Proper compression?

[LeviD]

Could someone please tell me what compression numbers I should expect to see on these motors? Thank you

 

[tuneman]

120 psi, give or take a few with elevation. Consistency between them is most important.

 

[SRXSRULE]

Lower then you would think. my 12 and 14 both tested at 105psi @ 6200ft. Thats with a good quality gauge, both spark plugs removed, throttle held wide open and 5-6 strong pulls of the rope. Eric

 

[LeviD]

Thank you very much!

 

[Jshlee3]

I get 95ish at around 9,000'

 

[tuneman]

Here's an estimate per elevation:

0000 - 120
1000 - 117
2000 - 113
3000 - 110
4000 - 107
5000 - 103
6000 - 100
7000 - 97
8000 - 94

Roughly 3% loss per 1000ft