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I am looking at an Edelbrock #7115 Tunnel Ram manifold. It comes in oval port and I have Rectangular port heads. For the most part the runners look pretty close to the same except at the ports would I loose anything using if I port match the manifold to the heads?
 

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steelcomp was here
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Can I ask why? Would I be better off installing it the way it is?
How big is the engine and what rpm are you wanting to run?
For any real benefit you'd have to port the entire runner all the way to the plenum and honestly, I don't think there's enough material in the oval port runners to do that. That's a ton of work, and so is just matching the ports- for no gain. The port mismatch isn't going to hurt anything.
 

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Discussion Starter #5
How big is the engine and what rpm are you wanting to run?
For any real benefit you'd have to port the entire runner all the way to the plenum and honestly, I don't think there's enough material in the oval port runners to do that. That's a ton of work, and so is just matching the ports- for no gain. The port mismatch isn't going to hurt anything.
Thank you. It is a 468ci. only looking to run about 6k rpm. I am currently running a 850 holley on a victor.
 

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I didn't think you could run an oval port intake on rect. port heads at all.

I know you can run a rect. port intake on oval port head tho.
 

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Back when I tried it, my oval intake wouldn't completely cover the rectangle ports. Would have had a slight vacuum leak :)
 

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Back when I tried it, my oval intake wouldn't completely cover the rectangle ports. Would have had a slight vacuum leak :)
Depends on the manifold. Its very common to run a Dart oval port manifold single plane on rect heads. Also very common to run the Dart 4150 manifold with an adaptor to fit a dominator as well.

But you could very well be right about a Edelbrock T ram not having enough flange to seal off the rect heads.



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Back when I tried it, my oval intake wouldn't completely cover the rectangle ports. Would have had a slight vacuum leak :)

I didn't think about that apsect, I was just thinking going from a small port to a larger made more sense, than a large manifold to a small port.
 

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steelcomp was here
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I didn't think about that apsect, I was just thinking going from a small port to a larger made more sense, than a large manifold to a small port.
As a general rule, you never want an intake runner to go from smaller to larger, in the direction of flow.
Always larger to smaller.
A well prepped set of large ovals can flow more air than most oval port intakes, so there can be some benefit to running a rect port intake on an oval simply because of more runner volume, even over the port mismatch. To make that oval port TR work on rect port heads, you'd have to port the entire runner, and make it bigger where it starts in the plenum than it is at the head. You want the intake runner to taper gradually (in area) form larger to smaller. Just opening the openings at the heads to match the ports does absolutely nothing, and in fact, can really screw up the airflow.
 

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You never see a properly designed T ram with runners that are smaller at the top, or even the same size. Although it looks like the oval port Eddy T ram has tapered runners top to bottom, I seriously doubt the are large enough at the plenum to accommodate the increase in size when the port opening is opened to rect size.
Like Steel says, this simply means the air is going to stall out and lose what ever velocity it had up to the point that the port size increases. Right where you really don't want to give up any velocity.



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not to take anything from anyone else but between steelcomp and gn7 you have boatloads of knowledge if they are willing to respond (and they seem to be) id listen
 

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OK now I understand, the increase in velocity going from big to small more than offsets the turbulence caused by the port mismatch.
 

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Rect port intake on Oval port heads use to be an old hot rodders trick to combine the low end power of an oval port with high end of rect. But then again that was before they had so many good oval port intakes.

X2 on listening to GN7 and Steelcomp. A lot of good knowledge there.

Rect port T/R's are so plentiful and for a good price, why would you even mess with trying to mismatch it? I'd just buy the right one. JMHO
 

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The Edelbrock Vic oval will bolt and seal just fine on square port heads. They will run good also, even with the ports in the intake being smaller. Factory oval / square ports arent that far off on the match up any ways.
 
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