Do dented headers kill horsepower? Engine Master David Freiburger explains

Time for Freiburger to face DriveTribe's questions

2y ago
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After the success of modding, fabricating and transforming wrecks into burnout monsters in Roadkill, David Freiburger felt there were more stories to be told by creating a show purely about engines. And thus, MotorTrend’s Engine Masters was born.

We caught up with Freiburger to find out more about the show.

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Who knew a technical show about putting engines on a dyno would be so successful?

“As part of my editorship of performance magazines such as Hot Rod and Car Craft, I did a lot of testing of engine parts and engine theory to create stories. This became one of my favorite parts of the job, so when I switched over to being a video guy, I pitched the show to MotorTrend.

“It’s the least likely topic to ever become a TV show because it’s so potentially boring; sort of scientific, and there’s not even any action because the engines just sit on the dyno test stand as we run them. To make it more interesting we decided to make it a buddy show, because I love throwing around ideas with my engine-building friends Steve Brulé, who is a professional dyno operator, and Steve Dulcich, who also has a background in technical writing.

“We have fun and don’t take ourselves too seriously. We also decided to give the show a dramatic lighting design on set just so it doesn’t look like every engine shop who posts iPhone videos of engines on dynos. Many people have been surprised that such a technical show has become so popular.”

What have been the biggest surprises on the show?

“We learn new things on every single episode, even when we are repeating tests we’ve done in the past. There’s no such thing as a bad day on the dyno.”

Freiburger and co take some of the internet's biggest V8 myths apart with data

Freiburger and co take some of the internet's biggest V8 myths apart with data

One of the best episodes is the one when you tested the effect of dented headers – has that been something you’ve always wanted to test?

“Yes. Every gearhead worldwide has found the need to put a dent in an exhaust header tube at some point, and people always worry that it will hurt power. I figured that a little dent here and there wouldn’t hurt much, but none of us had any idea how far we could go caving in the tubes without making a significant impact on performance. So many people think we faked the results that I have run similar tests twice since we produced that show, and we came up with similar results.”

Watch a clip from the dented headers episode at the bottom of this page!

Have you found any weird quirks common to a particular brand’s engines?

“Nearly every engine family has design quirks: big-block Oldsmobiles have terrible oil return and overly large mains, Ford 302s have weak blocks, Pontiacs have terrible lifter valleys, and so on.

“But on Engine Masters, we’ve proved time and again that basic performance theories apply to all four-stroke gasoline engines in the same way. We’ve done several episodes that show this: build two engines of the same displacement, with the same camshaft, and with the same airflow through the heads and intake, and they will make nearly the same power.”

What big questions do you want to tackle next?

“We have some very ambitious tests coming up to answer questions we see all the time in forums; we love challenging commonly held beliefs.

“In a few weeks we will find out what makes more power and has more detonation resistance, iron or aluminium cylinder heads (the common refrain is that aluminum heads dissipate more heat and therefore have more detonation resistance… we’ll see).”

“We also are going to test rod ratio, which is the length of the connecting rod divided by the length of the stroke. Many people believe that’s one of the most important factors in engine performance, others say it does not matter at all. We’ll test it and find out.”

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Stay tuned for more from Freiburger

We'll be catching up with David soon about another show that you might have heard of… stay tuned for some Roadkill Q&A!

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Comments (7)

  • A fact about Oldsmobilia engines to feed upon here.

      2 years ago
    • I just can't believe the Dyno HP results from that mangled mess.

        2 years ago
    • He's 100% correct about the later Oldsmobile engine blocks having oiling problems, but they are easily corrected. Early Olds 455s were better in the oiling department. I've never heard the part about "overly large mains". I assume he...

      Read more
        2 years ago
  • I wonder if the heads/manifolds were just so oversized that the modest restrictions did nothing.

      2 years ago
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