Use your A/C to cool your engine!

[masraum]

Originally posted by DARISC
My Dad always drove Detroit V-8's. One thing he told me, when teaching me how to drive, was to turn on the heater full blast if I'm in a situation where the engine is heating up, that this might slow the temp.rise untill I could stop safely and see what the problem was.

I know it worked in his 51 Olds 88, because it happened to me and it got me to a country gas station 10 miles or so down the road w/o burning up the engine. Seems to me that might work even more effectively on an air/oil cooled engine.

As other's have said, it won't make a difference good or bad on our motors. Either way the air is always flowing from the engine through the heat exchangers. The only difference is if it dumps to the atmosphere or the cabin.

The reason that it works on a water cooled car is that the heat comes from the heater core which is basically just a small radiator in the dash. When you turn the heat on hot coolant from the engine flows through the heater core and a fan blows air across it. It's like adding an extra radiator. The system is completely different in a 911.

[bigchillcar]

+1

what masraum said..
ryan

[BrokeMyCar]

500,000 hp eh? Damn. But.... is it air-cooled?! =)

If it makes anyone feel any less comfortable, last week I made water spontaneously run uphill...

Babak

PS the trick is to use the surface-tension of the water, still no free energy, alas

[patkeefe]

So, this thread is the guys who think you can cool the house by leaving the refrigerator door open, versus the guys who know you can't?

[bigchillcar]

lol..pat.

[bigchillcar]

jim, ever work with any liquids colder than liquid nitrogen? i know it's probably the standard for this kind of work..we used it regularly for storing various little critters when i worked research in molecular biology, etc.
ryan

[RoninLB]

Originally posted by bigchillcar
driving the car in 4th gear instead of 5th saw my temps creep up

are you saying that, for instance, driving at 65mph in 5th then shifting into 4th while maintaining 65mph saw your temps rise ?

if so it's not my experience.

[911mot]

Wacky out the box idea all the way from the UK:

Remove the A/C pump and fabricate a mounting for an alternator.
Then remove the original alternator from behind fan and replace it with an electric motor. You can then have very high fan speeds even at idle....

[bigchillcar]

We have a two story LN2 dewar outside our lab building and pipe it around like water.

pretty handy..i always had to keep track of ordering a bunch of cylinders. not too many smiles around when you found you ran short. of course we'd play the occasional sophomoric games..dipping a rose in it to drop and shatter.. etc etc. hey, it was 20 years ago..i was young..
ryan

[bigchillcar]

are you saying that, for instance, driving at 65mph in 5th then shifting into 4th while maintaining 65mph saw your temps rise ?

yes..absolutely. i had a frequent 50-mile drive i'd make on the highway where i could maintain constant speed/rpm ranges for little 'tests'. i have no idea where that thread went, but grady was involved in it and i was reporting my observations. cruising at higher rpms resulted in higher oil temps at same ambient temps and speed.
ryan

[Jim Sims]

Remove the A/C pump and fabricate a mounting for an alternator.
Then remove the original alternator from behind fan and replace it with an electric motor. You can then have very high fan speeds even at idle....

Yes, plus combine it with a variable pitch fan and control the motor speed and fan pitch thermostatically

[bigchillcar]

Then remove the original alternator from behind fan and replace it with an electric motor. You can then have very high fan speeds even at idle....

ahh..i see. there would be no need for the 'normal' alternator belt either, as the motor would be powered by the newly-relocated, belt-driven alternator. you could have a variable-speed fan, based upon engine and/or driving conditions.
ryan

[Grady Clay]

Oh!

Even better; have a one-way (or electric A/C) clutch for the fan/alternator and electronically spin the fan faster at idle and low RPM. That 3-Ø alternator will work just fine alternately as a motor and dynamo with the proper electronics. The data we need is the HP vs. RPM of the fan to see if this is feasible.

