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Single plane or dual plane with EFI?

Paul_G

Paul_G

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Is it really worth the cost and effort to swap out an Edelbrock RPM intake for a single plane intake like a Street Dominator with throttle body EFI? I currently have a 1" spacer under the TB on the Eddey RPM intake and it works very well. Hood wont close now. Running without the hood is super cool BTW
 
Your RPM intake will be better for all around performance than a street dominator.
 
Dual plane for the street unless you have big cubic inches and a very loose converter..
 
A single plane is recommended for efi.
You can mill the center divider down about a 1/2" on the dual plane.
 
if you are going e f i you need to know what you want and how much you want to spend. with a throttle body system a single plan is best if you read or watch vid's most duel plane intakes have cause problems due to puddling of fuel in the lower hafe of the intake. take your time as this is a commitment to wiring and fuel system upgrade then learning how the system works and the adjustments of tuning the system.
 
The factory magnum EFI "keg" intake is basically open.

However, the "turtle" mod is suppose to improve low end.

Kind of turns it into a "torker" style single plane
 
If you are going to go that route, look at the Edelbrock Pro-Flo 4.. Unless you have a 383..

Don't worry about manifold selection with EFI, your are looking for better air distribution with EFI not the air/fuel worries you have with a Carb..
 
R413 said:
Your RPM intake will be better for all around performance than a street dominator.
Click to expand...

This is debatable.... the Holley Street Dominator is actually an excellent intake manifold.

OP, I’d use the Street Dominator w/a throttle body F.I. system.
 
I've been doing a lot of research on this topic and from what I've read the mfgs all state it will work fine, now all ( vast majority) of the users say otherwise.
I've read that milling down the plenum divider will help, I've read about adding a turtle to the floor of a single plane.
I've decide until I get more familiar with the system I will run a single.
Although I havent had much luck setting up my ECU here lately.
I know my Terminator HP has a progressive linkage which may be one of the thoughts on why a dual will not work, starving back half of the motor at idle??? Just a guess...
 
Last edited:
The engine is a 440 based 505 cu". 4 speed manual trans. I could try removing the 1" spacer and see what the result is.
 
I would try it without the spacer, if that enables you to close the hood
Then, if you suddenly have drivability problems, either mill the divider down, or use street dominator.
Personally, I would use the sd. It's an excellent manifold.
 
R413 said:
Your RPM intake will be better for all around performance than a street dominator.
Click to expand...

I was thinking multiport, not throttle body. I will stay out of Old car fuel injection talks, I’m not up on it.

yes the Holley SD intake is good, but more for a racing car higher RPM, converter, 4:10 gears etc. not low RPM Street car.
 
Paul_G said:
Is it really worth the cost and effort to swap out an Edelbrock RPM intake for a single plane intake like a Street Dominator with throttle body EFI? I currently have a 1" spacer under the TB on the Eddey RPM intake and it works very well. Hood wont close now. Running without the hood is super cool BTW
Click to expand...

I believe your overthinking this. As long as the map sensor can see vacuum from both planes it should be fine. You could also "program" the EFI to work if the map sensor only was on one plane, the other plane should be about the same unless there is a problem.
Speed-Density EFI really only has a few sensors (I think just about all the aftermarket EFI are speed density, not mass-airflow?):
1. Throttle Position Sensor (TPS). How far open the throttle is, and how fast is the throttle opening/closing.
2. Engine RPM from Distributor or other trigger device. How fast is the engine spinning. If Sequential EFI, which cylinder is firing.
3. Manifold Absolute Pressure (MAP). How much pressure (or vacuum) is in the intake manifold. Also, indicates engine load, and normally used to set the regulated fuel pressure across the fuel injector.
4. Engine Temperature Sensor. Is the engine cold or warm, used to calculate how much fuel is going to stick to the intake and port walls for temperature related enrichment.
5. Intake Air Temperature (IAT). How hot or cold is the intake air. Again to trim the fuel enrichment based on temperature.
6. Exhaust Oxygen Sensor (o2 Sensor) and that is just when in closed loop, using the O2 to adjust the fuel mixture.
7. On some EFI, might have a flex-fuel sensor to modify the fuel curve depending on the amount of alcohol in the fuel.
 
R413 said:
I was thinking multiport, not throttle body. I will stay out of Old car fuel injection talks, I’m not up on it.
Click to expand...
Sequential multi point is a very nice system and definitely the way to go if you can afford it in tune it.
yes the Holley SD intake is good, but more for a racing car higher RPM, converter, 4:10 gears etc. not low RPM Street car.
Click to expand...
When you say “Holley “SD”, are you thinking strip or street intake? The “Street Dominator” is NOT a high rpm race intake manifold. I’ve used one with excellent results with 3.23 gears in 27-1/2 tires, stock stall converters in fully loaded B bodies.

The “Strip Dominator” is an excellent race I take manifold. I’ve only had the small block version. I can’t remember a big block version.
 
Paul_G said:
Is it really worth the cost and effort to swap out an Edelbrock RPM intake for a single plane intake like a Street Dominator with throttle body EFI? I currently have a 1" spacer under the TB on the Eddey RPM intake and it works very well. Hood wont close now. Running without the hood is super cool BTW
Click to expand...
Throttle body fuel Injection is still a wet manifold, just like a carb. It responds to low end throttle with dual plane manifolds. Straight runner intakes are best for dry systems like multiport sequential EFI. Watch Engine masters, they do a lot of testing and analysis. If you want high rpm power, straight runners work better.
 
Don Frelier said:
A single plane is recommended for efi.
You can mill the center divider down about a 1/2" on the dual plane.
Click to expand...

Ken Farrell, owner of FiTech, has stated numerous times that it doesn't make any difference on their EFI systems. Other brands may vary...
 
I can contribute for multiport
Dual plane works great. Been running it for 11 years. Start with the manifold you would run with a carb. My distribution has always been very good, which is a thing people guess won't be true.
SD intake on a 500" street engine is ok, on a 383 no. It does give up almost 40lb-ft at 2500rpm
 
Well we ran the RPM intake on my boys Dart all last year with the Holley Sniper EFI and it ran faster then when we went to a single plane. We went to a single plane because we will be super charging the new eng. Ron
 
Mine is turbocharged, no issue with dual plane, but mine is a heavy street car.
 
On my son-in-laws 318 we installed a throttle body efi on a performer manifold. we couldn't get it tuned real well at cruise rpm. connected laptop and watched the MAP sensor at it would bounce/vary alot up to peak torque. added a spacer - got better, added another spacer -1 1/2" total, a little better. swapped out to a single plane and we got it tuned easy.

I think the dual plane manifold and the small plenum amplify the pulses and single plane dampens the pulses for better MAP reading on his engine. I also think it would vary from combo to combo.
 
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