Home Shop Head Porting; Pictures and questions!

BramanteCummins

BramanteCummins

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Nov 1, 2012
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636
Finally got around to getting the head on the bench. Just been roughing the intakes and wondering what I should be doing with the bowl shape? Truck will have a mid size set of twins and bill Fletcher's "DP3" cam.


qa6yrata.jpg
e2e6asun.jpg

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Ummm... Why is it all rusty and your valve seats look like they need to be reground...
 
ImageUploadedByTapatalk1368152690.922878.jpgThis is what I'm doing. Not done yet. I've got to fine tune it and polish it.
 
This is a race head. I caution you not to go to big for a street truck.
 
Diehard Ram said:
This is a race head. I caution you not to go to big for a street truck.
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Why isn't it recommended? High flow at high velocity but poor flow at lower velocity?
My assumption and understanding is as long as the fluid isn't disrupted sharply and the port cross section remains the same it's fair game. In the most basic of ways to put it.
 
BramanteCummins said:
Finally got around to getting the head on the bench. Just been roughing the intakes and wondering what I should be doing with the bowl shape? Truck will have a mid size set of twins and bill Fletcher's "DP3" cam.


qa6yrata.jpg
e2e6asun.jpg

u7u7y9e3.jpg
aju2are8.jpg
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for what its worth, imo, spend time on the throat and seat area of the port. you will see way more air gains there than hogging out the bowl.
 
lenahan05 said:
for what its worth, imo, spend time on the throat and seat area of the port. you will see way more air gains there than hogging out the bowl.
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Would you agree with my statement earlier? That the cross sectional area should be maintained, this would keep the air from bottlenecking as it gets closer to the valve seat.

Or..... That's the point on working the valve seat first, figure out the maximum cross section. Then bring everything behind it to a minimum or that or greater.
 
scat said:
How well have to got them to flow? Any data to go with the hogging ??
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I've got some good flow outa them. Even better on a 24v. But i will not post numbers on here.

BramnteCummins: If you go to big you lose port velocity at lower speeds. Thats what someone way smarter than me told me.
 
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So it's too much to ask for you to send one for "sampling"?

Besides that. Any input on my cross section and valve seat theory? I just want to get the best flow for a street driven toy and occasional dailyish driver. What will hurt street-ability and how.

I'm planning on ordering an ultrasonic thickness gauge tonight. Under 150$ I figure it'll take the guesswork out of finding water jackets. I really want to avoid finding one the hard way.
 
I found a water jacket once, a long time ago. I have a cut up head i use.

I might be able to work something out with you on a (sample).
 
Not having much experience with porting heads personally, but taking a few classes on flow, here is what I learned:

Wall roughness does matter, just not a ton. Obviously, the smoother, the higher the velocity, and the more laminar your flow can be.

Profiles.jpg

Laminar on top, Turbulent on bottom


Cross sectional area does matter, but also, not as much as you might think. The way you approach a decreasing area makes more of a difference in pressure drop. A nice G0 curve is best, to a taper which is still okay, to a ledge which is very bad.

I have also heard that a plenum before the valve helps, so a big bowl. I have seen old school hot rod guys actually port through the head and then weld in filler and them smooth it out so that they can get a bigger plenum at the valve.


My thoughts on velocity would be, not to worry too much about slowing your intake velocities if you are smoothing your walls. It'll probably even out to have similar velocities to OEM velocities. And if you are building your own intake manifold, look into velocity stacks in the manifold. That helps velocities like CRAZY.

Velocity_stack_detail.gif
 
CorneliusRox said:
Not having much experience with porting heads personally, but taking a few classes on flow, here is what I learned:

Wall roughness does matter, just not a ton. Obviously, the smoother, the higher the velocity, and the more laminar your flow can be.

Profiles.jpg

Laminar on top, Turbulent on bottom


Cross sectional area does matter, but also, not as much as you might think. The way you approach a decreasing area makes more of a difference in pressure drop. A nice G0 curve is best, to a taper which is still okay, to a ledge which is very bad.

I have also heard that a plenum before the valve helps, so a big bowl. I have seen old school hot rod guys actually port through the head and then weld in filler and them smooth it out so that they can get a bigger plenum at the valve.


My thoughts on velocity would be, not to worry too much about slowing your intake velocities if you are smoothing your walls. It'll probably even out to have similar velocities to OEM velocities. And if you are building your own intake manifold, look into velocity stacks in the manifold. That helps velocities like CRAZY.

Velocity_stack_detail.gif
Click to expand...

Fortunately the mouth of the ports are basically velocity stacks.
 
BramanteCummins said:
Fortunately the mouth of the ports are basically velocity stacks.
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That is a good point. After I wrote that, I was actually thinking about what would need to be done to make good velocity stacks. You'd have to machine the ports to a circle and have the stack match up or something.
 
keifferscummins said:
keep the pics coming I want to do a 24v head some time.
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Just attack it with a die grinder!

Ok, maybe not. There's no point in porting without cutting the intake off. That, and your head is gonna be a pain because the split in the intake and joiner in the the exhaust.
 
Just because the shelf is on it doesn't mean you can't get good flow out of it. I've done so many with the intake shelf on.
 
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