I have a 2"X5"X12" oil cooler. With the 2 computer fans mounted the total thickness will be about 4.5"

Initially I was planing on mounting the unit under the trunk on the passenger side as many others have done.

It was suggested to mount it in the forward section of the rear fender well.

While mounting my race tires recently I took a good look at the space and there is a ton of room in the forward section of the fender well.

Doesn't Porsche mount some of their oil coolers in the same spot?

I would be really interested in hearing the pros and cons of this location.

Porsche did mount all the oil coolers in the right front fender for years. In the 993's they ran a fan on it, BUT it still had clean incoming air.

If you plan to track the car (ever) your fender mount/trunk mount wont work. I honestly donr beleive there are ANY computer fans that can move enough CFM to keep it cool.


My .02


B

QUOTE (joseph222 @ Jul 14 2005, 02:38 PM)

Doesn't Porsche mount some of their oil coolers in the same spot?

not really...

okay - the 911RSR had a transmission cooler in this location -- but it had big entrance and exhaust ducts...

'72 911's have the oil tank in that location (and the 914.6 has the tank on the oher side, still forward side of rear fenderwell). this area doesn't get much airflow but it does get a constant spray of dirt and grit coming off the tires.

the forward edge of the FRONT fenderwell works ok, because it's in the airstream. even so, those coolers typically need a gravel shield to keep them from being sandblasted from debris from the front tires - especially the actual radiator coolers - not as much the trombone "coolers" but they're basically just pipes to return the oil to the engine through the hardlines (that actually do the cooling...)

space or no space - i donno if there's a worse place for a cooler except maybe right behind the engine, next to the transmission, and over the exhaust (which i've seen...).

Okay, as long as we're on the topic...

How about this?...

Mount the oil cooler in the engine bay, but... Enclose it in a shroud with a nice sized radiator fan (say, 800 cfm), with a thermoswitch, and exhaust the shroud through an opening in the engine tin? No heated air from the cooler gets into the intake or engine cooling air. The question, will this be effective? Will it be counterproductive? I figure this has got to be better than hanging the cooler over the headers and next to the transmission...

Thoughts?

I'm thinking of this as a way of getting some extra cooling while staying legal for my class... I can't cut holes in the sheet metal to mount a cooler up front. Plus, the added weight in front of the wheels isn't that desirable... Less weight and lower polar moment the better.

-Josh2

How much CFM is needed? The computer fans are the perfect width for the oil cooler - 5" wide. They are "about" 150CFM each (I'm trying to confirm this).

So using two fans for a total of 300CFM not enough? I have no idea what an acceptable minimum would be.

The cooler is 5"X12".

Anyone have this type of info?

I can always purchase a Mocal cooler with fan - 160 bucks, but I was hoping these items I have on hand might do the trick.

QUOTE (joseph222 @ Jul 14 2005, 08:03 PM)

How much CFM is needed? The cooler is 5"X12". Anyone have this type of info?

the Earl's catalog has typical nomographs of heat rejection per square inch of cooler matrix per delta-T per airflow (might be vehicle mph, might be CFM, i don't remember. easy enough to calculate one from the other...)

the Earl's technical pages can be found somewhere at Holley.com

if you can't find it there, let me know, and i'll dig up my catalog and scan it for you.

an automotive oil cooler is going to want airflow in the 60-80 mph range. if your fans can't move air that fast, you'll probably be giving up a bunch of efficiency. and you have to watch the delta-T - if the air isn't MUCH cooler than the oil, you'll be giving up efficiency.

so let's work backward - how much heat are you looking to reject?
if you only need a 10F drop, you could be okay. if you're looking for 30F, you may be falling short. and in the end, you're going to have to test it anyway...

QUOTE (ArtechnikA @ Jul 14 2005, 06:13 PM)

typical nomographs of heat rejection per square inch of cooler matrix per delta-T per airflow (might be vehicle mph, might be CFM, i don't remember.  easy enough to calculate one from the other...) so let's work backward - how much heat are you looking to reject? if you only need a 10F drop, you could be okay.  if you're looking for 30F, you may be falling short.  and in the end, you're going to have to test it anyway...

"typical nomographs of heat rejection per square inch of cooler matrix per delta-T per airflow"

Uh...

Okay, let's work backwards.

Around town stop n'go with some freeway thrown in, engine temps are in the 180-200 range.

