compression

[Admin]

How much compression on premium pump gas/vs race gas...

[Punkur67]

There are many varyables that can affect what fuel you run. You can retard the hell out of your timing on a high compression motor and it will run, just not at peak performance. Also static (turbo, supercharger) and mechanical compression are different. You can run more static compression on pump than mechanical. Anything over 10 to 1 I like to run at least cut race fuel.

[SPEC]

[Admin]

2 stroker sorry...

[SPEC]

I got 168 across the board on my bad ass tripple
If I remember right a 2 stroke will run on as little as 90 psi.

[Admin]

I got 168 across the board on my bad ass tripple
If I remember right a 2 stroke will run on as little as 90 psi.

Pump gas?

[SPEC]

Premium with amsoil synthetic oil

[Enemy]

472 cc's in a Shee - 190 to 210 I have to run race (tt 111) with +8 degrees full timing. I've pushed as much as 220 with out the powervalves in to try it.

I could run pump on the same motor with stock timing @ 160 psi. Stock was round about 135.

Had more top end with lower compression on the dyno, but lost some down low....Always a trade off...

All seems to depend on displacement as far as how much they will take without detonation..

[Admin]

472 cc's in a Shee - 190 to 210 I have to run race (tt 111) with +8 degrees full timing. I've pushed as much as 220 with out the powervalves in to try it.

I could run pump on the same motor with stock timing @ 160 psi. Stock was round about 135.

Had more top end with lower compression on the dyno, but lost some down low....Always a trade off...

All seems to depend on displacement as far as how much they will take without detonation..

600 twin id have to see what the timing is, ski doo to...

[Enemy]

[Admin]

Yes ski doo is rotax, has rave valves yes...2001 mxz 600...

[Hoodlum]

I run around 165 on my pilot with premium pump gas and amsoil...I think it's more to do with compression ratio rather than the number you get from the gauge....There is a formula for it somewhere...I will try to find it....
Hoodlum

[Enemy]

[Enemy]

I run around 165 on my pilot with premium pump gas and amsoil...I think it's more to do with compression ratio rather than the number you get from the gauge....There is a formula for it somewhere...I will try to find it....
Hoodlum

But how can a compression ratio formula make up for a change in exhaust port height? 8.5.1 cr with 160 psi cranking compression with a 20cc dome is still 8.5.1 @ 140 psi cranking with same dome with a raised/widened exhaust port.. Isn't it??

[Admin]

I have read 175 psi elsewere... Doo has flat top pistons as well...