OttawaGSR

After browsing the world of wide webs, I've learned the following:

The JDM B20B P75 head has an 81mm dome and is the same as the B18B head.
The JDM B20B P8R head has an 84mm dome and flows more comparably to PR3 head.
The desirable head is naturally the P8R head.

In terms of cams, I've learned the following:
The P8R exhaust cams are the same as the P75 exhaust cams.

BUT, depending on who you talk to,

The P8R intake cams are better than P75 intake cams - or the complete polar opposite where the P75's are better than the P8R! :argh:

Well which is it? I have a P8R head, and want to use either the P75 cams or the P8R cams.

Which cams should I put into the P8R and why?

Thanks!

K7-1Ktrevor

I have both in my garage. I can measure lift when I have a spare second. Im pretty sure all b20b low comp motors have the lower lift cams. if your even thinking about building a non vtec all motor setup stock cams should be out of the question. you can get crowers for $300 on summit.

also a p8r head doesn't flow like a b16 until you do a fairly extensive amount of port work. its ports are alot like p75 ports with just +2mm intake vavles.

OttawaGSR

Thanks very much! I look forward to your findings.

I'm choosing to use Honda cams to keep the cost as low as possible. This build is going to be a daily driver and the gains are not worth $300 to me. Therefore, if I have two sets of cams available, why not put the better of the two sets in?

Yes, it was a bit of a stretch to say the P8R's flow is comparable to the PR3, but I'm sure anyone would agree that it's better than the P75 with the larger valve sizes considered.

My plan is put the P8R head on a B20Z, and throw it in my G2 Integra. I have affordable access to machining, so I'm considering milling the head a tad - but I need to read more into clearances. I have no interest in exceeding 11:1 CR, which means anything less than about 0.07 inches between the head or the deck. But again, I don't feel like tearing apart the block, so however far the head can be milled, will be it. Once the block and head are put together, they're staying that way as I have other more interesting projects to work on!

Any suggestions or comments are welcome! Thanks for your time!

unusual71

the b18b intake cam isn't too shabby i wouldnt be too surprised if it was the better one.

once you get the lift you'll know exactly but there is plenty of clearance the cam is good but its still quite a bit less than a mild aftermarket vtec cam

OttawaGSR

So I guess it's going to come down to whichever had the greatest lift.

If anybody else has these cams, some measurements would be fantastic!

dntnedvtec

OP, you are better off with an aftermarket set of cams. You will not be able to tell the difference between the two. I have had both cams on a stock ported P8R head, both tuned, and none made power. 1-2 hp, but that could have been from the weather and such.....get some cams, its good power.

OttawaGSR

1-2hp difference? Ok, that's fair. Not enough difference to justify fussing over.

I have no doubt that performance cams will give me good gains, but I'm just not prepared to dump $300+ for 10-15 hp.

If somebody had a used set of cams they wanted to get rid of for cheap, I might consider that. It'd have to be stage 1; I'm not about to go buying springs and retainers on top of cams.

Again, just trying to put together a daily driver with a little extra grunt for zipping around the city.

Does anybody know how much can be safely milled off the P8R head?

K7-1Ktrevor

I know you can do at least .035"

and just search around for cams and valve springs, I paid $260 shipped for 403s and supertech single springs.

sorry about measuring the p8r cams, my digital calipers were acting up. I remeber b19coupe had a thread where he measured them and the p75s were slightly bigger.