Re: piston porting
AHA! So you decided you are going to build it anyway, Didn't you? You have that go-fast hull and just can't resist. Been there, done that, bought the tee shirt, wore it, washed it. Let's face it, for guys like us: Too much horsepower is NEVER enough!
What do you want to port? The cylinders or the piston skirt?
Porting the bypass by squaring the ports will increase power. I have been told that the port top edge CAN be raised about .060 for more power, BUT this power comes at high RPM and low end torque will suffer. I never tried raising ports so can not comment as to whether it works or not.
Porting through the cylinder liner AND the piston skirt with two 3/4 to 1 inch holes in the bypass chamber will shorten the gas flow circuit and increase the volume of the bypass, thus possibly increasing gas flow to the cylinder. It will also cool the underside of the piston crown a bit more and allow more oil to the rod small end needle bearings. Combined with squaring the bypass ports for increased flow, this will produce a bit more power. However, I have not yet had a reason to tear down one of my ported engines so I have not yet tried piston skirt porting. Thus I can not tell you how much effect it will have, if any. However, to port the piston skirt requires (for best results) a Bridgeport and end mill so it is best left to a machine shop.
