Aller au contenu principal

Modifications et Puissance

Source : RX8Club.com - New and Potential Owners START HERE! Auteur : RIWWP

Power Modifications — Les modifications de puissance​

Newbie's Guide to Modding the RX-8: Newbies Guide to Modding the RX-8 (I wrote that one too!)

2004-2008 Power Modifications subforum: Series I Aftermarket Performance Modifications

2009+ Power Modifications subforum: Series II Aftermarket Performance Modifications

From the factory, the 8 is VERY well tuned (mechanically). There are only 2 things you can do for easy power:

  • Custom tune to remove some of the "safe" parts of the tune. The AccessPORT is available for Series1, MazdaEdit is available for Series1 and Series2.
  • Removing the naturally restrictive catalytic converter.

Doing the rest of the common upgrades piston cars get (intake, exhaust, pulleys, etc...) nets you MAYBE 5hp. MAYBE. Depending on the brand, a lot of them are inferior to the OEM stock system, and plenty cause you to lose power.

Pourquoi si peu de gains ?​

The basic engine design/configuration of the 13b used to only put out around 110hp naturally aspirated. Mazda has adjusted and tweaked everything to get it to a razor's edge of how much power they can pull out of the same basic 1.3L engine, and they have over doubled the original hp. A lot of R+D went into squeezing this much power out of the tiny engine, and companies that just slap something together typically make it fall off that razor's edge of peak performance, and the impact is considerable. Think of the engine as already modded to nearly peak N/A HP, and you will start seeing how it's hard to get any gains, and easy to create losses.

Another way to think about it would be to think about a Civic B16 engine. It's a 1.6L engine that from the factory makes about 160bhp. Someone can take that engine and go all out on modifying it to make as much N/A power as they can. Max power reported seems to be around 240bhp (sound familiar?). This includes more expensive engine management, higher compression, possibly some displacement increase, different cams for port timing changes, etc... So, what if Honda had released the engine from the factory with 240bhp from those changes? Well, think about how these compare to the RX-8's Renesis:

  • There would probably be quite a bit of trouble getting it to pass emissions standards (like the RX-8)
  • The stress on the cooling and oiling systems would be considerable (like the RX-8)
  • The engine wouldn't be expected to last forever, frequent rebuilds would be standard (like the RX-8)
  • It would cost THOUSANDS for tiny power increases (like the RX-8)
  • It probably wouldn't take to being turbocharged very well due to the high compression (like the RX-8)

Mazda basically already modded the engine to get near max N/A HP, detuning it only slightly to get it to pass emissions and having to add the obligatory catalytic converter. It's difficulty and costly to improve on their design as a result.

Comment obtenir plus de puissance ?​

If you want power, you have to go forced induction: turbocharger, supercharger, or nitrous. For turbocharging or supercharging, you need a starting amount of about $8,000 to $10,000 for a complete set up. If you find what you think is a "deal", please don't get fooled. If you spent $1,500 on your turbo system, you will still spend $8,000 to $10,000 in modifications, errors, swapping parts, getting stuff to finally work right, and probably an engine replacement along the way. There is NO complete kit that is 100% perfect. Every single kit has something wrong with it that you will have to correct. If you don't have an AccessPORT or MazdaEdit, you have very little chance in making it work. Piggy backs will not work with the RX-8, the ECU is too smart. Standalones are possible, but rarely pursued for street cars.

If you don't go that route, then the most you can expect is about 200 whp without a custom engine rebuild, which can run you $5,000+.

BDC has the higher N/A power recorded for a non-race team: BDC Street port vs. stock port dyno comparison — 223whp

Eric Meyer posted his 233hp dyno sheet: 233 rwhp dyno sheet

But keep in mind that it's likely his team invested $100,000+ into the R+D of the engine and drivetrain to get it there.

Attention aux faux "chips"​

Don't get fooled by any "chips", ebay or otherwise. There is no "chip" for the RX-8 that will do anything beneficial. The best you can hope for is nothing at all...a costly metallic sticker on your ECU. You can easily fry your ECU with one though, and that is $1,600+. The only reliable method of improving the ECU is through an AccessPORT or MazdaEdit. The piggybacks such as Interceptor-X and GReddy's E-Manager are terrible for the RX-8.

If you think you want to go turbocharging or supercharging your engine, start here: Series I Major Horsepower Upgrades and keep reading thread after thread.

Autres moteurs (Engine Swaps)​

Don't even think about posting a question about an engine swap. 20B (3 rotor engines) have been done, but they cost $20,000+ just for the swap itself. 4-rotor swaps have been completed I think twice. They run $100,000+. There have been a few swaps with the older 13Bs from RX-7s. They are cheaper, but still a lot of work.

There have been a few other successful swaps, including a couple of LSx engines and at least one 2jz engine. More have been started than have been completed, as they usually run out of money, out of patience, or out of desire.

Automatic vs Manual — Boîte automatique vs manuelle​

The Manual is overall faster and quicker than the automatic, even though they both produce about the same amount of torque, or acceleration Gs that you feel. The manual, having the higher redline, just means that it can hold those acceleration Gs, that acceleration rate, for longer before having to shift to a higher gear with a different torque multiplier.

One won't really feel faster than the other until you get to 125mph, where the auto's speed limiter will kick in (manual's don't have that). The manual will get there quicker than the auto, but it won't really "feel" faster.

Paddle shifters​

The paddle shifters on the 8 are just additional "buttons" that trigger up and down shifts, just like the shifter's + and - gates. You are still asking the ECU "ok, please shift now", and which direction to go. You still have the slush box reaction time, the same shift speed, etc... and the ECU can still decide to ignore your request, or shift on it's own.

The higher end supercars with paddleshifters aren't slush boxes, but rather what is essentially a computer controlled clutch foot and shift wrist. It disengages the drivetrain, moves the gears around, and re-engages the drivetrain. In less than a heartbeat.

Our auto's don't have that.

Ce n'est PAS du "Tiptronic"​

The RX-8's automatic transmission isn't "Tiptronic". That is a brand name of Porsche transmissions, that a few other manufacturers license the name from Porsche to use. Saying an RX-8's automatic transmission is a "Tiptronic" is saying that the RX-8 has a Porsche transmission in it, which isn't true. Yes, it's an automatic transmission that you can manually shift, but it is not a "Tiptronic".