Jap_Spec_Imports

I have an 84mm Darton sleeved block with no pistons which has been previously used. Now Im planning on putting new pistons in and I was planning on rehoning the block so I was going to purchase some 84.5mm Pistons for my turbo set up but to my disappointment JE doesn't offer 9.0:1 in 84.5MM Its either a 9.5:1 85MM or a 8.0:1 84.5MM. I am planning on doing a full build from the ground up and using a Garrett GT35R (Planning to see 600+ WHP). So let me know what you guys think! Should I go with the 9.5:1 or the 8.0:1

non-VTEC

je pistons part number 218909 84.5mm 9.3:1cr.

http://www.jepistons.com/cat/j...shtml

close enough to 9:1......don't nit pick over a .3-.5cr diffrence......just pick a good tuner

mrbsponge

Alot of times it really comes down to a couple things when a bore of this size might be used.

Most of the time its really not the bore that ruins a motor of that size, its the heat generated and the ability of the sleeve to pull and dissipate heat effectively. Sometimes an N/A motor will work with 84.5 & 85mm.

2nd would be the amount of material in between cylinders for the headgasket. YES they do make them, because comanies will make anything that we are willing to buy, but will it seal well enough for a moderately high HP motor, IMO no, or atleast i wouldnt trust it.

we ran into a similar problem with a boosted 85mm motor last year of a friend of mine, we just had cylinders getting coolant in them everytime we went above the 400 mark, eventually it worked its way to the problem happening all the time.


but i would see what darton says, i know some sleeves from some companies cant even be utilized above 84mm. You need to see when it was sleeved and what type they may have used at the time if they have changed anything. what i mean by that is golden eagle offers 3 types of sleeves, and i know darton offers a couple different types, just make sure you are positive which sleeve you have

nonvtecallmotor

85mm here. It lasted all last year and will be in the car for this year.

Jap_Spec_Imports

Thanks for all the info guys

96 GSR-T

My friend has an 85mm LS/V with a T67 on it running E85, put a ton of street miles on it this summer, and 20+ passes on it, no coolant issues. There is however very little gasket clamping area between the cylinders, and 85mm is the max for FI, after that its an all motor block. If you cant find 84.5mm JE's, find another brand, there is more than 1 piston manufacturer out there.

Supacharge

im at 85mm with 600whp w/ 6k on the motor. it's lasted thus far

Joseph Davis

I'm building an 85mm LS right now, targetting 600 whp.

I really doubt people can make 380-400 whp on craptastic B20B/Z sleeves for a year or so... or 500+ on stock B18/D16 sleeves... and have a one millimeter increase in bore weaken a substantially thicker aftermarket sleeve to the point of flagrant failure, mrbsponge. There was a problem with your friend's block, not with the bore size. There are plenty of people making obscene power at 85 and 85.5 mm.