Temps stay below 200 for AX except for one that only had 5 cars per heat - then it went to 220.

But constant 4k rpms on highway during the summer and temps climb to 220.

So I guess I'm looking for about 20 degree buffer.

I don't feel like I'm being much help here.

Why bother? 200F is just fine; I personally think 212F is "perfect". 220F is not "too hot"--you can start to worry when you see 240F.

--DD

If 220 is the highest you see, skip the cooler.

Demick

QUOTE

Around town stop n'go with some freeway thrown in, engine temps are in the 180-200 range. Temps stay below 200 for AX except for one that only had 5 cars per heat - then it went to 220.

I agree with the others. Find something else to spend your money and time on...

Josh, if you need a cooler you might want to think about a jailbar style and mount it in a front fender location. This is what I'm using in the RS.

Josh,

Nice avatar.. I love it.

so I've sung this story over and over, but nobody listens.

I'm in the frontal air camp.
and I once saw the perfect set up for your application
t'was a colorado Drivers ed car.

guy drove to the track and the cooler was mounted inside the engine lid
now before people reply about the location dumping hot air into the intake let me finish.......

car owner opened the engine lid and quickly disconnected the cooler.
cooler was mounted to a nice bracket.
cooler lines came through the little 6inch side grill on the side of the engine lid....
guy lifted the cooler up and used the factory ski rack 3 bolts (under the targa bar on the passenger side) to screw in his fancy bracket.

cooler stood just up over the roof and straight into the frontal airflow.

t'wasn't as pretty as some set ups, but totally functional.
short lines
no frontal weight
frontal air.
simple.

when he was done he hooked it back down to the engine lid and drove home.

I can't say what oil pump he used.
Only bad of it, would be that a TINY bit of weight would move upward.
but the trade off would be effective cooling....

enough rambling
brant

Am I just taking an overly cautious attitude?

I've heard over and over that 220 is the max operating temp and anything over that shortens engine life. And that excessive heat is what kills these engines.

Is this not true?

QUOTE (joseph222 @ Jul 14 2005, 09:15 PM)

Am I  just taking an overly cautious attitude? I've heard over and over that 220 is the max operating temp and anything over that shortens engine life. And that excessive heat is what kills these engines. Is this not true?

Not really. You -want- the oil to get up to 212 or so to boil off any adsorbed water vapor in the oil. And a little higher than that is just fine. Keep in mind that most "common wisdom" that out there in automobile land is dealing with water pumpers. Where there is a large volume of liquid coolant to pull heat away from the oil. For us, the oil -is- the coolant. Well, that and the air... But for the air cooled motors, temps of 220 are just fine.

Save the money for a set of Koni's and enjoy the drive!

Brant, I'll give the "hangin' in the breeze" concept some thought. Gotta see if it'd be legal for me to cut holes in the grille...

Thing is, I have to retain the rain tray (darn -rules- ), so it would have to mount somewhere else besides under the grille when inside the engine bay...

-Josh2

Josh,

is it legal to remove one of those little side grills?
that way you wouldn't have to cut it.

and you could build a simple hook type of mount to snap it into the engine bay in the stock Djet brain box location or somewhere.....

(it wouldn't do anything other than add a quart of volume on the road, but would work good on the track)

brant

Josh

If it's a race car only, could you just bolt a cooler to the sail panel? Then like Brant suggested, just remove the little side grill and run the hoses down through there. But if it's a street car too, you wouldn't want to do that.

Demick

QUOTE (joseph222 @ Jul 14 2005, 04:03 PM)

How much CFM is needed? The computer fans are the perfect width for the oil cooler - 5" wide. They are "about" 150CFM each (I'm trying to confirm this).

A 5" fan is probably the 120mm. Even the 1.5" thick ones only get about 110 CFM Max. Quoted CFM is only standing in free air, that is, no rad. The CFM goes down quite a bit when installed.

Note: at 60MPH the rad, without a fan installed but facing the airstream, would see 2200 CFM. So anything over 5MPH the fans would hurt cooling performance.

QUOTE (davep @ Jul 15 2005, 08:28 AM)

Note: at 60MPH the rad, without a fan installed but facing the airstream, would see 2200 CFM. So anything over 5MPH the fans would hurt cooling performance.

