I am running a cold air intake from the firewall to the air cleaner. The same set up Buick used in the late 60's as a towing package. Trans Am cars also had this set up. The opening that I can cut is 7"X2". This will bring cooler air from the high pressure area at the base of the windshield.Will this be opening be large enough to supply air to my 780 Holley DP? There is a formula to figure CFM but I don't know it. Motor is 462 Big block with TA 413 cam MT headers etc. Thanks for the info. Ken :grin: :grin:
7 X 2 = 14 square inches. Holley 780 has 1 11/16 diameter throttle blades (X 4) 1 11/16 = 1.6875 diameter 1.6875 /2 =.84375 radius Area =Pi X Radius squared 3.14 X .84375 X .84375=2.2354 sq. inch. 2.24 X 4 throttle blades=8.96 square inches of carburetor throttle plate. Although the carb has 9 sq. in. of throttle area, dividing that area into four passages increased the amount of surface area, and therefore friction 'n' turbulance through the carb. Offsetting this inefffency is the fact that at WOF, there may be 1" of vacuum under the throttle blades, and we want much less than that at the carb inlet. 14 square inches of vent, minus some loss from the ducting, should still be adequate to feed 9 square inches of carb, especially since the air will be mildly pressurized at the duct entrance. Anyone disagree?
Only drawback to that is if you pull fresh air for your car's ventilation system from that same area, the car's interior may end up smelling like gasoline. Might be a non-issue for your car.
The set up You have built into the car will work fine with no problems. I did the same thing on my 64 lark and was running a 950 cfm carb. I didnt get any fumes because the air is drawn from the windshield wiper chamber. The engine didnt starve for air and the hp increase was significant. Doc
Ken, I'll give you my CFM "formula"-- CID x 2-- Although not the scientific formula it has never failed me!
cfm questionI knew you guys would Hi guys: I knew you would come through with a answer. T he gaso fume issue is some thing to consider. I will let you know how it all works out. Ken:grin: :grin: :grin:
