The recent heat wave in the bay area caused me to wonder if there are methods to 'cool' or otherwise lower the temperature of our engines while we are driving?

I recall an article in Hot Rod magazine years ago, suggesting coasting in neutral,
preferably downhill, as a method to cool a V8 engine. The engine at idle slows the pumping of coolant allowing more time to cool in the radiator. When you would put it back in gear the colder coolant would enter the block and the temperature drop was noticable.
I assume at idle our engines fans are least efficient but at higher rpm more air is moved but operating temp should also increase making this a wash?

Is there anything one can do to get the temp to drop? Is driving at a constant speed, 70 mph for example better than varying speeds?

If the engine gets hot is there any way to cool it down while driving?

Thanks

Going downhill is not really a practical way to cool the engine. While it does work, big downhills are usually hard to come by whenever your engine is running hot. :-)

The only way my engine cools off is to slow down. The faster I drive, the higher the temps go. So slow down to 55-60 or so and it should cool down. Maybe slowing to 50 and putting it in 4th gear might help even more (higher rpm's provide more cooling air), but I've never needed to try that.

But the motor cools pretty quickly when you shut it down. So taking a 7-11 break is another way to go.

Demick

The methods I know of are:
External oil cooler with fresh air flow.
Fresh air flow into engine compartment from outside. Someone did a measurment of negative pressures at the engine grill and in the compartment and under the engine. It seem that there was little gradient for flows.
Additionally, I removed every other or kept every third fan blade, which is supposed to improve flow.
Additionally, there is the DTM down the middle modification that can be done.
Larry

how come no one has yet mentioned the most important cooling tool of all?



















Jack stands

Even in the recent "heat wave" here, my oil temps are no more than 180-190 at freeway speeds, unless I leave it in 4th and run it up to 80mph, in which case it can rise to 200 or so. Yesterday afternoon on 101, at 50-60mph, I could barely get the oil temps UP to 180. Totally stock cooling system on a Type IV.

If you're running carbs, having them "balanced" is paramount.

For that matter, be sure the engine is well tuned (valves, timing, etc).

Have all the engine tin in place and "holes" filled.

Turbulance flaps will help on the highway.

If non of the above does it, move to a cooler climate.


..

The needle on my stock temp guage moves only slightly to the right even in slow freeway crawl, it has never approched the red nor has it gone to the 'middle' of the guage. I don't know what actual temp is at those points. I guess it is running ok.

I suppose another tactic might be removing the rain tray for summer driving, this should enhance cooling?

How I cooled my motor on Tuesday during this recent Bay Area heat wave.

Drove from my office, James knows my parking lot all to well – thanks again, in San Mateo to Woodside road, over Skyline, through La Honda, to HGWY 1; winding mountain roads and 30 degrees cooler on the coast than the bay. Down highway 1 to Capitola. Margaritas and dinner at Margaretaville then home to San Jose.

T

Freeway crawl is easy on the temps. It's the high speeds that will push the temps up on these things.

My rain tray is out, but the impact on temps is minimal.

Based on what you say about your temp gauge, sounds like you should just drive and not worry about it.

The stock gauge is only oil temp though, and the head temps are important. If it's tuned correctly you shouldn't have to worry about it under any kind of normal driving conditions. But a vdo head temp gauge is a good $80ish well spent just to know where it's at.

Ceramic coating and header wrap.

Hey Treavor,

I know that drive, very nice, scenic and lots of curves. How's the Bursch working out?

Thanks for the tips, I guess I am running fine, with 33 year young cars constant concern is our co-pilot.

This would not be my first choice but I'm sure it would work, drive it into a lake. Shy of

that extreme just keeping my foot out of it makes a big difference.

Ed, there's not a lot that can be done while driving, other than slowing down and raising the fan speed (more RPM). 5th gear can be a killer on the engine if the RPMs are low. But there is nothing comparable to the turn-on-the-heater trick in water cooled cars.

BTW, I got your 'letter'. Thanks!

Hi Ed - The drive was great and the bursch is working well. Still have not put the HE on yet...in due time.

Thanks

T

Have you tried tuning it?
the correct mixture of gas and air does wonders for head temps and oil temps.
all the tin and gromets in place, clean fan blades, clean tin and clean oil cooler.
Headers can cool them down and timing is the #1 heat maker.

This was a hypothetical question. He mentioned his car doesn't even reach halfway to the red.

I've heard that synthetic oil will run much cooler than regular, but dont have any numbers at hand to back this up.
Konrad

Jake Raby has posted that he found as much as a 10 degree F drop in oil temp based on oil choice. But I'm not sure which oil it was. If you made me guess, I'd say Royal Purple.

It was Royal Purple. I'd say the best RP choice would be the max cycle 20w50. That's what I run in my high-strung 912. After 4000 mi and an average of 220-240 sustained oil temps, the TBN dropped from 8.5 to 6.5 roughly and the Zn and P where barely affected. Change in viscosity was nil. I'd say that RP recommendation of 15,000 mi is well earned. I'll just change it more often since it doesnt cost that much with so little oil. Not like my wife's W8 Passat - it takes more oil than my 911.

Yay! I remembered something. Thanks for popping in Charles.

My engine only gets hot ( 230-240° ) when I drive 5-7k rpms sustained for 25 minutes plus in 100 degree plus weather.


KT

hey guys, I have a handheld IR temp gun, and I'm wondering where I should take a temp reading, and what range it should be in, so I can put this thing to use! THanks!

On-off approch.
I discovered this last month driving my car up from cincinati. If you very the throttle on and off for equal amounts of time the car runs stupid cool. For example two seconds stepping on the gas, two seconds throttle closed. Up to like 5 or so seconds everthing is cool.
I was going to start a thread about this cause it makes it possable to use 5th(most beleive you do not get addaqut cooling air to stastain 5th gear). Even intentionaly luging my engine(50-55mph in 5th) my head temps would not go above 325 using this techneque.
I was doing 70-90 in 5th, for 3 hours of highway driving, and my Westach CHT gauge was reading between 300-340 degrees. For the first hour(before I made this discovery) keeping the throttle steady, in 4th doing 65, I was having a hard time keeping it below 375.
Give it a try. It worked for me
Samson

When I bought my car, I had this discussion with the PO. He is a family friend since they were selling these things new, and has been the "914 Guy" at Frank's Automotive here in Sacramento, which is the "914 Shop" as I understand it.

I asked him about oil coolers, overheating, carbs, rust etc.

His response, "Bah, external oil cooler, you don't need that, you make sure what is on the car is right, keep the valves adjusted, change the oil and it will run forever. If you put air conditioning in it, you are an idiot, they only put A/C in them for Americans. Those Germans know WTF they are doing now, and they did then. If you switch to carbs, you will always regret it. They rust from the inside out. When are you going to get a haircut?"

He has been the 914 wrench at Frank's for about 20 years. He had a lot of other stuff to say too, like, "When are you going to buy the rest of my 914 stuff, you can have that console with the gauges in it, that fog light switch in the car is broken, take this one, these 2 liter wheels were only on a car once and the gouge in the one rim is from the firemen. That dent in the driver's door is from when they were throwing stuff out the hole they chopped in the side of the house, those bumper tops wer perfect before they got all burned up"

He said a lot of stuff, upshot was the design is fine how it is, you are not smart enough to improve it. He is probably right with respect to me, some of you guys are smarter than me though

How about one of those spray misters you get at wal-mart, inside the tin? But spray something non-corrosive...

In 110F heat index at 125 MPH hammer down and flames coming out the exhaust pipes and never had her over 180F. How do I do it?

Stayed at a Holiday Inn!

I was going to try it but I couldn't find a garden hose long enough.

Dude, you are trying to solve a problem that you don't have. Just drive the car. If the needle never hits red as you say then you are doing fine.

If you use the pyrometer, shoot the sending unit and the oil filter.

Then compare these numbers to the guage.

My sending unit seems to be the hot spot and it reads 10 degrees lower than my guage does.

i shoot *everything*. oil tank, lines, cooler, t-stat, my arm...


KT

If you take temp readings, always use the same location and distance. BE CONSISTENT. That is the best way to see changes.

When you take your foot off the gas (throttle closes) then no fuel is injected into the engine. This mode is called "over-run" when done with the car in gear (engine is being turned by the road wheels). One of the reasons FI gets better mileage than carbs, which always have fuel flowing thru 'em And with no fuel to burn, no heat is genereated

As mentioned earlier a large external oil cooler since oil does most of the cooling if you give it a chance. The cooler has to have great air flow, in the front trunk is still the best. Next is to have all the engine tin and the seals between them and the body. Next is to block off all the holes in the tin or seal the ones that have something coming through them, such as the rubber boot that seals the oil pressure sender wire on top of the engine.

I installed a mister system on the race car to the front cooler, I used a JC whitney windshield washer with a built in pump and there are three nozzles at the front cooler. It drops the temps about 15 degrees but does leaave a slight trail of steam/vapor which track workers question as if the engine has a coolant leak. The little tank will last about 15 minutes of a race.