![]() 07/03/2015 at 12:50 • Filed to: None | ![]() | ![]() |
The following was copied from !!!error: Indecipherable SUB-paragraph formatting!!! 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:
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2009+ Power Modifications subforum:
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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
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.
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.
Why?
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:
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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 obligatory !!!error: Indecipherable SUB-paragraph formatting!!! . 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.”
![]() 07/03/2015 at 13:36 |
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Peripheral exhaust porting was probably the biggest change to the rotary design for the 13B-MSP, along with better seal technology. If you keep the peripheral porting, add direct injection, lighten the rotors even further and open up the overall dimensions for more displacement...( see “16x” rotary development ) that is about all there can be done.
The 13B-MSP redesign effort was a valiant effort on behalf of Mazda. What Mazda achieved was a high revving, smooth idling NA rotary that still passed emissions somehow. However, in the real world the 13B-MSP seemed to make a little less than the (I think twice revised)~230 hp figure. If you look at various stock RX-8 dyno sheets out there and calculate 15-18% drivetrain losses... the HP wasnt quite there.
There was a constant struggle with bad stock fuel pumps, ignition systems and catalytic converters. For a fact, the stock fuel system absolutely cannot reliably handle big power adders. IIRC, there were some instances that the OEM fuel pumps were blamed for destroying stock engines.
IMO the biggest factors that caused poor reception was the poor fuel economy (250mi max on a tank of req’d premium) and the extra attention needed for maintenance and operation:
The masses had no idea that it WAS a good idea to hit redline at least once a day. Or, other items like only using conventional oil and checking it after every other fill up, etc. Some didn’t have a clue about the dangers of flooding and how to treat the RX-8’s rotary engine when it is running cold.
Anyways, screw all that... the engine was brilliant and so was the chassis. I still want another one sometime. I still dream about the first RX-8 and going to car meets and autocross events in that thing.