Can someone double check my compression ratio math?
Posted: October 16th, 2017, 5:35 pm
Hello all,
I just got my block back from the machine shop, and I'm trying to pick a head gasket.
I used the compression ratio calculator and the results seemed low (9.09:1), so i followed Flash's calculations in the FAQ section and got 9.19:1.
Please look this over and let me know if you think this will work for 87 pump gas.
My parts are as follows:
Scat 4.0 rods
Russ's pistons; 0.60" over dished 28cc
Scat 4.2 crank
Russ's modified 232 Comp Cam with the .435/.448 lift
The block has not been decked, and the pistons are 0.003 out of the hole as is.
The shop also gave me a good deal on an Edelbrock head that has been set up for my cam.
So the math following Flash's post and using a 0.051 gasket (for a 0.048 quench):
.7854 X Bore 3.935 X Bore 3.935 X stroke 3.895=46.41 Cubic Inches X 16.387, =760.52364cc
Head volume ..........................................................55.00cc (according to Edelbrock)
Head gasket(.051")....................................................10.45cc
CC from flat top of piston and deck suffice (-.003) ................-0.59cc
Piston dish............................................................28.00cc
Total...................................................................92.86cc
760.52(stroke volume)+92.86=853.38 Divided by volume above piston (92.86)= 9.19:1
What are your thought? It seems like it wouldn't be worth it to have anything decked off, right?
Thanks for the help!
-Mike
I just got my block back from the machine shop, and I'm trying to pick a head gasket.
I used the compression ratio calculator and the results seemed low (9.09:1), so i followed Flash's calculations in the FAQ section and got 9.19:1.
Please look this over and let me know if you think this will work for 87 pump gas.
My parts are as follows:
Scat 4.0 rods
Russ's pistons; 0.60" over dished 28cc
Scat 4.2 crank
Russ's modified 232 Comp Cam with the .435/.448 lift
The block has not been decked, and the pistons are 0.003 out of the hole as is.
The shop also gave me a good deal on an Edelbrock head that has been set up for my cam.
So the math following Flash's post and using a 0.051 gasket (for a 0.048 quench):
.7854 X Bore 3.935 X Bore 3.935 X stroke 3.895=46.41 Cubic Inches X 16.387, =760.52364cc
Head volume ..........................................................55.00cc (according to Edelbrock)
Head gasket(.051")....................................................10.45cc
CC from flat top of piston and deck suffice (-.003) ................-0.59cc
Piston dish............................................................28.00cc
Total...................................................................92.86cc
760.52(stroke volume)+92.86=853.38 Divided by volume above piston (92.86)= 9.19:1
What are your thought? It seems like it wouldn't be worth it to have anything decked off, right?
Thanks for the help!
-Mike