E85B18

Hello everyone,

I've blown my piston rings and I'm not sure how bad the damage is, but my compression is 90 in 2 cylinders I have a sleeved block at 81.5mm right now. My question is, if the cylinder walls are damaged and I have to re-bore should I go with 83mm pistons or 84mm? I like the advantage of quicker spool and more torque with the 84s but if I have this problem again I’ll have to re-sleeve the block. Is there enough of an advantage to go with the 84s over the 83s?

Thanks

ValleySyder

its a sleeved block .. i would go with 84mm on the first shot..

96 GSR-T

85mm is the limit on boost typically, and you typically rebore in .5mm increments so you would have the 84mm build, the 84.5mm build and the 85mm build left if you go 84mm.

ITR-EKcoupe

83mm leaves more room for error. i wouldnt bore it more than it needs to be. for the just in case factor.

E85B18

Thanks for the advice guys. I forgot to add this is a B18 if that matters. I thought 85mm was too large for boost?... I guess not. Has anyone run both, what kind of spool difference and torque could I expect? Im running a 3076r

96 GSR-T

85x89mm is a true 2.0L, it will make a little more power than an 83mm, you already have a 30R so it should spool fast as hell already. My friend put 10,000+ miles on his 85x89 at 550+hp daily on corn and its still running.

non-VTEC

82mm pistons are avalible....but i would go with 83mm to leave room for error.

Ricer no 7

i would go with 83mm got one myself but only problem is the gasket is expensive hehe not a normal gasket size

eagles3

I would never go 85mm in a forced induction application. If you scuff a cylinder wall or something....time for a new block. 85 is huge and is about max even for N/A application. Stick with the 83 or 84 to leave room for the errors. It also would depend on who sleeved the block as to how much sleeve thickness you will have after re boring it.
You're not going to see that noticeable of a gain from 83 to 84 or even from 82-84 It's just not a huge difference. Besides, that's why you have the block sleeved, so you can crank the boost!!!

96 GSR-T

Eh not exactly, if its a GE block they will resleeve it for half price.......

85mm is far from max for NA Apps...........

People run 40+psi in 85mm stuff, where are you getting this incorrect info from??

90blackcrx

Go with 84, men with large ********* go with 84. Yeah 82 or 83 leaves more room to fail but how many times do you plan on failing before giving up...

96 GSR-T

haha good point, giving up and/or going broke

eagles3

i agree...84mm will be just fine for what you are doing. You will still be able to go to an 84mm w/ no problems

eagles3

Ok, so i guess you're correct in saying that you CAN go 85 on a boosted app but, I would never reccomend that to anyone who is trying to keep a safe setup. It just leaves you with an extremely thin sleeve.
40 psi is HUGE!!!! who are these people?

EARLdaSQUIRREL

84mm is the way to go, all the extra displacement you can get the better!

E85B18

Thanks for the input guys. I have an AEBS block if that matters. Youre right, these are expensive fails so Im not sure how many times I want to do this. If i blow the motor again I may move onto another project

DA TeG 90

I chose 83mm pistons. Room for error.