I don't think the radiator is going to see 2200 cfm at 60 mph. This would occur only if the free space was 5' x 12" = 60 sq inches, with no resistance. The free area of the radiator (space between fins) is probably 0.5 or less. The 60 mph airflow is going to meet a lot of resistance and the pressure is going to back up in the inlet reducing flow through the duct.

I appreciate all of your insight, comments and predictions.

Threads that wander a bit like this always bring a lot of good extra info to the table. I thank you!

Today I did some engine temps documentation.

The engine is clean, valves adjusted, carbs sync'd & timing set. All the tin & rubber is in place except for drivers side air deflector under firewall.

Ambient temp: 95 degrees

City stop & go 200 degrees

Highway constant speeds on rolling terrain:

3800 rpm 220 degrees

4000 rpm 225 degrees

4600 rpm 235 degrees

When the temp got to 235 I slowed back down (temps went down too).

I think I'll move ahead with the external cooler. The two fans and cooler were free, so all it will cost are hoses and fittings plus the sandwich adaptor. If it doesn't do the job, I'll be all set to install something larger. Like Rich said... try it out and see if it works.

I'll post whatever the results are once completed.

Thanks again guys.

Joseph,

sounds warm
do you have a supper low front spoiler.
I used to have a supper low spoiler on a street car with a hot motor...

and on the highway, you could affect the oil temp with the throttle pedal similar to what you describe.

seems that not enough air was passing under the car
and then those turbulance flaps had no turbulance.
and there was a reduced suction (double negative... less of a low pressure zone?) under the motor to help pull cooling air through the motor and the stock cooler.

betcha if you add an inch and a half ride height/ front spoiler clearance your cooling problem goes away.

brant

Joseph, I mounted my cooler in the front fender well area. With an 800 cfm fan pulling air into the fenderwell from the engine bay.

Plumbing wise it is a great location. I have a manual switch for it and honestly I only see an improvement when I have it on and I am sitting in traffic.

When I do my next car I will definatly look for more airflow.

Duane

With that setup, I would recommend running the fan at all times (at least at a reduced speed). When the fan is not running, the engine fan is pulling air through the cooler in the opposite direction and heating up the air in your engine compartment (hence, preheating the air that your engine uses for cooling as well as the air going into the intake).

Ideally, you want to keep the air flow direction always going from the engine bay to the fender. Running the fan will ensure this is always the case.

Demick

QUOTE (brant @ Jul 15 2005, 04:21 PM)

betcha  if you add an inch and a half ride height/ front spoiler clearance your cooling problem goes away.

Brant,

Good point, although I run a stock valence. But, my car is lowered. The front doughnut is 4.5" so as you point out, there has to be "some" loss of air movement there.

Plus, a stock cooling system is just barely adequate in warmer climates.

Plus, my engine has Euro P/Cs & flycut heads so compression is bumped a bit, plus a moderate cam. It produces a bit more HP than stock, so it's going to produce a bit more heat.

I'm not convinced that my cooling would be resolved by raising the car. Anyway, it is set up for AX and is corner balanced with a 50% cross reading. Not going to touch that!

I may just hang the cooler off the trunk, but I'm "thinking about" fitting it into the fender well, inspite of others opinions that are much more knowlegeable than mine.

Do you have any other pics of your car? I'm thinking of a similar paint scheme.

QUOTE (Dman @ Jul 15 2005, 05:27 PM)

Joseph, I mounted my cooler in the front fender well area. With an 800 cfm fan pulling air into the fenderwell from the engine bay.   Plumbing wise it is a great location. I have a manual switch for it and honestly I only see an improvement when I have it on and I am sitting in traffic. When I do my next car I will definatly look for more airflow.

Duane,

Thanks for the info and pic. That configuration had not occured to me. Demick has pointed this out... have you tried running the fan all the time?

My cooler is narrow enough that it can be placed at a right angle to yours.

I'm considering putting an air intake (scoop) on my rocker panel and also under it for fresh air. Plus the two fans. Along with a protective screen on standoffs on the back side to keep debris off.

If it turns out that it increases my engine temps, I'll just use it in the winter

Joseph....

so if your running a stock valance (no spoiler?)
then I'm probably wrong about the lack of airflow.

the situation I had back when was one of those rubber lipped spoilers that was 1 inch off of the ground and allowed no air flow at the highway at 80mph


send me your email address and I'll link you into my ofoto's for more pics.

brant