ok my buddy has a fresh fresh jdm b20 head and i was wonder if i could put that on the ls block... i know the vavle train sucks on them but i just want a fresh ass head nad he just got the motor and all ready built his b20v .... i know a lot about the vtec motors and combos just tryin ls all motor for now

Almost positive its the same head.

Look at the head casting, probably says P75.

P75 = LS

ok

do the b20 head flow better air

no not really, they dont flow any better or worse than the b18 head...the only difference are the cams...the cams in the b20 head have a little bit different duration for the lower compression in the b20, but its only a couple degrees of duration so i wouldnt sweat it...it will bolt right on no problem

but would it lower comp because it being a 2.0 head because of the combustion camber

no the compression is not lowered b/c of the combustion chamber...there identical in the that aspect...the main thing is the piston to done clearance (a.k.a. type of pistons)...the b20 pistons are just not as tall which give it the lower compression

Let me add to this that there is one BIG difference between say an LS head and a B20 head.

LS = 81mm and combustion chambers to match.
B20 = 84 or 84.5mm (whatever) and combustion chambers to match.

In short....will it work, yes. Do you have to change things up in either the cylinders and pistons or the head and combustion chambers??? YES!!! It's NOT a real direct bolt on.

No. You're wrong.

Well you're wrong. Most B20's had P75 heads. P75's are LS heads as well.

I'm just discussing here is all.

So does that mean that the combustion chambers are identical in volume and diameter at it's widest point?

I'm sorry if I'm not going on true hard facts. My info is just my thoughts. I've heard from many that it doesn't work is all. I'm just trying to figure it out myself.

We can all agree that the LS and B20 have different cylinder/piston sizes. Let's set aside the head casting code P75 for a second. The casting code PR3 is different correct right??? In an ITR it's got an upgraded valvetrain and is hand ported from the factory. Same casting as a B16 head, yes. Same head, no. This is kinda what I'm trying to get at.

Shouldn't the combustion chamber match up to its cylinder size? Wouldn't there be a problem mating a head with chambers that are for 84mm to a head that is for 81mm. I've heard many times that it's necessary to mill the head down like 3 thousandths or something similar to in a sense, to close the combustion chamber up a bit and reduce the overall diameter of it in order to be flush with where the cylinders will meet up on an 81mm LS motor.

Discuss.

no there is no problem...it doesnt really matter cuz if you think about it some ppl have bored out an ls to 84mm and still kept the ls head...the only thing that the bigger bore does is give it the 2.0 displacement the b20 is really just a bored out LS (same stroke and everything)...the valvetrain is all the same between the two. I have personally bolted on a b20 head to a LS block no problem and the other way around as well...it doesnt matter...

You're confusing the shit out of me.

You are aware there are two different LS/B20 heads right? There's the normal P75 head which was found on B18B1 and B20's, then theres the P8R which I'm not sure if it was a JDM only head or a B20Z head, but its combustion chamber width was 84mm whereas the P75 casting was 81mm in diameter.

you rarely see those...point is that a b20 head will fit on a LS block

yeah i was going to get it milled any way but head gasket you just use ls im going to try it out and see what power i make with p30 pistons and a built JDM b20 head

good deal

I think we're just all thinking differently about the same things. ha ha ha.

I know about the P75 and the P8R and the PR4. I know about the differences between each and every block and head in discussion. I was just confused if the B20 would or wouldn't fit based on the reasons I provided. I have just heard many times by many reputable sources that it's recommended to "match up" the diameter of the cylinders to the diameter of the combustion chambers. That's the only thing I'm wondering about. Oh well. I think I have wasted enough breath on this and thanks for clearing it up for me.

Sorry for being so dumb about the potential LS and B20 combinations. This is my first LS motor.
Sorry for jacking the thread. Back on topic.

yea that is what i was wonder if the combustion chamber is better than the bore ....... but you would think that the B20 head would flow better air than the LS head because its for a bigger motor and needs more air to mix with the gas

I have a b20 head on an LS block it runs fine ... if the head has a p75 stamp its fine ...

the heads are the fucking same, whats the discussion. SAME HEADS!!! everything except the cams are the same. same head same casting same everything, p75 = p75.

the P8R head is DIFFERENT!!! different casting different head very rare, if it doesnt say P8R on it its not a P8R. if its not off a japanese car its for sure not a P8R! P8R is JDM only. the P8R head has a 84mm combustion chamber the p75 has a 81mm. P8R has 33mm intake valves , P75 only has 31mm intake valves.

theres no honda engine builders at the factory hand porting combustion chambers larger here guys these arent hand built limeted production race motors like type R motors, they are motors that came in CRV's.....

its a fresh ass jdm b20 head son dude all getting mad over something relax bro