I was putting around most portions of the track nose to tail with other Porsches during those 2 parade laps, but occasionally we would open up some gaps to "get on it" thru the occasional corner, so I doubt I was suffering from oil sloshing/cavitation. It was close to 100 degrees air temp and we were averaging maybe 30 mph. Either way, I will not be doing any track days in the foreseeable future, but thus far my oil temps are definitely lower with the new cooler installed which should make my engine happier on the upcoming hot summer days in traffic.

Hi everyone,

Just thought I'd throw my two cents in here - when I first bought my '77 S, it ran incredibly hot. On a warm day it was not uncommon to see 250 on the temp gauge, without pushing hard. This was a stock 2.7l, with no external oil cooler, stock 5-blade fan, etc.

I installed something I don't hear much about on here - a complete mocal oil cooler setup (in the passenger's side fender). If I remember correctly, it was the cheapest way to go at the time - the whole setup, including cooler, thermostat, oil lines, etc. came in under $1000. That mod, along with an 11 blade fan, has completely eliminated the problems. The car now warms up to 170 and stays there - regardless of what I'm doing.

Very nice.

- Damion

Re: Thanks
 

Greg,

With all the things you have already done, I think your car is fine. I think you are just not driving fast enough around the track to get enough air circulating around the trombone and engine! :D

Keep us updated on your findings as I am interested in your outcome.
Take care!

Jon,

There are two basic 245 mm 11-blade fans; ’65-’74 and ’80-> (same as ’75-> Turbo). The ’65-’74 fan is easily identified by the larger diameter fan pulley.

The parts to get 1.82:1 ratio are the 134 mm crank pulley and the later fan with the smaller 84 mm pulley.

Something I learned on the Forum is the past few years is the 5-blade fans (all?) have an 80 mm pulley. This allows the hub to be removed from the 5-blade fan and bolted to the early (’65-’74) fan. This should give an even higher ratio than the 1.82:1 configuration.

Had it not been for the German (and even more draconian Swiss) noise regulations, Porsche engineers would have had even higher ratios as the engines got larger.

John, I just found a good used 134 mm pulley with A/C shiv for Pelican rbuswell for $50. He will use it on his ’82 911SC to get 1.82:1 ratio.


It is important we keep sight of an important fact; an air cooled 911 can be seriously thermally stressed in some situations. I personally apply the “All-of-the-above” solution. For a discussion form it is appropriate to order the effectiveness vs. cost.

Best,
Grady

PS, the oil pickup screen issue is important. Are there links?

Grady, if you will permit me one minor correction, the '64-68 fans were actually 250mm in diameter. Starting in 1969, the size was reduced to 245mm. If one is seeking an upgrade for an SC, I would recommend a "930 106 102 4R" from a Carrera or the one from a late SC because the alternator is thicker on the later cars and the early housings are incompatible.

I tried all the "usual suspects" looking for a single shiv pulley but none was to be found. I considered putting a double on a lathe and parting the extra pulley off until I bit the bullet and bought one.

John,

I learn something every day. Thank you.

I had understood from your find that the 250 mm fan was only VERY early 901 (like ’64-early ’65).

If MY ’69 it the transition, I may have erred putting 245 mm Turbo fans in pre-’69 250 mm housings. I’ll go look. I wonder how much detriment there is with an additional 2.5 mm fan-to-housing clearance?

Since we are pushing the envelope with a combination of Factory parts; the most advantageous ratio would be the 250 mm fan and ’68 only mag fan housing, the 80 mm fan hub from a 5-blade and the 134 mm crank pulley common to ’75-’79.

With a pre-’84 Carrera case, you can make an only slightly larger custom crank pulley. With an ‘84 Carrera and later case (relocated engine mount stud) it is possible to use a considerably larger crank pulley.

Where to look for the 134 mm non-A/C pulley is basket case ’75-‘77 2.7s that has no or VWoA “CoolAire” A/C. The A/C kit used a bolt-on addition to the stock single pulley.


This is why I enjoy this Forum so much.

Best,
Grady

Edit for spelling

This is why I enjoy this Forum so much.


+1 Thank you Gentleman. Another bookmark for me.

i hope i still have my 5 blade!

hytem,
One way to tell if your cooler is working is if it feels hot when the oil is hot. That means the oil is flowing through it. You should also see steam if you have been driving in the rain.
Telling how well it is working is another matter.

.........................

I quick note for those who want accurate information.
Most of the Porsche factory built 911 based engines (906, 907, 911R 956, RSR) ran a 225 fan and housing with a 1.3:1 ratio. the reason being that a fan like a propellor operates best at limited speeds. The closer the fan tips get to supersonic the less efficient the air flow becomes. Many IMSA teams actually ran a power pulley to reduce the fan speed and consequent horse power lost associated with driving the fan.
The reason Porsche went to higher ratios pulleys in later cars was to promote cooling at low engine RPMs. AC on while sitting in traffic and the like. As the engines got larger the red lines when down so max fan speeds were equally reduced. Also because the fan and alternators ran on the same pulley increased electrical demands created a need for higher speeds.
As soon as the 3.6 engine was developed with a two speed pulley system the alternator speed went up and the fan speed went down.

The best way to cool an oil cooled engine (yes 911 engines are primarily oil cooled) is with a proper oil cooler.The bigger the better. With a proper oil cooler a race engine can even run with a reduced speed 5 bladed fan. The big concern here is head temp which is why we run a head temp sensor whenever possible.

As for Rubbermaid Solution, poppy cock. No top flight team that I can find uses this nonsense. If there is someone out there running this solution, I would love to hear from them.


