Two Drivers - Keeping the car cool

[DougW]

Hey Everyone,

I am curious what experienced CM folks do to manage heat/keep the water temps down while running two drivers in one heat? I am curious about both hardware and methods...

At big events there is lots of time between runs, at smaller local events runs can be pretty close together. We have used a water sprayer. Anyone try a battery powered leaf blower? I know some folks have used cooling fans for the radiator. I don't know if anyone has used one on a Swift.

Thanks!

Doug

[mwood]

I will be interested to hear responses. My car got over 200 for the first time last weekend, hot lapping a 60 second course five times consecutively on a 75 degree day, with maybe 2-3 minutes between runs (just enough to heat sink the radiator with no air flow). Not a worry, but there was some temp creep going on and it isn't even summer!

[mwizard]

I have an electric motorcycle fan on a switch. It helps sitting on grid, but not much when the motor is off. So far it seems that my car tops out at about 185 and even gets a bit cooler during the run. I have not had a chance to drive on a real hot day. I would expect that a water spray on the radiators would help a lot. I have considered an electric in line pump so that the electric fan has new water to work with, but so far, no need.
Mark

[DougW]

Thanks Mark! I hadn't thought of a motorcycle fan (duh). The Swift has just one large radiator. I will have to stare at the ducting and see what is possible for a fan.

On a 90 degree day we were at 190 at the finish and 200 by the time the car stopped in grid. Watering the radiator and running the car for a brief period to circulate the water after spraying seemed to keep it cool for the next run but only just. The local regions are trying to make heats smaller which makes it tough to be a two driver car and keep things cool.

On a 100 degree plus day I suspect it would be problematic to keep it cool without some sort of fan.

[ahowe]

My Reynard cools very well. So, I'm not the best resource...

The only time I've seen over 200 was at Nationals last year with the high heat and the extra time at the scales. The best tool I've got for cooling the car between runs is a long runout between the finish line and the grid. My car will lose 10 degrees just rolling along at 2000 rpms in 1st gear if the runout is long enough.

Andy

[DanW]

Basics:

Distilled water, redline water wetter.

Distilled water has been deaerated, removing oxygen and dissolved air, reducing the formation of bubbles in the head. The water wetter is a non-ionic surfactant that reduces bubble size.

Make sure all of the air is bled from the system.

I like the motorcycle fan, the cordless leaf blower, and the water spray. I used to use the windshield washer with a mister nozzle for the radiator in my Elan. Just pushed the washer button on the dash and watch the temp gauge fall as I motored back into line.

[DHale_510]

My engine builder wants the temperature between 190 and 200.

[mwood]

The 180-200 range is pretty much agreed on, I believe, as the point at which the oil thins to the best combo of lubrication/viscosity/horsepower and all the impurity/condensation is sure to burn off.

My concern is, if I was touching 200 on a 75 degree day, what I'm looking at in 100 degree heat. I am going to drain the system and refill as suggested by DanW...which is also the same equation I've used in other track only vehicles. What's the right pressure cap? I'm also guessing a 180 thermostat is right?

[DougW]

I have the distilled water/water wetter combo in the car. So no extra help for me there.

[Locked]

A big help is communicating with the grid workers that you simply can't sit at the line. Once up to temp we like to have maybe 1 car at the line before we start the car between runs.

We typically hate grid "lanes." Typically with a grid lane we'll just put the battery at the very front and the co-driver not in the car will push the car to that spot to start the car.

I've only gotten the water sprayer out for my radiators maybe once.

[Dick R.]

A big help is communicating with the grid workers that you simply can't sit at the line. Once up to temp we like to have maybe 1 car at the line before we start the car between runs.

We typically hate grid "lanes." Typically with a grid lane we'll just put the battery at the very front and the co-driver not in the car will push the car to that spot to start the car.

I've only gotten the water sprayer out for my radiators maybe once.

Good advice! Our side rads certainly help also. One trick I do, even with one driver, is to restart the engine at least once after it has "cooled" for a few minutes in order to circulate the cooler water in the rads into the engine and the hotter engine water into the rads.

The Swift's central internal radiator is probably the worst configuration for an autocross FF for between run cooling.

When I autocrossed my Lotus Europa in Street Prepared I had a switch to turn the radiator fan on between runs. I also did the run the engine periodically trick. Even my Stock Datsun 260Z needed help between runs . . . but only to cool the carbs and manifold. Open Hood combined with a small spray bottle did the job.

Dick
CM 85

[Don Elzinga]

I used to have trouble with water temps getting above 100 C (212 F) on hot days. A previous owner had narrowed the radiator shrouds to try to make the car more aerodynamic, plus the radiator cores were old and the fins were in rough shape. I spaced the shrouds out to their original dimension, and had the radiators re-cored with three row cores. That and working with the grid folks, like Nick mentioned, took care of it. I thought about adding fans, but with a total loss electrical system that would be risky. Unless you only ran them off the boost battery.

Don