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My Supra Cooling Modifications

A Supra that is road raced requires a much more stout cooling system than one that is just street raced and/or drag raced. Last year when I had the Greddy front mount intercooler installed, road racing wasn't as much a priority for me as it is now, so I didn't care that it sat in front of the radiator. I also didn't know just how much it would compromise cooling on the road course.

It turned out that, with a 100% stock cooling system and the addition of the FMIC in front of the radiator, the temperature gauge would start to move after just a couple of hard laps at the tight Motorsport Ranch road course. In fact, even at a fast course like Texas World Speedway, I found myself having to take it easy down the front straight and use it as a place to cool the car down so the temperature and EGT gauges wouldn't start inching upward. At the time, I was already running the recommended (for the hellish climate here in Texas) 75% distilled water / 25% Toyota red coolant + 1 bottle Redline Water Wetter formula in the cooling system.

Since I already had the optimal coolant mix, there was really nothing I could do besides upgrading the hardware in the cooling system. Luckily, Powerhouse had just co-developed with Fluidyne a new, all-aluminum radiator upgrade that was significantly larger than stock (picture courtesy of Jeff Hood). I kept the stock pulley-driven fan, based on Jeff Hood et al's advice that the electric fan "upgrades" actually flow much less than the stock fans and increase the probability of overheating on the road course. I also removed the rubber hood seal under the back end of the hood near the windshield to allow hot air to escape through there.

At about the same time, I also installed a Greddy 10-row oil cooler in the driver's side brake duct. I opted for this model rather than the 16-row one because the big one wouldn't fit in this location -- it would have to sit in front of (and block) the radiator.

After doing these modifications in the Fall of 2000, I was able to road race without any movement of the temp gauge. However, I knew that the real test wouldn't occur until the hellish Texas summer would return.

One thing that always bugged me after road racing, though, was the fact that my power steering would get hot enough to boil over even my Redline synthetic power steering fluid when I would road race at a tight track like the Ranch. (The evidence was dried PS fliud on the fusebox cover when I would look under the hood after a track session). Granted, the power steering cooler included with the Greddy FMIC was smaller than the stock one, but I recall that a Supra with a stock PS cooler and stock side mount intercooler also boiled its power steering fliud at the Ranch. Whatever the cause, I knew that I needed a bigger power steering cooler. At the recommendation of a local shop, I had a nice Setrab oil cooler installed between the FMIC and the condenser to function as a power steering cooler. Hindsight is always 20/20, and I now know that this was a bad idea as it blocked cold air going to the radiator (why I thought of this when choosing the 10-row oil cooler yet was okay with putting a PS cooler there, I don't know.) After having the PS cooler installed, the PS never boiled again.

Fast forward to the Summer of 2001. Coolant mix is optimal (75/25 + WW). Fuel maps are VERY conservatively rich (EGT doesn't move past 660C post-turbo even in a long 1/2 hour session). Big radiator, oil cooler, and PS cooler are all installed. It's hot as hell outside, and I notice that after about 4-5 hard laps at the Ranch, the temp needle would move up to about 3/4 and stabilize there. I'm not happy.

Note that before starting any road race session, I am manually turning on the stock electric fans on the driver's side of the radiator shroud by disconnecting the A/C pressure switch near the driver's side strut tower (pic here). I'm also running the heater on max when I'm on the road course -- I've noticed that this makes a big difference in engine cooling. I don't even feel the heat, as the windows are open and the heat is all going to the dashboard/windshield vents and exiting the car immediately out the windows. Finally, I'm switching to a richer fuel map to help cool the cylinder temps since I'm at WOT for such long periods of time on the road course.

First thing's first -- I realized the stupidity of having a huge, dense 15 row Setrab oil cooler (for the PS) installed in front of the radiator. It needed to be moved somewhere out of the way of the radiator's air flow, but this would be a difficult task given the Setrab's hefty size. After a full day's worth of tweaking with different experimental brackets, we were finally able to install it flat under the Greddy oil cooler in the driver's side brake duct. Since it is flat, I'm depending on the Bernoulli effect to suck air upwards through it due to the high speed stream of air flowing across its top face. I also cut some small louvers in the front face of the shroud under the PS cooler so some cold air can get through from underneath before being sucked out the top by the air flowing across the top of it. I realize that the cooler isn't working optimally when placed flat, but it's better than nothing, and I think it's still better than the stock PS cooler, which is nothing more than a tube making a loop around the front of the radiator. Another idea was to install a small AT oil cooler for the PS fluid in front of the Greddy oil cooler, like Eric Typpo did, but that was a last resort as I didn't want to block the oil cooler's air flow. I'm hoping this setup will keep the PS fluid cold enough on the road course. If not, I will put a small fan on the top face of the PS cooler to actually suck air through it. Stay tuned.

