Which compression ratio?

[dan2288]

Well i need new pistons so I was wondering on which compression ratio i should go with. I have a 2.3 stroker kit and i plan on running a gt35 in the furure. I wanted to go with 9.1. I kno its more dangerous with that compression ratio, but with a good tune and everything, it should be fine, right? And how much boost do you think i could run with that compresison ratio?

 

[blownturbotsi]

It all depends on the tune, your supporting mods, octane of fuel, meth/alky injection. There are too many factors to answer such a vague question.

 

[cruisintalonawd]

yes with a GOOD tune it would be ok, but if your not gonna take it to the best to get it tuned then I would go 8:1 or 8.5:1

 

[andy4g63]

Go with 9:1 CR. Tune with 8:1 and 9:1 it isn't different. You would want a lower compression, if you run very big turbo/GT-42R/ at high boost levels 40+ psi. I have 9:1 on my car. People tell that it helps to spooll the turbo. I don't feel it, but itis true.

 

[1gDSM4g63]

My assumption is that higher compression would be better just because stroker motors have a lower redline anyways so it'd be best to further maximize the power in lower rpms with high compression pistons.

 

[Clutch GSX]

As long as you have a way to see knock and tune accordingly you will be fine. I wouldnt push it though. The stroker Im building now has 9.1 compression and i can only get 91 octane here in cali.

 

[boostcraver]

The Good- Higher compression would help you spool faster due to more exhaust from the higher compression ratio and you will have a little more power before full spool obviously. The not so good- It will be a little harder to run a higher amount of boost as safe. Yes it's possible to run the same amount as you could with 8:1 if your running 9:1, but you will have to have a pretty good tune, higher octane, and plenty of supporting mods to keep it safe.

 

[JayRolla]

Wiseco 8.8:1's are what I would get. A lot of people I know run them and love them. Perfect comp IMO.

 

[Black_Bullet]

Higher compression DOES NOT help your turbo spool faster.

It will increase your power and torque by a small percentage across your power band,( maybe 5%) making the car more peppy.
This will "feel" that you have quicker spool but the rpm point at which spool begins and full boost is achieved is roughly the same; but whats really happening is just that the additional power/torque is helping your motor get to that rpm quicker; Leaving the impression of a quicker spool time.

IMO for people who dont know much on the theory of tuning or those who dont have something to completely tune their fuel AND timing maps, lower compression is better just for ease and reliability.

Piggy back tuning ( i.e. safc) wont work with increased compression on pump gas . Hope you have dsmlink or Eprom chip, or AEM. Personally on regular pump gas I think 8.3:1 to 8.8:1 would be the best range to be in.

With methonal injection and or E85, or on a car that always run race gas then Id shoot for 9.1:1 or even greater depending on the goals with that particular set up.

FWIW I have heard higher compression will improve gas milage.

You can run high compression and high boost successfully on pump gas at the cost of less timing advance. The question is what makes more power, a little bump up in compression at the cost of timing retard, or more aggressive timing advance with lower compression....