I'de like to know your opinions on an airgap intake manifold for tbi. I've heard tbi needs some heat in the intake manifold for atomization. Is this true? What would be the downside to running an airgap as opposed to a traditional intake manifold?

 

Mine ran good with the AirGap.

Much better than with the Edel TBI manifold, even though it was Extrudehoned.

Then, I experienced icing of the throttle blades on a 50 degree day. Of course I am also using a CAI.

Anyway, I switched out to a single plane, with EGR provision, with no air gap. No icing on a 30 degree day.

Oh yeah. It runs even better with the single plane. Throttle response is nothing short of amazing, and I lost no bottom end with the single plane.

 

Atomization is what occurs at the injector, and at the butterflies edge at less then WOT, it basically the shearing of fuel. Vaporization is what heat does to fuel.
Minor nitpic, but makes it easier when everyone's on the same wave lenght.

For all out racing cold is better.
For a street car, you need to put some heat into the fuel so that it does start to vaporize before it gets to the intake valve.
I tried better part of a dozen manifolds on my car and the Wieand 7525 was the best. I cost a little HP just off idle but it was better everywhere else than any other manifold I tried.

From what I've been able to find out about gas usually the low end aromatics start to boil at 130dF, and in watching MAT temps on my car, you can feel it when the temp gets over 130dF the car does drive much nicer. Also if you google for Negative Supercharging they deliberately heat the intake air to about 120.
HTH

 

Do you have a part number for the intake you are using. I may be switching out my performer TBI for one very soon.

 

Don't think my p/n will work in your application.

Mine's for an oval port BBC

Bill

 

Yea I figured when I saw the 454 in your scnreen name. I wonder if the SB version would work well.

 

Hey va454ss... I'd just like to clarify. I'm building a new 355 for my '88 pickup and I was considering a single-plane weiand... I know where I can get one probably super cheap. Being a truck, I'm mainly going for low-end grunt, like 2-4k. Now, it seems to make sense that a single-plane wouldn't kill off as much bottom end as on a carbed vehicle, but I do desperately need it to haul around a 4600lb beast like this. So whadda you think... is the stock manifold good enough for say 5 grand, or is it restrictive enough to bother changing? I do have ported early-style 993 1.94 headsand a mild cam. Any help from guys who have already compared would be a big help.
Drew

 

LOL. My truck is a 90, so I know what you're talking about lugging around 4600 lbs!

With the Edel TBI manifold, my truck ran outta breath at 4600 RPM. It was very responsive off idle, though.

Really, I can tell no loss of low end performance with the single plane. I was willing to accept some, for the better performance up top, but now I have great response down low AND upper RPM pull. In my opinion, TBI with a single plane is a match made in heaven.

Again, my truck is a big block, but it is super mild, and only has a CR of 8.0.

I really need to start my own tuning, as it moves so much more air that now my tune is way off. Even with that, I can say that single plane was a great decision, and with tuning, can only be better!

I don't want to come out and say yes, do it, and you not be happy. All I can say is I'm extremely pleased with the results so far.

 

oops wrong post

 

Cool, thanks for the info man. Turns out it's a Street Dominator intake, kind of a high rise. Hell, mebbe I'll take the chance... then I won't have to mess with the intake bolt angles. Hmmm...
Drew