd best price isn't any better. Expect that the highest price you are quoted is probably from the only shop that can actually complete it, and for more than they quoted you.

Expect that once the engine is swapped, you will need to replace the suspension, wheels, and brakes to deal with the difference in the weight balance and dramatically different torque dynamics.

26b / 4-rotor swap:
(will void all warranties)
Take everything from the LS swap above and triple it. This is because there was never a production 26b rotary, so every 26b is completely custom created. There have been several 26b RX-8s built, and the usual price tag is over the $100,000 mark. No, that isn't a typo, no, I'm not joking. Completely serious.

(No impact to warranty)
Shocks are a critical component of the suspension feel. It's the shocks that provide the limiting factors to the spring's velocity (not it's position). Just randomly throwing shocks on the car is more likely to hurt your performance than it is to benefit it. Really understanding shocks takes much more than a short blurb here, but understanding them can reap significant benefits. If you change your springs for any reason, make sure that your shocks will have the appropriate damping for the spring rate you will be running! Stiff springs with shocks meant for soft springs aren't going to be able to control the springs, which is what you commonly see with many "lowering springs" where the car seems to bounce and quiver along at every sliver of pavement change. The reverse, soft springs with shocks meant for stiff springs, means that you are placing too much load on your shocks, and it's going to wear out the shock internals really fast, as well as hurting the ability of the springs to manage the load changes of the car.

The primary contributing factor to the quality of shocks is the valving. It's what makes a shock absorber what it is! Low quality shocks typically have poor valving, which you have no real way of solving. Some poor quality shocks won't hold their valving rates, or the adjustments on them are not consistent, or when you buy a pair or a set of 4, you end up with shocks that are valved differently. This can easily cause more handling problems than you are attempting to solve. It takes a shock dyno to match shocks properly, so if a shock dyno doesn't exist, it will be sheer luck if you actually have matched sets. An easy rule of thumb is that if the vendor or manufacturer isn't able to give you shock dynos, they are probably not actually equal. Don't just blindly accept any dyno though. (High vs low speed refers to the speed of the shock itself compressing and decompressing, NOT the vehicle speed) The low-speed damping of the shocks determines the car's balance during transitions (i.e. turn-in), where high-speed shock damping controls ride quality and keeps the tire in contact with the road over bumps. If you are looking to upgrade for better performance handling, low speed motion is the critical part. If you are looking for pure ride comfort, high speed is your focus.

(Can cause warranty issues with bumper to bumper if lowered excessively or on too-stiff springs)
Springs are often misused and heavily abused by people looking to move away from an OEM suspension. A common preference is to just "drop it" or "slam it", and is usually done by just grabbing cheap "lowering springs" that lower the ride height with little concern or attention to the impact that the springs have on the shocks and ride performance. There have even been cases where unfortunately minded individuals have cut their springs, which is all sorts of wrong.

Springs are critical to controlling the motion of the car's weight, directly contributing to body roll, squat, and dive characteristics, and for a given corner, the ability of the suspension to absorb surface changes. The springs work directly with the shock valving rates, and the spring rates should be selected that directly complement the shock rates (remember, shocks then springs).

Also, before you randomly lower the car, know that the suspension geometry was designed for the OEM ride height. Yes, there are benefits to lower, but there are also penalties. What you goals are will depend on how low is too low, and how high is too high.

(No impact to warranty)
Coilovers are basically a specific shock and spring combination that is designed to work together as one unit. They typically have the advantage of being able to adjust ride height for each corner. The is often used as an excuse to "lower in the summer and raise in the winter", but you should be aware that this rarely happens. Changing the ride height on a set of coilovers is not a small task, once you have everything set at a different ride height. Most owners will set it and never touch it again. The intended use for this ride height adjustability is so you can set the ride height to exactly where you want. People looking for an actual improvement in handling take this a step further and use the ride height adjustment to corner balance their car, which can lead to significant gains over just blindly setting the height. All coilovers are not created equal however, and usually the differences in performance and quality lies in the shock valving. The same quality rules apply to coilover shocks as do non-coilover shocks.

