Single plain intakes for small engine with FI

Small Block Mopar Engine

Small LA engine with single plane intake and FI?

  1. Would be better than dual plane intake

    63.6%
  2. Would be worse with dual plane intake

    18.2%
  3. Would not make one dang difference

    18.2%
  1. Syleng1

    Syleng1 Karma is real and Life is short... FABO Gold Member

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    So I want to know:

    If you are typically running on the street a small- small block, say 273 or 318LA and conventional thinking says they do not play well with single plane intakes ( I know people have done it... but without a good breathing heads, a higher lift cam, lower gears and headers and dual exhaust- I've yet to had this work successfully on the street. Single panes just need to much RPM to REALY do their job with a stock 318la motor)

    BUT all factory fuel injections use a single plane intake no mater what the size engine or if Throttle body injection or multiport fuel injection.

    So if you convert a 273 or 318LA to aftermarket fuel injection say Holley sniper or FI tech is a single plane intake better? O2 sensor constantly is changing A/F ratio?

    I know on my 318LA, automatic with a LD340 dual plane intake and minor head work and a decent street cam, dual 2.5" exhaust and the FI TECH throttle body set up... it works "o-k" but not mind blowing. I want to try a single plane to see difference - like "seat of the pants difference". I only have 3.23sg in rear but I have 24" tall rear tires ( kind takes off like a set of 3:55 would with taller tires IMHO)
    And what does the 66' Barracuda weight? 3,000lbs max.

    Any one have any data they want to share?
     
  2. rumblefish360

    rumblefish360 So close, yet so far away FABO Gold Member

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    I haven’t been there or done that... with that said, have you tried a single plane intake manifold? And which one? On the smaller displacement engines, IF the normally found/known single plane intakes were not friendly, perhaps a smaller runner intake from days gone past would help.

    Im thinking along the lines of the likes of an old Torquer or one speced for a 273/318. I’m not sure anymore what’s out there in that nature. But I have noticed the older single planes have reduced plenum volume by compare to what is being made today. This could help.

    Standing by & watching this thread.
     
  3. Syleng1

    Syleng1 Karma is real and Life is short... FABO Gold Member

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    Thanks for the reply, That's kind of my thinking. Smaller intake designed for a 273 / 318 vs most of the intakes are all designed for the larger ports and the difference in the head to intake port causes turbulence. The older single planes were tough on the street in a bad way. Back in the 80's I tried many out but with WAY less knowledge I have now in my 50's about how to make power.
    there is no stumble with FI engines today and if their is... there is a part broken. Most factory cars run flawless minus a few small individual issues. Now trying to find an intake to just "try it out" is what I want to do.
    I'm just curious if a single plane would correct my tip in hesitation on the FI Tech set up.
    It sometimes feels like its laboring - ive watched the numbers and boy do they cover issues with more fuel. A/F ratio goes to 7.0to 1 on accel then will auto correct to 12.0, 12.3 to 1 after a moment of too rich. Same hill, same mashed foot- its just interesting to watch the numbers. I imagine with a "universal fuel injection system" They have to have some protocol to cover stumbles and part throttle decel under ever vacuum drop from any engine CI size. Way above my pay grade. BUT none of the systems on the market I've looked into recommend a single plane over a dual.
     
  4. Professor Fate

    Professor Fate Push the button, Max...

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    I think the Edelbrock Streetmaster 318 may be your only choice for a single plane with the small port size- luckily you can usually find them pretty cheap.
    OP.TrUQXkIQS6AzMA474C474?w=160&h=150&rs=1&o=5&dpr=1.1&pid=21.jpg
     
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    • 67Dart273

      67Dart273 FABO Gold Member FABO Gold Member

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    • rumblefish360

      rumblefish360 So close, yet so far away FABO Gold Member

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      IDK how much water that thread holds since I have seen the FiTech on a B series 383 & a RPM intake. It was a otherwise dead stock engine with a Road Runner cam & headers.

      Im not sure how well the owner tuned it up. He gave the FiTech a, “Ehhhh, it’s OK” rating, a non enthusiast kind of OK.
       
    • Bobzilla

      Bobzilla Well-Known Member

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      OE applications are not really single planes or dual plane. The runners are so long they act like a dual plane.
      This does not matter if you are talking about modern throttle body injection like the Fitech. Throttle bodies still mix air and fuel in the plenum, so the intake has to work well with the mixture.
      On full actual fuel injection, not the throttle body stuff everybody calls fuel injection, you are only flowing air, so those really long runners can be used without risk fuel puddling anywhere.
      If you want to run a throttle body injection system, most guys find it works better at lower RPM if the plenum is not fully divided. So a single plane is fine, and dual plane is fine if the divider has an old school notch in it.
      I should also say that a Fitech system is not going to increase your horsepower much. Maybe little from better fuel atomization, but no real increase. Just easier starting.
       
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      • MOPAROFFICIAL

        MOPAROFFICIAL FABO Gold Member FABO Gold Member

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        great topic I'll refer you all to the Hughes RPM dual plane fuel injected intake for magnums thats a bolt on and a hp and fuel mileage increase.
        Ponder that.
        Then go back to basics and remember the injector is there for a reason and we're trying to get air in... so I don't know...app specific again
         
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        • Syleng1

          Syleng1 Karma is real and Life is short... FABO Gold Member

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          BobZilla I’ve got the notch on my LD340 currently on there. I agree with the HP being less sought after than cold start and drivability. Also I never thought of tbi that light.... your right, fuel puddling up in the runners does not happen with MPI. So simple but spot on. All the Chevrolet’s with TBI intakes I’ve worked on over the years including the 86’ Camaros 5.7 with the twin offset tbi were intakes all were quirky running.
           
