9.0:1 compression

[hungryjoseph]

will the stock ecu be ok to run 9.0:1 compression pistons with the stock turbo, injectors, and maf on my s14 sr? if not shold I be looking into getting a 1.5mm headgasket to lower it?

[fast_s13]

ecu dosnt read compression>>> should be fine

[hungryjoseph]

ecu dosnt read compression>>> should be fine

can you explain this?

[fast_s13]

stock motor is 8.5:1 bumping it up to 9.0:1 is a big difference..your ecu controls things like injectors and spark.. as long as you are keeping stock turbo and injectors youll be fine

[duffman1278]

Not sure about nissans but on my Integra I bumped up the compression from about 9:1 to about 11.5:1 and I run it fine with the stock ECU. I didn't have to change anything else. From the honda forums though, they say a tune helps to extract that extra power.

[jr_ss]

I'd get a tune if I were you...

[hungryjoseph]

how much would a 1.8mm headgasket lower the compression by?

[hungryjoseph]

um I did some searching and I found that for .4mm in stroke, that is .25:1 of a compression ratio. I don't understand how those numbers relate, can anyone elaborate on that? I understand compression ratio but how accruate is that .25:1 for every 4mm stroke?

[jr_ss]

That isn't the only way to raise/lower compression. Stroking a motor increases displacement, it doesn't necessarily raise it. You need more information to accurately measure the comp ratio you'll be running. Find a compression calculator and use the factory service manual to get all the needed info.

I'm running close to 9.2:1 in my motor because the block has been decked and the head has been milled, effectively raising compression without going to 9:1 pistons.

[hungryjoseph]

yeah I understand that also, and the reason I ask is because I want to buy this block with 9:1 pistons, both the block and head have been resurfaced, but I don't know hwo much has been lost. so I am wondering if a 1.8mm headgasket would get me closer to the compression I want