I am about to order High compression Pistons from JE... 11.5-1

Friends told me that it will add about 40 HP.. Howveer I must run on 92 Octane..

If anyone knows please tell me its tru or not..

 

Maybe if you're boosting, and that's only because the JE pistons will allow you to boost more. Just adding higher compression pistons alone won't net you 40whp.

 

I thought higher compression would create a more forceful burt, hence higher hp, although I was thinking more like 10 hp not 40

 

i wouldn't boost and raise compression at the same time. you'd blow the head off of your motor doing that. high comp pistons are something i would do for tuning and balancing an NA engine, and they only add about 10-20 hp i believe. If you're going to boost, leave the stock pistons, for a while, and consider getting lower compression if you want to run higher boost levels. Boe would be able to fill any questions you want about pistons and boosting.

 

it sounds to me that Devas is asking if running on 92 octane gas is necessary. with 11.5:1 compression ratio you would want to run as high of octane as possible... if 92 is premium at local gas stations then i would recommend that. As far as your horsepower gain 40 at teh flywheel seems possible but might be a bit of a stretch, i would think more along the lines of 10-15 whp.

 

FWIW the reason you need higher octane fuel (which is really the only reason anyone ever needs it) is because you're creating more compression in the engine (whether through raised CR or FI) and the octane rating is basically a measurement of how resistant to pre-detonation (knock) a fuel is. Detonation is BAD. You want to avoid it at all costs. It's one of the worst things you can allow to happen in a tuned (or factory high performance) engine.

 

I went on their website and I couldnt find any info on the pistons...anybody out there got a link or something?

 

I don't think there's enough demand for them to post the pistons. They definitely already have the dimensions though. You may just want to PM him and see if he's doing a "custom" order or if he's going through RRM or RPW.

 

How bad is pre-detonation...

 

so bad that if you like having a car you would spend n e thing to avoid it

 

oh yeah and when boosting you want lower compression, turbo's hate compression you could boost a lot mroe if you had lower compression pistons ie reverse domed pistons

 

Asking a question like that makes me think you may want to read up a bit before you purchase/install anything. In a forced induction or high compression engine, knock is pretty much your worst enemy.

 

Our CR's already way higher than most boosted engines. If you want boost in your future, do NOT go high compression. Go equal (9.5:1) if you want to run low boost and keep the bottom and middle of your powerband strong or go lower compression higher boost for a more laggy, *****-out all-spool ride.

 

I'm wary of raising compression until you could find some way to strengthen the head gasket and you install better valve springs. I really doubt the stock ones would be able to cope with that. Then there's the rods themselves which will certainly not like compression since they're puny needless to say. https://www.evolutionm.net/forums/sh...se+compression Few good threads on the topic, thank God for Bahamut.

 

from what i read on this site and talking to a local mod shop, the stock pistons NEED to be replaced if any serious mod is done. i have a 2003 OZ and was under the impression, when i bought it, that i was getting almost the same thing as the EVO without the turbo. dead wrong about that. i figure if i got an EVO, i'd be modding it anyway and starting from $28k.
anyone, especially with a turbo, know if the stock pistons NEED to be replaced like i've heard?