mk3 max piston size

[NashMan]

Just wondering this as I am about to have to free time on my hands


Hks mhg is 86 mill so is that the max size


if I remember right the hks 3.1 was an 86 max size ???

 

[emericaskater285]

I don't think this will help much, but I think I remember somewhere seeing Wiseco 85.5mm pistons. My question would be, what is the maximum safe size bore to run for higher boost and horsepower without compromising the headgasket between the piston's bores. (25-30psi, and 700+ hp just for reference)

 

[Enraged]

what does a bigger piston really get you that can't be done with a different turbo/tuning/etc? or are you trying to save your damaged block and just get it rebored?

 

[IJ.]

Late block with minimal core shift and a sonic check is the only way to be sure on the max bore, water jacket errosion plays a part as well.

My brand new 92 block had horrible core shift compared to my original 86.5, looked like they'd just given up trying at the foundry by that stage..

 

[emericaskater285]

Late block with minimal core shift and a sonic check is the only way to be sure on the max bore, water jacket errosion plays a part as well.

My brand new 92 block had horrible core shift compared to my original 86.5, looked like they'd just given up trying at the foundry by that stage..

Well maybe my late 88 block in my 89 will be in the midst of all this, and they did a good job on it. I can only hope
I don't plan on anything larger than 83.5 in mine if it even needs a bore, so it really shouldn't matter too much, but it never hurts to check.

 

[NashMan]

well my head is skribed around the 85.5mill rougly since it was traced from the hks stopper 59 thou over stock and 86 mill is 78 over stock

I really wounder what 78 mill over stock be in displacement ?????


tried the convertion again and I got 110 over stock at 3 mill over


dead lord

 

[Enraged]

83mm bore and 91mm stroke (stock) is 2954.2 cc, so a 85.5mm bore, if it works with your block, would get you 3134.8 cc.

 

[NashMan]

so if i match my head sribe then all be about 85.5 to 86

now i just have to remember if i what i sribed it too

 

[NashMan]

really wounder how big the hks pistons were

 

[Nick M]

HKS sold 85mm pistons, along with many other things like Auto trans upgrade kits. Those days are long over. I know of one that tried it, and the block failed. I don't know that it was x-rayed or anything else. But with what IJ is saying, don't bother. You want a bigger engine? Get an LS3 all aluminum and less weight than the 7M. If that bothers you, get a Toyota V8 1UZFE.

 

[NashMan]

well I have to run a bigger piston my block is 43 over stock

and getting custom pistons made so I am debating about a size right about now kinda wondering what failed on the block ?

wise-co make a 60 over piston 84.5 off shelf and think the is the biggest piston you can get off the shelf right now

 

[NashMan]

oh found out I had my head etched form a stock head gasket


just could not remember