9to1 comp

[Al_S14]

i am days away from having everything i will need to put my engine back together. head has been rebuilt, crank has been micro polished and balanced, block cleaned honed and decked. and now this close the end i have hardest decision to make. if i shoudl upgrade to 9:1 Weisco pistons or not. i know i will turbocharge my DE but since it may not be anywhere in near future i am slightly reluctant to put lower compression pistons. at same time i feel like its almost stupid to have everything apart and not upgrade the pistons but then ill loose good bit of power ....wont i?

[Maeda]

How much did you deck that head?

If you decked it quite a bit I'd say DO the pistons...

If turbocharging is in the near future do it.

If you have the money do it. It'll be worth it in the end when boost comes.

[Al_S14]

decked the block not the head. damit i cant remember ill ask call the shop tomorrow...i just dropped the chain cover today to get it done so they're working on it still . from what i can remember he said it was barely anything some crazy xthousands number .

[ultraDorksGarage]

10 thou is alot, and in terms of whether its the head or block it doesnt matter that much. but decking the block always results in more compression gain then decking the head.

u havent had any hard core machining done so how much boost are u planning to run? dont build a 8.2to1 static compression if u plan to boost 7psi. decide first how much power u want to build, how much boost u want, and what type of power band u want. thats my .02

[orion::S14]

^^^ Agreed.

And it also depends on what fuel management you want to use.

Any more, as fine as we can tune modern motors...8.5:1 is the LOWEST I'd ever consider...9:1 is a good compromise. If I ever build my block (I won't), it'll be 9.5:1, same as now...

...and in all reality, a 1 point change in compression is good for a ~4% change in power...so if you're making ~150rwhp now, you'll lose 6rwhp to lower compression...that's hardly noticeable...and isn;t going to kill you if turbo's in the future.

- Brian

[Al_S14]

thanks for your input guys . as far as power goals, i jsut want to be able to brake in to 5-6sec 0-60 and moderatly low boost more then 10psi......i have read that KAs can take this type of presssure but i am alll about reliability so that's only reason i am considering (very paranoid lol). this is my daily driver and with 135k on the clock i am looking forward to minor problems so want to at least be confident that my engine is not going to kick the bucket