Engine & Exhaust / Tech Articles

3 Automotive Myths That May Be Costing Your Vehicle Performance

Some are common misconceptions we hear from customers. Others are outright falsehoods we see propagated on forums, videos, and Facebook groups.

They’re performance myths—and they could be keeping your vehicle from reaching its potential. Specifically, we’re talking about three automotive myths that could be costing your engine power and performance.

Myth 1: Engine Airflow–Bigger is Better

Bigger engine components mean more power, right?

The simple fact is bigger is NOT always better. And bigger does not always equal better performance. This goes for carburetors, cylinder heads, headers, and other components.

Let’s start by looking at the carburetor.

Larger barrels mean that the incoming air does not have to move as quickly. If the barrels are too big, the loss of air velocity means the cylinder will not fill to its full capacity. For that reason bigger CFM is not necessarily the way to go…and a carb that is too big will actually put out less torque and horsepower. 

The same principle applies when choosing cylinder heads, too.  Find out how by watching the video.

Myth 2: Advertised Cam Duration

How important is advertised camshaft duration?

When shopping for an aftermarket cam, you’ll notice many camshaft manufacturers will list two duration values—advertised and duration at .050-inch lift.

You’ll want to downplay the role of advertised duration when choosing a camshaft…and the video will tell you why.

Myth 3: Backpressure is Good

Is exhaust backpressure really needed?

Actually, no.

The goal of your exhaust system is to get rid of spent gases as quickly as possible, and backpressure makes it harder to do this. So why do some people say backpressure in exhaust is good?

Much of it can be attributed to confusion between backpressure and exhaust scavenging. Exhaust scavenging occurs as a pulse of exhaust gas runs through the exhaust pipe and a little area of vacuum, or low pressure, is created behind it. This vacuum or low pressure area helps to pull along the next exhaust pulse behind it and can actually help better exhaust gas from your combustion chambers. 

So where does the confusion between scavenging and backpressure come in? Watch the video to learn more.

Three myths debunked in one video!

5 Comments

  1. Pingback: 3 Automotive Myths That May Be Costing Your Vehicle Performance

  2. Mark zimmerman says:

    Will cam# 12623065 work in a 2008 lc9 5.3 ? DOD is mechanically removed already. How would it compare to summit #8718 cam ?

  3. OnAllCylinders says:

    Mark, please contact the Summit sales/tech department and they’ll have all the answers you need! Thanks for reading!

  4. Richard M. Glover says:

    And a detail that is left out is that the exhaust cycle is followed immediately by the intake cycle in each cylinder so, when the exhaust stroke is efficient the intake stroke is more efficient.

  5. Pierre Carlsson says:

    I agree in most of what is told in this article. But when coming to backpressure I think you’re somewhat a quarter off the truth. Please reply with your opinion of my theory below. Im sorry for the lack of correct terms, due to my nationality.
    There is a hypersonic backpulse thats needed to prevent the incoming mixture from escaping thru the exhaust during the “flush”- the period when both intake and outlet is open. The underpressure created by the decelerating piston vs the higher speed of the exhaustgases from earlier in the scaveningstroke create a vacuum in the combustionchamber that help the incoming gases to enter faster, with a short reversing pulse from the exhaustport created by the underpressure mentioned in the video when piston is TDC. Fact is there is several differences in pressure within the processes. Ignition creates a accelerating flamefront with a vacuum behind. This vacuum is good due to the lowering temperature when pressure decreases. A factor to keep the sparkplug alive as the center of vacuum is where the spark occured. The flamefront continue and the piston accelerate due to the crankangle. As the piston is some degrees before BDC the piston has decelerated and the exhaust will open and the vacuum created at the top will help starting the scavening. The piston goes up and continue the process.

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