MrMiracle

I tried to run a search on compression and combustion chamber sizes but haven't found much since search only gives back 50 responses. Here goes nothing...

So the 90 HO has a compression ratio of 9.0:1. If each cylinder has a total stroke-volume of 625cc, then the combined combustion volume of X would be based on this equation:

(625 + X) / X = 9

Solving for X, I get about 78cc.

Now, if I want a compression ratio of 10.3:1, which seem manageable for aluminum heads and premium gas, we get this equation:

(625 + X) / X = 10.3

Solving for X, I get about 67cc.

Now, what I need to know is the difference that I'm already getting by changing from the stock heads to my 61 cc trick flows. Running a search, some say the stock heads are 68, some say they are 64. Its a 90 GT with the HO engine. Unfortunately I recycled the heads, so I no longer have casting numbers.

my77stang

stock heads were E7TE and i believe they are 64cc's

MrMiracle

Well my TFs are 61s, so I need to shave another 8. Datasheet says .006 per cc, so I have to mill .048

my77stang

watch it, cause you mill too much and you end up throwing off your head to intake alignment. if the motor is getting rebuild you are better off milling the block and shooting for a zero deck situation as every .001 equals more cc's your removing than by milling the heads.

how did you come up with 10.3 anyways?