Adjustability is not a solve-all however, as a complete stock non-adjustable RX-8 will beat the most adjustable Ford Pinto silly if the owner of the Pinto doesn't know what they are doing. And most owners REALLY DON'T know what they are doing when it comes to suspension.

Sway Bars and End Links
(No impact to warranty)
Sway bars are what helps to control the difference in suspension action from side to side. If both front corners are reacting the same (acceleration or braking in a straight line, a bump or dip that hits them equally) then the sway bar has no impact. It's when one corner is compressing or extending greater distances or more quickly than the other that a sway bar impacts the handling. Cornering (when the weight compresses the outside corners and uncompresses the inside corners), bumps or dips that only hit one side (like track curbing) are the key points here. The sway bar then acts to try to keep the corners as similar as possible. Put another way, a stiffer sway bar allows you to run a softer spring to account for bumps and desired weight transfer on braking and acceleration, without losing stiffness on cornering.

In general, a thicker sway bar with shorter arms will act against the difference more greatly than a thinner bar with longer arms. The length of the sway bar arms is largely fixed for a given vehicle, though sway bars like Progress are adjustable vs end-link mounting holes, so you can effectively shorten the arm length by using holes closer to the bar. Tubular bars have a slightly stiffer torsional rigidity than a solid bar of the same thickness. However, due to the weight saves, it will be rare that you will find both types of the same thickness for the same car. Vendors will make the tubular bar larger because the weight reduction allows them to manage it easier. And thickness is by far the bigger king in sway bar stiffness. An increase from 1" diameter to 1.25" diameter is about a 60% increase in stiffness. 1" to 1.5" is an increase of nearly 3 times stiffness.

Don't automatically assume that stiffer is better however, as too stiff of a sway bar can lead to unpleasant vehicle behavior, such as lifting the inside front wheel on accelerating out of a corner (making you horrifically understeer) or lifting the inside rear wheel on braking into the corner (leading to snap oversteer) or on acceleration (more oversteer plus making the LSD work overtime trying to put the power down). Many raced RX-8s end up removing the rear sway bar completely... assuming they have their shocks, spring rates, and front sway bar all working together to make the rear sway bar unwanted. The key critical point is that the sway bars much be selected along with the springs and shocks to work together. The sways and the springs are what work together to control body roll, and the shocks work to control the rate of change of the springs (and thus the sways as well). Adjusting front and rear roll-stiffness will determine the car's steady-state balance (understeer / oversteer / neutral). Which swaybar is appropriate for your application will depend on spring rates, ride height, static camber, suspension geometery, grip level, aerodynamics, and desired handling traits.

The end links used to attach the sway bar to the lower control arms is largely a matter of preference. Breaking an endlink is certainly possible, however there are no real brands more or less prone to braking than any other. Many people go for adjustable end links. Ideally you want them to be relaxed with the car sitting on level ground (relaxed but still secured on each end, shouldn't be under tension). Adjustable length end links can assist with making this happen. Don't "pre-load" your sway bar with your adjustable end links, as this can lead to unpredictable behavior. If you can do the last tightening of the end link bolts with the car sitting on the ground and the suspension settled from rocking it forward and back a bit, it is certainly best.

Suspension Bushings
(No impact to warranty)
Suspension bushings are something that many people overlook or ignore. The bushings are there specifically to reduce vibration from the road that travels through the A-arms. This means that the bushings are inherently flexible, and can degrade over time. This also means that you can change the compound of the bushings for more or less flex. Less flex will generally improve your feel of the road, which is a good thing for feeling what the car is doing on the track, not so good for feeling the less-than-stellar paving job that Mr. Joe Contractor did to pocket a share of the funding. So it will depend on what you want, and what you are willing to sacrifice.

Some of the compounds possible:
- Solid metal: Several different materials are viable, though aluminum are probably the most common here.
- Delrin: A newer material that has been quite successful for race cars, and technically is "softer" than solid metal bushings, but kind of how asphalt is softer than concrete. It is self lubricating, doesn't deform or degrade as easily as polyurethane, but it is still quite hard, so you won't be improving the harshness much over solid metal.
- Polyurethane: This is the most widely used compound that people upgrade to, as it still reduces much of the harshness while also providing a noticeably firmer joint. It can degrade over time more than most other materials however, and proper regular care will help dramatically.
- Rubber: This is the most common compound for OEM use. It's cheap-ish (though going up with the price of oil) and flexible, but binds easily and introduces more slop in the suspension then anything else.

