I'm going to purchase a JDM B20 head(P8R) on put on my B18b block.

They are different sizes head 84mm and block 81mm, will this work. I'm afraid the combustion chamber might ovelay on the top wall of cylinder and worst on the coolant chambers.

1. how much room do I have, I know that a b18b(81mm) can be bored to 84(not going too) but know it can be done.


Anyone that deosnt know what a JDM P8r head heres some info.

"This is a super rare head casting of a B20 head. Want to make good nonvtec power? Ports are different than regular LS heads, chambers are already opened up to 84mm, and intake valves are 33mm (vtec size). This head out of the box will flow as well as most ported LS heads, and you port this thing and get custom valves like another h-t member (fastone beast LS motor) you can easily be destroying vtec setups because of its 33mm intake valves seats."


Any help would be appreciated, thanks


Modified by volcom40street at 7:35 AM 12/21/2004

 

Get a vtec head...

 

I'm trying to shoot for 200hp on a 81mm non-vtec.

Plus whats the fun of doing that, my grandmother has a ls/vtec.

 

im pretty sure youll be fine

 

combustion chamber on both heads are 81mm

b20 heads do not open to 84mm

 

<TABLE WIDTH="90%" CELLSPACING=0 CELLPADDING=0 ALIGN=CENTER><TR><TD>Quote, originally posted by na200whp &raquo;</TD></TR><TR><TD CLASS="quote">combustion chamber on both heads are 81mm

b20 heads do not open to 84mm</TD></TR></TABLE>

p8r head has larger valves and is 84mm

P75 has smaller valves and is 81mm

with that said, I think you may have problems with sealing when using the p8r on the 81mm

 

<TABLE WIDTH="90%" CELLSPACING=0 CELLPADDING=0 ALIGN=CENTER><TR><TD>Quote, originally posted by na200whp &raquo;</TD></TR><TR><TD CLASS="quote">combustion chamber on both heads are 81mm

b20 heads do not open to 84mm</TD></TR></TABLE>

JDM P8R deos read my first post.

UP

I need a real answer: So I have a Yes:1 and a No:1

HEEEELP:

 

I've never heard of putting a larger bore head on a smaller bore block. But i know you can put a smaller bore head on a larger bore block.
That doesn't mean it can't be done it's just that the B20 is unique in this manner. All the 1.8's have the same bore and 1.6's etc. The P8R is the rare misfit.... it would be something that nobody has tried yet (i think).

BTW...P8R will a vtec motor anyday. stock for stock. It's basically a vtec head with non vtec cams. Slap in the crower 404's etc n' valvetrain, and you have one sick head.
I'm running this head and I have to say it's amazing in stock form...nothing against vtec but it's just over glorified. I romp on B16a and B18c1 powered crx's. Honest. Haven't raced a B18c5 powered REX yet tho. I think that would be a good race. It's not really the vtec that makes vtec motors better, it's just the superior head design with the larger ports and intake valves. Believe it or not, some guys actually get gid of the vtec function in their vtec heads. But now....there's a nonvtec head that can flow just as well if not better...and it's the P8R but super rare.
can't wait to slap the crowers in mine.

 

<TABLE WIDTH="90%" CELLSPACING=0 CELLPADDING=0 ALIGN=CENTER><TR><TD>Quote, originally posted by na200whp &raquo;</TD></TR><TR><TD CLASS="quote">combustion chamber on both heads are 81mm

b20 heads do not open to 84mm</TD></TR></TABLE>

sorry...you're very misinformed.

<TABLE WIDTH="90%" CELLSPACING=0 CELLPADDING=0 ALIGN=CENTER><TR><TD>Quote, originally posted by beerbongskickass &raquo;</TD></TR><TR><TD CLASS="quote">Get a vtec head...</TD></TR></TABLE>

LOL!!!

 

my friend did that. it ran fine.
14.9 1/4s i/h/e
i think its not worth it....do a b20 block w/ a ls head

 

404

Look what I bought 405a





I going with Pct pistons in the block also. Going for 200 hp all motor non-vtec. I will prove it can be done. Piecing the motor together right now.

 

Better go buy some play-dough.

 

The heads are the same BOTH OF THEM ARE THE SAME
The only head that is different are the 90-93 LS heads all the other heads are the same.

 

P8R head is not the same as the P75 head

 

does your P75 look like this?

https://honda-tech.com/zerothread?id=796878

 

<TABLE WIDTH="90%" CELLSPACING=0 CELLPADDING=0 ALIGN=CENTER><TR><TD>Quote, originally posted by nonvtecallmotor &raquo;</TD></TR><TR><TD CLASS="quote">The heads are the same BOTH OF THEM ARE THE SAME
The only head that is different are the 90-93 LS heads all the other heads are the same.</TD></TR></TABLE>

 

is it possible that thats the head from the b20a, the older prelude engines? Ive never heard of a b20 head being any different than an LS head. Weird **** man, there is too much misinformation on the internet whether its from a prelude or a crv

 

the prelude b20 is 81mm bore. so do all CRV B20s come with this head???

 

<TABLE WIDTH="90%" CELLSPACING=0 CELLPADDING=0 ALIGN=CENTER><TR><TD>Quote, originally posted by Dan GSR &raquo;</TD></TR><TR><TD CLASS="quote">P8R head is not the same as the P75 head</TD></TR></TABLE>

Exactly!


I want a P8R head! Nice pics.

