S4 block with rx8 rotors, Haltech fuel only ecu (12 years old!), 50mm TB, electronic dist.

Initial tune on 91 octane fuel gave 255rwhp @ 7900rpm and 420rw ft/lb @ 6900rpm. Spark is breaking down at high rpm so I'll fit an MSD box and should get a fair bit more power. I need to bring oil temps down also, for every 10deg increase in oil temp above 190F about 7 or 8rwhp is lost. I belive this is due to the rotors being thinner walled than earlier items and transferring more heat to the oil. Oil temps are getting as high as 240F at the mo.

Inlet manifold is too long but it seems to give a lot of useable torque. Engine does not need to be revved above 8500rpm. It feels like driving a v8 rather than a rotary! I'll try an IDA style mani later on.

 

Think your numbers are a little out mate, 400ft/lb at 6900rpm should produce more like 550hp - just dont stack up...



Read this then have a word with the guys who's dyno you got those numbers from:



http://www.epi-eng.com/BAS-PwrTrq.htm

 

I was wondering about the torque reading, its according to the dyno sheet but I'll have to ask the dyno operator what its actually a measurement of. This is the first engine I've dynoed so its all new to me.

Working backward and calculating torque from hp gives 194ft/lb @ 6900rpm(peak torque) and 169ft/lb @ 7900rpm (peak hp).

 

Good link by the way. Good explanation of torque and hp not just a formula.

 

Whoops I don't think thats right either I'll have to check the dyno sheet again.

 

with 310rwhp I torqued at 170 all motor. good news about the rx8 rotors.

 

Is that wheel torque maybe? what gear was the pull done in?

 

what kinda porting?

 

Dyno pulls were done in 4th gear (1:1). Engine is peripheral ported.

I re-checked the dyno sheet and max torque was 178ft/lb @ 6700rpm.

 

My friend had similiar results with rx8 rotors , we switched back to s4 rotors.