The following was copied from http://www.rx8club.com/ and if everything here mentioned is true then the relatively high maintenance makes since and I’m quite impressed by the engine’s longevity. Ever since that RX-8 post it reminded how awesome that car is and how it felt behind the wheel. It’s literally been in my dreams back to back nights. It’s an amazing piece of engineering. Hopefully somebody that knows more about rotaries or the B16 can also chime in.
Here goes the good stuff:
“Power Modifications: (Updated January 26th 2013)
Newbie’s Guide to Modding the RX-8: (I wrote that one too!)
2004-2008 Power Modifications subforum: Series I Aftermarket Performance Modifications - RX8Club.com
2009+ Power Modifications subforum: Series II Aftermarket Performance Modifications - RX8Club.com
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, alot of them are inferior to the OEM stock system, and plenty cause you to lose power.
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 (plus or minus a bit depending on what car it’s in). 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)
Does it make more sense now? 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 obligatorycatalytic converter. It’s difficulty and costly to improve on their design as a result.So...how DO I get more power?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 key 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+. The advancements in porting work have been slow coming, but they are still moving the needle upwards.”