Mirrorimg's build thread

mirrorimg

Well-Known Member
Well after doing much research on my P8R head, with its 84mm combustion chamber, I do not think it will be a good choice to mount it on my 82mm block. I plan on talking to the guy at my machine shop to get his perspective. One issue is that it will restrict some flow, having a larger head than block.
|___| <----something like this.
..|_|

Another issue, would be because of the lip/pocket created, there could be a hot spot that forms and causes detonation. Not something I want. I really dont want to build another block. I dont have the room for it, nor do I want to have the expenses associated with getting the block and building it. I am completely content with just building the head...

My block currently has ARP rod bolts, 82mm bore, 82mm ITR domed RS Machine Pistons and ARP head bolts. I would either have to transfer the hardware to a b20 block (Which will mean more downtime for the car), or buy new hardware for it. Thats more money.

If I do have to buy a block to mate it to the head, this project is going to be MUCH longer than originally planned. Will update with the information I get from the machinist/shop owner tomorrow.
 


mirrorimg

Well-Known Member
Woot. I was so excited this morning. I got a call soon after getting to work from Abacus Racing, letting me know my head was ready. When I got off of work, I headed over there (like 5 minutes from my office), and immediately identified her among the domestic motors.

He explained what he did, most of which was done on Monday when I went in to talk. The head was milled .004. Some people mill all the way down, until the quench is flat, but he assured me there wouldn't be any hot-spotting and detonation from the over lap. I may lose some flow because of the overlap, but this head will be better overall.

What was done:
Hot tank, bead blast the head, blast the valves.
Check valves for damage, guides for wear (Lucky for me none of my oversized, rare intake valves were bent)
3 angle valve job
Resurface






In the last one, you can see pretty clearly how much larger the intake valves are than the exhaust valves.
I will be measuring the ports on this head against the PR4 in my garage to see if there are any differences in them. There isnt any conclusive information I have found for this.

I may also get a grinding bit to smooth out the casting marks inside of the ports. Not sure if I want to go that route, or just leave it alone.
 
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mirrorimg

Well-Known Member
:D She's going to be sitting around for a while, as I buy some internals. It was missing all but 2 exhaust studs, and has 3 missing intake studs. I scavenged the exhaust studs off of my spare PR4 head, but the intake studs really don't want to come out.

When I clean off a portion of my dresser, she will sit inside instead of the garage. I will probably order an intake manifold and cam gears first, before the cams and springs/retainers.
 


speedin

The Transporter
Oh and id get a B20 block. IMO that overlap isnt a good idea. I mean if you do a nice build only to leave the head/block mis-matched its a shame.

Also what type of cams are you dropping into the P8R?
 

mirrorimg

Well-Known Member
Oh and id get a B20 block. IMO that overlap isnt a good idea. I mean if you do a nice build only to leave the head/block mis-matched its a shame.

Also what type of cams are you dropping into the P8R?
I technically already have a built block. It would run me another 1k-1.5k (or more) to do another block (probably more because I would have to purchase a b20 block). I have a b18a1 casing in the garage, but in order to run 84mm, it would need to be sleeved.

I will be running Crower 403's and Crower valve train. I don't want the huge lobe/camming from 404's. Not sure on cam gears, I am leaning towards Blox. And as for an intake manifold, I would prefer longer runners to keep the powerband/peake torque a bit lower. The two I am looking at now are the Blox and Skunk2 manifolds.

damn i really really wish i built the ls now
I still wont make as much power as a built B18C ;) Don't be too jealous.
 

mirrorimg

Well-Known Member
Just ordered some valve seals and intake studs. After that, the real parts can start going in :twisted:
 

mirrorimg

Well-Known Member
Got my order from Acura. I forgot that I needed a couple of things, but I can pick them up from the dealer locally.

Things on my dresser include:
Intake manifold studs
Intake Valve seals
Exhaust Valve seals
2x A/C Compressor bracket bolts
Timing belt tensioner spring
Rubber stoppers for the doors and trunk.


I also snapped some pictures to measure the size of the intake and exhaust ports to see if there is a visual difference in size. This is just the area that mates up to the manifolds, as the chamber may be slightly different between the two also.

P8R Intake

PR4 Intake


P8R Exhaust


PR4 Exhaust


As you can see the port for the manifold's are the same. Because the Intake valve is larger, it should have a larger chamber around it to allow more air in, but I havent done any testing to determine the volume.
 
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mirrorimg

Well-Known Member
nice jason!
Thanks :)

Im popping in the valve seals tomorrow, and I will be looking for a tap to chase the threads for my cam cover bolts. I may also order one of the main parts for the head after I get paid this weekend, but I'm not positive on this. Theres a couple other debts that need to be paid before that happens.
 
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