Dual Plane vs Single Plane Manifold with TBI

[65 Dartman]

Wondering if there are any advantages or disadvantages to using a dual plane intake (such as the LD4B) over a single plane intake such as a stock 66/67 Commando when using a TBI such as the Sniper/FiTech? I have both manifolds and see the TBI will bolt right up to the LD4B. If using the Commando, an adapter is required. Would like to see Any and all comments from the guys and gals in the know on this subject

 

[Mr. Sinister]

I think a single plane would be the better choice *almost* all TBI setups appear to a smooth straight forward design. JMO

 

[Locomotion]

No F.I. experience here, but it would seem that the A/F ratio would be more consistent with a TBI when using a single plane intake. With a Holley 750 DP carb, I have experienced different jetting requirements between plenums on a dual plane by 2 jet numbers. The deeper plenum ran leaner than the shallower plenum. I happen to notice one day, when I had all the plugs in a holder, that the plug coloration coincided with the plenums. Car ran several hundredths faster when the "square" jetting was adjusted accordingly.

I can't be sure if that applies to all dual planes. However, also with carburation, it appears that in most cases when an adapter is used, it has a negative affect on airflow. Spacers, on the other hand, can be a useful tuning aid.

 

[Mike67]

I have a Terminator set up and researched this question heavily. The techs on the Holley forums say there is no issue running a dual plane, however everyone else says that if using a TBI you need to machine down the divider 1" x 2" to help keep the signal balanced unless running a 1" spacer..
With all that said I've never dialed mine in completely, basically it has been just @ idle... Was just about to get it in the road for some learning miles but found some metal in my pan, so I'm having to start all over.
Which ever set up you are going to use I highly recommend you joining one of their tech forums and get it straight from the horses mouth('s).

 

[RustyRatRod]

Tons of TBI systems used dual plane intakes from the factory. That said, even though it's a "glorified carburetor", I would imagine being fuel injection, would lend itself somewhat immune to the effects of "which" intake to run. In other words, I don't think it makes "much" difference. At least not like with a carburetor.

 

[MoparMike1974]

I have read countless threads where its said that the divider needs to be milled down if running dual plane. I think engine masters did a dyno test and was having issues until they milled the divider. I dont know if its true but it seems to be common opinion.
I have msd atomic on my swinger with an air gap intake, divider intact. Have not driven it so it can learn. It does have problems coming back down to an idle off revs. A couple feathers and it idles down and will idle fine after that. Im hoping it will tune itself and that will go away. Maybe I will have to mill the divider....hope not.
If your intake is off the engine I would go ahead and mill a slot in it. It wont hurt anything and it will eliminate having to do it later if your having issues with the FI.

 

[famous bob]

I think a single plane would be the better choice *almost* all TBI setups appear to a smooth straight forward design. JMO

I saw a test , ''dont remeber where '', but a single plane had better readings for the f.i. to operate -------
ALSO FUEL DISTRIBUTION IS BETTER BETWEEN THE RUNNERS ----------

 

[65 Dartman]

FWIW while looking at the Edlebrock Pro Flo 4 system, their intake is a single plane

 

[Ted Carlson]

I have a SB with header and I had a single plane. When I put A dual plan on my engine my drivability went through the ceiling. If you are just cruising a dual plane is the answer. A single plane needs gears and stall to be really effective.

 

[famous bob]

I have a SB with header and I had a single plane. When I put A dual plan on my engine my drivability went through the ceiling. If you are just cruising a dual plane is the answer. A single plane needs gears and stall to be really effective.

KINDA DEPENDS ON UR ENGINE SIZE AND TOQUE , STROKER BIG BLOCKS HAVE AMPLE TORQUE -----------dis regard caps , cant keep my fingers off of it .

 

[DionR]

I will have to go back a look later, but I know on Engine Masters they mentioned they have had a situation where one of the TBI systems could not be tuned with a dual plane. Ran fine on a single plane intake.

 

[65 Dartman]

I have a SB with header and I had a single plane. When I put A dual plan on my engine my drivability went through the ceiling. If you are just cruising a dual plane is the answer. A single plane needs gears and stall to be really effective.

Was that with a carb va or TBI?

 

[dgibby]

I've run the Holley Sniper for a few years with a dual plane with no issues, no center divider modifications either. I have also run it with an open 1 inch spacer on it and did not see any difference in drivability or performance.

 

[DionR]

It was episode 86 of this season of Engine Masters where they were comparing a carb to TBI (Holley Sniper) in a blow through application. But they spent some time talking about how they had trouble tuning TBI on a dual plane.

Might be an issue at full throttle rather than constant state? Don't know.

Looks like people make it work on a dual plane and the manufacturers don't seem to care.

Edit - I should add that I didn't find them saying they couldn't run the TBI on a dual plane. So maybe I am mixing that up with something from a different show.

