"A Tiger Reverse Cold Air Scoop"
An Article by Larry Paulick
Preface: Larry Paulick explains his new design for a reverse cold air scoop for the Tiger. As opposed to the LAT hood scoop, and other period methods, Larry examines obtaining the fresh air from the rear of the hood with a rearwards facing scoop.
Tiger Reverse Air Scoop
One of the old NASCAR tricks is to provide cold denser air, with a ram effect to the carburetor. The interesting part is they normally don't use forward facing air scoops, but rear facing hood scopes, or intake at the air intake vents, at the high-pressure area at the base of the windshield.
Another point, is that many forward facing air scoops, are not placed in the proper position to provide the ram effect of air into the scoop, because they are actually in a depression of the air flow over the hood. They do not have a positive pressure at the intake, but in some cases are in a negative pressure area.
The old GTO Pontiac was one of these designs, and was put on the car as styling point; event though the engineers knew the air scoop was the wrong design, in the wrong place. Looked good, buy was for styling only.
I have no experience with the Tiger LAT-79 hood scoop.
After the air intake location, you need to direct the cooler air into the carburetor, without mixing it with the hotter, under hood air.
But, first the intake scoop.
The Intake Scoop
Underside of hood with hole in hood for cold air box
When I did the restoration of the car, I asked the body man to make a second hood, with a medal air scoop facing the rear of the car. I also had him cut a hole on the underside of the hood, which was 1 larger than the oval dimension of the Tiger air cleaner.
I calculated that this would allow enough air volume into the new scoop, and just miss the firewall area, when the cold air box was installed.
Since the car was in parts, and no engine or air cleaner on the car, much of this measurement was I hoped it fits right.
The measurements were correct, or I was lucky, with the final results, as it fit just right.
If you want to add an air scoop of this style, there are many styles available on the aftermarket, in both plastic and metal.
The Air Box
Front view of reverse air scoop