suggested compression ratio under boost

[TURBOACCORD]

alright, i have a 96 accord ex with tsi turbo setup. stock compression ratio is 8.8/1. i am running 12 psi and want to go more but am worried that the increased compression ratio will be to much for the engine. any suggestions on what compression ratio i should be around with 12 and approximately how high i can go would be helpful. thanks

[SleeperCivic]

I ran 11psi with my D16Y8 and 9.6:1 CR. You need fuel management.

[TURBOACCORD]

i have fuel management. complete stand alone (2 venom injectors the spray variable depending on boost and/or rpm level when in vaccum. i am just curious about the compression ratio or if anyone knows how to check it while in boost.

[boosted331]

Originally Posted by TURBOACCORD

i have fuel management. complete stand alone (2 venom injectors the spray variable depending on boost and/or rpm level when in vaccum. i am just curious about the compression ratio or if anyone knows how to check it while in boost.

That isn't a fuel management, that's a shitty bandaid fix. 8.8:1 is fine for turbo.

[SleeperCivic]

Originally Posted by TURBOACCORD

i am just curious about the compression ratio or if anyone knows how to check it while in boost.

Your CR is what you have - it doesn't change in boost or out of boost. It just is...

[YellowITR479]

Yea, the C/R isnt variable....be kinda tight if it was

[TURBOACCORD]

i don't see how the compression ratio can possibly be the same under boost. think about it logically, normal engine in vaccum sucks air through the valves on the down stroke...now force induction is as it says. the air is forced through the valves on the down stroke. psi is the volume amount of air in the cylinder over stock vaccum. now if the cylinder is getting more air in it, when it hits the upstroke it is going to compress more than usual thereby increasing the compression ratio...this seems logical to me and every mechanic that i have spoken with about it...if you have any explination for what you are saying i will listen and if it proves to be true then all the better. thanks either way for ya'll help

[SleeperCivic]

Originally Posted by TURBOACCORD

i don't see how the compression ratio can possibly be the same under boost. think about it logically, normal engine in vaccum sucks air through the valves on the down stroke...now force induction is as it says. the air is forced through the valves on the down stroke. psi is the volume amount of air in the cylinder over stock vaccum. now if the cylinder is getting more air in it, when it hits the upstroke it is going to compress more than usual thereby increasing the compression ratio...this seems logical to me and every mechanic that i have spoken with about it...if you have any explination for what you are saying i will listen and if it proves to be true then all the better. thanks either way for ya'll help

Read this and you won't need an explanation: it's all about measurements.
http://www.nightrider.com/biketech/x...200_page04.htm
Let me know if you have any questions.

EDIT: Just in case you're wondering, CR on a bike is measure the same way on a car.

[SleeperCivic]

Just a thought for you, too:

Why is it when you're ordering pistons that they ask you what compression ratio you want? Ever heard them ask how much boost you're going to run for reasons other than strength?

[TURBOACCORD]

they ask what compression ratio you want b/c they assume for the most part that is a natually aspriated engine...

[TURBOACCORD]

nice article on the page, but even he admits a change in the compression ratio simply between the hot and cold engine...all together it didn't really say anything about a force induction engine, the info was great i will give you that though. thanks

[TURBOACCORD]

http://www.turbofast.com.au/welcome.html

here is a great website to help with just about any kind of formula that you will need including compression ratio, hp, et, ect.