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Username Post: TBI on a Dual Plane Manifold??        (Topic#361060)
Posts: 41

Age: 73
Loc: Phoenix AZ
Reg: 09-08-09
05-21-20 12:35 PM - Post#2794404    

New question: I am being told I should run a dual plane intake manifold under my Throttle Body Injectors.

I am told that such a intake will improve my engines torque at lower RPMS like 1500 to 2500.

So what has any of your guys found out: Is this a good or bad idea??




Very Senior Member
Posts: 4819

Reg: 12-29-02
11-21-20 06:29 AM - Post#2808217    
    In response to racprops

Dual planes are to assist a carburetor with doing the proper fuel mixing at idle and low throttle. Not needed with fuel injection.

Super Senior Member
Posts: 3894

Loc: Bedford, Texas, USA
Reg: 11-13-02
11-25-20 09:45 PM - Post#2808626    
    In response to racprops

Factory TBI manifold is a dual plane. The GMPP TBI vortec intake and most aftermarket dual plane carb intakes swap the injectors between cylinder pairings compared to the stock intake. I swap the injector output left and right at the ECM to run manifolds with the opposite pairing. Performer RPM or a single plane like a Torquer 2 is what my TBI engines ran best with. If you run a single plane it is best to setup the ECM to run in Asynch only.

That being said I ran a mercruiser dual plane MPFI intake on the 383 in my Express van. Gave it a signifigant low-midrange torque bump compared to the equal length runner cross ram style L31 marine intake. The dual plane manifold will always give a little more torque with or without fuel flowing through it. The length of the runners offer resonance tuning. Since air pressure waves act the same way as a fluid it can assist the intake charge at lower rpm.

That being said I have run dual planes and single planes on the same Vortec head 350 TBI engine and never noticed a torque loss with the single plane. Had plenty of torque even down at 1,500 rpm. Not like you can really feel 15-20 ft/lbs less torque in a 5,500 lbs van.

1983 G20 Van, 350 TPI, Ported 906 Vortecs, Edelbrock 3817 Base, ASM oversize runners. Reed Custom Roller cam, 700r4, 12 bolt with 3.08 gears, Doug Thorley Tri-Y headers, true duals

Edited by 1983G20Van on 11-25-20 09:55 PM. Reason for edit: No reason given.

Posts: 359

Reg: 07-09-18
09-01-21 01:20 PM - Post#2826399    
    In response to racprops

I have ALWAYS, repeat ALWAYS been suspicious of cousin Elmer and neighbor Bob who have cracked the secrets of the universe in their garage.

General Motors, Ford, Mercedes, etc. have thousands of people and millions of dollars at their disposal and their systems work well. I'm not saying that they cannot be improved, but when cousin Elmer says to do something, I question it.


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