Quote:
Originally Posted by Phantom
Not to offend but I highly doubt that there is a real ram air effect, more likely what you are experiencing is a less restrictive intake since there is now more area to pipe in the air and cooler temps allowing for more power.
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No offense taken but I have to say that I do not think we are talking about the same principle here. The scoop, at highway speeds, gathers and forces more air into the air box than the engine is consuming which, by definition, is ram air. I guess in order to put this to rest I will hook up my manometer to the air box and record the pressure increase. And again, I am talking about air volume and not velocity. Pressure increase indicates more air entering the air intake than is being drawn into the engine.
Quote:
Originally Posted by Phantom
To start the calculation using my car a 3.8l V6 @ 2000rpm consumes about 67CFM assuming 50% VE. For a straight Flexable 3inch pipe to flow 67CFM the velocity of the air in the pipe would need to be 1364.91fpm ( Air Duct Calculator - EfficientComfort.net) or the speed of the air needs to be 930.62mph. Even if the speed of air is 11 times faster than the speed of the car I would need to be moving 84.5MPH. |
Again, I disagree. I never said anything about air speed but rather air
volume
Additionally, you state above that your car is a 3.8 liter engine and consumes 67CFM at 2000 RPM and then state below that my 4.7 liter engine consumes 39 CFM at 2000 RPM. Nope. Sorry.
Quote:
Originally Posted by Phantom
Your truck at 2000rpm 50% VE uses 39CFM with the velocity needing to be 794.5 fpm or moving at 541.7MPH going by the 11 again (highly doubt the air would be moving that much faster than the car) the speed needed is 49.25MPH.
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I believe your numbers are off a bit here:
- At 2000 RPM (I quoted 2200 RPM at 70 MPH but I digress) the engine would consume (285 X 2000 X .5) 285,000 cubic inches. There are 1728 cubic inches in a cubic foot so (285,000 / 1728) = 164.9 cubic feet.
- 794.5 fpm is a little over six and a half miles per hour.
Maybe I am not explaining this clearly enough. The ram air intake scoop has a frontal opening of 48 inches and converges at the rear where it connects to a flexible aluminum tube that is plumbed directly into the air box. Because of the direct connect the air box, at highway speeds, becomes pressurized because more air is gathered and directed to the air box and intake than the engine can consume. This is not theoretical formulas but empirical data.
I attempted to post pictures but apparently they are too big. Pictures and articles can be viewed
here.