Greg,
Yes - raising the compression ratio is probably the single most
effective change that you could make. More torque at all engine revs, &
more efficient. The only down side is increased fuel octane required.
9/1 would be ideal. Actually it would be slightly more effective without
the longer duration cam.
I agree with you on the low revs. From what I have read, the fours have
crankshaft torsional resonance points at around 5200, 5800, & 6200 rpm.
Running for prolonged times at these speeds without a modified
crankshaft & a good torsional vibration damper will likely result in a
broken crankshaft. with the stock parts you can probably get away with
running it to 5500 once in a while, but not under sustained conditions.
A three main bearing crank with a 4 3/8" stroke is definitely a torque
engine, or I should say, not a high rpm engine.
Dave Russell
BN2
Greg Lemon wrote:
> When I pursue my long overdue engine rebuild on my hundred I was thinking of
> raising the compression ratio from the paltry 7.5 to 1 to 8.5 or 9.0 to 1,
> my thought was that the engine will never be revvy so work on torque, would
> this mod be effective without the M or otherwise modified cam?
>
> Thanks
>
> Greg Lemon
> 54 BN1
|