Hey whats up ht been a while.

I'm working on a new build for my ef, using a basic jdm b20b with a p75 head for now. looking for some advice though. I put a block guard in the block (that sucker fit tight!) and dropped it off at the machine shop to get resurfaced and have the bores checked, which ended up being 10 thousandths out of round, needing a re bore.

that brings me to my dilemma, pistons. I'll be blunt, I'm not looking to spend a lot of money on pistons. I've read and read and read all about b20's and their sleeves, how joe ricer has blown three of them but his buddies never done it. personally, my head came off of a b20z that was boosted, and cracked 3 sleeves from running stupid lean due to a bad injector (not mine).

Back to pistons. Since I have to bore over, I'm looking at piston options, which there aren't many. there's ebay stock replacements for cheap, then it jumps up to 600+ for some forged pistons (again, not spending money on those just to have a sleeve crack and take out said pistons.) then in the middle are some ycp jdm itr replica's, which if put into the b20 with a stock head gasket would yield compression ratios beyond what i feel is safe for pump gas.

I'm using the zeal autowerks compression calculator, so it's not perfectly exact, but it's looking like if i could get the head spaced out about .086's from the block it should drop the compression down to a much more street friendly 10.5ish range. looks like cometic offers custom head spacers exactly in the size i need, has anyone done this? i know it's big in the vw community on vr6 turbo's, and i've personally worked on a b16 turbo that has a head spacer on it, but it was already installed when i got my hands on the car.

TLDR: turbo b20, need pistons, ycp looks like my only option but compression ratio is way too high for street use, need a head spacer option or pistons with lower compression ratio.

for anyone curious set up will be with a greddy 18g kit with custom 2.5" bell mouth down pipe, b18b intake manifold (for now) and some delphi injectors

Have you looked at Supertech pistons? They're usually pretty budget friendly for a forged piston. As for a head gasket spacer...what? Are you just talking about their thicker head gaskets?

yeah well it's actually a solid piece of metal that you put in between the two outer layers of an mls head gasket. i'll look at supertech thanks

compression shouldn't be a problem if you have a competent tuner.

first off you are not using the compression cal right if u need that much hg to get it back down to 10.5:1 another thing when it comes to building a motor and its more imporant on a turbo motor is dynamic compression !!!!!! **** static compression!! get it out of your head. so not thats over. if u want 300ish whp go ycp itr 84.5 mm pistons arp pro series rods bolts and arp head studs supertech block gaurd. get a set of crowler 403 cams and drop in srpings and be done motor will be 10:1-9.8:1 dynamic which will make turbo spool nice and fast.

what he said just finished my friends b16a2 turbo build its 11:1 with wiseco pistons arp pro rod bolts studs itr cams and valve springs ultra street 70mm tb and a turbonics 60mm makes 350 on 91 cali fuel and 450 on 114 only reason we stopped at 450 was thats all thats needed for the 11.5 index class lol

What about Mahle pistons? I've used them before in a stock bore stock sleeved motor at 446whp street (autobahn) driven with no issue.

edit: I did threw a rod with this motor, but pistons did not fail.

If you are really worried about the static compression, get the ycp pistons and just have a couple tenths machined off the dome. Do some measuring, im sure you could get a nice even 1 or 2 cc off. Obviously you will need to balance them afterwards. Just a thought.

I wouldn't over bore b20 sleeves period

You won't get more than 350-360 out of the 18G, possibly less due to the 2.5" exhaust. If you're using the Greddy turbo outlet and stock wastegate actuator then you're looking at even less. Add in you're using a non VTEC head with stock ports, stock cams, and a stock intake manifold and you're going to make even less, maybe 330.

Either way the power potential of the 18g on your particular setup doesn't warrant strengthening the internals. Get another set of stock pistons and throw some ARP bolts on the rods and you're good to go. No sense going through a ton of work for 0 gain.

Also the sleeves were likely warped when you installed the block guard. If you didn't file the guard to fit the coolant jacket and just forced it into the block then that's exactly what happens. 10 thousandths isn't a lot and is usually an indicator of an improperly installed block guard. Granted a block guard won't really help you, especially since you've basically put the sleeves under external tension. You've basically put additional stress of the wrong kind on every sleeve which simply honing/boring the cylinders won't fix so don't be surprised if you crack another sleeve sooner than later.

^^ Listen to this man lol. I've personally run a stock sleeve/high comp B20b at nearly 240HP all motor for a couple years, then turned around and boosted the same motor and was making ~450 with a GTx3076 for another year before I sold it. Was I worried about the sleeves at times, yes, but nothing ever happened. I did not bother using a block guard either, just a b20b block with 84.5mm CP pistons, Manley rods, ARP hardware throughout, stock 89mm B20 crank. I was running a 4Piston CNC B16 head though, not a NonV like yours. Also, I was around 12-12.5:1 static and my tuner had no problems giving me a safe tune. (I used 93 octane Shell or Sunocco pump E10 mixed with "Race Gas" concentrate @ 4oz per gallon when boosted with zero issues, engine is still alive today for the new owner now sipping ethanol)
Basically though as WantBoost already said, your particular setup/combo is not going to make enough power to even warrant buildings a serious rotating assembly. Stock LS/B20's with just ARP bolts can easily handle the type of power you will be producing, so especially since your on a budget, just use stock replacement Pistons and go to town. Hopefully your BG install didn't already compromise the sleeves, and you will have a long service life as I and many other have. Anything over 84mm on stock sleeves is risky under boost, but One thing I have noticed as a common denominator between most if not all trashed B20 blocks has been improper workmanship. Tuning and engine assembly are always critical to a successful build anyway, but throw in an already notoriously weak block to begin with and proper tuning and assembly becomes a 100% requirement if you want it to survive.