Pistons Question

[GUN_METAL_GTR32]

hay guys and gals

im about to do a rebuild on my engine and i am going the route of forged pistons i am thinking about going the rebuild kit that horsepowerinabox.com offers i just wanted to know 1 thing

it says u can get them in 3 different types

standard size (i obviously know what this on is lol)

20thou over

40thou over

now what i wanted to know was does going the larger size pistons increase the displacement of the engine??

i want to get around 380rwkw with this engine and a gt35r 0.84 that i have already

cheers

julz

[OMGGTR]

yeh whoever knows i wana know too

[STATUS]

hay guys and gals

im about to do a rebuild on my engine and i am going the route of forged pistons i am thinking about going the rebuild kit that horsepowerinabox.com offers i just wanted to know 1 thing

it says u can get them in 3 different types

standard size (i obviously know what this on is lol)

20thou over

40thou over

now what i wanted to know was does going the larger size pistons increase the displacement of the engine??

i want to get around 380rwkw with this engine and a gt35r 0.84 that i have already

cheers

julz

Strip the engine first to determine what size you actually need, as it may already be 20 or 40 up. going from std to 40thou up is a negligible increase in capacity.

[GTScotT]

The increase in displacement is minimal, the overbore is more so for re machining of the block for when it is worn.

for reference 20 thou is half a MM

edit: beat me to it trent must have posted at the exact same time

[N1GTR]

Hahaha if you're thinking it can be bored out to 2.8, sorry to be the bearer of bad news but that won't happen. I guess you could technically call an 88mm bore a 2.7L

use the 20thou, leaves you more rigidity and the ability of another rebuild in the future if anything bad was to happen

[GUN_METAL_GTR32]

Strip the engine first to determine what size you actually need, as it may already be 20 or 40 up. going from std to 40thou up is a negligible increase in capacity.

the engine will be stripped down as it is a lil tired and i ran it a lil low on oil by accident

so is 20thou bigger than 40thou ???

[STATUS]

the engine will be stripped down as it is a lil tired and i ran it a lil low on oil by accident

so is 20thou bigger than 40thou ???

no 40 is bigger. It is best to go the smallest you can get away with as it allows another rebuild down the track (if something goes wrong) without getting custom pistons made.

[GUN_METAL_GTR32]

alrightie

thats what i wanted to know thanks trent

[r33cruiser]

Try spool imports man. They will supply you with the BULK of your needs.

I went the 40thou route, fully knowing if something happens, i will need a new block.

I doubt if you could test both sizes, you would actually notice a difference anyway.

Choose what you want. 20thou would be the safer route

[GTRNUR]

If your wondering about the thickness of typical 05u blocks, the last block i sleeved broke through on a couple of cylinders when bored to 92mm to fit the sleeves. The sleeve design was made to suit a maximum piston size of 87.5mm, allowing for a 2mm cylinder wall thickness which Dartron (sleeve manufacturer) consider to be safe for this kind of sleeved block.

So what im saying is that if that same block had been used to run a 0.040" oversize piston the wall thickness at its thinnest point would have been just under 2mm. Thats not a lot considering the block is cast iron. Its no where near as strong as the spun cast sleeve material so that more or less explains why 87mm is considered maximum for most normal blocks.

Edited March 13, 2010 by GTRNUR

[**RB2530**]

Mmmm