 

[Phreakish]

I've run my fitech on both a single plane (victor 340) and a dual plane (rpm airgap) - no major changes in part-throttle driveability.
I did notice my spark plugs are more consistent, cylinder-to-cylinder, with the victor. The cylinder-to-cylinder difference on the airgap was pretty minor though.

 

[famous bob]

I've run my fitech on both a single plane (victor 340) and a dual plane (rpm airgap) - no major changes in part-throttle driveability.
I did notice my spark plugs are more consistent, cylinder-to-cylinder, with the victor. The cylinder-to-cylinder difference on the airgap was pretty minor though.

FAST RECOMMENDS A SINGLE PLANE FOR BEST PERF. .

 

[Mean416]

I think it mostly comes down to the overall combo. Just like with a carb. A dual plane with throttle body should exhibit similar behavior carb or EFI.

I *think* the milled center divider is more about making sure you have a smoother signal to the map sensor. I would probably try doing this with a spacer instead and experiment.

 

[famous bob]

I think it mostly comes down to the overall combo. Just like with a carb. A dual plane with throttle body should exhibit similar behavior carb or EFI.

I *think* the milled center divider is more about making sure you have a smoother signal to the map sensor. I would probably try doing this with a spacer instead and experiment.

Not entirely so, the readings to the throttle body can be affected by a dual palne , guess it depends on where the sensors are at ---------??

 

[George Jets]

Sounds like you are running a 318. Here is the perfect TBI Dual Plane intake manifold mopar used on their '89 to '91 318 TBI engines for their 318s.

Factory plenum is dropped on this one. Ma Mopar built this one for TBI.

Can easily redrill and tap threads into the mounting flange if they don't line up with your new TBI setup.

They are a bit of a mid rise manifold and have the port runner sizes to match the 318 heads. Port Matching the heads to this manifold is recommended, although you can go without. Me I would port match it, easy enough to do.

Not sure if they make a 4bbl TBI, some more options:

I use these TBI mid rise manifolds with the 4 bbl adapters for the 318s because the port runners are the right size for the 318 heads. Running the 318 TBI intake with a 4bbl carb in my 318 truck right now. (LD4B intakes are becoming few and far between and expensive for the 4 bbl 318 carb setups)

 

[George Jets]

Interesting, Interesting:

2bbl Sniper could be used with the Factory '89 - '91 318 TBI Intake.

Also the the 4 bbl Sniper would be a nice setup with the ready to bolt up LD4B 318 intake.

Then the subject of the plenum comes up with the LD4B. I think I would likely leave it as is and run it without cutting down the plenum, using the Sniper setup.

The theory I understand of the single plane vs the dual plane intakes is that at lower rpm the single plane manifolds allow cross pull of intake gasses from the other bank of the engine because both banks share the plenum.

On dual planes the 2 banks are blocked off, separated by the plenum divider, so you don't get that cross bank intake gas pull from side to side. Resulting a more controlled lower rpm range.

Have fun looking into things, I always like experimenting with ideas that will work.

☆☆☆☆☆

 

[George Jets]

If you don't want to hack up your LD4B plenum divider you can use a carb spacer to give the same effect as cutting down the plenum divider.

Can experiment easily this way without doing irreversible damage to your rare LD4B intake.

Good Luck

☆☆☆☆☆

 

[65 Dartman]

Sounds like you are running a 318.

Nope, a 66 273/235 Commando

Not sure if they make a 4bbl TBI,

I don’t think so

 

[George Jets]

If you don't want to hack up your LD4B plenum divider you can use a carb spacer to give the same effect as cutting down the plenum divider.

Can experiment easily this way without doing irreversible damage to your rare LD4B intake.

Good Luck

☆☆☆☆☆

Think the D4B 4bbl intakes were for the 273s, they have different angled bolt holes.

Can ask @toolmanmike as he has worked with 273s and knows them. Some have re-angled the bolt holes on the LD4B so that they will bolt up to the 273 heads.

Not sure if the newer 302 heads will bolt onto the 273 block? If so then your LD4B intake will bolt right up to those.

 

[toolmanmike]

Think the D4B 4bbl intakes were for the 273s, they have different angled bolt holes.

Can ask @toolmanmike as he has worked with 273s and knows them. Some have re-angled the bolt holes on the LD4B so that they will bolt up to the 273 heads.

Not sure if the newer 302 heads will bolt onto the 273 block? If so then your LD4B intake will bolt right up to those.

The D4B's were for 64 and 65 heads with 5/16" bolts at closer to vertical angles. The LD4B intakes are for 65 and newer 273/318 heads with 3/8" bolts closer to 90° to the intake surface.

 

[George Jets]

The D4B's were for 64 and 65 heads with 5/16" bolts at closer to vertical angles. The LD4B intakes are for 65 and newer 273/318 heads with 3/8" bolts closer to 90° to the intake surface.

OK great, ^^^^ so for the sake of conversation the '89 - '91 318 TBI intake manifold will bolt up to those '66 273 Heads.