The lubrication you use on your bushings is critical as well, as the lubrication is what keeps the bushings from binding, and binding is what makes them split and break. There are many options, from lithium grease to copper grease etc... Ideally, you want to pick something that will continue greasing for a VERY long time, and should be a 'dry' grease so it doesn't pick up dirt. Dirt + wet grease = grinding compound.
Suspension Modifications

(No impact to warranty)
An alignment is the cheapest handling performance mod you can do. At ~$80 for a 4 wheel alignment at most shops in the US, you can make dramatic changes to your car's handling away from the OEM alignment specs.

Getting an alignment done:
- Ideally, you want your alignment done with YOU sitting in the driver's seat. Barring this, weigh yourself (correctly) and assemble bags of kitty litter, dog food, or whatever else you can stack and pile in the driver's seat to simulate your weight. A 180lb guy is just over a 5% weight addition to an RX-8, and you aren't sitting on the center of gravity. YES, this can indeed change the suspension geometry!
- If you can manage it, have your fuel tank at half full (or half empty if you are pessimistic!). The weight of fuel is smaller than the driver, but it does change the balance of the car slightly. Having the fuel tank at half will keep the far ends of this balance as close as possible to the intended settings.
- Get the alignment done with the sway bars disconnected. Doesn't have to be both sides, and leaving 1 side connected will keep the arms from just hanging, but this prevents the sway bars from introducing false measurements. If you drive to your local shop down the road, just disconnect the end links on one side. You will pick up more body roll than you are used to, but otherwise there is no harm in it as long as you keep the lateral G down. Reconnect at home. Or, if the shop doesn't object, they can disconnect an end link while it's on the rack, reconnecting after. Which is the easier method. due to access.

The 3 dimensions are:
This is the "lean" of the wheel. 0 camber is when the wheel is standing verticle. Negative camber means the top is leaning in toward the center of the car, positive camber means the top is leaning out away from the center of the car. When the weight of the car shifts under cornering, it will make the inside wheel lean further inward, and the outside wheels lean further outward. This directly changes the amount of rubber of the tire's contact patch. So if you add negative camber, this means that the outside tire (which has more of the vehicle weight) starts standing up straighter, increasing the contact patch. The greater your negative camber, the greater the cornering force is needed to make the outside wheel stand up straight. For a vehicle perfectly balanced with front to rear weight, generally the end that has more negative camber will grip more during turns. The OEM alignment specs have no camber in the front, and about 1.5 degrees of negative camber in the rear. This makes the rear grip more under morerate cornering than the front, and the front starts gripping less. This induces understeer, which is a common thing for manufacturers to do to assist the average driver. If you track or race your car with OEM suspension, you will likely add as much negative front camber as possible, and more negative rear camber than OEM, but not max. However, your suspension setup and tire grip will change this. A stiffer suspension means that the car will roll less, so you need less camber to get the tire to stand up straight. The greater your tire gripping compound, the more the car will roll, so you need more camber to achieve the goal of getting the tire vertical.
Note: Adjusting camber so far negative so that your tire isn't contacting the road across it's full width while driving straight is making your car handle WORSE under all circumstances.

