Oil circulation upgrade

[blue72s]

Quote from Anderson's book on pg 188: "There are mixed opinions on whether the oil cooling in an engine with a dry sump should be done on the scavenge side or the pressure side of the oil system. Porsche actually cools on both sides of the system for the 911 production car engines. The engine-mounted oil cooler cool the oil in the pressure side of the system and the front-mounted external oil cooler cool the oil in the scavenge side of the system. All Porsche racing cars with 911-derived engines use the scavenging system for the oil cooling because the lines are so long that you would risk starving the engine for oil if you did this cooling in the pressure circuit. However, I have some friends who have experimented with using a small external oil cooler at the rear of their car in place of the engine-mounted oil cooler and said that it is amazing how much more effective the cooler is in the pressure circuit. The car originally had a large front-mounted external oil cooler in scavenge circuit, and now there is a small helicopter cooler at the rear of the car with air ducted through it. This much smaller cooler keeps the engine cooler than the original large front-mounted cooler."

So, I would like to try this on my car ('73), and remove my front-mounted external cooler. Do you know which make, type, and size of the new cooler I should get? And whereabouts exactly at the rear of the car should the cooler be located? Above the engine, under the lid grill? And what is 'helicopter'? Electric fan I guess?

If I do this, would it be possible to use 993 full-flow oil filter in the pressure circuit also? If so, how?

TIA

[Wil Ferch]

I've always been interested in this statement by BA myself....it looks as though the pressure-side is always "full liquid", and cools better than the oil/air mix that may exist on the scavenge side. This allows a smaller, more efficient cooler. I believe helicoptor cooler is exactly that...a small, high quality ( high $) aircraft component. With all the oil-cooling threads on this board, I always wondered why this option never surfaces ?

Hoping someone chimes -in with more detail. BTW....can someone also explain the caution not to use high-pressure circuit to cool a front mount cooler? ( reference to possibly starving the engine due to long lines?) Can't quite visualize the problem if everythung is filled full....

Wil

[svandamme]

just guessing here, but if you have long lines , then you will have a delay in the pressure, no matter what


what goes in , will come out , that's not the problem
but when pressure increases at 0 secs
then you won't have the increase at the end of the pipe at exactly 0 secs

air pockets, distance, tubes that expand in diameter, etc etc

so i would assume that this is not a good thing in an enviroment where the RPM and thus the pressure is not constant

your revs go up , and the oil delivery to the engine is not instant
the revs go down , but the pressure maintains a while ( actually , that last bit wouldn't be so bad)


maybe some hydraulics experts can comment, but as far as i get it
longer distance = more pressure required at the beginning of the pipe

or a pipe that is bigger at the beginning , than it is at the end ( that should raise the pressure at the end automatically)

[blue72s]

Thanks.
Are there any differences between helicopter and aircraft coolers? Just did a search and found some aircraft ones but can't find any helicopter's:

http://www.aircraftspruce.com/catalog/eppages/ndm.php

http://www.aircraftspruce.com/catalog/eppages/aeroclassiccooler.php

http://www.aircraftspruce.com/catalog/eppages/stewarnercooler.php

http://www.cubcrafters.com/cc/products/OilCooler.asp

Now, where should it be located? In the engine bay? Under the decklid grill? In the rear fender? (obviously has to be in the airflow)

[svandamme]

i would guess the only practical setup would be in the rear fender ( but they'de have to be seriously wide, with some sort of air holes in em )

anything else would require to much plumbing to be practical ( anything in the engine bay will require either a fan , or be integrated in the decklid , both would heat up the engine bay temp , which ain't a good idea imho)

personally , i don't think it's a viable setup for a 911
front coolers on the non pressure circuit , don't add weight to the rear,
and there's plenty of room in the front to mount em directly in the air flow

[Elombard]

their is a really prominent vintage race team, I think they are called club 906?? I looked at some of their 911 race cars a while back and all or most had the on engine cooler removed and the ports were plumbed to a cooler. I did not notice where the cooler was located (I assumed it was at the front). You might give them a call and see what they sell/say??

