911 Air Cooling - it's HOT NOW

[1983Cabrio]

Quick question that's been bugging me in this SoCal heat. Is it better to run the car with high RPMs to let the fan cool the engine? OR bog it down to low RPMs to try to generate less heat??
Which is better?
...and any other cooling options in the wicked heat?

[911obgyn]

I found driving in 4th gear at 65 in traffic reduced oil temps. I had an air cooled VW van that would pull hills at 50 in 4th gear put a head temp gauge on it and watched temp climb to 450. Dropped it into 3rd going the same speed and temps came down to 300. RPMs in an air cooled are your freind!

[Michael7810]

If you're talking head temps; higher rpms provide better cooling. If you're talking oil temp; lower rpms are your friend. It's a balance.

[stownsen914]

Drive normally. Running it very hard or at high RPMs will of course raise temps. Lugging isn't good for your engine, so don't do that.

Higher RPMs naturally makes the fan go faster, sure, but the engine produces more heat too

[Tremelune]

Is there an issue? What temps are you seeing?

If it's hot in traffic, you want a better fan up front. If it's hot when pushed, more cooling surface area up front.

If temps are only hitting 230°F in the hot heat and the car is below 210°F for most of the year...I wouldn't worry about it too much...

[Noah930]

In my experience, as long as you keep the car moving, temps stay down. Get stuck in traffic (or stop and go), and temps go up. Engine speed is less of a factor.

[Mountainman]

Grady Clay told me several times when asked the very same question that
higher rpms are better, more air movement. He also suggested his Rubbermaid cooling
solution. If you do some research you should be able to find it in our forums.

I lived in lake Arrowhead for 20 years and climbing Highway 18 on a hot summer day from 900 feet elevation to 5920 would push me to 235 degrees ( 83 911SC ) I put a Carrera cooler on rt front fender throwing out the trombone and used a 4" Spal fan with a manual control switch to conquer the problem.
Temps still got to 220 degrees but at least I could get home without stopping for an hour to let the oil cool down. Look at Grady's solution, it might get you out of a jam on a 108 degree afternoon. Good luck.
DW

[redridge]

Does anyone know what temp the fan kicks in?

[manbridge 74]

Originally Posted by Mountainman

Grady Clay told me several times when asked the very same question that
higher rpms are better, more air movement. He also suggested his Rubbermaid cooling
solution. If you do some research you should be able to find it in our forums.

I lived in lake Arrowhead for 20 years and climbing Highway 18 on a hot summer day from 900 feet elevation to 5920 would push me to 235 degrees ( 83 911SC ) I put a Carrera cooler on rt front fender throwing out the trombone and used a 4" Spal fan with a manual control switch to conquer the problem.
Temps still got to 220 degrees but at least I could get home without stopping for an hour to let the oil cool down. Look at Grady's solution, it might get you out of a jam on a 108 degree afternoon. Good luck.
DW

Regarding rpm vs more cooling I think it depends on the configuration of each car. When I ran CIS it made a difference to have a somewhat higher rpm when I climbed from 6000 to 8550, so 4th gear. My current MFI engine definitely is cooler when in 5th.

[HaroldMHedge]

Originally Posted by redridge

Does anyone know what temp the fan kicks in?

The factory fan switch for the 87-89 Carrera cooler turned on at 118C Deg. (244.4F). This was too high for me so I purchased switch that energized the fan at about 190F.

[redridge]

Originally Posted by HaroldMHedge

The factory fan switch for the 87-89 Carrera cooler turned on at 118C Deg. (244.4F). This was too high for me so I purchased switch that energized the fan at about 190F.

interesting, thanks! I just saw it on the "101 projects for your 911" book.

[famoroso]

Since I deleted my fog lights, I made a jumper harness to repurpose the fog light circuit such that I could operate my oil cooler fan manually using the dashboard switch...







Details here...

Manual control of 3.2 oil cooler fan via existing fog light circuit / dash switch