This is the direction of roll of the wheel. It doesn't take much toe to have a dramatic impact on the car's stability. Toe In means that the front of the wheel is pointed further toward the center line of the car. Toe In on the rear promotes straight line stability, and will slow the car's reaction to corner entry and slightly promote understeer through the corner. Toe Out in the rear will make the car more unstable in the straights, and make the rear really happy to help you change direction.
Toe In on the front promotes straight line stability, though less than the rear. It will also slow the car's reaction to corner entry, however once the weight has shifted to the outside tire, it will help promote the rotation of the car through the rest of the corner. Toe Out on the front will make the car more unstable in a straight line, though less than the rear. It will increase the twitchiness of turn-in, but will help induce understeer through the rest of the corner.
The amount of impact on the handling is directly related to vehicle speed. The higher the speed, the more pronounced the effects.
OEM specs are zero toe in the front, faint toe in on the rear.
Note: Any toe in or out away from zero will directly reduce tire life. The more toe, the more tire wear you will see

This is only for the front wheels, caster is the angle of the vertical axis that the wheel pivots around when turning. A zero caster means that the wheel's center axis when the steering is turned is completely vertical, and the toe/camber does not change at all because of the steering. Adding caster means that the greater the steering wheel turn angle, the more of a change will be introduced into the camber and toe. Since the wheels are moving to point in different directions compared to the camber/toe adjustment points (left wheel has them to the right, right wheel has them to the left) the change of camber and toe is different for each side.
Most cars run about 6 degrees of caster, as this helps to add appropriate amounts of camber to each front wheel to assist with the appropriate contact patch for that wheel, as well as pronounce the toe change more.

(No impact to warranty)
The OEM brakes are actually very very good. You will need different pads for track use, but otherwise the OEM stuff is some of the best street quality you can find. Most upgrades are done for appearances, or because the car is going to get tracked more. The "best" upgrades are usually to 2-piece rotors, or big brake kits with superior calipers. Lower upgrades are usually just pads, maybe rotors. If you upgrade the rotors, avoid cross drilled if you are going to track the car. Cross drilling, no matter how well done, will make the brake rotors more prone to cracking. The grooved method of slotting is far less compromising on the rotor's integrity. Slots and drills are mainly used to promote cooling of the rotor and cleaning of the pads when contaminates such as water or dust are present.

The most important thing you can do for your brakes however, is to bed the brakes in on first use. There are many subscribed methods, so do some searching for one that appeals to you, or that you can do in your local area without getting arrested (many cops would take exception to the acceleration->hard braking cycle repeated over and over)

Regular brake fluid flushes can also keep your braking solid, since brake fluid is silicone based, and silicone is an excellent water absorber. Water contains oxygen however, which is released as it is boiled, and you can easily top 212F on stock brakes on the street. And oxygen is compressible, meaning your brake pedal moves a portion without the pads getting that pressure. The more water contamination you have, the lower the boiling point and the worse your braking will match your pedal.

(No impact to warranty)
Wheels are more subjective in nature than most upgrades, as they tend to be selected more for appearance than for performance. However, there are three factors for performance to keep in mind:
- Wheel weight: More important than other metrics, a heavy chrome wheel will directly reduce your acceleration, lengthen your braking, and make your shocks and springs work harder. A lightweight wheel improves all of these dramatically. The Enkei RPF1 is the commonly selected wheel, being both light and fairly cheap.
- Wheel width: Increasing the width of the wheel allows you to run a wider tire without stretching (which can be dangerous with high lateral Gs). However, wider is only better to a point. Going wider means going heavier, and you can start losing steering feel as you go wider as well.245-255 is typically considered to be the sweet spot with increased grip before the steering feel starts to fade.
- Wheel diameter: Assuming that you size your tires to have the same overall diamter, a smaller diameter wheel will mean an increase in tire sidewall, which means an increase in sidewall flex. This isn't immediately terrible, as flex can be very important in the correct amounts. This can also help to absorb road/track imperfections as a 'second spring'. Smaller diameter wheels are lighter, and tires are usually significantly cheaper. Going larger reverses all of this.

(No impact to warranty)
Tires can be the single biggest contributing factor to handling ability that you can make. Within the Summer Tire category, you can largely base the general life and grip on the treadwear rating. A lower rating means more grip, lower life. Generally. Some tires, such as the R888s, have significantly more rubber contacting the road in the contact patch than other more road friendly summer tires, so even if they might have close treadwear ratings, the grip levels will be different.
The other factors typically don't come into play with dry grip unless you are tracking your car, stuff like heat cycling.

