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Video: Understanding Backpressure and How to Choose Exhaust Tubing Diameters

In this Summit Racing Quick Flicks video, you will learn the basic of backpressure in your exhaust system, how it works, and why it’s important to your engine performance.

Trying to decide what diameter of exhaust tubing to choose? This video will also help you make the best choice for your application based on your engine’s horsepower production and whether you’re using a single- or dual-exhaust setup.

Check it out!

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  1. In the video about back pressure and choosing pipe diameter, it was said that for a single exhaust with 200-250 hp to use 3″ exhaust. Does this mean the y-pipe too ? Or how should that be sized ?…98 gmc sonoma 2wd 4.3 v6. Thanks

  2. This is a joke video… right??? Because dude has no clue as to what he is talking about

    • I was thinking the same thing, this guy has no clue about why smaller diameter exhaust can improve performance, back pressure IS a bad thing, and it is not (directly) related to atmospheric pressure

    • Read the book “emptying and filling solutions”. It will more indepth explain how back pressure and exhaust noise affect performance.

  3. Ok get the horsepower marks for power but what if I run a true dual exhaust system on a motor that does not produce over 500 no

  4. In the video you say true duals. What if I am running an X pipe with about 500hp?

  5. Lamar Newton says:

    2 part question: 1st is it ok to go from 2.5 to 3 inch and 2nd I run BBK Shorty headers with SLP X-pipe and SLP Loudmouth, question is, is better to run a muffler or does running a muffler delete hurt or effect performance?

  6. OnAllCylinders says:

    Not only do mufflers quiet sound but, they also add some restriction in exhaust flow too. By deleting the mufflers the sound will increase, of course, but flow will increase potentially leaning out the air flow ratio. You may need to re-tune the computer!
    Going to a larger pipe size will have a similar affect. It will increase sound, decrease restriction and potentially lean out the air fuel ratio

    • Brandon Harrison says:

      No, reducing exhaust restriction does not lean out the air fuel ratio. You are implying that larger exhaust pipes increases an engines air intake which in most applications if not true at all.

      • Don’t comment unless you know what you’re talking about. Fuel mixture has to do with the readings from the O2 sensors. If the readings from the O2s are affected, the fuel delivery will be affected, but the air intake will remain the same with the throttle. Therefore a tune is needed to adjust the fuel delivery to fix the mixture.

  7. So I’m assuming he was talking n/a. I would think a when I ran a turbo setup, I ran 3 inch single on a 1.8 270ish hp. I saw dramatic increases in power and delivery as lag decreased when I put a y pipe on with a dump. So would turbo setups be able to run larger due to increased back pressure from the turbo. My other question is about understanding his description of back pressure. I wouldn’t dare argue with him as summit is so highly regarded, but my logic applies a little bit differently. My understanding; back pressure is the resistance to the piston on the exhaust stroke. What he was referring to with the exhaust valve opening overlapping the intake valve opening is called scavenging. This happens because more air can come into the cylinder with less resistance because of a “leak” made by the exhaust valve. So based off this i would think that these losses he describes have more to do with bake duration than exhaust size.
    My other thing is that power band was not mentioned. Wouldn’t a bigger exhaust create more low end and a smaller more high end? So wouldn’t purpose change your decision on size?

  8. Ok for all of you questioning and arguing with this video you are actually fighting over half the story. Which he didn’t say anything about. Exhaust Scavenging. Back Pressure is created by EVERYTHING in the exhaust from the manifolds/headers to the muffler. Which includes the I.D. of the tubing and the CATs. The part about the cylinder was a reference to the scavenging aspect that needs to take place.

    Every motor needs some amount of back pressure to aid in scavenging properties and emissions. It’s also the reason why a vic with no mufflers and cats sound LOUD but no actual profile, then a properly sized and equipped exhaust that’s not as loud but very good profile.

    And it has NOTHING to do with a damn Cam.

    Get it straight people.

    • Back-pressure is harmful to scavenging, but so is having too wide a pipe, which is why this myth exists. Think about it, why would pushing against your engines gas flow ever be helpful? it isn’t. The reason having too large of an exhaust diameter decreases power (especially in the low-end) is because your engine isn’t pushing enough gas through to fill the entire pipe, which cause the gasses to expand, slowing them down and greatly reducing the benefits of inertial scavenging. This is simple physics, and the Bernoulli effect is a great example of this.

    • You sir lost your credibility when you said back pressure aids scavenging. Those are forces in two different directions. Second there was no reason for you to be a douche. As I clearly stated in my arguement that I wasn’t questioning his credibility only trying to understand him better.

  9. Thanks for this video. I’m a happy summit customer.

  10. Just read the comment thread here, y’all really acting like that over a discussion on exhaust? Can’t imagine how you would get if it was something really worth arguing about.

  11. Steve Schlosser says:

    Ha ha! Glad to see the video cleared this topic up for everyone! LOL!

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