Now that the big cooler was out of the cold air's way to making it to the radiator, the next step was to make sure that air going through the front fascia and FMIC actually made it through the radiator. Notice that your stock radiator has weatherstrip foam all around its perimeter so air doesn't leak around the radiator. The Fluidyne had no such foam around it. After a trip to Home Depot for some thick foam weather strip and about half an hour's worth of work, the gaps around the Fluidyne radiator were sealed and another issue had been tackled. I also added a Nomura panel above the FMIC to not allow air to go around the top of the radiator.

Finally, Jeff Hood had the great idea of creating a lower inlet air scoop for the radiator, kind of like C5's and F-Bodies have from the factory. Here is a picture of Jeff's lower radiator intake scoop. This is a great idea, but would work even better if the FMIC were higher and more out of the way. Interestingly, my Greddy FMIC sits about 3" higher than Jeff's HKS FMIC... which meant that I was able to leave the stock under-FMIC shround in place to make sure that air that goes through the FMIC is actually rammed through the radiator rather than escaping through the low pressure zone under the car. What I've done so far is to simply modify the lower front shroud to create mini cold air scoops for the condenser/radiator. I'm not yet sure how well this will actually work, but I'm confident that it will be a great improvement over the previous setup of just having the shroud bubble downards from the bottom of the FMIC to the bottom of the radiator 3" lower. Below are a few pictures. The reason I made it 5 separate scoops rather than one wide one was to leave the ribbed portions intact, so the shroud wouldn't collapse and allow air from the front fascia to escape under the FMIC. Note that the first two pictures were when I only had 3 scoops; the latter two are with all 5 scoops cut out.

I plan to go to the track in the near future, so I'll also update this page with the results of all this work.

FYI, here is a list of options still available to me in the case that I still need even better cooling:

6/25/2001 -- Here are some new suggestions I just received from John Hein:

6/25/2001 -- And here's a suggestion from Pete Dykinga:

6/28/2001 -- Keith Verges wrote me and said:

7/2/2001 -- This past weekend I went to Texas World Speedway for lapping sessions with the NasaTX group. It was about 90-100 Fahrenheit outside, and the car ran like a champ. As long as I took all the precautions (15-16psi of boost, ultra rich fuel map, unhooked AC switch to enable the electric fans, and heater on at max heat evacuating out the dash vent and out the open windows), the temp gauge never moved even after long series of balls-to-the-wall laps. I even turned it up to 18psi for a few laps and the temp gauge wouldn't budge. By the way, the 2psi difference gave me an extra 5mph at the end of the front straight.

The power steering fluid was also fine, with no signs at all of boilover such as the telltale blobs I used to see on the fuse cover, etc. The brakes were great, with no fade at all throughout the whole weekend. I highly recommend Hawk Blue race pads for the front and stock pads on the rear for the road course. This combination worked great. Of cousre I'll be switching back to stock pads for the street. The Motul 600 Racing Brake Fluid also worked well, never failing on the road course. I did notice, however, that the pedal started to feel mushy in the parking lot after each session when I drove around in the parking lot. So the Motul did suffer a bit from the heat, but it was still able to perform and not fade on the road course. If I ever notice fade on the road course on a weekend like this I'll probably just start bleeding the brakes at the end of the first day with fresh Motul, but as it stands now I think it's fine to just run the whole weekend on the same Motul and live with a mushy pedal in the parking lot on the second day.

10/10/2001 -- I finally had a real lower air dam made to scoop air up into the radiator behind the intercooler... IIRC it's 3/32" ABS plastic, formed with a heat gun. This past weekend at the track was between 65 and 80 degrees. I now have a real temp gauge, and it never moved past 94C. To put this in perspective, my temps before would hit 110+C. (the stock gauge starts moving upwards from the midpoint at ~107C, at 110C it's at 2/3, and at 115C it's at 3/4.)

Here are some pics of the new scoop...

 

 

Comments? Questions? Email me at andi@airmail.net

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