SOHC 16V Head swap?

[hot4dl8ly]

I question your C/R math, sir. At 34cc it would be 9.7:1, but you need to add head gasket thickness, valve reliefs, piston below deck height and area around the piston top down to the first ring. Figure 2 - 3 cc, call it 2.5. That would be 1324 divided by 4 = 331, 331 divided by 36.5 = 9.1:1 C/R. I think I will mill the head 0.035" to 0.040" to get somewhere around 10:1 C/R.

[hot4dl8ly]

sent TWFodor a PM

[Dragonhealer]

I question your C/R math, sir. At 34cc it would be 9.7:1, but you need to add head gasket thickness, valve reliefs, piston below deck height and area around the piston top down to the first ring. Figure 2 - 3 cc, call it 2.5. That would be 1324 divided by 4 = 331, 331 divided by 36.5 = 9.1:1 C/R. I think I will mill the head 0.035" to 0.040" to get somewhere around 10:1 C/R.

And you are right to question. Math assumed a flat piston at deck hight. CR=(swept volume+static volume) / static volume
(331+36.5)/36.5
I think you will need to cut valve reliefs in the pistons if you cut the head.

[hot4dl8ly]

I really must apologize. I wasn't adding the combustion chamber volume into the amount being compressed - I had to look it up and that is exactly correct. It is part of the amount being compressed, even if it is the amount being compressed into. I might have wound up with a 11:1 premium only engine. I thought the factory was fudging the C/R #'s all these years. Thank you for setting me straight, M

[Dragonhealer]

No worries!
(Room made in inbox)