Here is an example of a power pulleyas used on a Daytona 24 hrs winning 2.5 Porsche engine. Note the reduced diameter which of course will reduce the fan RPM.

http://forums.pelicanparts.com/uploa...1177807347.jpg

A fan does not have to go supersonic to be inefficient.
Generally a ducted fan will function it's best ( most flow/hp) at around 560 ft/s and still be relatively quiet.
Anything over 650 ft/s will tend to be very noisy.
Strangely enough when I calculate the tip speed of a 245mm fan at 7000 RPM I get 541.33 ft/s.
Later model Porsches generally redline between 6400-6800.
Racing Porsches used small fan turning @ a reduced ratio 1.3:1 because they ran at higher RPMs. Sometimes as high as 8000 RPM.

diameter mm rpm pulley ratio fan tip speed ft/sec volume l/s

early 911.......245.......6100.......1.3.......334...... .1360

76-77 5 blade.......245.......6100.......1.8.......462.... ...1265

SC.......226.......6100.......1.8........426...... .1380

930.......245........6100........1.68.......431... ....1500

964/993........279.4.......6100.......1.6.......468... ...1010

993tt.......279.4........6100.......1.8........526 .......1210

Check the fan on this 956 engine. 225 carbon fiber. Note the ratio. Although I have no real knowledge of the true ratio it is obviously less than 1.3:1.

http://forums.pelicanparts.com/uploa...1177809435.jpg

WOW!

nicely put henry. +1

Thank you everyone for all the info. As it turns out the problem was my own mistake. When it was posted about needing to update the sump etc. i checked my numbers and the engine allready had the update.
My plate does not have a drain plug so every oil cahnge i remove and drain, so guess what, I found out that i mounted the plate a quarter of a turn off which did not allow good circulation at track speeds. Just a quarter turn back and everything lined up great.
Had a DE at Willow Springs this weekend and drove the piss out the car and no heating issue, even in 100 degree wheather.
Thanks again for all the input.SmileWavy
greg

Guess what i just found on mine.
:(


50% pinch.

"No top flight team that I can find uses this nonsense. If there is someone out there running this solution, I would love to hear from them."

Henry,
Not an authentic "Rubbermaid Solution" as these are water-cooled engines, but our solution - for brake cooling in pro racing series.

Paul Gentillozzi's stable of TransAm Championship XKR Jags (Gentilozzi, Pruett, Kendall, Miller, Graf)
http://forums.pelicanparts.com/uploa...1178951758.jpg
http://forums.pelicanparts.com/uploa...1178949747.jpg

Also, Pratt & Miller Engineering's Cadillac CTS team in the Speed World Challenge GT series (Fellows, Angelelli, O'Connell, Pilgrim).
http://forums.pelicanparts.com/uploa...1178952020.jpg

Sherwood
www.seinesystems.com

This rather arcane system surfaces every few years.
Nascar teams tried this in the 80s then SCCA and Porsche club cars in the 90s. Most teams that tried this simplistic cooling system discovered that brake rotors cracked prematurely and warping was uncontrollable.
Trans Am cars are running short races now so I would assume these teams have decided that the trade off (cooling vs safety) is worth it.
There is a safety issue with this system in that cracked rotors are known to explode if used long enough.
Nascar may have outlawed this cheesy response to brake cooling for this very reason.

My 82SC has the trombone type cooler, and the oil temp has now crept up over 200F to the 9 oclock position--in the hot weather and highway traffic today. Trouble is I have a small oil leak which appears only in hot weather when the oil temp gets above 180-190F--the normal temp this winter. Hadn't seen it since last fall.
I'm wondering if changing to a radiator type of cooler would cool the oil just enough more to stop the leak. The leak isn't in a great place to fix.

I don't know how much the radiator change would cost. Anybody have an idea?

Just saw this post after I posted about switching from the trombone cooler I have to a radiator cooler. I started dropping a bit of oil today coming down the driveway after a trip in hot weather/traffic where the oil temp went up past 200F to the 9 oclock position. I hadn't seen that leak since last summer--this winter my normal oil temp didn't exceed 190F--and no leak.

I guess the question is whether going to a radiator cooler would cool the oil enough to stop the leak? How much would that cost ?I think the leak is in a bad place to reach.

I'll have to check the tube to see if it's hot next time I drive it. I don't drive in the rain.

"No top flight team that I can find uses this nonsense. If there is someone out there running this solution, I would love to hear from them."

.... and then:
"Trans Am cars are running short races now so I would assume these teams have decided that the trade off (cooling vs safety) is worth it."

Henry,
I thought you wanted to hear about some top flight team using them. Now it's something else. Okay. You don't subscribe to the theory. Thanks. Are different points of view okay? Maybe not.

Short races don't mitigate the temperature a rotor will reach, and a water mist isn't going to cryogenically freeze the rotors and/or shock a 1500º rotor into pieces. However, it will reduce the air temperature that cools the rotor by about 18-20ºF. A modest improvement, but in some cases, that's what it takes. Please contact Rocketsports Racing and/or Pratt and Miller Engineering and advise them what works and what doesn't.

Speed World Challenge Pratt & Miller Cadillac CTS brake duct:
http://forums.pelicanparts.com/uploa...1179007960.jpg

The TransAm and World Speed Series organizers decided it's safe. That's why it's allowed in their rule book. NASCAR has its own set of rules as does ALMS, F1, WRS, POC, PCA, SCCA and the various Vintage Racing series. Some regs allow it, some don't.

Do you think 911 cylinder heads will crack from a water mist too?

Sherwood
Seine Systems