Intake Manifold Porting Show ‘n Tell

[Joe-71]

The outlet of the intake manifold port needs to be the velocity point in the runner. Opening it out to a gasket size will slow down the flow every time unless the ports are larger than the gasket size. As a retired USAF crew chief on fighter jets, I was always in awe of the afterburner closing up to make more power, speed up the gases through the engine, and produce more power. It is the same principle of a garden hose where you close the nozzle up and squirt the water further out than an open hose. I have been porting for over 50 years, and seen every style of porting that was the hot ticket over those years. The runners need a taper out to the head and opening up the outlet the last inch or so to a gasket size will slow down the flow. Line of sight is always going to be a plus in any port, and the longer the straight with a taper, the faster the flow. I still try to maintain at least 115% of head flow in any manifold runner, and 120-125% in a race intake manifold. Joe-71

[skinny z]

I still try to maintain at least 115% of head flow in any manifold runner, and 120-125% in a race intake manifold. Joe-71

Now this begs the question (or my question anyway), who has flow data on the Vortec RPM Air Gap (7516)?
I've come across a few manifold/head combined flow tests (IIRC Weingartner did a series on this recently) but nothing with this popular dual plane.
One of my reasons for asking (and I asked in another thread here somewhere) is with respect to simulations. Is the manifold killing the flow bench data for the heads or enhancing it?

[SpeierRacingHeads]

I have used this over the years. I also had plates CNC'd to my heads I offer so I can use that as a template on the manifold.

[ChopperScott]

Intake is the Holley 300-110 OTB

How is the port alignment on that one? What gasket are you using with it?

[Bigchief632]

Intake is the Holley 300-110 OTB

How is the port alignment on that one? What gasket are you using with it?

Alignment is pretty decent on this one. Set it on one engine to compare awhile back. Haven't gotten to far on this one yet, but likely a modified 1206. It's going on a pretty snorty 434. Unless the plan changes in the meantime, which usually happens often.

[ChopperScott]

Intake is the Holley 300-110 OTB

How is the port alignment on that one? What gasket are you using with it?

Alignment is pretty decent on this one. Set it on one engine to compare awhile back. Haven't gotten to far on this one yet, but likely a modified 1206. It's going on a pretty snorty 434. Unless the plan changes in the meantime, which usually happens often.

Keep us informed. Any details on that engine? I still haven't decided what to do with the 300-110 that I have.

[skinny z]

Unless the plan changes in the meantime, which usually happens often.

Ain't that the truth!

[1980RS]

I am still a believer in what Joe Sherman said years ago, that "port matching is a waste of time". In 2019 I ran my GM super victor Vortec intake but the ports were so bad on it I had to open them up to a 1206 gasket from the Vortec pattern. When I decided to run that on my flat top 406 with my 062 2nd Vortec head test, the side walls and port roof were horribly off, but I ran it anyway. Didn't seem to matter, the car ran like a scalded cat and I blasted down the track into the high tens. Never in a million years would I have ever though that something that badly matched would go that well. Reminds me again of the Square port intake on oval port heads, still seems to work.

A 1206 manifold opening to a Vortec port? That's about as far off as I could imagine.
Looking at the RHS port and the Edelbrock 7516 intake, it's night and day compared to the mismatch above. In fact I'd say it's pretty good judging by the imprints on the gasket.
It may be that aside from a little trimming of the gasket that's edging into the port in various locations, that this will go back together just as it came apart.

All I know is that darn thing worked.

[ChopperScott]

Work in progress...

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[ChopperScott]

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[ChopperScott]

The ports were a little wonky on this one, but straightened out well enough. It stills needs some plenum work before completion...

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[ChopperScott]

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[ChopperScott]

Plenum work is finished on the 300-25...

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[Wetflow]

Does anyone here cut their own intake gaskets to match the head/intake flanges? Or does the small void left when not "gasket matching" not have enough on flow to matter?

[EDC]

Does anyone here cut their own intake gaskets to match the head/intake flanges? Or does the small void left when not "gasket matching" not have enough on flow to matter?

Gaskets are for "sealing" and not porting templates.

Hence, nearly any properly sized port would require a modified store bought gasket.

On the Ford cylinder head packages I provide, the intake gaskets are custom made for each of the runner sizes.

https://www.flowtechinduction.com/custo ... b-ford-xl/