Potomac-Greg

I had the car at a track day at Summit Point, Shenandoah and ambient air temps in the shade were over 100 degrees. On track, my temps went up close to (but not quite reaching) the red line on the temp gauge. I watched it and it held steady just under that red line, so I did not pull back in.

Ordinarily, on a temperate day, the temps are at the middle of the gauge and often lower. So this was significantly higher than normal, but still not in the red. Obviously, nothing blowed up, so no-harm, no-foul.

What are your experiences in extreme heat?

PS: Below is a video of one session. Fairly uneventful.
http://vimeo.com/13633472

M758

My 944 spec will race fine in 105 temps. How the driver hold up is another issue. I know you are more humid, but air temp is air temp when it comes to cars. So my 105F is a bit wamer than you 102 even if you sweat more due to humidity.

My water temp does run wamer in the heat, but I have engineering the cooling system to work in these temps. I cut the bar between the fog lights in the spoiler and manually run my fans. I also run 100% water and water wetter and the external oil cooler keep water temps lower. I also use the stock under tray to improve airflow through the radiator. Of course no A/C means better flow to the radiator and I often clean the fins to minimize the rock/sand/rubber that blocks cooling. Of course the radiator was new a few years ago because I did not want to race in the heat on an old radiator.

BeerBurner

Do you still have the stop sign undertray? If so, that may not be helping things...

BB.

Potomac-Greg

No. (And it's a speed limit sign! 30MPH IIRC).

I had already cut vent holes in that thing (after comparing it to an OEM unit) but rather than take a chance, I took it off before heading to the track mostly b/c I didn't want to be taking it off in 100 degree temps at the track.

BeerBurner

It may be worth trying to find a proper undertray for the car. I know you've been having a hard time with that but I'd keep looking. When I replaced the screwed up undertray with a fresh on in my miata, it resulted in a ~30*F reduction in on-track oil temperature at the sump so it definately helps with cooling.

I'm not sure how big of a deal it will be in the 944 (although I've read that it is) but I'd guess it would definately help.

BB.

M758

Most guys run wamer with no undertray as compard to stock. However I think the louvers in the stock one are key to providing an exit to radiator air to ensure it flow right. No tray it does not flow as well. No louvers in the tray it does does not flow as well either.

Kind like the thermostat. Works best when you have one as without it does not cool right even if it better than a stuck one.

xschop

I'm running my 5.3L V8 in 100+ temps in OKC, stop and go traffic, hiway hole shots, the last few days and have not gone over 190 degrees. I have only had the low fan kick on at 190....
I have the factory NA radiator and the factory fans in their location simply running without a T-stat....

M758

And how this relevant?

V2Rocket

to show that the NA cooling system is up to the task. (as long as air gets to it, which i have discovered a 25-year-old condenser will prevent)

M758

idling along is nothing like track driving. I don't care how big the motor is.

Runing at 4500 to 6000 RPM on a track put alot of heat in a motor is nothing like stop and go driving.

xschop

Oh, I'm sorry, I forgot to mention that I have been driving like I stole it. It was 100 again yesterday and was rumnning it in the 5k rpm range all over the metro. And my point was that the NA radiator will handle the heat as long as there is airflow and coolant flow (T-stat delete)

Most folks don't know that some of these radiators have pull rods in the water channel vanes that can be removed for even greater flow and more cooling.

M758

Street driving does not equal track driving. Heck even track driving does not put as muct heat in a motor as racing. Racing puts motor heat in the motor since often times you need to follow closely the car infront. On a hot day that can reduce airflow and elevate water temps. This can force you to get out of the draft into clean air and impacts your race.

You cannot sustain 4500-6000 RPM and full throttle on the street. The only chance is twisty mountain road, but can you where can you sustain that or 20-40 minutes at a pop. Even the autobahn is easier since the high speed means more airflow.

xschop

The whole point is that if you remove the T-stat, you can get better cooling at running higher rpms. The joke around here is that the Turner Turnpike is the Oklahoma Autobahn. I've seen a few bikes top the 200 mark....I plead the 5th personally

M758

Not on the stock motor. These cars run best with a properly working T-stat. I have seen it on track in racing conditions. If you have bad t-stat ripping out can save your weekend, but you will run warmer than if it is working properly. Also if you are racing (or tracking hard) at 100F you need the entire system working perfect to prevent overheating. If you have weak spot you will notice. Even so if it s all working fine you can race to 105 maybe 110 air temps and not over heat.