im getting my b18b block sleeved for turbo application...would it be better to go with stock 81mm bore or get it bored out to 84mm...i already have a 81mm pistons so if i go 84mm i would have to buy another set of pistons....so is it worth going 84mm turbo on straight LS non vtec motor...thanks

 

you would probebly need to get your valves done in the head.

 

Why?

 

Of course it will be better to get it bored out for the higher torque, but its just a matter of $$$ for you to get new pistons.

If I were you, I would save the pistons you have and spend the extra money on the head or swap on a vtec head.

 

<TABLE WIDTH="90%" CELLSPACING=0 CELLPADDING=0 ALIGN=CENTER><TR><TD>Quote, originally posted by intekragsr &raquo;</TD></TR><TR><TD CLASS="quote">Of course it will be better to get it bored out for the higher torque, but its just a matter of $$$ for you to get new pistons.

If I were you, I would save the pistons you have and spend the extra money on the head or swap on a vtec head. </TD></TR></TABLE>

I agree, you already have the pistons so put the money on something else

 

I'd just like to comment on the whole 81mm vs 84mm debate. You will never make 400whp on a 1.8L displacement unless running a huge laggy turbo on pump gas. To me a street car encompasses a useable powerband and pump gas. I will see well over 400whp with my fully built 2.0L on pump gas, on the street. If you are rebuilding the engine, do it once, do it right.

 

if you have pistons already stick with 81mm bore. If you have extra money for another set of pistons then go ahead, go with 84mm.

 

Are you already using your pistons or are they new and still in the box. If they were new I would see if you could sell them first, then youre back to square one.

 

<TABLE WIDTH="90%" CELLSPACING=0 CELLPADDING=0 ALIGN=CENTER><TR><TD>Quote, originally posted by trbo823 &raquo;</TD></TR><TR><TD CLASS="quote">....so is it worth going 84mm turbo on straight LS non vtec motor...thanks</TD></TR></TABLE>

Why yes, yes it is worth it.

Torque is your friend
No replacement for displacement
Bigger is better
etc.

 

<TABLE WIDTH="90%" CELLSPACING=0 CELLPADDING=0 ALIGN=CENTER><TR><TD>Quote, originally posted by boosted hybrid &raquo;</TD></TR><TR><TD CLASS="quote"> If you are rebuilding the engine, do it once, do it right.</TD></TR></TABLE>


What he said, plus with ~10% more displacement, your turbo will spool faster.

 

<TABLE WIDTH="90%" CELLSPACING=0 CELLPADDING=0 ALIGN=CENTER><TR><TD>Quote, originally posted by trbo823 &raquo;</TD></TR><TR><TD CLASS="quote">im getting my b18b block sleeved for turbo application...would it be better to go with stock 81mm bore or get it bored out to 84mm...i already have a 81mm pistons so if i go 84mm i would have to buy another set of pistons....so is it worth going 84mm turbo on straight LS non vtec motor...thanks</TD></TR></TABLE>

I was in the same boat as you were and i went with 84mm, why? because of displacement which will add horsepower, it's all about gaing horsses. If you've got the cash get yourself the larger pistons. The one thing i did was enlarge the chambers on the head to match the big bore.

Goodluck!

 

I was reading up on this conversation because I have a b1 that is bored to 84mm running and pulling hard on stock head from what I believe, but it recently started smoking and burning a little bit of oil, only when I let off the gas, downshift or come to a stop, everyone tells me my rings are bad but i ran a compression test and it’s all normal on all 4.

 

old thread bump for no resson

if your psi on all four cylinders good
do a leakdown test
that’ll tell you if your piston rings leaking

you could be smoking from valve stem seals fyi

 

Coltin... From what you're describing, you need valve stem seals.. Go for a drive, on a downhill street, downshift 1 gear and let off the accelerator.. Coast for about 5 seconds, then shift and get back on the gas. If you got smoke after that, it's your seals. I had this issue last year. New seals took care of it.