standard bore is 86mm. i know the sleeves are pretty strong in the Ks. but what if you bore it out to 87mm? has anybody had success on it?

 

can it not be 86.5mm for some reason? .020 over seems reasonable..

 

it cant, i got a free block cuz it had a decent scar in the wall. the machine shop could 87mm minimum to make sure the scar was fully gone and safe and its mint again.

my goals are 350-400 on pump, low boost, city driving. weekend warrior 600+ (if i can), race gas/e85 on forged internals and built head. car wont see the race gas map on the street

 

thats an awfully deep scar. can't they do that one cylinder in increments? seems a little unreasonable to just go full 87mm if it can be avoided

 

its really that bad to go 87mm? making it seem like its gon blow when i start the car

they did the cylinders little at a time already. block is already bored out to 87mm. that was the safe minimum that he was confident in doing. the wall was pretty scared. rod snapped and did some damage

 

no but if you have another issue down the road you might not be able to bore the block again and are stuck sleeving it or finding a new block. less is more in this case

 

well the block was free. i only spent the $300 to bore/hone, hot tank and deck. if anything goes wrong i will just use the block in the car now (i have a 08 Civic Si w/ K20z3) and then go sleeve that.

just seeing if it can be done or has been done with success. i understand stock sleeves can only hold so much and ive seen them on k20a make 700+ and the pistons or rods go before the sleeves.

would that extra .5mm (from 86.5-87) really greatly reduce the strength of the sleeves?

 

its not so much the sleeves but the area the headgasket has to seal

 

For what you have in it I say go for it. If it fails you still have your z3 block.

 

what would be the reason for this? if the block as decked straight, head was checked and milled straight. a good 87mm cometic headgasket, and arp head studs wont hold it?

 

The thin spots between cylinders means less for the headgasket to seal to. It's been known to cause headgasket failures on almost every large bore motor

 

wow ill have to watch for that. i didnt think 1mm would make so much of a differance. i can see going from a 86-88 or 89