Cooling fan interchangeability?

[30KFT]

I'm curious to know if it is possible to update the 3.0 cooling fans by installing one from a later model like the 993? They look like they would move a lot more air and if the mod was reversible it might make sense.

[spuggy]

Originally Posted by 30KFT

I'm curious to know if it is possible to update the 3.0 cooling fans by installing one from a later model like the 993?

Anythings possible if you want it badly/try hard enough & have enough money and time.

If going the other way, it seems you have to replace the fan housing along with the fan: Anyone replaced 994/993 engine fan w/964 Turbo/965 fan

I have no information about required alternator/shroud changes or induction interference.

What 3.0 are you talking about? There's at least 3.

Originally Posted by 30KFT

IThey look like they would move a lot more air and if the mod was reversible it might make sense.

The later curved 964/993 fans are quieter. They flow less air (driven at 1.6:1 for 1010 l/sec) than the 245mm/11 blade setup used by 3.3 930s, 80-up SCs & the 3.2 - driven at 1.67:1 for 1500 l/sec airflow.

So most (I have no idea what the RS variants used) N/A 964/993 fans flow about 2/3 as much air as the earlier fan setup, used from '78 on the 3.3s, and into the life of the 965, post G body.

Engine Fan Drive Ratio
3.6 fan on a 3.2 ?

[30KFT]

Thanks, Spuggy. Application would be an early 76 Turbo 3.0. Sounds like an SC/3.2 would be a likely option. I'm at 5,000+ ft elevation and would like to drop operating temps about 10/15 deg F.

[spuggy]

Originally Posted by 30KFT

Thanks, Spuggy. Application would be an early 76 Turbo 3.0. Sounds like an SC/3.2 would be a likely option.

Eh? Are you missing the fan entirely? Did someone retrofit the wrong fan?

The "Turbo Carrera Model 76 Self-Study Program" in my FSM makes no mention of a fan difference between the '76 and the middie 911s - which all ran 245mm fans 74-77 (albeit a few years of those got the reviled 5 blade versions).

It does mention pulley ratio changes (the 3.0 got the identical ratio as the 3.3, late SC and 3.2 fans at 1.67:1) and air vanes and baffle changes between the 930 and 911.

And has a picture of a 930/51 (US-spec) motor with the separate wastegate input into the muffler - and very obviously an 11 bladed fan (or "cooling blower impeller", as they call it).

Originally Posted by 30KFT

I'm at 5,000+ ft elevation and would like to drop operating temps about 10/15 deg F.

Well, I could ask if it's US or RoW, what fan you have now, if it's got US thermal reactors (eek!), what oil coolers you run, why/under what conditions you think it runs too hot. And what "too hot" means to you/if you've checked it really is running that hot, or just what the gauge registers.

But that all seems like a lot of work, so if you're happy, I'm happy, LOL.

[Billiam 911 2.8]

Change your fan pulley to spin it faster and maybe get a newer more efficient oil cooler. Works for me on my early 911 HPDE car.

[spuggy]

Originally Posted by Billiam 911 2.8

Change your fan pulley to spin it faster and maybe get a newer more efficient oil cooler. Works for me on my early 911 HPDE car.

The 1.67:1 pulley ratio (122mm crank/84mm blower pulley) used by 930s, 80-up SC and 3.2s is already the highest (overdriven) ratio available with stock pulleys.

[flightlead404]

Originally Posted by spuggy

The 1.67:1 pulley ratio (122mm crank/84mm blower pulley) used by 930s, 80-up SC and 3.2s is already the highest (overdriven) ratio available with stock pulleys.

could probably get a shop to whip up something custom fairly inexpensively

just make sure the prop tips stay out of the transonic range or bad things may happen

[30KFT]

Spuggy,
11/75 DOM 3.0 cooling system complete and original except for Elephant cooler lines to the trombone. Fresh rebuild on US model w/K27 & Carrera cams, SC exhaust & PowerHaus muffler, no smog. Just looking to see if there is a simple fan update that can move more air and be done using factory parts. Runs at about 220F when thoroughly warm and moving. Moves up to 235 or so in stop & go traffic on 91 premium at this elevation (5K ft).

[mepstein]

Replace the trombone with a modern cooler, shroud and electric fan.
An engine fan with better airflow won’t help stop and go traffic if the engine is mostly at idle. The electric fan will kick on when the temp demands.

[spuggy]

Originally Posted by 30KFT

Spuggy,
...
Just looking to see if there is a simple fan update that can move more air and be done using factory parts

Well, maybe. But this won't help that much IMHO (because it's not the problem), and it'll cost you power.

You already have the same fan all the 930s, the 965 and (apparently) the 997 turbo used.

Originally Posted by 30KFT

Runs at about 220F when thoroughly warm and moving. Moves up to 235 or so in stop & go traffic on 91 premium at this elevation (5K ft).

