Need help with compression ratio.

[2002_red_gts]

I'm trying to figure out what my compression is going to be and if I need to mill my heads. I would like 10.5:1 to 11.0:1 for my n/a build. I just had my heads CC'ed at 74cc and I plan in running a gen IV head gaskets that I believe are .027 thickness (correct me if I'm wrong) I ran the calculators and keep coming up with 12:1 is that right? Seems pretty high

 

[Tail lights]

More information is needed, At top dead center how far down is your piston? Do you have valve reliefs in your piston? If you do,you have to cc those also, it sounds like your calculations are off. 11:1 compression is a good number to have. you can get away with 91 octane and a stock computer. get the other info and let's crunch some numbers.

 

[Greg Good Cylinder Heads]

CR is the swept volume of one cylinder, plus the volume at TDC / volume at TDC (chamber, gasket, deck)

Head volume is 74 cc's.

Head gasket volume (.027") is 5.72 cc's.

Deck volume (piston .033" in) is 6.79 cc's.

Volume at TDC is 86.51 cc's

Swept volume of one cylinder is 799.83 cc's.

799.83 +86.51 = 886.34 cc's.

886.34 / 86.51 = 10.245:1

 

[Tail lights]

Nicely done

 

[Tail lights]

Nicely done

 

[MTGTS]

http://www.diamondracing.net/tools/

 

[2002_red_gts]

Thank you Mr.good so milling them .030 will put me rightvwhere I'm shooting for

 

[99 R/T 10]

Thank you Mr.good so milling them .030 will put me rightvwhere I'm shooting for

Is it smart to take that much metal off?

 

[2002_red_gts]

Ya from what I've read .030 ist to bad. A few guys have taken twice as much off

 

[Jack B]

Is it smart to take that much metal off?

Jeff Moray took .030 off of my 97. Remember to take it off the intake side also.

 

[Greg Good Cylinder Heads]

Plus .024" more if an .027" gasket is used.

 

[2002_red_gts]

Plus .024" more if an .027" gasket is used.

To make up the difference in head gasket thickness? I need a gen 4 head gasket to make 100% sure it's .027. Some one on the alley told me it was .044

 

[MTGTS]

The compressed measurement is .027, they might be .044 if you were to measure them off the shelf not installed.