Llew

Need new Pistons what kind and what compression ratio shud I get ? 8:5,9,9.5.10.10.5? pump gas in my country is 98oct(95mon) and I run 22psi daily and 25-30psi for drag racing.

So long story short after a drag run I was misfiring and getting lots of blow by. teared down the block and the pistons seemed like they've shrunk. Engine is a 2.3L pistons were Wiseco sport compact forged asymmetrical skirt 85.5 9:0:1 CR . The cylinder walls also seem to have some scruffing so wondering if it would be best to rebore the block and use 86mm Pistons. considering more compression to run less boost on my 25G td06 turbo.

LetsGetThisDone

iTrader: (1)

I would get wiseco HD's in 9:1.

Llew

thanks bro

evo8vz

if you plan to use pump gas and race on it some times I wouldnt go higher than 9:1

Abacus

iTrader: (9)

If you're stuck with pump gas its better to stay around 9:1 and run more boost. If you had high octane/Ethanol you could see around 10hp more per hole more with every point of compression on a good running engine at the same boost. Its best to rebore/hone to get the proper size of the piston. A good machinist will want the new piston to properly size the bore to it.

Wiseco HD's are nice since they have a bigger pin also. CP is also nice, but needs bigger then shelf pins for the power the 4g63 can put out. Both are 2618 alloy

There is also Mahle, if you weren't going to make a huge amount of power. You could run them tighter since they expand less since they are 4032 low expansion aluminum. This could lead to better ring seal and less noise. One of the reasons alot of OE use Mahle for performance stuff.

Something to keep in mind is the stock pistons were Hypereutectic Cast and usually didn't have problems unless someone had fat fingers. People usually broke a rod or rod bolt leading to a windowed block at big power or a rattling engine.

All engines,fuel have a limit and its important to keep that in mind. Alot of people get caught up in the internet and people running xxx boost on pump with xxx timing . You have to think for a second, Maybe that was only one cowboy pass late at night and it knocks on the rest of the pulls leading to failure. Its the last two degrees that get you..

Just my .02

Llew

thanks, I think i'll indeed go with the 9:1 again. my car did feel quite good off boost compared to stock but was just wondering if a slightly higher compression ratio like 9:5:1 would've made the car more economical on a daily running 22psi and on race day use racefuel(c16) and 25-30psi.
my car held up for years on 30psi daily with the old pistons but seems like something caused it to go lean and pistons slightly shrunk since they didn't break.

Llew

The other question is standard,asymmetrical or HD1400 what would be best for a daily driven Stroker(2.3L) engine. cant seem to find the HD1400 assymetrical in 9:1 only available as 10:1 or 10:5 . Ive noticed some signs of side loading (some scratches on the skirt coatings of the old pistons) engine uses standard length 150mm rods and 100mm stroke manley crank

LetsGetThisDone

iTrader: (1)

Sounds like the pistons collapsed. Being subjected to too much heat and stress will do that to a full round piston. I would go with HD's. Here's a link to the piston you need, you just have to select the right size:


https://www.extremepsi.com/store/pro...at=1586&page=1