[scxc15]

Ok so explain this to me. How do you change the compression ratio of your car? Like can you use your stock internals and rebuild it to raise or lower the compression ratio.? And I saw on SSM if you buy the 4.3 stroker somehow your compression can be between 8.7-11.5:1.... Also is my understanding that higher compression ratio is better for engine only applications and nitrous. While lower compression is better for s/c and t/c, is that correct? Also does having a higher compression ratio mean more horsepower? Yea I know its alot of questions.

[Avaric3]

Originally Posted by scxc15 Ok so explain this to me. 1 How do you change the compression ratio of your car? 2 Like can you use your stock internals and rebuild it to raise or lower the compression ratio.? 3 And I saw on SSM if you buy the 4.3 stroker somehow your compression can be between 8.7-11.5:1.... 4 Also is my understanding that higher compression ratio is better for engine only applications and nitrous. While lower compression is better for s/c and t/c, is that correct? 5 Also does having a higher compression ratio mean more horsepower? Yea I know its alot of questions.

ill try my best to answer your questions:

1-you can mill your heads or change pistons to change the ratio. im not sure if there are other ways tho
2-no
3-yes, ssms can alter the compression ratio by using different pistons. dish pistons give you a lower ratio, flat tops are the medium and domed pistons give the higher ratios
4-try to keep it below 9:1 for blower or turbo apps and about 10:1 or 10.5:1 for nitrous. for n/a you can go as high as 11.5:1 on pump gas but itll require premium
5-yes, it means more hp. how much tho, im not sure

[itschristorres8]

^ nailed it
let me just fine tweak it
1- you can also use a thicker head gasket. VW did that way back. theres no thicker head gasket for our car anyway.
2-you can use the stock crank thats about it.
3-correct
4-depends on what your goal is..if you dont plan on breaking over 500rwhp i'd do a 9:1 CR for more power vs 8:1....example..9.5:1 CR for 350-450rwhp area
nitrous 10:1 is good! n/a 11:1 no doubt!!!
5-8:2:1 ran like 226rwhp 284rwtq fully built and SSMS ran 10:5:1 at 260rwhp 260rwtq built as well

[ESG-642T]

Originally Posted by itschristorres8 ^ nailed it let me just fine tweak it 1- you can also use a thicker head gasket. VW did that way back. theres no thicker head gasket for our car anyway. 2-you can use the stock crank thats about it. 3-correct 4-depends on what your goal is..if you dont plan on breaking over 500rwhp i'd do a 9:1 CR for more power vs 8:1....example..9.5:1 CR for 350-450rwhp area nitrous 10:1 is good! n/a 11:1 no doubt!!! 5-8:2:1 ran like 226rwhp 284rwtq fully built and SSMS ran 10:5:1 at 260rwhp 260rwtq built as well

Actually chris, their are thicker head gaskets for our cars:
Tom Morana Racing Engines

[scxc15]

So if I wanted some of those to raise my compression I would get the 4-layer gaskets?

[Onemanzu]

to raise it you want the thinnest gasket you can get... and maybe even shave a bit of your heads

[scxc15]

Which one on that website is the thinnest?

[whitemustang02]

I believe the thinnest is the 3 layer one

Also what octane rating would I probably need if I went with a 12:1 or 12.5:1 set up

[Avaric3]

Originally Posted by whitemustang02 I believe the thinnest is the 3 layer one Also what octane rating would I probably need if I went with a 12:1 or 12.5:1 set up

you can run 12:1 or 12.5:1 if you want but one bad octane tank of premium and your fucked and can say goodbye to your engine or whatevers left of the internals

personally i think and i think most others would agree that on pump gas, the highest you should go is 11.5:1 or 11.6:1

[itschristorres8]

i wouldnt go to far past 11.5:1 for 93octane and really 11.1:1 is still kinda high for a DD
a thicker head gasket will lower your compression a little
milling your heads is like shaving them. that ALSO can RAISE compression
but if you swap the cam for a bigger lift at all you stand a good chance of your valves hitting the piston with the stock piston. i dont know if just milling it will do it but
truly...its not worth it...the power difference wont be to noticable from just milling
you im not sure how much power but id say you'll be lucky to see 20bhp off just milling SAFELY