My 930/60 with SC cams, K27 & headers - and a full-width FMOC in the Ruf valence - would run somewhere between 180-190F at cruise (for all "normal" ambient temperatures), spiking to 210F briefly after boost.

What does this tell you? The external thermostat opens at 185F and begins to divert oil to the front cooler. When the car was moving, the Mazda cooler had sufficient capacity to remove all excess heat from the oil - with the result that the temperature was maintained where the external thermostat wanted it.

If the external cooler can't remove that heat (eg because no airflow through it and the heat exceeds its ability to simply radiate it away), then the temperature will either keep climbing, or reach equilibrium at a higher temperature than the thermostat is trying to maintain.

The same car would see climbing oil temps, up to 230, 240F when stopped in traffic for 20-30 minutes. Zero air flow over the front cooler/minimal airflow at idle meant the system was accumulating heat faster than it could shed it.

Running the motor at fast-idle (say 1800-2400 RPM) would increase oil flow, and move more air over the cylinders/heads and the engine-mounted oil cooler. 5-10 minutes of this would knock 20F or so off the oil temperature.

Originally Posted by mepstein

Replace the trombone with a modern cooler, shroud and electric fan.
An engine fan with better airflow won’t help stop and go traffic if the engine is mostly at idle. The electric fan will kick on when the temp demands.

^^^ +1 what he said.

The trombone is the worst cooler available. All it gets you over no cooler is the external thermostat, and a small amount of extra oil capacity from the external oil lines. But the trombone "cooler" itself does almost nothing at all - it's just a loop to return the oil. There's more cooling function from the feed/return lines than the "cooler"

The 28 row brass cooler is better than the trombone - either moving or stopped. It works better as a radiator when stationary, and airflow through it actually does something.

But, if you're concerned about temperatures in traffic, Carrera cooler with the shroud and a thermostatically-operated fan is what you need.

Originally Posted by 30KFT

Runs at about 220F when thoroughly warm and moving. Moves up to 235 or so in stop & go traffic

Assuming your temperature sender is correctly matched to your gauge (74-76 w/ the 0-300F gauge take one sender, and the '77 with the 0-340F gauge take a different one) and that both are working & reading correctly, I still wouldn't be greatly concerned by that. Especially if you're running a decent oil.

My Owner's Handbook states that the oil temperature shouldn't exceed 300F. And that's for oils made & available in the 1970's - whereas I currently run a German-made full-synthetic (Liqui-Moly 2332).. Also provides lower viscosity for better flow on winter cold starts.

Low-quality oils break down sooner/at lower temperatures than better quality oils. Don't run a crap oil in an air-cooled car. Especially a turbo. And you should be fine.

Many diesels routinely run 200-230F oil temps towing a load, especially up grades, with 250F not being unknown or especially remarkable. Apparently. I ran Rotella for more than a decade - standard shop fill for turbos at more than one shop I've used. Yes, diesel-rated oils are fine for petrol motors - Shell say so. Diesel oils are designed for pressures/temperatures that water-cooled gas engines will probably never see.

That said, the temperature gauge isn't showing the whole picture. For example, engine oil gets pumped through the hot-side housing - and that puppy glows cherry-red under boost. And you probably don't want to know just how hot the heads get after idling for 20 minutes...

[30KFT]

Thanks to everyone commenting. Looks like I have the best available fan in place. I'm running 20W50 conventional Porsche oil. Is there a typical vintage fan powered unit you all would recommend? I would like to install something that was available (and efficient!) in the late '70s or was offered as optional equipment on a later factory 930/Carerra 3.0 model.

[spuggy]

Originally Posted by 30KFT

Is there a typical vintage fan powered unit you all would recommend? I would like to install something that was available (and efficient!) in the late '70s or was offered as optional equipment on a later factory 930/Carerra 3.0 model.

The short answer is "not that's period-correct for your car, no".

For some years (looks like 1972?) the S model of the 911 had a fender cooler, thus:



The SCs had either the "coiled cooling pipe", aka the trombone, or the optional 28 row brass cooler:



The Carrera oil cooler with fan came along for the 3.2s in 1984:



You can retrofit the Carrera cooler, optionally with the fan (which most would want). Our host does a kit (which at a glance, seems to not include the fan).

You can even fit two coolers, one in each fender like the ST/R cars, Elephant do a kit fopr that Complete Oil Cooler Kits For Porsche 911, 930

But you can't make an oil cooler that the factory didn't use until 1984 "correct" for a 1976 car.

[30KFT]

Thank you Spuggy. Looks like the SC 28 row cooler is as close to a "bolt in" (HA!) as I can get and still have it easily reversible. I'll be looking for one. If anyone out has one please advise.
thx

[Bucketlist]

I put this Mocal 44 row fender cooler kit on my 81 SC Turbo, added a switch operated fan. Mine came from BAT and has worked great for 10 years. Now you can get it from our host for about what I paid back then.

https://www.pelicanparts.com/More_Info/BATKPORD.htm?pn=BAT-KPORD&bc=c&SVSVSI=0572