Pic request... lt1 with raim air box

[fastTa]

Read this:

http://www.vetteguru.com/ramair/

Did you guys read this article? It is actually very interesting and has some very good info to back it up.

I wonder if anyone has ever tried testing this on a chassis dyno using some type of large fan or something.

[Injuneer]

I've read that article numerous times..... the guy is either way over my head, or babbling... and I haven't figured out which. I get the feeling he is trying to apply the dynamics of closed channel flow to what is really an open channel application.

The concept of "velocity head" says that the static pressure will increase proportional to the square of the velocity.... that's how you use a "pitot tube" to measure the speed of an air stream, or the speed of an airplane. And the measurements are very accurate.

I have an automotive calculations handbook, and it gives formulas for evaluating velocity head, the resulting static pressure increase and the coeficients of "pressure recovery" (% of static head actually reaching the flow channel) for various shapes and styles of openings.

Do you think racers like Warren Johnson would have that huge scoop about 15" above the hood, if it didn't improve air flow to the engine? The design of the opening in those scoops has become a "science", trying to maximize the pressure recovery aspect.

This would be relatively easy to check. Run the car on an engine dyno, and measure the MAP vs. MPH. Without changing anything, take the car out on the open road and measure MAP vs. MPH. If there is any pressure gain at the inlet, it would be reflected in increased MAP. It would also be possible to do a similar experiment by mounting a MAP sensor in the Ram Air box, and measuring the airbox pressure with the car standing still, and with it moving at various speeds.

Theory - at least the velocity head version - says that you can gain about 1% HP at 100MPH. At 150MPH, that would increase to 2.25%, or about 10HP on a well built NA stroker. At 50MPH it would be only 0.25% or about 1HP on a mildly modified LT1/LS1.