Lowered temps with Updated Shroud ('67)

[Fred999]

Bottom line: an updated shroud (circa 69-73) with a oil cooler duct lowered my temps by 30F!

Previously my 2.0 911S would hit 210F, and now its 175F prior to adjusting the themostat to open later. (as I want it to run at 180-185F). My mechanic also installed a Carrerra 3.2 fan pulley, which increased the air flow over the cylinders in addition to the improved oil cooler duct. Now I don't have to worry about a front external cooler

Am I a happy camper/driver

[bob tilton]

for real? 30 degrees difference? that's voodoo. not trying to be a smart arse but that's an incredible difference. good for you err, i mean good for the engine!

[Fred999]

Yep, no voodoo.
If you check out a '67 engine shroud there is barely an inch or less gap (I think much less) at the back that enables air to blow onto and through the oil cooler. Basically, the fact that Porsche "updated" the shroud to include a duct (with no engine capacity increase) up to 1970 shows that there was an original design "weakness".

The conditions I have been running the car have been identical or hotter than before. Truthfully, I am kinda blown away myself.

Compared to a front cooler, this seems like a pretty inexpensive upgrade if you ask me. That said, I am not sure what year Porsche introduced the updated shroud, so maybe its only applicable for 1967 cars such as mine.
You also have to remember that the new fan pulley is blowing a ton more air than before, so its not just the shroud. I am still using the existing original 11 blade fan.

Also, Bob, there are other early P-car owners who believe that the 210F I was getting before is fine and I didn't need to lower my temps - so who knows. What I do know is that I was getting 210F before when I wasn't driving the car hard and no amount of standard air cooling would bring this down (ie going from a stop/start traffic condition to open road at 45MPH).

[bob tilton]

i have the shroud from my 2.2 sitting in the garage and pics from my 2.7 as it was being built up. i am going to have to take a good look to see the differences but i know you are referencing the earlier shroud. from memory between my 2 shrouds i know that the later one is 2 pieces as it routes to the cooler.
my 2.7 runs at 210 which is why i will follow this thread. thanks for posting as i am looking into external front oil coolers. might save me a pretty penny and i don't have many to spare these days.
post pics please!

edit: how are the pullys different?

[Fred999]

This is the original shroud off my '67 911S. You can see there is really no major provision for the front oil cooler.



This is a closeup of the backend of the shroud which would reflect the gap on the shroud enabling blown air down through the oil cooler. I measured the gap and its a hair under one inch. Not much really.


As you can see (badly) with the new setup it has the duct that runs to the oil cooler. Now, ignoring my badly pitted fan you can see that there is about 3 inches of space and specific ducting to the oil cooler. The shroud is from a T model as all the other later year models have MFI, which would be messy with a carb setup.
Again, maybe this "update" is only applicable to my year, I dunno. What I can say is that its made a huge difference! Combined with this, my distributer is getting rebuilt and I am using a loaner which is playing havoc with my timing, which I am sure would be increasing temps. The only other variable I can think of with the change, is my mechanic fixed one piece of the engine tin metal that had broken off, but he didn't think it was signficant (although every bit helps).

[Neilk]

Here's a picture where you can see the '73 shroud that has a the large oil cooler area.



Grady mentioned changing pulley but I had no idea which one to get. I will look into getting a Carrera pulley as well since I don't have a front oil cooler.

[Fred999]

Originally posted by bob tilton
edit: how are the pullys different?

The 3.2 Carrera pulley is larger diameter, which results in spinning the fan faster. I am not sure what the ratios, calculations are - more knowledgable people can chime in on that one. There are a number of older threads on the pulley upgrade to enable greater volume of air blown over the engine.

[304065]

You want the "overdrive" pulley from a 930-- it's all in the archives here.

[NevenM]

Fred

Nice colour (my 73 911E is about the same), thanks for posting the 67 shroud photo you can definately see the mod they did for the oil cooler, I wonder if your loaner distributor is lowering the temp (which it would if the advance curve was milder)

Neven