[blue72s]

Originally posted by svandamme
( but they'de have to be seriously wide, with some sort of air holes in em )

SV, If you'd read the dimensions, the 7 row one is only 8 inch long by 4.5 by 3.6 thick. (To be mounted vertically as the inlet port must be at the bottom and the outlet port at the top.) Perhaps helicopter ones are even smaller??

don't add weight to the rear,

The weight is only 1.7 Lbs.


Elombard, how do I find the url of that team?

[Early_S_Man]

Helicopter engines were at one time all reciprocating ... and varied in design just as with fixed-wing aircraft, and both radial and flat examples existed. Old, '60s vintage surplus catalogs from Earls showed both conventional designs exemplified by current Setrab or Earls products, and curved 'segment' designs ... from some of the radial engines of the '50s and '60s. My suspicion is that all current product development is done with turbine [jet] engines, so oil coolers aren't exactly off-the-shelf products for helicopter engines any longer ...

The one significant design feature of the 'segment' oil coolers for radial engines that was quite different was that they tended to be very deep, say 4" - 5" thick, and relatively small in cross-sectional area ... maximum cooling specifically tailored for a ducted-fan installation!!! The same type cooler was used for radial enginers on fixed-wing aircraft of WW II vintage, so maybe the proper descrition BA should have used was 'arc' or 'segment' design oil cooler for a radial engine ... rather than 'helicopter' cooler!!! I am quite sure that a single cooler for a P-47 or Corsair would be more than adequate for a 911 engine under racing conditions ... might not be so great waiting in line a the bank, though!

There are a couple of guys on the board with Bell 47 helicopters in their signature's stable of vehicles ... but, they used flat-6 engines mounted vertically, and their oil coolers aren't any different from a Lycoming or Continental engine for fixed-wing applications, IIRC.

[Elombard]

Not sure on the web site, I was hoping some one would chime in and confirm the name....

[blue72s]

Warren, many thanks for the clarification.

[svandamme]

Originally posted by blue72s
SV, If you'd read the dimensions, the 7 row one is only 8 inch long by 4.5 by 3.6 thick. (To be mounted vertically as the inlet port must be at the bottom and the outlet port at the top.) Perhaps helicopter ones are even smaller??

The weight is only 1.7 Lbs.


Elombard, how do I find the url of that team?

1.7 lbs, sure , empty , without pipes, without mounting bracket, protection from road debris , no fan ( the internal one has a fan, so i would think you need one in this setup as well, or you'll be in trouble when you hit a traffic jam )

i'm also not convinced that you can take the smallest cooler you can find, and mount it, it might be enough for normal cruising, but what about track driving, what about city traffic driving)

helicopters don't cover such a wide range of revs that the 911 engine does, so i would guess it's easier to tune cooling for such an engine

[blue72s]

SV,
Re-read BA's quote: "This much smaller (helicopter) cooler keeps the engine cooler than the original large front-mounted cooler."

The car would not gain any weight because the original engine-mounted oil cooler will be removed from car and possibly the front scavenge cooler as well, so it's a minus weight gain.

With this kind of set-up, I think it's a good idea to move the location of the (non-72) tank to the smugglers box in the front trunk like this:

[svandamme]

Originally posted by blue72s

With this kind of set-up, I think it's a good idea to move the location of the (non-72) tank to the smugglers box in the front trunk like this:

now that IS sweet

i'm allready planning to run pipes through my heater channels
for a front oil cooler

didn't think of moving the oil tank to the front as well
any pro's and con's to moving the oil tank?
has anyone done this?

i was thinking , left side of my engine case, run one of them hoses through the left hot air duct
connect to oil tank in trunk
then back via the right hot air duct

not to much difficult pipes to rout around corners either, very straight forward

then for my front cooler, i can simply run my stuff from the oil tank area to the fender(s)

might even mod the oil tank , with cooling fins, little schroud , then cabin blower sucks air from it ... presto .. heater in cabin works again ! man , i'm getting all giddy about it... can't wait to try this out

one thing i don't get with the above tank though :
how does oil go back to the engine? normally gravity makes it flow to the oil pump , but in this pic , the tubes connect to the top?!? is there another tube down below? or am i missing something here?

[blue72s]

Originally posted by svandamme
how does oil go back to the engine?

is there another tube down below?

Yes