Getting more power out of an RX-8

[TREMAiNE]

Hello

I've spent the last month or two strongly debating whether to keep my RX-8 or to sell up and buy either a Chimaera or a Monaro.

I think I'll keep the RX-8 though because its a virtually brand new car.

Having said that, I'd like to beef it up a little (if I can) as it is a little bit sluggish.

Currently it just has the MadzaSpeed exhaust upgrade, which supposedly adds a rather pointless 4-5bhp.

Ideally, I want my 231-or-so bhp RX-8 to be running 280-300 BUT I don't want to stay Naturally Aspirated.

Does anyone have any suggestions on what I could do to achieve such big power gains? Is it even possible with out spending silly money?

[EmmaJ]

Hiya Ed

Best option would be to super charge your RX8 BUT the go to company Petite Racing I believe have stopped doing their S/C kit and only offer a bespoke solution now which would be unnecessarily expensive. I think if you have a hi-flow exhaust with some other minor mods you can get a remap which will boost power by 20-30 bhp. I suppose the other option is to look on ebay and hope someone puts their petite super charger up from sell....

[lilwashu]

Where can you get an extra 20BHP out of an RX-8 without forced induction?

[otolith]

TREMAiNE said:

Ideally, I want my 231-or-so bhp RX-8 to be running 280-300 BUT I don't want to stay Naturally Aspirated.

That's just as well, because if you do stay naturally aspirated you won't get that!

Supercharger.

[sherman]

I always thought the way to go was a turbo or two? I have no idea about cost though. The other option is to add another rotor or 2 and turn the engine into a 3 or 4 rotor monster.

http://www.youtube.com/watch?v=bdpiDG1bGVM

[otolith]

Seems a shame to ruin that lovely NA character with a turbo, so an engine driven supercharger would be my choice. A triple or quad rotor would make any rotary fan drool, but they are unbelievably expensive and MOT compliant emissions might need a fair bit of work.

[rotarymazda]

TREMAiNE said:

Ideally, I want my 231-or-so bhp RX-8 to be running 280-300 BUT I don't want to stay Naturally Aspirated.

Does anyone have any suggestions on what I could do to achieve such big power gains? Is it even possible with out spending silly money?

Greddy do a turbo kit. There are weaknesses that have been addressed by a company called BNR.

Performance Design (Australia) did an Opcon based supercharger which was high quality but very expensive. It may not be available any more.

http://www.rx8club.com/ have a section on forced induction but read all million pages before asking anything or you will be shot down.

Adaptronic do RX8 plug and play ECUs that can allow remapping.

I went to extreme lengths with the RX8 engine in my MX5, getting +30bhp up on stock engine using custom intake/exhaust/decat/map and street-ported/polished housings.

280-300bhp only requires around 5psi. The exhaust ports and side seals on the RX8 are vulnerable to a lot of heat but 5psi is manageable unless you are racing.

Call Pip Gardner at WGT Auto Developments, he could do a custom turbo for you at whatever power level you want. 01606 837277.

"Street Rotary" is a good book to read if you are thinking about upgrading your engine.

[EmmaJ]

Not driven a turbo'd RX8 but the big issue with the rotary engine is it's complete lack of low end torque. Try driving at 30mph in 4th then give it WOT. Do the same thing in my Monaro which is twin turbo'd and even though it'll be nowhere close to it's boost threshold it'll pick up speed nicely as there is plenty of torques on hand from the 6lt V8. So surely turbos are the last thing you'd throw at an RX8 because you'd surely want to cure the low down lack of grunt? Unless you always drive yours like you stole it

....BEEP....

[sherman]

Thats the only way to drive one is it not?
Nothing happens really until 4000 rpm and then all hell breaks loose after 7500 rpm

Its good for the engine if you redline it once its warmed up. The car even gives a beep to tell you you are doing it right.

[probedb]

EmmaJ said:

So surely turbos are the last thing you'd throw at an RX8 because you'd surely want to cure the low down lack of grunt?

