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Old 02-06-2007, 06:31 PM
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xntrik xntrik is offline
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Originally Posted by
That's news to me!! If that's the case, why doesn't Detroit put tunnels on all production cars? Why do Edelbrock and Weind, et al, produce dual plane manifolds? Guess my physics books are all wrong.

Single-plane and dual-plane intakes operate differently, as you know.

All new SFI cars ARE long single-plane tunnel-rams with small plenums, layed over sideways because they are dry flow, so they can lay them over. That is also why they require such large LSA cam angles to idle.

The primary purpose of a tunnel ram is not to shorten the runner, but to give the air a straight shot into the intake valve, which improves fuel atomization because the fuel does not get slung out by centrifugal force and run down the port walls. (New cars with SFI eliminates the fuel distribution problems.)

The true tunnel rams can be short, or long. Plenum big or small.

Look at the new Weiands for good tunnel rams. Lots of things have changed over the years, including tunnel rams. I just put a new one together last week.

Properly done tunnel rams will make more torque and power across the board, except at the very lowest rpms where all single plane intakes suck, literally, figuratively, and poorly, pulling exhaust into the intake manifold.

You are probably like most of us. We have always seen big carbs on big plenums on overcammed engines with crappy ancient heads running for 7500 rpm. Ya, they really suck, in every sense of the word.

Last edited by xntrik; 02-06-2007 at 06:44 PM.
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