I've a 998 S motor in kit form and some complete wrathall tuned 749R heads itching to be fitted to something and this initially appears to be reasonable folly. Has anyone actually done this mod and if so what issues did you find? Real world info rather than guessing please as we've all got theories ;-) Cheers, Q
I have seen it done the other way around. we have put an 749r engine with 100mm bore cylinders and 63.5mm crank what makes it an 998cc engine. like the 998/999 series. This increased the hp from 123 at the wheel to 148 at the rear wheel measured. With the right fuel mapping of course.
Don't suppose you recall the cam timing do you? And what sort of piston to valve clearance did you use?
Measured with 1mm lift. and zero valve clearances Inlet opens at 21 deg B.T.D.C. and closes at 53 deg A.B.D.C Exhaust opens at 54 deg B.B.D.C and closes at 21 deg A.T.D.C
Can't find were I have written down the piston to valve clearance. But with that timing I have checked it and it was no problem with plenty of clearence I remember.
I'm hearing good things about tighter valve to piston clearances... however a grenade is not really what i'm aiming for. :grin:
