Re: Do slant heads really make a difference in power?
Here's some numbers for ya.
But they apply directly to the PK80-J Slant Engine.
The stroke length will detirmine the swept area of the piston which is the volume being compressed into the head.
As far as i know there ar two different happy time strokes out there.
Different location of the piston wrist pin.
The voulme of the head is approx 8cc / same as 8ml
The volume of the compression chamber with the piston at TDC = 5cc / 5ml with 2 head gaskets.
This is possable because the piston dome is above the top of the cylinder inside the head.
the swept volume of this engine is 47.1291 cc.
47.1291cc / 5cc = 9.43 : 1 "SOUNDS LIKE TIRE SKIDDING TO ME"
I wouldn't reccommend going much higher without some serious octane.
This is also about the same as the Rock Solid Billet head.
Even at a 6cc / 6ml combustion chamber the ratio = 7.854 : 1 "not bad"
now say the piston was a flat top.
the combustion chamber would be 8cc / 8ml.
The ratio = 5.89 : 1 probably typical for the Happy Time.
So if you put the PK slant head on a motor with a flat top your not helping much.
But that dome shape piston and the head combo make a real winner.