Caution: A common mistake made is to buy tires for the best conditions you will see, rather than the worst. If you daily drive your RX-8, don't go for high dry grip tires and sacrifice rain grip and have to dangerously limp around in the rain. If you can swap off to a different car or avoid such weather completely, this advice goes out the window. All too often however, a rain storm through the sunny south will catch an owner off-guard that has had summer tires on for a while, ignoring their fading rain grip because it doesn't feel any worse in the dry. Rears loose traction suddenly and into the guardrail they go. If we see a thread of a wrecked 8, and the ground looks wet in the pictures, the story is inevitably "suddenly snapped loose and couldn't react in time". And a closer look at the pictures shows nearly bald rear tires. Don't lose your 8 because you ignored the more dangerous conditions you will see.
Cooling Modifications

Water Pump (series 1 only)
(can cause warranty hassle)
There is only 1 aftermarket water pump "upgrade" available, the ReMedy Water Pump from Mazmart. It's designed to flow significantly smoother than the OEM pump, and eliminate cavitation at high RPMs. High coolant flow rates are important to help equalize the temperature of our engine block. Better flow means more stabilized temperatures.

(can cause warranty hassle)
Similar to the water pump, the only aftermarket upgrade available is the ReMedy thermostat from Mazmart, which has a cooler opening temperature than the OEM thermostat. The benefit of a lower temp thermostat is that it will start flowing water to the radiator sooner. The OEM thermostat starts opening at 180F and should be fully open by 205 or so. The Mazmart thermostat starts opening at 170F and is fully open by 190F. You can test any thermostat easily by using a pot of boiling water and a laser/IR thermometer. If your water temp is having trouble getting down to the opening temp, you could have a slow or sticking thermostat, or your radiator can't shed the heat fast enough.

(no impact to warranty)
The stock radiator is sufficient for most cooler climates and normal street driving, but can get overtaxed in track driving and street driving in hotter climates. This is less of a problem with the radiator itself, and more of a problem of air flow though, so before you upgrade your stock radiator, make sure that the air is getting fed to it correctly, and can escape from it completely as well. The common problem points are:
- The splash pan sags as speeds increase, even normal legal speeds, allowing air flow under the radiator, which decreases it's effectiveness.
- The foam around the radiator sides is there to help keep air flow from escaping around the sides of the radiator, and can degrade or fall out over time
- The fans on the back of the radiator are prone to getting blocked or jammed from debris, usually the rubber grommets from the air box but sometimes other items.
- The stock air box and battery box create lots of blocking, restricting the escaping air flow. Changing to an aftermarket intake and removing the air box is the easiest solution to this, though keep in mind the intake modification factors above.

You will know when you need a radiator upgrade when your water temp is staying more than a few degrees over the thermostat opening temp. It means that water is moving through the radiator, but the radiator isn't shedding heat fast enough to keep up with water temps.

Coolant Passages
(no engine rebuilt by someone else is going to be warrantied by Mazda anyway, so no warranty considerations here)
If you are having the engine rebuilt, many engine builders offer to re-work the coolant passages for better heat transfer and more flow. There are no real tests measuring the effectiveness of this, but the theory is sound.

Splash Pan
(no impact to warranty)
The OEM splash pan can start sagging under the high air pressure in front of the radiator, and can push it down, allowing air to bypassing the radiator underneath. This problem is increased as speeds go up, as well as the AC condenser or radiator vanes get slowly flattened by road pebbles and bugs. There are a few solutions for this, including metal splash pans, and brackets that anchor it to the bottom of the radiator.

Fan Trigger Temp (series 1 only)
(if changed through the ECU, it means a different flash, which will void the engine warranty if found. If it is changed through hardware/wiring, it could create warranty hassle)
The OEM fan trigger temp is set too high, and can let your engine run hotter than ideal when idling or low speed driving. There are several methods to reducing the fan trigger temp, and is always recommended. There is no drawback, and plenty of benefit.

Some of the methods:
- An ECU reflash that lowers the stored ECU trigger temp (common with AccessPORT flashes)
- A simple controller
- A more complex but good variable controller
Oiling Modifications

Single Oil Cooler
(can create warranty hassle)
This isn't a common modification at all, but can produce benefits with higher oil pressure from the reduced oil system complication. The main drawback is that it can be difficult to find a good point to mount the cooler, though there have been successes with a horizontal splash pan mounted one and a low one in front of the radiator.

