i would like to know how many cc's a p8r head combustion chamber is. if i have to i will take it to a shop but if someone knows it would be a great help. i need this to figure out what kinda head gasket im going to need. thnaks

 

Send DonF a six pack of Budweiser and he might do that for you. He has a P8R head at his shop.

 

lol can you send beer in the mail? it might be my only choise though

 

Pack of smokes is another vice of his.

 

bump

 

<TABLE WIDTH="90%" CELLSPACING=0 CELLPADDING=0 ALIGN=CENTER><TR><TD>Quote, originally posted by Rocket &raquo;</TD></TR><TR><TD CLASS="quote">Send DonF a six pack of Budweiser and he might do that for you. He has a P8R head at his shop.</TD></TR></TABLE><TABLE WIDTH="90%" CELLSPACING=0 CELLPADDING=0 ALIGN=CENTER><TR><TD>Quote, originally posted by Rocket &raquo;</TD></TR><TR><TD CLASS="quote">Pack of smokes is another vice of his.</TD></TR></TABLE>

If thats the case, send him $10 through paypal! That should cover a 6-pack and a pack of smokes!

 

good idea i sent him a IM

 

I was wondering the same thing. I would like to know to calculate the compression on these p8r b20b's. I'm thinking that if the USDM B20b's with the P75 head had an 8.8:1 compression, what do the P8R b20's have with a much larger combustion chamber? scientifically, the compression ratio would be much lower. Also, since the P8R uses 33mm intake valves, does it have different pistons that use totally different valve reliefs? That would also affect compression. I am NOT going to tear apart my engine to see what pistons it has and measure the valve reliefs either. Would a compression test be an easy way to calculate the compression ratio on these P8R equipped motors?
I've only heard of 3 different B20 compressions...the 8.8, 9.6, and the 9.2 (which is a verified CR listed on the JAP site). Everyone assumes that the 9.2 motor came in the Honda Orthia. But, those orthias came with low rise manifolds and my b20b w/ P8R came with a high rise, so it definitely isn't from the ORTHIA. I'm thinking it's from the SMX....it's the only other car i know of w/ the B20b made during those years.

Help me find out my compression ratio!

 

49 cc's

 

how did you find out that information? A stock LS?b20 P75 head only has 45. 49 is huge!

 

Well, using the C-speed racing compression calculator...

B20b w/ P8R head:

W/ 2 layer OEM head gasket: 8.48
W/ 3 layer OEM head gasket: 8.33
W/ 2 layer OEM head gasket and PHK pistons (B20Z): 9.22

I'm wondering if the last one is the one that the jap honda site is talking about with the 9.2 CR. I've seen plenty of people w/ pictures of P8R heads. But, it would be interesting to see if the P8R equipped B20B's have PHK pistons and not P3F and also what their valve reliefs look like. That would settle the questions out there. Anyone got any pics? Also, what is the stock compression numbers on a stock 9.2 LS motor? I'm assuming it should be near the same as my B20b is putting out across the cylinders. That would back up my theory. Also, that 9.2 B20b came out of the Honda Orthia. So that would settle the confusion on what car this P8R came out of.

This is the only logical solution as the 8.33 CR B20b or the 8.48 CR don't make any sense and i doubt that those are the comp ratios for a B20B. i'm pretty sure that my P8R B20b has a 2layer head gasket stock. So all I need to know about is what pistons are inside the damn thing.
Any body have any other thoughts?

 

<TABLE WIDTH="90%" CELLSPACING=0 CELLPADDING=0 ALIGN=CENTER><TR><TD>Quote, originally posted by erebunicrx &raquo;</TD></TR><TR><TD CLASS="quote">49 cc's</TD></TR></TABLE>

I thought it was 48cc?

 

anybody? anybody know the real size of the P8r head? 48 or 49cc?

 

alright, if you were to use the 48cc volume, you would come up w/ these CRs:

P8R head w/:

3 layer headgasket: 8.44
2 layer headgasket: 8.60
3 layer headgasket & PHK (B20z) pistons: 9.17
2 layer headgasket & PHK (B20z) pistons: 9.36

The only one that might make sense as the 9.2 motor is the 3rd example.
So it's still up in the air if it's 48 or 49cc's.

But, I'm almost positive that B20's w/ the P8R have the 9.2:1 CR. it's the only logical solution as all the other possibilities don't make sense.

I'm pretty sure we can all agree that there's NO WAY that the B20 w/ a P8R head has an 8.8:1 CR or a 9.6:1 CR....it's not possible w/ 84mm combustion chambers and assuming it would be using the B20B p3f pistons....or the B20Z PHK pistons.

BUT,....i've seen both 96, 97 and 98 head stamped P8R heads as well as 99 and 00. So, that means it came on both gens of motors. Now, with the fact that P8R equipped B20's were only made in japan, you know that it only came on the B20B (because there are no B20Z's from japland). Also, if it had a 9.2 compression, it would have to use the B20Z pistons in 97 and 98, which would mean that they used the high comp pistons in 97-98 which goes against the rules for B20's.

Anyone care to shed any light? I think a picture of the pistons from a P8R equipped B20B would be nice.....


Modified by bambam at 11:10 AM 3/10/2005

 

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