Speed Secrets: Putting the Wrong Camshaft in an LS Engine

What happens when you put a cathedral cam in a rec-port motor? Richard Holdener finds out on this episode of Speed Secrets. 

GM made two different port style heads for the LS engine family, the cathedral port and the rec-port, and while everyone knows that LS engines respond very well to cam swaps, what happens when the “wrong camshaft” is used in an LS engine? To find out what would happen if you took a cathedral port cam and installed it in a rec-port engine, Richard Holdener with Speed Secrets and Comp Cams teamed up to further explore camshafts for LS based engines. 

Starting with the LS3 Crate Motor the team picked up from Gandrud Chevrolet, they upgraded the stock valve springs to dual valve springs from Comp Cams, installed a 93mm Fast throttle body, and controlled the setup with a Fast XFI ECU. With the stock cam the LS3 made decent power. 494 HP @ 5,900 RPM and 491 Lb-Ft of torque @ 4,700 RPM is great, but with a more aggressive cam, the LS3 could be making a whole lot more power. 

Removing the stock cam, Richard then installed a Comp 54-459-11 cam. The camshaft, originally designed for cathedral port applications, features a .617/.624 lift, 231/239 duration, and a 113 LSA. Being that one has three timing chain bolts and the other only has one, the visual difference in the two styles of camshafts is obvious but what about power differences? The only way to find out is to put it on the dyno. 

With the cathedral port cam, the rec-port LS3 gained 72 HP and 26 Lb-Ft of torque. The peak power gains were not the only benefit to the LS3 either, as the entire power curve profited from the “wrong cam.” It really does go to show, that if you’ve got an LS engine and you haven’t done a cam swap, you’re missing out on some power.