overheating with CTSC

[nsx-ray]

Has anyone encountered overheating with a stock radiator/coolant/smaller aftermarket overflow bottle under vigorous track driving on a FI NSX?

If so, what causes did you find?

So far, no coolant leaks, head gasket sound, cats OK, thermostat replaced, pressure cap does not leak, water pump OK. During hard driving at the track there is CLEARLY a large amount of coolant overflow coming from the aftermarket overflow bottle. This usually begins after about 15 minutes of hard driving.

Thoughts?

Wei-Shen

 

[RP-Motorsports]

You do not need FI to get overheating in an NSX. Some cars are prone to it more than others, and we have been battling this R&D at many tracks for 3 seasons now.

A few items that need to be checked before you move on to the next step.

(1) fill coolant bottle to at least 3/4 full (important)
(2) burp all air out of system several times front and rear. If you do not know how, let us know.
(3) make sure that your coolant bottle cap is TIGHT!

Most of the overheating issues we have found to be a slippery slope. Usually starts with the level in the coolant bottle being around the 1/2 to 2/3 mark, and for some reason the car will begin to gas off at this level, causing air in the system, and fluid loss, which just gets worse and worse each session. I have fixed the issue in many cars by burping all of the air, and running a higher than normal 3/4 level in the tank.

Here are the next steps....

(4)If the fins on the oem radiator are bent (pressure washer, stones, etc) a new radiator may be needed.
(5)add a higher pressure radiator cap try 16, and then 18
(6)wire fans to work with a toggle switch auto/always on for the track
(7)vented hood
(8)flush system and add water wetter per instructions when re-filling
(9)try running a mix that is closer to all water (not tap)
(10)aftermarket oil-cooler (it will actually help coolant temps stay down)
(11) larger radiator
(12) try FAL aftermarket dual fans
(13) top and bottom ducting to force all air in front of radiator to go through it, and not up or down around it.

On my "not tried yet" list
(a) run a lower temp therm.
(b) run with no thermostat

We have one more car to get to the bottom of some overheating issues, and I will be back to work April 9th @ Road America, but with the cool ambient temps, it may not show itself.

Good luck

 

[Batoutahell]

(5)wire fans to work with a toggle switch auto/always on for the track

While the car is moving on track, is it possible that the fast moving air would be impeded because the moving fan blades cannot keep up? This is kind of a common conception among race car drivers, and many track cars remove the fans altogether. I've always wondered if there's any truth to it.

 

[dynomike]

What we have found here at the shop is that the aftermarket coolant bottles sometimes do not seal very well where the cap is screwed on. What happens is that the cooling system never pressurizes and causes the coolant in the system not move through the whole system. Kind of makes the water pump cavatate.
The way to check this is warm the car up and feel the coolent hoses if they are hard the tank is not the problem. If they are soft I would definetly suspect the coolant tank.

 

[RP-Motorsports]

There is a difference shown with fans on even at 70 mph. True, when you are going a buck 40 down the straight, the fans will not be needed, and even if the fans can't keep up as you say, this is NOT when any issue is at hand. It is during the tight sections at full throttle while turning, that causes the heat. And most of these sections are UNDER 70 mph.

I have been kicking around a custom fan forced caliper/rotor cooler due to brake fade at certain track set-ups. Take Road America (motorcycle chicane set-up) You have a down hill straight into a 90 degree turn @ turn 8. After this turn you have a constant carousel leading to another 90 degree turn. Well during the carousel, your car sees no straight on airflow, and does not cool off enough to handle the next hard braking point. Same goes for radiator airflow. If you are NOT going straight, or worse following a fat Z06 or Viper, constant fans will only help, not hinder.

 

[latzke]

On my "not tried yet" list
(a) run a lower temp therm.
(b) run with no thermostat

I'm sure you've already noted this...but for everyone's education...

http://www.nsxprime.com/forums/showthread.php?p=461019&postcount=46

Start at the post I linked to and read down.

Down one or few posts Edgemts puts it this way...

I cut my stock thermo but it didnt work on the NSX at track speeds, tuning it/ driving on the street it would never even get up to operating temps, but as soon as I went to the track the gauge was pegged after 3 laps.
The NSX seems to need a thermostat, if you look at it it actually has 2 different plungers.

ATERPAK has an informative post on the second page of that thread also.

 

[titaniumdave]

Have you tried changing coolant?

I run 1/2 Honda coolant with 1/2 distilled water and water wetter. This gives a 25% anti-freeze dilution, which still protects to below 0 degree F, and increases the capacity of the coolant to move heat from the engine to the radiator. Theoretically this will drop engine temps by 8-10 degrees.

I have not had any over heating problems sense I put a vented hood on my car, but I still run this coolant which I went to to help with heat issues on my last NSX.

 

[nsx-ray]

Thank you all for your informative inputs. Will let you know what we find at our next event April 15.

Wei-Shen

 

[Onsoku]

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