Intake porting question?

jasonn · Sep 13, 2006

Anybody ever port their intake? Looking for any pics of the plenum area of a ported intake. I have ported many heads and matched the intake but I was wondering how to shape the plenum area and weather or not to open up the whole port (cross section). I have an edel perf rpm on the 408 right now and just bought a vic jr. I know that some people will say leave that to the pros but I have learned you never learn anything without trying.

302 coupe · Sep 13, 2006

I don' tthink there much you can do with a dual plane's plenum area. You could notch the didivider and do a port match, but I don't see how you could do much with the rest of it.

The single plane is more workable, but it depends on the engine combo. Some people knife edge the runner ends, some grind 'em back, some make 'em longer. I'd just make sure everything is smooth and the ports line up.

fasttback · Sep 13, 2006

On my single planes I clean up all casting flaws and smooth out any sharp-machined areas. I try to have consistent measurements between runners when applicable. I've heard (never verified) that some of the roughness in the plenum helps "mix" the air/fuel, so I don't polish it. Of course, they are gasket matched to the heads.

Hack · Sep 13, 2006

fasttback said:
On my single planes I clean up all casting flaws and smooth out any sharp-machined areas. I try to have consistent measurements between runners when applicable. I've heard (never verified) that some of the roughness in the plenum helps "mix" the air/fuel, so I don't polish it. Of course, they are gasket matched to the heads.

You really want to match the ports to each other rather than gasket matching.

67Dylan · Sep 13, 2006

Hack said:
You really want to match the ports to each other rather than gasket matching.

How do you match ports on 1, 4, 5, & 8 from intake to heads?

fasttback · Sep 14, 2006

Hack said:
You really want to match the ports to each other rather than gasket matching.

Although I did not stated correctly, this would be included in my gasket matching. Both gaskets and ports should be considered when porting. Some of the flow gains could be lost if your gasket is protruding into the runner, so don't forget about them completely.

Gaskets provide a good template, have consistent dimensions between the ports and can be aligned using the block, head, and bolt holes. So no worries about that gasket moving around when you tighten those manifold bolts because you know where it’s suppose to be in relation to your port job.

brianj5600 · Sep 14, 2006

jasonn said:
I know that some people will say leave that to the pros but I have learned you never learn anything without trying.

I am all for DIY, but with out a way to verify results, I am afraid that what you learn will be to leave it to the pros. Runners with different flow will run richer and leaner, which could be bad. Cleaning up casting flaws is good, but redesigning runners w/o a way to verify results is not.

jbuening · Sep 20, 2006

I too am curious how you match the ports on a dual plane intake. Anyone?

Hack · Sep 20, 2006

jbuening said:
I too am curious how you match the ports on a dual plane intake. Anyone?

Maybe I'm missing something, but it doesn't seem that difficult to me. Wouldn't you just make a template similar to a gasket except keeping the ports as small as possible? The template would either match the intake or the head, whichever is slightly larger.

My only point in my original post is that it's not the best idea to have the ports' cross sections change. I would expect the gasket is oversized to allow for tolerances in the equipment making the gaskets. That and every gasket/brand of gasket is going to be a little different. So if you make the ports as large as the gasket you have this low velocity area where the fuel can separate from the air. You've also created a situation where the next gasket could be slightly smaller and it will hang out into the port(s).

I'm no expert, it just doesn't seem like a good idea to me.

Intake porting question?

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