Camshaft (Cam Drive)
Name: Shane Smith
Title: Design Responsible Engineer
Years with GM: 9
Other experience: Project Engineer—GM Racing and Performance Parts (with NHRA Pro Stock teams) and Lead Mechanical Engineer for dynamometer development
What LS3 parts are you responsible for? Camshaft, lifters, valves, valvesprings, timing drive, rocker arms, and pushrods
What LS7 and LS9 parts are you responsible for? Same
What other Corvette parts have you been involved with in the past? None
Why do you think your LS3 part is the most important part on the engine? The camshaft is what sets the personality of the engine. The LS3 cam design runs smoothly and efficiently during cruising, and delivers the wide torque band and big power numbers, too. The lobes and timing are optimized for that balance. The intake-side specs of 0.550-inch lift and 204-degree duration at 0.050-inch give the engine the air it needs all the way up to redline. The hollow-stem intake valves are a must-have to keep this valvetrain in control with that cam profile.
What is a focus area you watch when designing the LS3 part, especially knowing it is for a Corvette engine? The challenge is to make the power target and run strong through hundreds of hours on the dyno, and in real-world track testing at the very highest engine speeds. The Corvette customer likes power, but we can't sacrifice driveability. Anyone can throw in a lumpy cam and develop power, but that doesn't make for a good car to drive all the time. The LS3 cam's behavior was critically reviewed for all aspects of driveability by a select number of folks who know what Corvette owners want.
What are the current trends with your LS3 part? Where is it going? Cam development is highly proprietary. What I can share is that we're always looking for ways to be more aggressive in the profile department, for obvious reasons. We must, however, preserve a certain acceptable level of NVH and emissions.
Compare your part to aftermarket parts of the same item. What makes yours better? The LS3 camshaft is designed to pass durability tests that aftermarket companies don't have to think about. We use the latest technology in laser equipment to measure what the valves are doing at all different running conditions. We work to minimize the velocity of the valve right before it closes against the seat in the head, and the height of the valve bounce right after it closes. This is a key area to watch when you design for long life.
Do you own a Corvette, a classic car, or have a related hobby? My first experience with small-block Chevy cams was in high school. My friend and I spent a whole weekend changing the cam and adding headers to his 350ci '71 Chevelle. The thing ran about the same as it did before all the work, so I can't call it a success.
Outside of work, my hobby is playing with old Mopars. It all started when I bought a '66 Coronet at age 14, and spent a year-and-a-half getting it ready for the road. I bought my '71 Challenger right after I was hired by GM in 2001. My daily driver to the office is a '77 New Yorker.