Over the past few months — years, really — we’ve talked a lot about Edelbrock’s Duramax Diesel Cylinder Heads.

And for good reason.

Until Edelbrock introduced the heads, there really wasn’t a CARB-certified aftermarket cylinder head for Duramax engines that could also flow coolant. That is, there really hasn’t been a Duramax competition head that you could also run on the street.

So when Edelbrock teased these cylinder heads back in 2015, we were excited. We were even more excited when Edelbrock finalized the design and announced they’d be available in 2019.

The Duramax heads, available for LB7 and LML applications, landed at last on Summit Racing’s website a couple months ago with the promise of greater airflow — up to 20 percent more. The water-jacketed castings also promise 40 percent more coolant, and the HIP (Hot Isostatic Pressing) process makes these heads three times stronger than billet, according to Edelbrock.

While the Edelbrock Duramax diesel heads have generated a lot of talk, it’s been just that — talk. Our friends at DuramaxTuner.com, makers of turbochargers and computer programmers for diesel trucks, decided to actually put the heads to the test on a 1958 Apache. Through a series of tunes on the dyno, they discovered where the heads perform best and who might benefit the most from them.

Watch the heads in action:

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Author: David Fuller

David Fuller is OnAllCylinders' managing editor. During his 20-year career in the auto industry, he has covered a variety of races, shows, and industry events and has authored articles for multiple magazines. He has also partnered with mainstream and trade publications on a wide range of editorial projects. In 2012, he helped establish OnAllCylinders, where he enjoys covering all facets of hot rodding and racing.