Lower manifold mod

[Don W.]

I've searched but struck out. Is there a how-to somewhere on exactly how to mod the lower intake for Vortecs? Reason being I have access to a good welder who, in turn, has access to a heliarc machine and I don't have to pay much. :tup:I need info.

If I can do this and get some heads I'd sure like to go all the way to Vortecs on my build.

TIA

 

[MikeRenz]

Re: Lower manifold mod

www.michaelrenz.com/typhoon/vortecs/

 

[Don W.]

Re: Lower manifold mod

Cool, it's coming out of the printer now.

Thanks!

 

[JSM]

Re: Lower manifold mod

Renz forgot the machine it back flat step.

Heliarc term is very old and not used much if any anymore. Was a brand name referring to tig.

 

[turbodig]

Re: Lower manifold mod

Renz forgot the machine it back flat step.

Heliarc term is very old and not used much if any anymore. Was a brand name referring to tig.

Maybe I'm old, then, but I still call it Heliarc from time to time.

Renz's write up is good, but it doesn't address the port mismatch. Set a vortec intake gasket over that modification and you'll see what I mean.

Nothing that a HF die grinder and some stones/cartridge rolls can't fix, though. There's some pics in tooky's vortec thread.

 

[MikeRenz]

Re: Lower manifold mod

yea...my writeup is basically a "make it work" kinda deal. I did no porting of the heads/intake....no matching....i was curious to see how it'd perform "as-is".

And yes, I forgot to mention the machining flat part...thanks jeff! Surprised no one caught that till now...i wrote this up like 5 years ago at least. :lol:

 

[Don W.]

Re: Lower manifold mod

You could say I assumed that things were machined. Port matching is something I'm still curious about. I know what it means of course, just as to how it applies here with the tall Vortec heads and our low manifold. It seems to me at this point that the lower manifold ports never truly "match" the heads. That the mod just makes it so the manifold bolts up and covers the ports. Correct?

 

[turbodig]

Re: Lower manifold mod

You could say I assumed that things were machined. Port matching is something I'm still curious about. I know what it means of course, just as to how it applies here with the tall Vortec heads and our low manifold. It seems to me at this point that the lower manifold ports never truly "match" the heads. That the mod just makes it so the manifold bolts up and covers the ports. Correct?

Unless you do a *lot* of material adding, you never really get a true match. There's always a bit of a "ski-jump" in the roof of the intake runner where you're blending into the vortecs.

However, almost any blending is gonna be better than leaving them alone. You end up closing off about 15% of the roof of the port by doing nothing, and there's a lot of flow up there in a vortec head.

Ideally, you'd build the runners up so you had a more gradual transition into the port. This gets complicated, since the injectors are in the way, and there's a limit on how much you can grind before you lose integrity on the bung. If you're really going whole-hog, you'd fill the runners in and put in new injector bungs that would raise the injectors slightly. This is past what most people really need.

The manifold pics E-rue posted (somewhere) were a very good goal of what to shoot for. Bear in mind, though, that this is gonna take a fair amount of time to grind.