i'm building an LS/vtec using PR3 pistons standard bore (81mm). i took my block pistons, and other parts to the machine shop on saturday and the guy checked the walls of the cylinders. he tells me cylinders 2 and 3 are out of round by .004 of an inch and says i'll need to bore .020 over. is this guy trying to get more money out of me or will .004 of an inch make any difference at all? i've already got the pistons and just shelled out some cash for std sized hastings rings, i don't wanna have to buy new pisons and rings again.

thanks in advanced

 

it's actually a common problem for B18's to have out of round cylinders.

if the machine shop is telling you they are out of round they are only trying to cover their own asses so that you don't come back to them after the engine is built complaining of oil burning.

you can run with the cylinders as is....but chances are it will burn a bit of oil down the road.

sell your standard sized pistons/rings and just get the OS ones.

 

Sound legit to me.Most of the blocks I see need to go oversize.If your really worried just have him show you.And yes,.004 will make a big difference.

 

he checked them right infront of me. am i safe to go 1mm over with out having to install a block guard?

 

the max you should go on stock sleeves is 82mm. just have it bored to 81.5mm and be safe.

 

<TABLE WIDTH="90%" CELLSPACING=0 CELLPADDING=0 ALIGN=CENTER><TR><TD>Quote, originally posted by doood &raquo;</TD></TR><TR><TD CLASS="quote">the max you should go on stock sleeves is 82mm. just have it bored to 81.5mm and be safe.</TD></TR></TABLE>

Agreed. Bore it only enough to clean it up.

 

ok so i should stick with only .5mm overbore. consider it done. this now brings me to my next question. i'm purchasing the GE ls/vtec and the head gasket options doesn't include 81.5mm am i safe using the 82mm? is there any makers of headgaskets the do offer 81.5mm?

 

ok so 82mm is the biggest bore you can go on stock sleeves?? wats the highest bore you can do on aftermarket sleeves

 

I know you already got an answer, but I thought that i'd add that max service limit for taper or out-of-round on the B18A/B is .001"-.002", just incase anyone else might be wondering.

 

The stock bore (81mm) gasket will be ok for a 81.5mm bore.You could also use the 82mm,either will work good.

 

<TABLE WIDTH="90%" CELLSPACING=0 CELLPADDING=0 ALIGN=CENTER><TR><TD>Quote, originally posted by NJIN BUILDR &raquo;</TD></TR><TR><TD CLASS="quote">The stock bore (81mm) gasket will be ok for a 81.5mm bore.You could also use the 82mm,either will work good.</TD></TR></TABLE>

wouldnt an 81mm gasket protrude into the bore on a 81.5mm cylinder? would that be enough to alter flow characteristics or is the difference negligible?

 

it doesnt really matter. the bore on the head is still 81mm too.

 

i believe the stock headgasket has an 81.5mm bore already

<TABLE WIDTH="90%" CELLSPACING=0 CELLPADDING=0 ALIGN=CENTER><TR><TD>Quote, originally posted by 99hondacura &raquo;</TD></TR><TR><TD CLASS="quote">ok so 82mm is the biggest bore you can go on stock sleeves?? wats the highest bore you can do on aftermarket sleeves</TD></TR></TABLE>

most companies will say 87mm would be the max. but that's for race apps only.

 

.5mm oversize you can still use stock head gasket. Honda sells oversized OE pistons but same head gasket for all apps. GE suggests 85mm max bore on there sleeves for b-series.