Saifskyline

iTrader: (1)

Ok so i have a stock 2nd gen B16A, i am going to be turboing it shortly i have all the turbo kit here everything including eagle h beam rods and arp hardware.

My question is if i change the pistons to forged ones, will it be ok if i just buy stock size 81mm pistons, hone the bores and fit those?

or do i have to get the next size up so 81.5?

I know a little bit loose on clearances is good for boost, so if my bores are in good serviceable condition then just fitting 81mm 9:1 compression pistons will be ok..

A few builds on here have done this and it seems to work well.

power goal = 350-400 bhp.

lolv8s

No you're right the stock bore is 81mm so if you order forged pistons just make sure you by 81 mm. If you get the block sleeved or bored than you're looking at 82-84 mm. 9:1 is perfect for 350-400.

Saifskyline

iTrader: (1)

Yea that was the plan just get standard 81mm forged pistons and fit those. That depends on the condition of the bores, hopefully they are in good condition which they should be because the engine is very good low mileage and never had any machine work done to it.

So 81mm stock pistons, check all clearances like piston to wall, new rod bearings etc and give the bores a hone gap new rings and its good to go.

wantboost

iTrader: (2)

You can run 81.5... don't need to jump to 82. Also 84 on stock sleeves is brave

But yes, you just need to measure the piston diameter and your bore diameter and hone enough to ensure proper piston to wall clearance.... don't go nuts with the hone, do it little by little and measure constantly... you want a fairly consistent p2w on all four cylinders.

This is all assuming the existing cylinder walls are damage free

Saifskyline

iTrader: (1)

Thanks, they should be clean since its got a good service history to back it up. Will start stripping the engine soon.

Would a block guard be good to use to prevent sleeve vibration/movement?

wantboost

iTrader: (2)

Nope, all they do is cause cooling issues and can actually distort the bore. Plus once you get them in its a bitch and a half to get them out.

A motor I got from a buddy ended up having a block guard in it(we didn't know) and I'm still trying to figure out how to get it out without totally destroying the deck of the block

Saifskyline

iTrader: (1)

I guess thats right too, but what about the Darton MID sleeves they have flanges which act as block guards, don't those have issues with water cooling?

Anyway the weather in the UK is always crap and cold !

So basically once i strip the engine, inspect the bores if they are ok then hone them, get piston to wall clearances, and fit 81mm forged pistons such as CP/JE etc.

rich7777

You need the correct tools to do so. Your best off taking your block to a machine shop and getting them to check the bores over. I don't like the idea of running 81mm at all. Considering these engines have been around for a while now I'd always recommend a over bore.

Saifskyline

iTrader: (1)

My dad has all the required tools for the job, if the bores are in good shape then ill keep it 81mm, if not then i'll bore out

rich7777

That's fine. If you can keep them at 81mm then all the better.

Saifskyline

iTrader: (1)

Hope so man my eg6 been off the road for ages i miss it lol.

rich7777

I know that feeling to well lol.