        • pishta

          pishta I know I'm right....

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          MPFI intakes flow air, the more the better. The atomization is done by the injector at the last inch so you dont have to have the runners even straight, look at the folded intakes of a lot of newer cars. Getting a TBI is akin to getting an electric carburetor. If your gonna go EFI, go MPFI. Everyone makes them now, no excuse. Making a street master an EFI intake will require the injectors to be almost 45 degrees off the runners if you want an outside chance of hitting the valve instead of the floor. The reason the dual planes are not modded is the 2 planes of the intake runners at the ports would make a very strange fuel rail unless you go 240Z style and run hard lines to individual injectors.
           
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          • flingdingo

            flingdingo Well-Known Member

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            I'll agree with pishta, dry-flow intakes are worlds apart form wet-flow intakes.

            An engine is basically just a big air pump, fuel is secondary, roughly 14 parts air to one part fuel. Therefore, the more air you can get in, and the faster you can get it out, the more HP you will make.

            Dual plane intakes were developed to overcome the shortcomings of a carburetor.
             
            Last edited: Oct 15, 2020
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            • flingdingo

              flingdingo Well-Known Member

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              Syleng1... to answer your question... and I feel unqualified to to so... because I have always felt like you were smarter than me when it comes to engines... but I would try a small single plane like a Victor Jr., my theory being that airflow takes precedence over gasflow, and see what the result is...

              If I had a Victor Jr., I would loan it to you just for the knowledge.
               
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              • MOPAROFFICIAL

                MOPAROFFICIAL FABO Gold Member FABO Gold Member

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                Which is what I said... but then again you have anomalies to that thinking when you look at the that Hughes intake...

                Cant ignore it unless you also like burning books as well...
                 
                Last edited: Oct 16, 2020
              • MOPAROFFICIAL

                MOPAROFFICIAL FABO Gold Member FABO Gold Member

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                Vic 340 and super vic. This isnt a chevy forum
                 
              • flingdingo

                flingdingo Well-Known Member

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                Shhh!!!! I'm a Chevy guy at heart... don't tell anyone!
                 
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                • MOPAROFFICIAL

                  MOPAROFFICIAL FABO Gold Member FABO Gold Member

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                  Been in and around all of them.
                   
                • Bobzilla

                  Bobzilla Well-Known Member

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                  I just realized in the original post you say you are running an LD340 on a mostly stock 318. Now I wonder if you have enough port mismatch to cause a loss of airflow on your 318 heads.
                  Any chance of getting a cheap bore scope down those ports to check how much of step is present where the intake mates to the head?
                   
                • famous bob

                  famous bob mopar misfit

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                  I just read all these posts .
                  No one mentioned that the sensors in the throttle body dont take readings as well in a dual plane , as a single plane .
                  If I were going to run a dual plane it would definitly have the notched divider , altho I haven`t messed with small block mopars , only sbc , hemi`s and my 440/505, which I run a victor intake w/ a throttle body = no complaints !
                  I dont have any low rpm torque problems tho.
                   
                • Syleng1

                  Syleng1 Karma is real and Life is short... FABO Gold Member

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                  Engine is coming out in the next month for other reasons. ISO a proper intake with correct ports as we speak. I’ve read a few old magazines from back in the day that said there is no issues from port size but velocity has to decrease from going from one size port (273/318) to large port (340/360).

                  when I built the engine I was going for “period correct.” Not high performance. But like every gear head.... now that it runs- I want MORE! Lol!
                   
                  Last edited: Oct 16, 2020
                • Syleng1

                  Syleng1 Karma is real and Life is short... FABO Gold Member

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                  Books are my fav! Lots of info to be had with out drama. My post is to show people where to start landing for these throttle body injections for conversions... and learn a bit myself in the process. Kinda like a P.S.A. From my childhood- for adults! Lol!
                   
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                  • Garrett Ellison

                    Garrett Ellison Amateur driver on public roadway, do not imitate.. FABO Gold Member

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                    Long runner tunnel rams are purported to work very well with MPFI. I always thought that a Weiand Xcellerator (7510 or 7545) would make a good street MPFI intake because all the runners are symmetrical and are longer than on most other single plane intakes.
                     
                  • forphorty

                    forphorty Well-Known Member

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                    Syleng, you might want to reread your poll questions. I believe you have your wording mixed up. I would vote in favor of the dual plane .
                     
                  • Syleng1

                    Syleng1 Karma is real and Life is short... FABO Gold Member

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                    Nope! I like the wording.
                    Thanks for reading
                     
                  • TT5.9mag

                    TT5.9mag Two atmospheres are better than one

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                    I’ve done a few multi port efi converted intakes by welding bungs on them. The short answer is “maybe”. On lower hp street stuff you are likely to never even notice if it’s a dual plane or a single plane. If you really get in to tuning it and start looking at afr in individual cylinders and start trying to make big power, you will want a single plane. @MOPAROFFICIAL, I have tried the Hughes magnum airgap and it does work. But never on big hp stuff. And I think that is their intended demographic. I don’t think you’ll ever see that intake making more than 5-600hp.
                     
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                    • MOPAROFFICIAL

                      MOPAROFFICIAL FABO Gold Member FABO Gold Member

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                      I agree with you, and maybe not even 600 but I wouldn't know.
                       
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