[enkeivette]

So I now have probably 5 hours into port matching and smoothing out my intake manifold. Lots of rough spots in there, I was surprised. And I had to take a bunch of material off the ports to get them to match up to my heads. Hope I gain more than 10hp for all that work!

[anthonydalrymple]

You probably will gain a good bit of some HP..... One way to find out...

[enkeivette]

I'll probably gain the most hp from no longer having a leaking intake manifold gasket.

[anthonydalrymple]

True.... Port matching is a tricky subject of which I've only barely communicated with a know "superb \ well known" porter. His theory involves two types of porting; one for the street & one for pure race track only. The street version involves making the port large at the opening, smoothly transitioning to a smaller dimension in "the middle", and then back to the same diameter as the opening at the "exit'. This is both for the intake and the heads individually by the way..... His theory for the race only version of course involves equal port dimensions of the largest matching dimension; enlarging from the intake through the head. Of course this involves taking the worst intake \head port, enlarging it and maximizing the flow of that given port, and working the other ports to match..... IMHO.... Yes, he's one of the guy's whom have built engines for the Car Craft Engine Builder's challenge and has consistently placed in the top three over the last 2 years....

[BRUTAL64]

Originally Posted by anthonydalrymple

True.... Port matching is a tricky subject of which I've only barely communicated with a know "superb \ well known" porter. His theory involves two types of porting; one for the street & one for pure race track only. The street version involves making the port large at the opening, smoothly transitioning to a smaller dimension in "the middle", and then back to the same diameter as the opening at the "exit'. This is both for the intake and the heads individually by the way..... His theory for the race only version of course involves equal port dimensions of the largest matching dimension; enlarging from the intake through the head. Of course this involves taking the worst intake \head port, enlarging it and maximizing the flow of that given port, and working the other ports to match..... IMHO.... Yes, he's one of the guy's whom have built engines for the Car Craft Engine Builder's challenge and has consistently placed in the top three over the last 2 years....

That's pretty much Basic Head Porting 101.



I've been porting heads since 78. One thing to remember, "It is sometimes more important what you DON"T remove than what you do remove".

[Vettezuki]

Originally Posted by glenn64vette

That's pretty much Basic Head Porting 101.



I've been porting heads since 78. One thing to remember, "It is sometimes more important what you DON"T remove than what you do remove".

What's the basis of the theory, particularly for the different dimensions in the street application?

[enkeivette]

Not sure but they do the same thing with headers. Maybe decreasing the diameter (so to speak) of the port in the center causes the velocity of the air to increase, and the widening of the port causes a sort of scavenging effect? I really have no idea though.

[anthonydalrymple]

Originally Posted by Vettezuki

What's the basis of the theory, particularly for the different dimensions in the street application?

From what I think I understand about this: It has to do with the "pulse waves" created by the valve opening \ closing timing events of the natural combustion process. Exhaust scavenging operates in a similar manor and the Thorley Tri-Y header claim to fame.

[SeanPlunk]

That's really interesting. It's amazing all the science and physics behind making big horsepower.

[Vettezuki]

Originally Posted by anthonydalrymple

From what I think I understand about this: It has to do with the "pulse waves" created by the valve opening \ closing timing events of the natural combustion process. Exhaust scavenging operates in a similar manor and the Thorley Tri-Y header claim to fame.

That would suggest the porting techniques are RPM related and the analogy of the Tri-Y to Long Tube is good.

Tri-Ys: great for low end torque (what is most needed in street applications).
Long Tubes: great for high rpm power (what is needed for race applications).