[Tom Vaught]

Going to talk a bit more about Holley carbs and what happens when you change the AIR TEMP (density) going thru the carb.

Say you have a Holley 850 CFM #4781 Holley Double Pumper mounted on your engine under the Hood of your Trans Am 455 cid engine.

You measure the air temp going into the carb and it is 112 degrees F air temp.

So if we plug that into a spreadsheet I have it says that the Air Mass (in Pounds per Minute) is 58.873 going thru the carb.

So then you install the hood off of a Formula vehicle (the one with the forward facing scoops that can be opened up. Basically now getting fresh air from the front of the vehicle. Air temp is 77 degrees outside. With a sealed to carb system, the air mass going thru the carb/ engine is now 62.822 (in Pounds per Minute).

If you opened up the Trans Am scoop (which is not quite as efficient as the Formula scoops) you would get a bit less air mass with a similar sealed system.

But comparing 62.822 lbs/min vs 58.873 lbs/min = 3.949 difference times .80 volumetric efficiency = 3.150 difference.

So for easy math 3 lbs/min difference on average.

Rough rule of thumb is 1 lb/min air mass change will get you from 9.5 to 10.5 HP change. So call it 10 horsepower.

SO A PROPER COLD AIR INDUCTION SYSTEM COULD GET YOU UP TO 30 MORE HP VS CONSUMING UNDERHOOD AIR ON YOUR VEHICLE.

So the Ram Air probably did not do much but the difference in actual air temp in the two examples shows the air density change/ AIR MASS Change to be worth 30 HP.
(Ram Air really only works once you get above 150 MPH.)

Tom V.

You might need a 1 jet change to the carb in all 4 spots to allow for that air mass increase.