Interesting rule..... but I don't agree with it when you base it on Super Vic intakes and 95% of the 23° heads out there.

I have a set of 300cfm heads here now with a super vic that IMPROVES flow at under .500" and at .600"+ it's only down to 288fm. That's 4% loss, not much at all. Now a perfect intake would probably be worth about 3hp which in this application is about .5% Now back that off to a 272cfm flow (10% loss)with the intake on and you are looking at 15-20hp which is about 3% here.

The thing is a simple port match the intake to the heads, do some minor radiusing around the carb flange and bolt it on Super Vic is going to flow within 4-5% of the heads when it's bolted on. Most times you don't see the mid lift and low lift flows improve but still having flow within that is not hard to do.

Now if you look at LS1 stuff, that intake only flows in the mid 280's with a head bolted to it no matter what you do. Even then a 330cfm head makes more power than a 300cfm head even though the motor only sees the 280cfm. Thing is the motor isin't pulling a constant 28" so it doesn't really matter, at least that's what the dyno says. If you improved the flow of the intake, yeah you would get more power.

I've used Super Vics in low RPM situations and they work really well even there. The ports are tall and skinny as they move from the head to the pleanum and that helps drivability in any motor. Think of a LS1. They usually also have lots more low end TQ than a shorter runner intake like a LT1. You could go to something like a RPM Air Gap dual plane intake converted to EFI, but the thing would have to use a 4bbl type TB on top of it to work correctly.

Also given the same heads I could build a 355 that had more TQ and HP than a 383 if the 355 had a single plane and the 383 had a LT1 intake on top of it.

Bret

 

Interesting rule..... but I don't agree with it when you base it on Super Vic intakes and 95% of the 23° heads out there.

I have a set of 300cfm heads here now with a super vic that IMPROVES flow at under .500" and at .600"+ it's only down to 288fm. That's 4% loss, not much at all. Now a perfect intake would probably be worth about 3hp which in this application is about .5% Now back that off to a 272cfm flow (10% loss)with the intake on and you are looking at 15-20hp which is about 3% here.

The thing is a simple port match the intake to the heads, do some minor radiusing around the carb flange and bolt it on Super Vic is going to flow within 4-5% of the heads when it's bolted on. Most times you don't see the mid lift and low lift flows improve but still having flow within that is not hard to do.

Now if you look at LS1 stuff, that intake only flows in the mid 280's with a head bolted to it no matter what you do. Even then a 330cfm head makes more power than a 300cfm head even though the motor only sees the 280cfm. Thing is the motor isin't pulling a constant 28" so it doesn't really matter, at least that's what the dyno says. If you improved the flow of the intake, yeah you would get more power.

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I was comparing a stock to a sheet metal.
I didn't compare the Super victor because I don't know what it flows or looses on a good set of heads.
The basis is that if ya get an intake that looses less than 10% when on the heads it will make more power than one that looses 10% or more.
If the SV only looses 4% on a set of heads then it will make more power and as i said if the ports are not hogged out it won't effect drive ability much.
It's good to know it only looses 4% cause Wilson told me his lost more than that on his bench. And the manifold I got looses less than that on his bench.
Thanks for the update on the SV.
Could be why all the big flow heads on an LS-1 are going to the Fast intake and 90MM throttle body.

 

I was thinking of having the Rpm Air Gap done, but I did not know you would have to use a 4bbl TB . Would a custom elbo with a stock type throttle body not work?

If not, could you just have someone remove the divider to make a milder single plane?? The reason I ask is because when I can ,I plan to have an intake converted ,but I plan to run a lower compression setup with a turbo on my daily driver. If I was running an 11 to 1 compression 355 , I would not hesistate when the time came to have the super vic done. But I am probably going to be looking at between 8.5 to 1 - 9.2 to 1.

I know a longer intake might not matter as much on a forced induction setup. (although i doubt a super vic would hurt on a turbo or blower setup as many guys seem to convert to victor style intakes , but they are usually more race type stuff.) I like the longer runners, because with lower compression I figure I could have better driveability out of boost vs the lt1 setup . Especially since it's a daily driver. Only issue is , I wonder how a super vic would do compared to an l1t intake on a 9 to 1 compression 355 while not in boost. That's why I thought about the Rpm Air Gap.

 

For a boosted application I would not even bother, the stock intake will make alot of power.


David

 

Unless you are going all out with a race setup the single plane, dual plane or ANY converted carb style intake is a waste of time. Just stick with the LT intake and port it if you have to.

Bret

 

How much gas mileage shoud I be expecting to lose with one of these single-planes?

 

None, the intake doesn't effect part throttle fuel economy but it does usually need more fuel at WOT.... most times guys who do these don't care about fuel economy... it's not a rookie bolt on, you have to play with a lot to get one operating on your motor after you have the intake on there.

Bret

 

Besides tuning and fabbing everything up to fit, what else do I have to do?

 

The fabbing to get the connectors to fit, throttle cables to hook up, air intake setup to work right... fitment between the hood and the cowel... things like that. It's probably more fun that doing a set of LT's or plugs... hell I would say it's like doing both but with less frustration because you can see mostly everything.

Bret

 

Thanks to this thread, I now have a Super Vic / new cam / springs in the works, my pocketbook thanks you all

 

Anytime.
Good luck with it.

 

http://www.gcfba.net/cgi-bin/ikon/ik...;t=5475;st=0;&

Heres some pics of Jared's car. I have read were people in MILD 355's with ported LT1 heads with mild cams were picking up 35-40RWHP and 45-50RWTQ OVER THE PORTED LT1 intake.

This is the intake we need to make Stupid power like the LS1's basically in fact this intake kicks the crap out of ANY intake the LS1 boys have to offer (LS6, 90 FAST LSX). This intake would love some 300 CFM heads in say a 396, I will let you guys know how it goes can you say 500+RWHP

 

That's exactly what this thread was all about,one like that.
It aint a magic cure but it will help.

 

Larry, thanks you sig gives this thread that much more meaning!

"No ones idea is a good idea, until it becomes someone else’s idea" - John A. Stine

Bret

 

Alright, Ive been reading the thread and will bite.

The intake is on and running.

300+ cfm heads, mid 11:1 CR 383. I dont have any worthwhile dyno's or track times since the car really has just been sitting and sitting and, well, sitting. Too busy with other things to get all the kinks of the new setup worked out.

But i can answer a few questions I guess if anyone has some.
http://memimage.cardomain.net/member...06_14_full.jpg