Thoughts on compression/build

[QB93Z]

When I was talking with Marc Haibeck last weekend at Carlisle, he pointed out that the ZR-1 is essentially an engine with two different cams. In normal power, there is a civilized, smooth performing, "low-end" cam. When the secondaries kick in, the engine characteristics are dominated by a hotter cam. He said that it is one of the ways the designers got such a broad useful power band out of the LT5.

This might explain why there is not much improvement seen by swapping out cams.

Jim

[Aurora40]

Originally Posted by QB93Z

When the secondaries kick in, the engine characteristics are dominated by a hotter cam.

But it's only controlling one of two sets of valves. That's why I'd think if both cams had that profile, the max power would be improved, though I'd think low throttle driveability would suffer. But I guess that's not the case as people don't seem to gain much with cams on a 350.

[QB93Z]

Not exactly related to the cam discussion, but interesting, Marc also said that the combustion chamber flow was a swirl in normal power operation with only one valve flowing. The swirl was very effective for low power operation and emissions. But at full power operation, the combustion chamber flow was different with two valves flowing and was better for high power. Once again showing the genius of the LT5.

Jim

[cward]

I believe that Fastlane's drag car had solids but that engine had tons of R&D in it. His cam profiles were developed to make power at very high (for LT5) rpm. That engine also had 16:1 compression. Used leaded race gas. Lane did stuff to the LT5 that no one else has done and probably never will. He spent mega bucks on both his 368 engine and the 431 engine. I have a great deal of respect for Lane. He really pushed the envelope with that car. And he took the car for us to see perform many times from California to Bowling Green. No short trip. Thank you, Lane.

Curtis