Cylinder Heads
Name: Dennis Gerdeman
Title: Design Responsible Engineer
Years with GM: 31

Other experience: Cylinder Head Casting Process and Tooling Engineer

What LS3 parts are you responsible for? Cylinder heads and head gaskets

What LS7 and LS9 parts are you responsible for? Same

What other Corvette parts have you been involved with in the past? I was also design responsible for the LS1, LS6, and LS2 cylinder heads shortly after they were released for production. I came into the small-block engineering family after these head designs were initially developed, and then integrated various changes and upgrades through their life.

Why do you think your LS3 part is the most important part on the engine? The cylinder heads are the key to achieving the maximum performance and output of the engine. A Corvette engine won't make the horsepower if you can't flow big-time air. And these cylinder heads flow big air for a production piece with as-cast ports and chambers. We were able to achieve maximum valve-lift airflow of more than 168 grams per second (g/s) for the inlet ports, and more than 123 g/s in the exhaust ports. There have never been production small-block heads that flowed as much air as the LS3 intake and exhaust ports, or valves as large as the LS3's—except, of course, for the monster LS7 CNC-ported heads.

What is a focus area you watch when designing the LS3 part, especially knowing it is for a Corvette engine? The LS3 was the natural progression for the small-block cylinder heads. We had to push the envelope from a head-packaging standpoint by using the strengths of the new 103.25mm bore. Precision manufacturing requirements restrict what you can do, but we worked hard to widen the intake ports in order to get the floor of the ports as high as possible, without sacrificing cross-sectional area. Keeping the air attached to the floor of the ports at high valve lifts is crucial to minimizing turbulence and flow restrictions.

The machined angles and widths of the valve seats have to be perfect in order to maintain that huge airflow from the intake ports to the combustion chambers. Countless hours were spent on the CAD tube adjusting the machined valve seats, and also perfecting the transition from the machined seats into the combustion chambers. When the cylinder heads are going into Corvettes, you can never spend too much time in these areas.

What are the current trends with your LS3 part? Where is it going? Of course, more power and refinement are always considerations for future Corvette programs, and the cylinder heads are at the heart of the discussion. We are always looking at different casting methodologies and new machining processes. You name it; if it makes it stronger, lighter, and flows more air, we're tuned in and probably trying it out.

Compare your part with aftermarket parts of the same item. What makes yours better? The LS3 cylinder heads have more structural analysis, component testing, and engine validation than any other aftermarket cylinder heads you will find. The specifications built into the GM analysis and validation provided a level of structural integrity that isn't present in any aftermarket head castings. The other advantage we had was our ability to interact with the C6.R racing team during the LS3 cylinder-head development, which actually helped drive our LS3 valve sizes and airflow targets.

Do you own a Corvette, a classic car, or have a related hobby? I'm a major Corvette fan, and someday I hope to own a C6, preferably with the LS3. I've loved this body style ever since it came out. I did let my small-block passion overflow into my finished basement, a good portion of which I have decorated in Corvette memorabilia.