Competition 12 V Head Flow Bench Numbers

[Red Stroke]

I am porting my head on my 12 valve. I was wondering if any one has flow numbers for a stock head as well as stage 1, 2, 3. I have heard:



Stage 1 increases 15% flow no valve changes



Stage 2 Use intake valves in place of exhaust and port out exhaust side more than stage 1 Flow increase 30%



Stage 3 same as 2 in addition mill off intake plenum and really hog some material out. Flow inrease ?? alot, and not really streatable



I am getting my head flowed in stock form first to see if I can achieve the 30% stage 2. I am running a Scheid street cam, does anyone know what valve opening distance this will achieve I believe around . 350"?



I will post my flow numbers as soon as I get my head flowed.



Thanks in advance.

 

[JTEdieselram]

I ordered a head from Haisley machine a few weeks ago, It is getting stage 3, but they are leaving the intake plenum on, so I'm sure it won't be as much flow, but I wont have to fabricate an intake I will be sure to let you know as soon as I hear from the porting shop on #'s as far as valves, if memory serves correct, intake and exhause valves are exactally the same?

 

[glhs]

Stage 2 Use exhaust valves in place of intakes and port out exhaust side more than stage 1 Flow increase 30%... .....

I think you mean intake in place of exhaust... ..... :

 

[DBraunig]

The head off my 98' flowed 149. 7 intake and 148. 2 exhaust @ . 400 lift in stock form



here is a link to PDR's website PDR ported head



Dave

 

[glhs]

Flow benches are like dynos... ... . every one will get a different number, so the only accurate comparison will be your before and after numbers on the same bench.

 

[zstroken]

Piers says a stage 3 has new exhaust valves. They don't cut off the intake.

 

[Red Stroke]

ZStroken:

Cut off intakes?



Seems there is talk of some black magic that goes into porting a diesel head. Don't see how it can be any different than porting a gasser turbo'ed or not?

 

[Forrest Nearing]

gotta cut off the intake if you really want to get at the intake ports...



it's not black magic compared to porting a gasser head... same stuff applies, but as an added bonus, you don't have you worry about fuel suspension

 

[Red Stroke]

Duh, cutting off intake I was thinkin intake valves.



Anyways Forrest what stage head did you go with from RAYMAC? How do you like it? Didn't you go to a SB66 turbo?

 

[Forrest Nearing]

not sure what "stage" it is, but it's mostly bowl work w/ a little exhaust port work and a trick valve job



I did put a sb66 on recently, and I loved it, but it came time to pay for the new clutch, so something had to give... I had to pick between the sb and the sps62, and we go up over 10,000ft every summer to get to our cabin (which is at 9000ft) and I don't think the SB would do so great up there, so the little turbo won out.

 

[Bobcat698]

As far as the "cutting off the side of the head" to get the porting done more efficiently, has anyone done it and not used the ZZ intake manifold?

I'd like to do it but I'm a bit leery as far as attaching my own custom manifold once the porting is down. . Don't know where it's safe to drill & tap.

Any input?

 

[Red Stroke]

Looks like when you machine the intake off you can leave enough of the intake protruding from the flat on the side of the cylinder head to have enough material for the tapped holes. That is prob the easy part getting the port job right is were its at.



Any body know what valve combo's have been tried?



DBraunig:

Thanks for the link I am taking those numbers with me to the porting shop.

 

[Timebomb]

Ive also wanted to know this. I tryed to get my head flowed but the guy was backed up with smoker tractor heads and didnt have time for mine. So I spent 12hrs porting and put it back on. Cant say anything changed cause I made other changes at the same time. But Im sure it helped.

 

[DBraunig]

Red Stroke,



Your welcome, but the thanks goes to PDR for posting that kind of info. By the way, my measurements were taken @ 28 inches of water. I'm not sure what that means, but it meant something to the man flowing my head



here are some pics of the head after porting, but before the machine shop



Dave

 

[Forrest Nearing]

Dave, looks great!



make sure someone blends the valve seats into the face of the head... blending the chambers is one of the biggest bang for the buck w/ head work

 

[DBraunig]

Thanks Forrest,



The porter wasn't sure how far he could come up on the new seat because the head hadn't been decked and the seat is still square :-laf . He got the intake to 162. 4 and the exhaust to 181. 7 before the seat work and back cut valves, so i think it should on par with a stage III once it's finished up. I think i will put the head back on first, and then, i a week or two i will change the cam during a retorque. I really want to see what difference each makes.



Dave

 

[RustyJC]

By the way, my measurements were taken @ 28 inches of water. I'm not sure what that means, but it meant something to the man flowing my head

Inches of water column is a measurement of the vacuum he was using to establish flow through the head. Inches of water column divided by 27. 68 equals PSI, so the flow numbers were measured at a depression of approximately 1 PSI pulling the air through the ports.



Rusty

 

[Forrest Nearing]

Thanks Forrest,



The porter wasn't sure how far he could come up on the new seat because the head hadn't been decked and the seat is still square :-laf . He got the intake to 162. 4 and the exhaust to 181. 7 before the seat work and back cut valves, so i think it should on par with a stage III once it's finished up. I think i will put the head back on first, and then, i a week or two i will change the cam during a retorque. I really want to see what difference each makes.



Dave

oh man, it's gonna be on once you do the VJ and do the chambers! I do think you're nuts for not just doing it all at once from a labor standpoint, but more power to ya for testing each component!

 

[DBraunig]

I hear ya on the labor, but my labor is free... . sorta :-laf I hate to do more than one thing at a time, hard to know where the problem is, if there is one, but really just to be able to see what change each piece makes. I wish i had my drive pressure gauge hooked up before i lost the gasket, i would have liked to compare those readings as well



Here are some pics of the head before porting



Dave

 

[Jim Fulmer]

Randy, my head porter said on my head as well as another he did that you have to concentrate in the valve stem are also so stop the turbalence(no spell checks) our heads are allot like Chevy Vortec heads. On mine he basically openened both ends and smoothed the center, convergent duct, works like a jet engine, velocity increases, pressure reduces. He did this without cutting the manifold off! I had to ask him recently about doing this and his answer was it probably wasn't worth the money spent looking at what I already have, I could add 10 psi of boost and do better.



And before you ask 213. 4 intake, 191. 6 at . 500 lift.



Jim