Best,
Grady

[bigchillcar]

The data we need is the HP vs. RPM of the fan to see if this is feasible.

this might become interesting. can't you see this being a practical upgrade, sometime during the next 5-10 years, seen on more and more of our old 911's? electronically-controlled (or thermostatically?) electric-powered fans..higher-powered alternators that reflect 'today's loads' re-located to the site of the present a/c compressor. only thing is, the guy's who really need high fan speed at idle are the same guys who mainly drive in town..and they need a/c. the track guys are already hauling ass and may not benefit as much from increased electric fan speed..or am i wrong about that? guess we'd have to see how much speed we could reliably obtain from our electric motor..and maybe even design a better fan? perhaps one that borrows more from current jet aircraft technology and their systems of vanes..compressor section, etc. could there ever be too much airflow? a point where more airflow simply doesn't bring 'more to the table' in terms of cooling cylinder heads?
ryan

[bigchillcar]

grady..i just happened to notice (our posts are adjacent)..that we have identical 'total posts'. guess that's pretty much where the similarities end, eh? lol.
ryan

[Grady Clay]

Ryan,

You are right on point. One of the issues not addressed with our air (air/oil) cooled 911s is warm-up. A controlled fan wasn’t economically feasible in ’65. Allowing the fan to run at part speed during warm-up and cold weather is desirable now that we have electric fans for the heaters. Having the ability to spin the fan faster than the engine RPM ratio at low RPM is also very desirable.

Today, with varying connection to the crankshaft and the sophisticated use of a 3Ø 1500W (2.0 HP) motor-generator some subtle improvements can be had. With temperature sensing and feedback that can be doubled for short periods.

In the early ‘80s I considered a 2-speed fan and using the alternator as a motor under certain conditions. The technology was too expensive and too heavy then.

We need to understand how recent electric fans are. Think of a pre-’50s ship and the funnels used to ventilate the ship or belt driven fans on early locomotives. When considering our 911s, every HP counts for something; the art is applying it when and where it is most effective.

Best,
Grady

[RoninLB]

I think I'm correct that higher oil temps are not caused by an oil cooler deficiency in cars above?

The more power the engine produces the hotter the heads. The hotter the heads the more oil cooling necessary? For instance my CHT, went up from 210F/CIS/stock cam To 230F/Carbs/E-cams in general during tame driving. The engine up-dates created more hp = higher CHT. The up-dates create A CHT of 275F at a constant 4k in 5th.

If I was running at a DE and I was able to read a CHT of 325F[safely doable imo] and my oil temps were getting too high I would assume I had an oil cooler deficency.

Disclamer: My CHTs are not the most representative readings of true CHT but the plug gasket is good enough for monitoring up to full race where it turns into another ball game imo.



Am I all correct ?

[Duckworth]

The idea to run a high tech elec Fan is a neat one - but would it work WITH the belt driven fan - or replace it entirely ?

Example, even though electric waterpumps are widely available today, no one uses them as an 'equal' swap with the belt driven pumps simply because an electric pump can go out in a heartbeat and you've had it ! The reliability of the belt driven pump is why it's such a good thing... however, I may have misread your idea above.

The increases in air may work alright for someone north of Mason Dixon line - but how will they work for guys in New Mexico, Arizona, Ca - July thru September ? You may get a tiny benefit if finding yourself snagged a few hours on a hot freeway, but that's it !

For ex, Say it's 3PM and mercury is pushing 95 degrees
Farenheit. An aircooled motor's CHT - even with 3 X's the volume of 95 degree air - again, (as you're inching along the freeway) is not gonna help you much on your temps. Guys who are crunching numbers may differ - so the results are unofficial. Say you can keep move along at 20 -35 mph and you have 3 X's the volume of air. At 85 - 95 degrees F you're likely to see your temp gauge with not very nice readings.

No mention thus far about reducing the motor's compression to produce less heat . The conclusion seems to be that all the fun will vanish out of the motor. How do we know that for sure ? If a few guys here with Steve Wong chips in their 3.2 were willing to give it a try - there may be a surprise in store. Is dropping the horses from 240 to 215 something that could be offset in other ways ? Granted, it's the opposite of what guys usually do with their porsches...bumping 'up' that aspect of the motor is the by far the usual practice.


Phil
_______

'80 928
'82 Targa - sold

[Bryan A.]

I believe the 911 cylinder cooling airflow runs backwards. Heat rises. Seems it would be better to reverse the flow and draw air from underneath via inertial seperator, across the engine and out the lid. Would draw air from where you don't want it in the first place. Perhaps see some tangible negation of lift at speed or even downforce sans wing. Electric fans for use at slow speed. Nothing for high speed would seemingly be adequate. have to side mount the alternator among some other things.

[rnln]

:lol: a friend of mine used the engine heat to cook hotdogs when we passed by Arizona desert years ago :lol: Worked.