Keeping Your Cool in a Tiger

An Article by Dan Walters
September, 2001

Page 3

Today's Story (cont.):

.... The previous dimensions are of the core only. The original radiator has a maximum thickness of 2 1/4 inches at the seam between the core and the tank. When contemplating a custom radiator, beware of the position and overall thickness of the radiator at the seam. The installed position of the radiator can be a real problem with clearance if the seam position does not fit the car well or the thickness of the radiator at the seam is excessive. Depending on the dimensions (up to a point), you can use the fan shroud with thicker radiators. The next thing to suffer is fan clearance. The limit (before modification) is reached with clearance at the steering rack housing.

....The above descriptions are of typical brass tube/copper fin radiators. Aluminum radiators are becoming more popular as the price and availability are becoming competitive with the brass/copper radiators. One clear advantage of the aluminum radiator is weight. An aluminum radiator typically is only 1/3 the weight of a brass/copper radiator. Comparing the overall effectiveness of a brass/copper vs. aluminum radiator is difficult. Aluminum conducts heat about 1/3 better than brass. However, copper conducts heat about twice as good as aluminum. Then again, the brass/copper is held together with solder which conducts heat poorly at a rate about 1/5 as good as aluminum. If aluminum radiators had to use the same design dimensions as brass/copper radiators, aluminum radiators would be less efficient than brass/copper radiators. However, with a slightly different design, aluminum radiators are comparable to brass/copper radiators and may totally dominate in the future.

....Aluminum radiators have bigger diameter tubes squeezed flat to give more tube surface area than a brass/copper radiator. An aluminum radiator has one tube for every 2-3 tubes of a brass/copper radiator. Because aluminum radiators have such big tubes, there are fewer choices in core thickness. One row may be 1 1/4 inches thick and 2 rows may be 2 5/8 inches thick with nothing in between. A one row aluminum radiator may be too small for a Tiger (we'll soon find out, stay tuned) but several Tigers have 2 row aluminum radiators shoe horned in (with modifications) and working well.

Fan-Tastic

....The standard Tiger cooling system fan is 14 inches in diameter and has 4 rigid blades. It may qualify as the least desirable original Tiger part! At least if the percentage of Tigers currently using one is an indicator. The percentage of non-stock fans on Tigers is high and the complaint of over heating is high. Is there a correlation? Maybe. Am I suggesting that a stock Tiger fan is the solution to all over heating problems? Not quite, but I have seen replacement fans on Tigers that fit into the category of "High performance" which usually means "uses less power" which usually means doesn't do the job.

....One way to solve a problem is looking to see how someone else solved a similar problem. A good example in this case is a late 80's Ford Mustang V8. The Mustang uses a thin core in the radiator, but oh-baby does it have a FAN! It is the FAN FROM HELL. Of course, it's mounted on a thermostatically controlled clutch. I know two individuals who attempted to go the "hi-po" route by removing the stock fans on their Mustangs and replacing them with electric fans. Both Mustangs over heated! One went back to the stock fan, the other received a thicker core radiator which helped but didn't solve the over heating problem. Given the choice of a thicker core or the fan from hell, don't underestimate the benefits of more fan (as long as it REALLY IS MORE fan).

....So what's wrong with an electric fan? Typically, power! Power is needed to move air through a radiator. If we use the example of a water pump mounted fan that conservatively uses 1 horsepower, the equivalent electric fan would need to use 746 watts (53.28 amps at 14 volts)! I have yet to see a cooling system electric fan with that much power! And when I find one with that much power, the next problem is that the stock generator only provides 450 watts! And what self-respecting FAN FROM HELL would use only 1 HP anyway? The point is, electric fans have their limits but they still can be useful. The example would be the newest Mustang V8 has only an electric fan for the cooling system but has a thicker radiator core. The new Mustangs are also down on power and can ill afford the power loss of the FAN FROM HELL.