Intake manifold advice for VORTEC style....

[rewguy]

3900 lb chevy pick up truck.
381 cube engine, 4.020 bore, 3.750 stroke
10-1 compression
Hyd roller, 243/257 on a 107lsa, .560/.550
145#seat, 390# open
howards link bar retro lifters
GM Fastburn heads, 2.0/1.57, PORTED pretty well. Flow 279@.550, 293@.700
750 HP carburetor
4.10 gear/4000-4200 converter, th350
which intake would you run? Its a weekend cruiser/toy. Need something fun from stoplight to stoplight. Has plenty of converter and gear, SO........airgap dual plane? Or since the heads flow decent air, and it has a decent converter in it.....a single plane? I'd hate to cripple a Decent cylinder head with a dual plane, if the dual planes only advantage was below 4500 rpm. Plan on shifting about 6300-6500 max. Hoping to make 475-490hp if that sounds realistic.

[RevTheory]

Since you've got the convertor and gear, how about sizing a single-plane so that it's good and fast at the lift your engine will see? Maybe a one and a half inch, tapered spacer with an anti-reversion plate from Reher-Morrison?

An annular booster carb to help with throttle response and shift-recovery with the reduced signal of a single plane?

[Walter R. Malik]

3900 lb chevy pick up truck.
381 cube engine, 4.020 bore, 3.750 stroke
10-1 compression
Hyd roller, 243/257 on a 107lsa, .560/.550
145#seat, 390# open
howards link bar retro lifters
GM Fastburn heads, 2.0/1.57, PORTED pretty well. Flow 279@.550, 293@.700
750 HP carburetor
4.10 gear/4000-4200 converter, th350
which intake would you run? Its a weekend cruiser/toy. Need something fun from stoplight to stoplight. Has plenty of converter and gear, SO........airgap dual plane? Or since the heads flow decent air, and it has a decent converter in it.....a single plane? I'd hate to cripple a Decent cylinder head with a dual plane, if the dual planes only advantage was below 4500 rpm. Plan on shifting about 6300-6500 max. Hoping to make 475-490hp if that sounds realistic.

I have tested a bunch and the "Professional Products" single plane is hard to beat ... and it is also inexpensive, too.

[steve cowan]

I done a lot of testing this year at the track 50 plus passes and differences in air gap and single plane VIC JNR was 2 tenths and 2 mph up on the single plane.
The air gap was quicker in the 60ft by a few hundredths, this is after also testing a 830 annular, 950 hp and 850 race demon.
Best results were with 950 hp, would pull 1" vacuum through finish line at WOT.
Tried alot of different spacers, with the tapered you will have to blend carb base/ plenum area but then it will mess you up for standard 1"/2" etc spacers for alignment, something to consider.
On a linear acceleration scale my car ran well
383sbc
235-242 SFT
Dart 165cc heads out to 178cc. 1.94"-1.5"valves.
261cfm@550" in
177cfm@550" ex
3650 pound streeter
1.57
7.42 @ 91.50mph
11.71 @ 114.48 mph
In my opinion yours will run very well either way, air gap is not an issue to 6000rpm

[rewguy]

Since you've got the convertor and gear, how about sizing a single-plane so that it's good and fast at the lift your engine will see? Maybe a one and a half inch, tapered spacer with an anti-reversion plate from Reher-Morrison?

An annular booster carb to help with throttle response and shift-recovery with the reduced signal of a single plane?

Intersting. I wish there was a smaller single plane available...........

[rewguy]

What do you think realistic power would be for something like this?

[CGT]

What was ported on the heads and where? A stock fastburn could likely meet your goal. GM 12496822 manifold or Edelbrock 2913 are both smallish single plane manifolds...not cheap though. But yet neither are fastburn heads these days.

[rewguy]

What was ported on the heads and where? A stock fastburn could likely meet your goal. GM 12496822 manifold or Edelbrock 2913 are both smallish single plane manifolds...not cheap though. But yet neither are fastburn heads these days.

There was quite a bit of short turn work done, deepen/widen bowl, etc. Basic full port I suppose youd call it.

[rewguy]

Its been awhile, but I wanna say they peaked in low 260s stock on my bench around .650? But Its been a year ago

[RevTheory]

Since you've got the convertor and gear, how about sizing a single-plane so that it's good and fast at the lift your engine will see? Maybe a one and a half inch, tapered spacer with an anti-reversion plate from Reher-Morrison?

An annular booster carb to help with throttle response and shift-recovery with the reduced signal of a single plane?

Intersting. I wish there was a smaller single plane available...........

Check out a Super Victor. As intimidating as it looks, I don't think it's all that big on the inside so maybe your epoxy work isn't as daunting as it sounds. It's been awhile since I checked so definitely do your own research.

[rewguy]

Holley makes a new intake part # 300-264. Looks promising as a smaller single plane/vortec style

[77cruiser]

I done a lot of testing this year at the track 50 plus passes and differences in air gap and single plane VIC JNR was 2 tenths and 2 mph up on the single plane.
The air gap was quicker in the 60ft by a few hundredths, this is after also testing a 830 annular, 950 hp and 850 race demon.
Best results were with 950 hp, would pull 1" vacuum through finish line at WOT.
Tried alot of different spacers, with the tapered you will have to blend carb base/ plenum area but then it will mess you up for standard 1"/2" etc spacers for alignment, something to consider.
On a linear acceleration scale my car ran well
383sbc
235-242 SFT
Dart 165cc heads out to 178cc. 1.94"-1.5"valves.
261cfm@550" in
177cfm@550" ex
3650 pound streeter
1.57
7.42 @ 91.50mph
11.71 @ 114.48 mph
In my opinion yours will run very well either way, air gap is not an issue to 6000rpm

Thanks for the testing Steve. I'd thought about trying a dual plane on my 421 but after reading your testing thoughts I think it would be a waste of time.

[CGT]

Holley makes a new intake part # 300-264. Looks promising as a smaller single plane/vortec style

I never knew of that manifold...must be farely new. Looks decent for the money in the pics.

[rewguy]

I have to believe......the more cfm a head flows......the bigger the demand for the single plane, no? Could the Airgap manifold in his testing done well because its so much easier to support 260 cfm, than if the heads moved say.....300cfm?

[dfarr67]

There is another dual plane made by Edelbrock- I found it on a Volvo Penta, high rise marine for Rochester quad.