Lower compression for Supercharger?

[fastbacker]

I have a stock 3.6 that I was thinking of supercharging. I'd want to cross drill the crank and upgrade the rods/bolts but was wondering if you could leave the compression ratio the same. I'm guessing you wouldn't seeing that these engines are already high. Anyone have any knowledge on this? Thanks- Craig Backer

[WydRyd]

Depends how much boost you want to run. You can get away with 0.4-0.45bar on the stock C/R with intercooling and the appropriate changes to fuel & ignition timing. Any more boost and you have to decompress the motor.

You wouldn't have to upgrade the rods... they are the same as the Carrera/930 turbo rods. Just upgrade the fasteners.

Common practise for the 964 motor is to machine down the crown of the pistons, since they have a lot of "meat" on them. You can get them down enough to run ~8.5:1 C/R and run 1.0+ bar

[fastbacker]

What kind of bhp are we looking at for a tight 964 3.6 with 8.5:1 cr at 1 bar using a whipple type supercharger?

Thanks-
Craig Backer

[WydRyd]

Sorry, that should be 8.25:1 C/R

Not sure, but you're looking at about 560+HP with a turbocharged setup, but with a SC it'd be less due to the extra parasitic losses of the SC.

964 pistons can be shaved down to within .100" of the deck. It's a common mod, for aftermarket forced induction for the 964