NoPistons -Mazda Rx7 & Rx8 Rotary Forum

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-   -   s4 6port 177whp (https://www.nopistons.com/dyno-charts-98/s4-6port-177whp-54638/)

slvr7 07-22-2005 09:51 AM

Best chart is attached to this post, but unfortunately every run was plagued with breakup of the rpm input to the dyno computer at higher rpms (note gap in trace line). So although this chart shows 177 rwhp @ 7,250, I'm pretty sure it would have nudged 180 with a clean pull beyond 7,500. And the fat, flat torque curve make it very drivable - the result I think of keeping the aux port & the VDI operational.



Here are the details on the motor:

'86 6-port, with a mild 'mazdatrix' style streetport & smoothing of runners

S5 VDI swap with DIY rpm switches controlling 6 ports & VDI

Port runners & manifolds matched to gaskets

New rotor housings, plus all new rotor seals, springs

DIY 'Pineapple' aux port sleeves, diffuser in exhaust sleeve ground out

Cone intake, MSD 6A, RB Header to hollow cat, Trust dual 50mm cat back, RB alum flywheel, SAFC II with AFR's tweaked to 13:1 ish.



I built the motor (first time rebuilding, thanks to all those on nopistons who advised!!) paying attention to maintaining good compression [tight clearance on side seal to corner seal, new housings], keeping air velocity high by smoothing runners and straightening / back cutting transitions. Small changes made to port timing [primary now closes 50*ATDC, secondary added only 2* to closing, aux. timing not touched]. Oh, and passed emissions test here in Ontario too!


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