I hope to not get flamed...

I have my b18a1, and am keeping the block. Going to go ls/vtec. Going to have Benson sleeve/bore/balance the block. My question is: Id like to go 2.0 liters and have some after market pistons to bump compression, but I'm not sure what the best route is? I'm thinking the grs head will create higher compression do to chamber design? use b20b pistons? or a pr3 head with b20b pistons? Or aftermarket pistons with either? I know its up to me, and my money. my brain says gsr head with b20b pistons?

can anyone with experience help me please?

 

the common route is to use some rs machines or ycp itr replica pistons. they give a compression ratio i think somewhere around 12:1 with that gsr head.

what cams do you plan to run? what would you like to do with the car (daily drive, road race, etc). what kind of fuel are you planning on using?

 

What kind of budget are you on? I assume you will use the 89mm crank? Since you spent the money on sleeving a block I would spend the money for some forged pistons and rods. BC sportsman H-beams and a set of wisecos will run you 7-800 bucks and you will never have to worry about the bottom end again.

85x89 w/ 12:1 compression pistons will make for a killer DD/mild track combo. If it's a track only car, I'd look into some 13:1 pistons and some E85 or comparable fuel.

Just my .02... but a sleeved block IMO means just make the whole thing bulletproof....and put nitrous on later

 

I'd go for a flatter dome piston and short skirt such as weiscos. Flatter dome for better burn capabilities. If you happen to go that route, make sure it says "ap " K567M84AP is part number for 84mm. I posted a pic of the particular pistons. You could also consider 2 layer gasket and a little milling of the head for more compression. Just a suggestion.

 

91 octane, DD, Type R cams/valve train. Forged H beam rods would be nice but that's why this thread, to see if its necessary. 8200-8500 red line is fine by me.

Thank you all for your responses.

and yes, nitrous would be fun!

 

Do you have aspirations to do more with this build later? Sleeving a B18 block for a "DD type r cam" build seems steep IMO. I would find a B20 block and save a pile of cash.

 

I see your point. I must just be planning overkill... thanks for the wise advice.

 

Check out my build thread I started a couple weeks back. The block I built would be perfect for what you are looking to do. You can build the same complete shortblock I have for about the same or a little less that sleeving costs.

With all machine work and parts I have right at 1000-1200 into my short block with all brand new parts minus the crank and rods.

 

my opinion from personal experience but i wouldnt want to run itr cams with a compression ratio much over 11.5:1 you will be pulling a lot of timing. i did it last year and my rebuild version2 is right about 11.0:1. i can run more timing to compensate i bet it makes the same power with more flexibility in the tune.

that said, an 84x89mm motor with a workable compression ratio and the right header/intake manifold to match the itr cams would make a fun *** car to drive. those cams will make a nice amount of midrange tq, peak power right at 7800-8000 and leave you with a shift point in your goals of 8200ish.

carry on lol

 

wow! that sounds wonderful!

 

What pistons did you run to get that compression number? With the B20Z pistons and a GSR head 10.5:1 is about the max you can get unless you mill the head/block a good amount...then you run into p2v clearance issues w/ ITR cams and the stock B20 pistons, at least that has been the problem in the past. The RS machine pistons will be 11.7-12:1 depending on the head used and any machine work. That is the tough part w/ the B20..unless you do some sort of expensive aftermarket pistons there is a "dead zone". Even with the aftermarket options most of them are 9.5-10:1, 11.5:1-12:1 and 12.5:1+

Maybe I am not looking the right places but those middle numbers (10:1-11:1) are tough to find unless you start milling and manipulating that way (which I don't personally recommend)

I take that back...Arias has a flat top option which will put CR right at 11:1...but they are $600 set

 

B20z pistons with gsr head has no clearance issues with itr valves/cams?

I have not bought the head yet. If pr3 head, aftermarket pistons to bump CR and call it a day with the itr valve train/cams?

 

well its only 82mm, so nippon gsr pistons. its fucked up motor with the pistons almost out of the hole on ls rods and crank so im using a .040 hg and milled the head down a bit .010 to recover. lord help me lol. i just brought it up as a example of static compression goals.

at 84mm i think a 2 layer hg is like .0193" crushed not .026 according to zeal so you can grab another few tenths. the head can be milled something serious before it bottoms out the wear marks like .030-.035" i think(i wouldnt come close to it but it "can" be done). since i would notch the valve reliefs anyway with any vtec head i dont feel ptv contact much of a issue so the main negative effect is altered cam timing which can be dialed back out with adj. gears.

this dead zone you're talking about is a big issue imo. i still have those rs machines pistons we had discussed a while back. that block is machined and spec'd out ready to go for something im just waiting for lots of spare cash to buy a relatively large set of cams to bleed some of that compression back out. if there was no dead zone and i could get high 10s low 11s static out of it id use it instead of 82mm in a heartbeat with my itr cams

i remember the user seelback on here had a nice stock piston b20vtec that i was always envious of. if i remember correctly he ran some spray through it and went pretty darn quick.

 

If you wanna spend some cash Arias has a set of flat tops in 84mm bore w/ a GSR head that are dead on 11:1...but that's $600 just for a desired compression ratio LOL. It's just a pain to have to notch pistons and adjust cam gears to run STOCK parts IMO. If someone were to make a PR4, P61 or P72 (gsr) piston in an oversize (84-85mm) it would solve this problem and save people cash that want a mid comp ratio motor with good clearance. The CR would range 10.5:1-11.5:1 depending on piston and head combo from any of those 3 choices.

OP if you have the resources to notch B20Z pistons they work great w/ ITR cams and make good power. 200whp is kind of the "run of the mill" number with that setup. With a B16 tranny that motor will get up and move pretty quickly. otherwise you are stuck with expensive aftermarket pistons or cheaper aftermarket w/ a higher comp ratio.

Seelback was running an untouched B20Z bottom end on spray if I remember correctly. I think he may have even seen an 11 on a 100-125 shot. Pretty impressive.

I may play with a 50-75 shot for the track in the future on my motor trying to find an 11, but for now I'll be chasing it naturally w/ the higher comp and bigger cam combo.