Hughes Engines Tech Center: Single vs. Dual Plane Intake Debate


Aside from being a top-shelf supplier of performance parts for Mopar applications, Hughes Engines is an absolute treasure trove of knowledge on how to squeeze every last pony out of your small block, big block, or modern Mopar engine. Their technical article index is chock full of information including this great little snippet answering the age old question of single plane versus dual plane intakes:

A single plane intake will flow more air than a dual plane intake for the same engine! Does that make it better? In about 90% of the cases, that’s a big no good, buddy! In fact, in 90% of the cases, a dual plane intake will outperform a single plane. Some years ago, we did a dyno test of a small block Mopar 408” (see our dyno test #19). This engine produced 630 horsepower with a single plane intake and 580 horsepower with a dual plane.

However, the dual plane was within single digits of horsepower and torque up to 5,500 RPM. And, at 4,000 RPM, the dual plane was 60 hp and 80 ft.-lbs. of torque better. The single plane was only stronger from 5,600 RPM to 6,800 RPM. So, unless you had a 4-speed or a 5,000+ RPM stall speed and drove with your foot on the floor, the dual plane would dominate, especially on the street when you nailed the throttle anywhere near 4,000 RPM – hang on!

If you want to brag about your maximum horsepower, use a single plane. If you want to drive your car and enjoy it, use a dual plane. This is another one of those trade-offs you must deal with when building an engine. As a side note, there are ways to make a dual plane intake act more like a single plane intake – in other words move the power range to a higher RPM level – with some mid-range power traded off. But there are no ways to make a single plane act more like a dual plane.

So does this mean that the flow bench lies when it says the single plane flows more? No, what it means is that flow numbers alone don’t tell you the whole story; it’s the combination of parts and, just like any powerful sports team, the keyword is TEAM! What this tells you is to pick a combination that meets your needs, not some pie-in-the-sky dream engine that is a nightmare to drive or because some “chatter” on the internet says it will work.

Now, the next question to be asked and answered is, “How are you going to use your engine?” If it is on the street up to 70% of the time, the dual plane will be your best choice. If it is 50/50 street/strip, you have a tough decision and know that neither manifold is perfect for a 50/50 engine. If it is a 4-speed and you are going to be shifting at 6,500 RPM+ or you have a high stall automatic (3,800/4,000 RPM), the single plane would be your best choice. And get a trailer! You will probably need it.

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Kent Will

Kent Will

News Editor Kent grew up in the shop with his old man and his '70 Charger R/T. His first car was a 1969 Super Bee project when Kent was fourteen. That restoration experience lead to pursuing a degree in Mechanical Engineering and a career in manufacturing. Since then, the garage has expanded to include a '67 Satellite, a '72 Scamp, and a 2010 Mopar '10 Challenger.

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  1. Avatar
    George Polidoro Jr 31 December, 2019 at 07:43 Reply

    Would enjoy having Hughes run tests with an STR-12 cross ram (which I have unused, never bolted on) on a 340 for the street. Using a nice cam, 650 Holleys or ?, 340 X heads based on running 3.55 rear gears and a 4 speed and 60’s series 14″ tires. Opinions are all over the place but hard copy facts are nowhere to be found. I know these are frail when cold, again by the number of cracked ones people tell me about.

  2. Avatar
    Con 3 January, 2020 at 17:02 Reply

    Ok. Im gonna ask a age ol question that never seems to get answered…… ls anyone out there looking to make an aftermarket la block that can take big power such as dart? At reasonable price?
    Please dont tell me that there is no market for it since edelbrock afr etc .etc . Have no issue making go fast pieces for the LA. Plenty of market for parts to make the small block mopar produce serious power and i doubt they would go to the trouble if demand wasnt there.

    • Avatar
      Richard Gehring 21 March, 2020 at 07:25 Reply

      Well I hate to say it but there is no market for it, I know Dart and KB have looked seriously at doing SBM blocks, the market is just not there , Call Ritter and ask them how many blocks they have sold. it took Moperformance how long to sell off the Supply of R3 blocks.

  3. Avatar
    Chetwyn Parker 4 January, 2020 at 04:56 Reply

    What about the NASCAR RP7 blocks? If you look around you can usually find them for a reasonable price.

    • Avatar
      Dartsport 9 January, 2020 at 05:45 Reply

      It all depends on what you think a reasonable price is. The Mopar market is limited due to very low sales compared to Chevy ,GM, Ford ect. Very hard to justify laying out millions to develop something that is going to have a very low sales figure. This is the only aftermarket available Chrysler LA block today and I guarantee you Kent Ritter is barely making any money on this at this price. He has done this project because it is a labor of love for him and it has not been an easy process for him. https://www.racingjunk.com/Blocks/183988964/Ritter-Racing-Block-Small-Block-Mopar.htmll

  4. Avatar
    Dartsport 9 January, 2020 at 06:02 Reply

    It all depends on what you think a reasonable price is. The Mopar market is limited due to very low sales compared to Chevy ,GM, Ford ect. Very hard to justify laying out millions to develop something that is going to have a very low sales figure. This is the only aftermarket available Chrysler LA block today and I guarantee you Kent Ritter is barely making any money on this at this price. He has done this project because it is a labor of love for him and it has not been an easy process. ps://www.racingjunk.com/Blocks/183988964/Ritter-Racing-Block-Small-Block-Mopar.htmll

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