TBI on a dual plane Manifold??

[Pinger]

Am I correct in thinking a non TBI Vortec 5.7 has a single plane manifold?

 

[95nProgress]

Erik, that Engine Masters link is for dual/single plane intakes for carbureted applications. TBI is quite different in regards to needing the smaller plenum volume for low end torque. The computer controlled TBI can be programmed to compensate and exceed the old carbureted single plane idealogy. As stated if you are doing your own ECM programming I would highly suggest a single plane intake for all across the board increases including low end towing.

Brian

 

[ccreddell]

Ive been running a dual plane for years-way better than the stock manifold. When I rebuilt my 350 into a 383 I used the same manifold with a 7.4 throttle body-and scored the adapter/plenum with it. Now each of my throttle bores can feed either side of my manifold.

 

[L31MaxExpress]

It's been a while but I clearly remember that when I went from the common dual plane intakes (stock & Holley) to a single plane (Weiand 7525) on my TBI it was a tremendous improvement. None of that single plane low end loss that you hear about when using carbs because of the TBI. I would highly recommend a low rise type single plane over any dual plane for a TBI specifically if your doing your own programming.

Brian

Same experience here. It was stronger eberywhere over the 2,400 stall speed. Also ran the edelbrock small runner single plane mpfi TBI conversion intake once on a TBI 350. It gained a very noticeable amount of power everywhere.

 

[95nProgress]

Ive been running a dual plane for years-way better than the stock manifold. When I rebuilt my 350 into a 383 I used the same manifold with a 7.4 throttle body-and scored the adapter/plenum with it. Now each of my throttle bores can feed either side of my manifold.

What dual plane are you running?

 

[kenh]

Not to muddy the water here but would a spacer plate under the throttle body do any good. (Over the whole range or low down)

Or this an old carb trick that has no place with TBI?

Ken

 

[95nProgress]

Not to muddy the water here but would a spacer plate under the throttle body do any good. (Over the whole range or low down)

Or this an old carb trick that has no place with TBI?

Ken

Ken, a spacer under the TBI unit is also slightly beneficial. This is where it IS similar to carburetors. It lenghtens the path for the air/fuel mixture. An open spacer, open between the two TBI bores, evens out the mixture as well. Same benefits as spacers under carbs. Now multi-port FI thtottle body spacers are worthless.

 

[L31MaxExpress]

Ken, a spacer under the TBI unit is also slightly beneficial. This is where it IS similar to carburetors. It lenghtens the path for the air/fuel mixture. An open spacer, open between the two TBI bores, evens out the mixture as well. Same benefits as spacers under carbs. Now multi-port FI thtottle body spacers are worthless.

I recently saw in a FB group I follow a guy that had a 500cfm 2bbl on a dual plane intake with a very tall custom built twin tube spacer. The spacer was probably close to 6" tall. Claimed the spacer really made the old TBI long block very torque. Charge cooling must have been very noticable because the tubes were sweating with moisture on an 85°F day.

 

[L31MaxExpress]

Found the posts and the pictures he posted.

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[Gramps]

Not to muddy the water here but would a spacer plate under the throttle body do any good. (Over the whole range or low down)

Or this an old carb trick that has no place with TBI?

Ken

I can vouch for the spacer on a tbi motor - at least on a not stock build. We dynoed without and then with the spacer, and actually gained 8 ft lbs and 10hp. Put us over the 300hp mark while running the stock ecm.