Name: Tim Carr
Title: Design Responsible Engineer
Years with GM: 34
Other experience: Quality Control/Gauge Design Engineer at the GM V-6 3800 engine plant in Flint, Michigan; Design Responsible Engineer for intake manifolds for the 3.1 and 3.4 V-6 engines; and Design Responsible Engineer for the small-block V-8 truck engine intake manifolds
What LS3 parts are you responsible for? Intake-manifold assembly
What LS7 and LS9 parts are you responsible for? LS7 intake-manifold assembly
What other Corvette parts have you been involved with in the past? Design Responsible Engineer for the LS2 intake manifold
Why do you think your LS3 part is the most important part on the engine? Airflow is critical in order for the Corvette engine to meet its performance targets. The LS3 intake manifold has a precise balance of extremely low airflow losses, good cylinder-to-cylinder flow balance, and optimum runner length for engine tuning. At peak valve lifts, the LS3 manifold flows more than 155 g/s. The LS3 and LS7 share a common architecture; however, the LS3 runners are sized for the lower peak horsepower speeds of the engine. The LS3 manifold has 89 percent of the flow capacity of the LS7 manifold. This is significant considering the LS7 engine develops about 70 more horsepower. [It's also] accomplished in a very tight vehicle-packaging environment.
What is a focus area you watch when designing the LS3 part, especially knowing it is for a Corvette engine? Airflow is the primary concern with developing the intake manifold for Corvette. Extensive analysis is performed to reduce flow losses, and [to develop] package-runner geometry that provides the torque and power the Corvette driver expects. The composite material used on the Corvette intake manifold is very light, and its smooth surface finish reduces flow losses. Appearance and noise are also considerations. The textured manifold noise cover reduces the high-frequency sound, which most Corvette owners would consider objectionable.
What are the current trends with your LS3 part? Where is it going? The future trends for the LS3 manifold include providing even better airflow performance, with less packaging space underhood than in the current Corvette. We are not leaving any stone unturned in the development of future manifolds. We are analytically pursuing many design iterations to find every additional cfm possible and we have many resources dedicated to this pursuit of additional efficiency and power.
Compare your part to aftermarket parts of the same item. What makes yours better? Many aftermarket manifolds achieve better performance only by compromising features on the production part. One example of this type of compromise is to fabricate a larger, taller manifold to increase plenum volume. While this might improve performance, it is likely that the manifold would contact the hood, or that noise would be [increased]. It's difficult to provide a better manifold and still meet emissions regulations, provide sufficient clearance to other components, and function reliably for the life of the vehicle.
Do you own a Corvette, a classic car, or have a related hobby? I enjoy car shows during the summer. My favorite classic Corvettes are those from '58-'62. I enjoy family time, downhill skiing in the winter, and boating during the summer.