12:1 vs 11:1

[Quad Dude]

i have a stock bore 11:1 comp wiseco in my 400ex what would i gain by puttiing a stock bore 12:1 comp piston in ??? torque, top end, low end?? oh and if it makes a difference i got a higher reving cam and full dmc exhaust and tc rev box. i know it will probably need higher octane fuel

thanks for any in sight
josh

[krt400ex]

from what i have heard, u will see gains throughout the whole powerspread. and u will need to mix race fuel with pump gas

[stocktires]

You'd gain torque. I wouldn't do it for just the performance gain, it just wouldn't be worth it when you could get a nice cam and some porting with the money.

[400 SS EX]

Once you step up the compression to 12:1 or higher on a 400ex its is highly suggested, and common practice to run heavy duty head studs. Which cost 59.95 from gtthunder then you have to have them installed at a machine shop. You could tell a difference in power but like stocktires said I would go with just a cam right now. Then you don't have to take off the head, but with the cam off it's just a matter of a few bolts so that is up to you. Keep in mind the heavy duty head studs when thinking compression though, and with 12:1 a 50/50 mix race and pump would be nice.

[Quad Dude]

i already have a good cam. i was just wondering if it would be worth it to put a 12:1 in next time i rebuild it. and tearing the whole thing to peices is no big deal for me. i do it once a week it seems anyway.

[wilkin250r]

Higher compression will give gains everywhere, but not equally. You see a little gain in the upper revs, but where it REALLY seems to help is the low-end torque.

A lot of engine builders will use the philosophy of a high-rev camshaft for upper RPM gain, and higher compression to restore the power you loose on the low-end.

[400 SS EX]

Bottom line in my opinion is yes it will be worth it. If you tear it down that much and have the money. But keep it mind what I said earlier about heavy duty head studs and race gas mix. Those are kinda hidden costs that go with a 12:1 piston that few companies will openly warn you about. Expect some turn around time on the head studs too.