Oil Pressure increase (series 1 only)
(can void warranty if found, though it is unlikely)
This is growing in popularity, especially as our engines are dropping out of warranty. It is basically a set of shims that changes the spring strength in the oil pump's bypass, and increases the oil pressure to approximately the same oil pressure as the RX-7s and the Series 2 RX-8s have. This may also be accomplished with a complete replacement moving to the FD RX-7 unit. While there are no real direct know or documented benefits, and there have been significant debates over pressure vs flow, it is oil pressures that Mazda used to have, and returned to for 2009+ RX-8s.

OEM oil cooler vents
(no impact to warranty)
Similar to helping the radiator breath, the OEM oil coolers can be helped by opening up the wheel well liner behind the oil coolers, allowing better air flow. The only drawback is in how you modify the liners. Open them up too much, and you could end up having your front wheels throwing road debris into the back of the oil cooler, which isn't helping you at all. Care should be taken in the modifications to make sure you are still shielding the cooler from the debris being thrown by the wheels.

(no impact to warranty)
Premix is mixing 2-stroke oil with the gas in the gas tank to assist with lubrication of the apex seals. Why 2-stroke? Because 2-stroke (in general) is designed to be burned. Unlike 4-stroke that you use in during oil changes. Why premix? This gets a bit more vague when answering. The short answer is as noted, to assist with apex seal lubrication. But do we need it? That's a tougher question to answer with facts. Some people swear by it, others do just fine without it. Series 1 has 2 injectors pointing at the side seals, Series 2 adds a center injector to help with lubricating the center of the apex seal. Mazda added this, so they must have found excessive wear in the center of the apex seal, so it's circumstantial evidence for the need to premix. It's hard to say if this will save your engine from apex seal wear failure though. About the only confirmed difference premixing really makes is that the carbon buildup inside the engine appears to be "softer". In theory, makes it easier to clean, and if it comes off it won't come off in dangerous flakes that could cause carbon lock.

"Typhoon" intake insert
(No impact to warranty)
This is completely a scam. Yes, in theory it is possible that a smoothing and 'spinning' of the intake air flow can feed more air to the engine than a stock intake, any improvement requires that the stock intake be designed incredibly inefficiently, AND the placement of the Typhoon is such that there are NO bends, kinks, splits, etc... between the Typhoon and the point that the air is actually getting into the engine. In today's world of mileage at the core of marketing, there are no OEM intakes which are inefficient enough and simple enough to meet these requirements.

Auto: Mazda Rx-8
kW / HP: 231
Pomógł: 5 razy
Wiek: 28
Dołączył: 07 Gru 2012
Skąd: GOP
Wysłany: Czw 28 Mar, 2013 18:43   

ECU retune
(Will void engine/powertrain warranty if found)
There are potential benefits here. Functionally, an engine is at it's efficiency peak when it is also at it's torque peak. So moving the torque peak to where you drive at will have some small minor mileage gains. However, this isn't really doable for the RX-8, as our torque peak is largely based on the design of our intake. You will have to redesign the intake to move the curve significantly.
A tune specific to your engine and ECU will produce some gains, but they will likely be 1mpg or less.

The only other tuning impact is with the still-being-explored method of lean burn on negative split timing. (search this site for the thread) It has been shown to momentarily increase mileage by around 50%, however there are significant engine damage dangers in doing so, and significant power loss while under this condition. The ECU also refuses to allow this condition to persist, and will bring the engine back into expected norms before long. The tolerance of the rotary to this is greater than expected however, so it is something that Mazda may leverage in future rotaries if they can solve or address the dangers associated.