 

P8R is from a JDM B20 , its acutally pretty rare
but not all of them are P8R's

I have a B20 in stock that has a P8R head , check my sig

 

<TABLE WIDTH="90%" CELLSPACING=0 CELLPADDING=0 ALIGN=CENTER><TR><TD>Quote, originally posted by volcom40street &raquo;</TD></TR><TR><TD CLASS="quote">


Anyone that deosnt know what a JDM P8r head heres some info.

"This is a super rare head casting of a B20(JDM) head. Want to make good nonvtec power? Ports are different than regular LS heads, chambers are already opened up to 84mm, and intake valves are 33mm (vtec size). This head out of the box will flow as well as most ported LS heads, and you port this thing and get custom valves like another h-t member (fastone beast LS motor) you can easily be destroying vtec setups because of its 33mm intake valves seats."


Any help would be appreciated, thanks


Modified by volcom40street at 7:35 AM 12/21/2004</TD></TR></TABLE>

 

<TABLE WIDTH="90%" CELLSPACING=0 CELLPADDING=0 ALIGN=CENTER><TR><TD>Quote, originally posted by nonvtecallmotor &raquo;</TD></TR><TR><TD CLASS="quote">The heads are the same BOTH OF THEM ARE THE SAME
The only head that is different are the 90-93 LS heads all the other heads are the same.</TD></TR></TABLE>

Don't speak about something unless you know what you're talking about.
Here's some info fore ya:
B20a and b21a (from pre 92 preludes) are 81 mm bore head and block.
B18a, B18b (from 90-01 integra LS, GS, RS) are 81 mm bore head and block
B20b4 etc., and B20z (from USDM 96-00 CRV) are 84 mm bore block and 81 mm bore head (same p75 head found on LS)
NOW, here's the catch:
99% of B20's from japan come equipped with that same head as the american motor has.
That 1% is the exception. It is a B20B from a 97 Honda something from Japan. It is a normal B20B block but with a 84 mm P8R head (not a 81 mm P75). It is only from japan. You can tell this because there is no number after the B20B (example B20B4) None of the japanese motors have separate number designations after the second letter.
Anyways, I have found that on all the P8R equipped motors I have seen, they were all made in 1997 (as evidence of their "97" casting on the head).
Many people say that this motor was not from a CRV but rather a "HONDA Orthia" whatever that is. But, the question is why was it only made in 97 and not any other year ever.
It is an amazing head. It is comparable to a vtec head in the fact that it has 33mm vtec sized valves, and intake ports that are opened up to match this. Other than that, this head still comes with the P75 cams which are the basic 96+ integra LS cams. On P75, and PR4 heads, they have the common 28 mm intake valves and smaller ports. This head performs better than most P&P p75 heads and it does that in stock form!
As for the intake manifold, I'm not too sure about which one it comes with, Mine came with the low rise manifold. It had a P75 casting right on the back of the manifold. BTW, this motor was imported straight from Japan.
Now if you want some true, raw, nonvtec power, this is the way to go. Slap in some wild cams and sit back and watch this thing breathe baby. The only problem is that it came in low-comp B20b's so to get the full-on effect of this head, it is wise to up the compression to atleast somewhere in the higher 9's at least. (maybe some B20z pistons or aftermarket).
With I/H/E, a skunk2 IM, and some crazy cams (such as the 404's) you should be able to easily put down 180- 200 WHP (depending on the level of tuning involved).
I'm pullin' low 14's in a CRX with just I/H/E and some fuel tuning! (with the P8R)
Can't wait for the Skunk2 and the 404's...

 

I'm not doubting the head is better but if all you are getting out of it is low 14's maybe it isn't that great. I had a 93 SI with just a stock JDM LS motor with I/H/E and it would pull a 14.3 14.2 all day long with traction problems through third gear........... A Crx is much lighter then that car and should be atleast a 14.0 13.9 car if that motor is as good as you say it is..........

 

<TABLE WIDTH="90%" CELLSPACING=0 CELLPADDING=0 ALIGN=CENTER><TR><TD>Quote, originally posted by bambam &raquo;</TD></TR><TR><TD CLASS="quote">
On P75, and PR4 heads, they have the common 28 mm intake valves and smaller ports. This head performs better than most P&P p75 heads and it does that in stock form!</TD></TR></TABLE>

Just FYI, ex is 28mm, in is 31mm..

Good luck with that killer 81mm build volcom.... However you do scare me with the fact that you are putting that 84mm chamber on an 81mm bottom end. I would assume the little pocket will carbon up in no time. But I would be on the lookout for detonation. Please keep us all posted on your build.

 

<TABLE WIDTH="90%" CELLSPACING=0 CELLPADDING=0 ALIGN=CENTER><TR><TD>Quote, originally posted by AlLMoToRvOtEr &raquo;</TD></TR><TR><TD CLASS="quote">I'm not doubting the head is better but if all you are getting out of it is low 14's maybe it isn't that great. I had a 93 SI with just a stock JDM LS motor with I/H/E and it would pull a 14.3 14.2 all day long with traction problems through third gear........... A Crx is much lighter then that car and should be atleast a 14.0 13.9 car if that motor is as good as you say it is..........</TD></TR></TABLE>

calling a bluff on this one....anyone else?
slips please...
let me guess...you lost them?
traction problems in third? makes no sense...what tranny are you using?

Fully bolt-on b16's in a 5th gen hatch pull mid to high 14's.