B16 – Air Dam for the Tiger

by Larry Paulick in the June 2002 RootesReview:

The Tiger has an inherent problem in the cooling system design. The bottom of the fan shroud does not complete the 360 degree shroud. If it did, the shroud would interfere with the rack and pinion. There are also no seals around the other parts of the radiator.

At the bottom, this allows air going through the radiator to recirculate back under the radiator and feed hot air back through the radiator. This really taxes a cooling system and is especially pronounced when the car is at idle or in stop-and-go traffic.

Tiger Tom has an excellent article on cooling that explains and covers many proven – and, tested by Tiger Tom, – ways to help keep the Tiger cool. This helpful article can be found in this section of the Tech Tips.

Objective

I looked at the Air Dam to do five things.

1. Stop the recirculation of air coming back through the radiator when at idle or at very slow speeds.
2. Provide a vacuum area under the car, especially the engine bay, so that the air going through the radiator will be drawn through and away from the engine bay while the car is in motion.
3. Provide a device to help block air going under the car that tends to lift the car at higher speeds. If this works, as it does on other cars, then the lightness of the Tiger at high speed, due to the air pressure, would be less.
4. It should not be very visible, but unobtrusive.
5. It should have a flexible lip, so that if the Tiger hit a curb, or other object, that portion of the air dam would bend and not be damaged; just like the modern sedans of today, with their plastic air dam lip on the bottom.

Design Criteria

The air dam that I designed is very simple, made of metal and plastic, and just extends down from the front of the radiator about two inches past the cross member. This design is very similar to the air dams on ordinary sedans you see on the street today.

The Design

I used very stiff cardboard, and laid out a preliminary design, that was modified after fitting it to the car. This design allowed the air dam to fit to the bottom of the radiator support. It is connected to this frame by two small bolts through new holes drilled in the radiator frame support. The third support of the air dam, is where the metal portion of the air dam rests on the cross member.

It is snug and does not rattle.

I used a bead roller to add stiffness to the 20-gauge metal of the air dam. You can use thicker metal, if you don’t have access to a bead roller, or get your body shop to put the beads into the metal for stiffness.
The design allows clearance for the sway bar. Under the sway bar, the air dam bends towards the rear on each side to help block the air from recirculating.

To meet objectives #4 and #5, there is a piece of plastic bolted to the bottom of the air dam that was cut to fit. This plastic was cut from stiff lawn edging plastic that is available at any Home Depot, Lowes, etc. You can buy the plastic edging for around $7 and have enough plastic to do 20 cars, or actually use the rest of it around the house and garden.

Yes, Dear, I actually bought this for the house.

Results

Does it work? Well at idle, using a incense stick, which gives off smoke and a nice smell, the air from the front of the car goes through the radiator. In this test I moved the incense stick all around the front of the car, including the bottom of the air dam, to watch the flow. Air at or above the air dam goes through the radiator and air below goes towards the back of the car. So objective #1 above was met.

I have also been driving the car in 85 degree weather and the temperature is still in the 170-190 degree range. But I do not have enough time on the car to say that it is a complete test, so Objective #2 has not been fully tested. I suspect that it is met.

Does it meet Objective #5 by stopping or reducing lift at high speeds? I will tell you after more testing, but this is such a common fix for this problem. I would be surprised if it did not help.

So, it’s cheap, you can do it, and it will help the idle and slow speed cooling problem due to the lack of recirculation of air back through the radiator.

PS – You may also notice the holes in the bottom of the radiator support. This support was of an odd trapezoidal opening, and the bottom portion blocked the bottom of the radiator. A hole punch, or saw, will allow more air to get to the bottom of the radiator. Every little bit helps.