(No impact to warranty)
There are only 2 practical gearing changes available, swapping between the series 1 and series 2 transmissions, and swapping between their rear gears. With the exception of some wiring, the transmissions are compatible. The rear differentials are compatible. The series 2 RX-8 got a taller gear to assist with acceleration, however the transmission gearing was changed so that this wouldn't impact the highway mileage, only lower gear acceleration. Between the 4 possibilities though, you can find several gearing options that may work better with the rest of your mods to assist mileage. Several members with forced induction are approaching 30mpg with light highway cruising and gearing changes. If you stay NA, the gearing is unlikely to provide significant benefits.

Your driving habits:
(No impact to warranty)
I have personally seen 24mpg in my RX-8 when it was healthy. Smooth throttle usage is the most important trait, and to hit that it was basically "no throttle usage". Steady state speed for hours on end. Frankly, it's rather boring. My mileage drops as the speeds go up, and as I get frisky and wanting fun. This is true for you as well. If you are serious about saving gas on the highway, set cruise control to 65mph and leave it there, dodge all the traffic pounding down your ass in the rear view mirror, and assuming everything about your car is healthy and the road is flat, you will be able to hit 23-24mpg. Bump that to 70mph, and it's probably going to drop to 22. 75mph gets about 20, and 80mph drops it to 18-19. Air resistance is unavoidable. But it is also something you can mitigate a little bit. AC on and windows up is better mileage than AC off and windows down, unless you are staying under ~40-50mph, when it starts to swing the other direction.

(No impact to warranty)
The big killer of any highway mileage is aerodynamics. You can improve your car's co-efficient of drag in a few ways that are simple, like leaving the moonroof and windows closed. The OEM spoiler reduces the coefficient of drag by a point or two (but most others will not). Beyond that, you have to get more drastic if you really want to make improvements here. For example making custom under-body paneling to smooth the airflow under the car. You can see noticeable gains here, but it will be quite a bit of work to properly size, cut, and securely mount an APPROPRIATE material.

Drivetrain Modifications
Items here are not directly related to power. Drivetrain items that are related to power are listed above in the Power section.

(No impact on warranty)
The OEM clutch can handle quite a bit more torque than the N/A Renesis can throw at it (torque # needed please, I think it's in the high 200s range), so upgrading the clutch is often only going to impact your clutch feel. Hopefully in a direction you prefer. If you go FI, then clutch selection can easily become more of an issue.

Warning: Exedy Stage1 clutches are becoming increasingly suspect on the RX-8. Vendor reports, plus several members here (including me) are having problems with proper clutch engagement, strange noises, and premature failure. The suspected reason is an inconsistent 'stack height', resulting in improper clearances when disengaged.
Recent thread here:

(No impact on warranty)
There are no real publicly noted instances of people running a different transmission, though it's certainly possible. The 2 common swaps are between the series 1 transmission and series 2 transmission. Different gearing, reverse is in a different spot (next to 1st gear vs next to 6th), and differing internal strength are the usual reasons, series 2 being considering the "superior" usually, though there are exceptions there as well.

(No impact on warranty)
There are no real "driveshaft mods", however automatic transmission equipped cars do not have a carbon fiber driveshaft like the manuals. Be very wary of buying salvaged driveshafts however. Carbon fiber does not react well to shock that may have been delivered in a crash, and it could be a driveshaft just waiting to shatter. If you are removing the carbon fiber driveshaft for a different modification, be VERY wary of dropping it or banging it. Cradle it carefully and if you have to store it for a bit, make sure it's protected. You don't want to be buying a new one because a moment of inattention made it roll off the work bench.

Rear Differential
(No impact on warranty)
The common mod here is to swap gearing between series 1 and series 2, 4.444 (S1) vs 4.777 (S2). There are some aftermarket LSDs as well though, which are occasionally used.

Caution: If your RX-8 sees extended track duty, consider adding a rear diff cooler, as the OEM unit can boil the fluid.

(No impact on warranty)
Axles are largely also unmodded. The only exceptions are the really high power cars, typically after engine swaps or full race packages. The stock axles are plenty strong enough for anything less.

Note: Series 1 and Series 2 automatic transmission axles are the same, however the axles for the manual transmission RX-8s changed from Series 1 to Series 2

Rear Diff Bushings
(No impact on warranty)
Following much the same concept in the Suspension Bushings, upgrading the diff bushings will stabilize the diff's movement more when you are trying to put power down. If you are experiencing wheel hop on acceleration, this is most likely because of rear diff bushing failure, or the particular tire compound you are running is overwhelming the good bushings.

