[racerboyrt]

Originally Posted by Walt Fricke

I have a 2.8 long stroke, and a 2.8 short stroke.

The long stroke was built with an early aluminum case and 2.7 heads. Ported some, but the normal valve sizes. Doesn't make the HP numbers (308? flywheel) Porsche advertised (110 hp/liter). About 250 at the rear wheels. I've been wondering how much I can increase the valve sizes on those heads and keep within the 92mm cylinder diameter, and if that might get closer to the factory numbers.

I don't think a guy can get to the real 2.8 valve sizes, as that called for changing the valve guide angles, which meant a whole different head casting I think. I long ago wrote off trying to purchase an original set of RSR heads. Or having the guy in Florida make them. Huge $. That may be a reason it is hard with stock valve sizes to get closer to factory HP numbers at the rather modest CR they used (10.3/1)

The short stroke 2.8, using an early '76/7 Euro SC/Turbo case, has 3.2 heads. Ports plenty large (per Steve) as they are, and easy to go to larger intake valves too. I was working to find where I wasn't making the HP I had hoped when a J&E piston ripped in half on the chassis dyno, but by all reports that is a great 2.8 if you have a reason (like class rules) to run that instead of a bigger motor.

Some of the Club Racing guys with really well professionally built 2.8s (made me feel a bit slow the one time I raced a bunch of them) are contemplating running heavier cars with bigger motors - like the 3.6. They say those cars can motor by them on long straights (theory - you need horsepower to push air, and more hp to push more air, especially as drag is exponential), even if the lighter cars have somewhat of an advantage in the corners.

How do the two 2.8's compare to each other in terms of driveability and feel in the car?