Try driving a turboed rotary before making any comments about it.

[EmmaJ]

probedb said:

EmmaJ said:

So surely turbos are the last thing you'd throw at an RX8 because you'd surely want to cure the low down lack of grunt?

Try driving a turboed rotary before making any comments about it.

It wasn't a comment it was a question based on ownership of two NA RX8's and numerous other turbo chargered vehicles. My EVO was bad if caught in too higher gear and the turbo hadn't spooled so unless you're saying most RX8's that have a turbo setup are either using tiny turbos that's spool in a instance or are running a sequential setup I think my question is valid. More than happy to take a passenger ride in one to be enlightened

[TREMAiNE]

Thanks for all your responses guys.

I think I'll look into supercharging, I'll see if the bank balance will let me stretch to it.

IMO That lack torque and low end power is the cars biggest downfall.

[R26Andy]

lilwashu said:

Where can you get an extra 20BHP out of an RX-8 without forced induction?

Pettit racing also do an ANP kit. Induction, exhaust and remap which claims to get around 20hp+ but will cost close to £1k.

I used a onboard data logger to do before and runs with the re-map and I estimate it added about 10-12hp to my rx8. A further 3-4hp from a induction kit and another 3-4hp from a exhaust is plausible.

[EmmaJ]

TREMAiNE said:

Thanks for all your responses guys.

I think I'll look into supercharging, I'll see if the bank balance will let me stretch to it.

IMO That lack torque and low end power is the cars biggest downfall.

From those that I've spoken to that have had s/c'd RX8's they all said that's how the car should have left the factory.

I'm sure a turbo'd one would be mental on the boil and secretly it's probably what your heart wants but that's missing the point.

Alternatively you could drop an LS2 in it

[TREMAiNE]

EmmaJ said:

TREMAiNE said:

Thanks for all your responses guys.

I think I'll look into supercharging, I'll see if the bank balance will let me stretch to it.

IMO That lack torque and low end power is the cars biggest downfall.

From those that I've spoken to that have had s/c'd RX8's they all said that's how the car should have left the factory.

I'm sure a turbo'd one would be mental on the boil and secretly it's probably what your heart wants but that's missing the point.

Alternatively you could drop an LS2 in it

I'll definitely look into it now - would never do the LS2 though! Might as well just my a Monaro

[lilwashu]

R26Andy said:

Pettit racing also do an ANP kit. Induction, exhaust and remap which claims to get around 20hp+ but will cost close to £1k.

I used a onboard data logger to do before and runs with the re-map and I estimate it added about 10-12hp to my rx8. A further 3-4hp from a induction kit and another 3-4hp from a exhaust is plausible.

A few people on the RX8 OC had this remap with full induction kit and exhaust and gained between 3 and 4 HP from it (total), which is why Pettit never published any figures on it. You won't get any gains from an exhaust and induction kit.

[Defcon5]

Rotary revs do various porting/tuning packages

[The Flying Ox]

lilwashu said:

Where can you get an extra 20BHP out of an RX-8 without forced induction?

Depending on how confident you are/how much cash you have to burn, it's easy if you go down the porting route. A street port would easily get you your extra 20bhp, probably more. Go for a more extreme bridge port or into the crazy-ass J ports or peripheral ports and you're talking a lot more power. And a lot more noise. And a lot less driving between fuel stops.

Did I mention the noise?

[Silent1]

If yours is making more than 210bhp already I'll be amazed, I don't think I've ever seen a stock rx8 make power.

[Andy30241]

I've been looking into this for my own RX-8, I've done the normal cat back, forced air induction and k&n filter. From what I've been told by Petit and rotary revs and few others you either stay N/A get it ported and re-mapped and live with that or go Turbo or Supercharged.

Turbo and Supercharge will of course give you the best power increase but think about the rest of the car as well gearbox, clutch so on it will but a lot of pressure on the rest of the car and of course the lovely rotary engine which although I love is not the best thing to annoy :-)