Motor Mounts
(No impact on warranty)
This follows the same concept as the other Bushing items in terms of material, although with the size and shape of the motor mounts then it's possible to take an existing set of mounts and fill them with the substance of your choice to firm them up to the degree that you are looking for. More than any of the other bushing items though, the motor mounts can easily impact quite a few things, most noteably transmission gearing selection. The sloppier your motor mounts are, the harder of a time it can be to get the car into the desired gear, usually starting with 4th gear. Not a universal statement, but quite common.


(no direct warranty impact, but may prevent you from passing safety inspections)
Many aftermarket seats fit the RX-8, however most of them will lead to codes and problems with the airbag system. This is largely in part due to the sensors that are within the seat to detect the presence of an occupant, as well as the position of the seat so that the appropriate airbag charge can be made. The side airbags are also located in the side bolster of the seat itself, which can contribute to the difficulties. These are all correctable, but expect to face them.

Steering wheel
(no direct warranty impact, but may prevent you from passing safety inspections)
There are no particular guidelines regarding steering wheel selection other than what you prefer. However, if you change your steering wheel, you can expect to have issues with airbag related trouble codes, similar to the seat ones noted above. They are not unpassable however.

Caution: Any work with the steering wheel MUST be done with the battery completely disconnected! Failure to remove the battery as the power source can lead to an accidental airbag trigger, which will cost several thousand to remedy, in addition to having the potential of causing serious injury if they go off with you, someone else, the disconnected steering wheel, and/or tools or other items laying around are unfortunately placed.


No, I am not joking here. There are a few tools that you can get that will save you quite a bit of money, hassle, and pain in the long run, and can be useful regardless of what modifications you do.

ODB2 Reader
There are many options here. You can find readers that will simply pull CEL codes for as little as $30. The price increases from there as you add features, such as code lookup, live data, logging or recording the data, graphical charting, etc... The most expensive consumer options for just reading don't get above about $150.

One popular option is getting a bluetooth ODB2 dongle and pairing it to a smartphone or tablet, and downloading an appropriate ODB2 App. Torque is by far the best for Android (someone give me the best for iPhone/iPad?) The dongle options are numerous, but in general the cheaper they are the lower the data transfer rate. There are also a few web stories about really cheap ebay ones frying ECUs. I am not convinced that this is a specific danger, though it is certainly possible.

Metric 3/8ths drive socket set and ratchet
This is pretty much a "must have". With wrenches and sockets of sizes 10mm, 12mm, 14mm, and 17mm, you can disassemble and reassemble ALMOST the entire car. There are a few 19mm, 21mm, 23mm, and 24mm nuts and bolts, several #2 phillips screws, a few specialty tool items, and a pair of 8mm bolts, but nearly every nut and bolt on the car is one of the basic 4 (10, 12, 14, and 17). I personally know this having done plenty of work on my own 8 (and several egine replacements on my Miata, which shares lots of the same hardware), and assisted with the complete down-to-frame disassembly of another member's 8.

3/8ths drive is enough strength and length for most of it, although a varying range of extensions, a larger breaker bar (probably 1/2 drive), and a torque wrench will make most projects much easier.

Jack Stands
These are critical. Jacks, even the OEM scissor jack, will eventually fail. It's not a matter of IF, but of WHEN. And it won't fail sitting in the garage, shed, or closet, it will fail with a car sitting on it. Will you be under it when it happens? Get a pair of jack stands and save your life, or that of a friend or family member who is assisting you.

Wheel chocks can be just as valuable.

Don't be another one of these:

A cheap multimeter from an electronics store can tell you an incredible amount of information about your electrical system. It's cheap and simple to use. If you don't know how to use one, take an hour out of your day to buy one and educate yourself on how to use it.

Please remember that this is meant for newbies, beginners. It is not meant to be a fully exhaustive list of everything you can do or the impact of every possibility. Just the basics that people should be aware of before modding.
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