Does raising compression usually yield more power? I have a bunch of ppl telling me I can pull more power out of my engine w/o the headwork or chip..How would one go about doing this? What are pro's and cons? Is it dangerous? thanks!
From my experience if you up compression you get more power,but you should be weary of using a turbo. The integra type R uses high compression and they are not good for turbos. But that is just my opion. But upping compression can be a good thing.
vince dont bother doin it w/o headwork. the time/labor u'll spend in havin only that done is a real waste. if u did it, expect only a 2-3% gain in hp if u were 2 go up a full pt in CR.
if u did do it, u have 2 go 2 a machine shop and have the head milled or skimmed. as i dont believe there's a thinner head gasket than stock available 4 our cars (which is another way of changin CR). the down sides r that u'll have 2 run better gas (assume ur doin that now) and if FI is in the cards u'll have 2 look into lowerin the compression ratio 2 facilitate FI.
just get this done w/port and bowl work (bowl work reduces compression, thus u'll have 2 look at doin the work twice) all in 1. b/c u dont wanna b spendin all the time and money in takin ur head back 2 an engine shop over and over again, more labor charges, and then more time puttin it back on the car, not 2 mention that u should never reuse head gaskets or head bolts/studs.
btw stock is 9.6:1
go no farther than 10.5:1, remember this is ur daily driver.
Raising compression is a lot like boost. It adds power, likes octane and when done wrong gets messy and expensive.
On a street motor, the main reason to raise the STATIC compression ratio is so that the DYNAMIC compression ratio that you have altered by swapping in long duration, high overlap cams goes back to where you want it. Yes, by itself without a cam change, a bump in the CR will add some ft/lbs, but when you see a cam swap that ups the peak hp, but looses on peak torque, that is an indication of reduced dynamic compression ratio. Cams and compression go hand in hand.
I do not know enough specifics about the Crane cams, the flame propogation properties of the Zetec head or the timing curve of the Diablo chip program to make a judgement. Many people run cams and about 10.5:1 (static) with no problems. although I do not know if this is with or without a chip.