Maechtlen El Monte wrote:The pics I've seen show lowest pressure near the front edge of the hood, High near the windshield.
So the vents should be closer to the front for best results.
Don't know about cowl air, that's closed off on mine.
ducted.jpg
The hood shown is being developed on my in construction V8 car and will eventually be the plug for a composite unit which Arch will make. It may (or may not) get louvres on top.
Air pressure builds at the cars front and at the windshield with the lowest relative pressure area between. Conventional wisdom (insert grain of salt here) says that the low pressure area on an LM is at the wheel center line, and not on the lower nose of the hood. My duct ends just behind that line and considerably ahead of the air grill and windshield. It's without a doubt MUCH lower pressure than the air hitting the front face and air dam of the car so I'm not expecting any problems ducting out of the vent, and in fact hopefully will get an assist from high speed air crossing the top. The duct shown is above an 18 1/2" x 24" core two-pass double-row aluminum radiator sitting at 25 degrees from horizontal (forward tilt) with full ducting from front air opening to the hood. A fan should never be needed while the car is moving, but I'm putting a 16" one in front (pusher) and NOT running a shroud (which would only restrict air movement at speed). I chose a pusher because a well operating system should not require much fan use, and unless you install flaps in the shroud a rear puller is more restrictive and would not offer as much "flow through" area. Yes, I know pushers aren't quite as effective, but I have no doubts that 444 sq. inches of radiator should do the job!
As noted before, the fresh air inlet wouldn't do much good. I'm blocking that off and routing fresh air from the plenum in front of the radiator down the sides of the trunk and through holes cut in the front bulkhead. Net result is fresh outside air using the factory vents!
Jim Hart
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