high comp build.

CRX304 · 06-28-2009, 06:03 PM

I just picked up another CRX, but it's got a Z6 block and p29 slugs... I wanna stay non Vtec, and have an A6 head that I wanna mill.

As a rough estimate, before I rebuild and clay... how much "should" I be able to shave off of my head?

Just trying to get a maximum and an estimate on the C/R I'll expect.

Thank yalls!
Dr. Mike

rushi · 06-28-2009, 06:07 PM

No P29s....

CRX304 · 06-28-2009, 06:12 PM

Originally Posted by rushi

No P29s....

and why? enlighten me

The_Beave · 06-28-2009, 07:20 PM

P29s are terrible. Low compression height, high domes that split the combustion chamber into a terrible chamber, no quench to speak of, engines built with these require higher octane and/or more timing retard to survive, but are prone to detonation before peak power limits on available pump gas (knock limited), and generally are not conducive to any sort of cumbustion efficiency.

76mm PG6s from FJT. 30mm compression height, which puts the piston at .002" below the deck, 1.5cc dome, which is low enough to not interfere with any sort of flame-front travel, slight valve reliefs and plenty of meat on the tops to shape any relief you ned for extreme mills of the head and cams, dirt cheap, can run well on lower octane and less spark timing which makes for a much more efficient engine, offset wrist pin bore to apply power more quickly to the crank through the crankshaft, more oil drain holes than any other stock-type piston, and making your life easier in tuning.

That's why.

Eighty-Nyne · 06-28-2009, 09:03 PM

Originally Posted by The_Beave

P29s are terrible. Low compression height, high domes that split the combustion chamber into a terrible chamber, no quench to speak of, engines built with these require higher octane and/or more timing retard to survive, but are prone to detonation before peak power limits on available pump gas (knock limited), and generally are not conducive to any sort of cumbustion efficiency.

76mm PG6s from FJT. 30mm compression height, which puts the piston at .002" below the deck, 1.5cc dome, which is low enough to not interfere with any sort of flame-front travel, slight valve reliefs and plenty of meat on the tops to shape any relief you ned for extreme mills of the head and cams, dirt cheap, can run well on lower octane and less spark timing which makes for a much more efficient engine, offset ring bore to apply power more quickly to the crank through the crankshaft, more oil drain holes than any other stock-type piston, and making your life easier in tuning.

That's why.

rushi · 06-29-2009, 02:07 AM

Yea Beave expressed it quite perfectly.

I had PM7(same as P29 but with coated skirt) pistons in my previous D16Z6. With 12.5:1 CR and Crower 3 cam, it required minimun of 33deg of advance to make any kind of power at higher RPM. Now with my new D15B2 (Bisi 2.2 cam) I run 23 degrees and still get plug ground strap colored almost full lenght. I wonder, if you can have ten crank degrees less duration of negative work done, what kind of effect it will have on engine's output..

See here how much the PM3 head can be milled and a couple of tricks to make it work
Milling the head ALOT and problems related to it

CRX304 · 06-29-2009, 05:23 PM

Originally Posted by The_Beave

P29s are terrible. Low compression height, high domes that split the combustion chamber into a terrible chamber, no quench to speak of, engines built with these require higher octane and/or more timing retard to survive, but are prone to detonation before peak power limits on available pump gas (knock limited), and generally are not conducive to any sort of cumbustion efficiency.

76mm PG6s from FJT. 30mm compression height, which puts the piston at .002" below the deck, 1.5cc dome, which is low enough to not interfere with any sort of flame-front travel, slight valve reliefs and plenty of meat on the tops to shape any relief you ned for extreme mills of the head and cams, dirt cheap, can run well on lower octane and less spark timing which makes for a much more efficient engine, offset wrist pin bore to apply power more quickly to the crank through the crankshaft, more oil drain holes than any other stock-type piston, and making your life easier in tuning.

That's why.

Thank you... exactly what I was looking for.
Dr. Mike

The_Beave · 06-29-2009, 08:37 PM

You're welcome.

CRX304 · 07-06-2009, 07:33 PM

so I decided....
Z6:
block, crank, and rods
PM3 Pistons (d15b2)
D16A6 head
yields a 10.8 ratio w/ a z6 gasket.... not bad since I'm thinking about running 5 psi on it..... YEA YEA I KNO.... but, I'm addicted to boost, and I can tune like a MOFO.

The_Beave · 07-06-2009, 08:15 PM

You are going to put PM3s n a 1.6L block?

PM3s have a 30.7mm compression height. That will have the pistons stick up .7mm from a stock deck 1.6L engine.

Just so you know . . .