 Need Advice - Best Location for Oil Cooler, Passenger rear fender well???? |
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| Joseph Mills |
 Jul 14 2005, 12:38 PM
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#1
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on a Sonoma diet now...  Group: Members Posts: 1,482 Joined: 29-December 02 From: Oklahoma City, OK Member No.: 39  |
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. |
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| Brad Roberts |
Jul 14 2005, 01:39 PM
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#2
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914 Freak! Group: Members Posts: 19,148 Joined: 23-December 02 Member No.: 8 Region Association: None |
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 |
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| ArtechnikA |
Jul 14 2005, 01:41 PM
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#3
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rich herzog Group: Members Posts: 7,390 Joined: 4-April 03 From: Salted Roads, PA Member No.: 513 Region Association: None |
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...). Attached image(s) 
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| jhadler |
Jul 14 2005, 02:35 PM
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Long term tinkerer... Group: Members Posts: 1,879 Joined: 7-April 03 From: Lyons, CO Member No.: 529 |
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 |
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| Joseph Mills |
Jul 14 2005, 06:03 PM
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#5
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on a Sonoma diet now... Group: Members Posts: 1,482 Joined: 29-December 02 From: Oklahoma City, OK Member No.: 39 |
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. (IMG:http://www.914world.com/bbs2/html/emoticons/rolleyes.gif) |
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| ArtechnikA |
Jul 14 2005, 06:13 PM
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#6
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rich herzog Group: Members Posts: 7,390 Joined: 4-April 03 From: Salted Roads, PA Member No.: 513 Region Association: None |
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... |
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| Joseph Mills |
Jul 14 2005, 06:41 PM
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#7
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on a Sonoma diet now... Group: Members Posts: 1,482 Joined: 29-December 02 From: Oklahoma City, OK Member No.: 39 |
"typical nomographs of heat rejection per square inch of cooler matrix per delta-T per airflow" Uh... Okay, let's work backwards. (IMG:http://www.914world.com/bbs2/html/emoticons/biggrin.gif) 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. (IMG:http://www.914world.com/bbs2/html/emoticons/biggrin.gif) |
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| Dave_Darling |
Jul 14 2005, 07:13 PM
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#8
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914 Idiot Group: Members Posts: 14,984 Joined: 9-January 03 From: Silicon Valley / Kailua-Kona Member No.: 121 Region Association: Northern California 
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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 |
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| Demick |
Jul 14 2005, 09:23 PM
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#9
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Ernie made me do it! Group: Benefactors Posts: 2,312 Joined: 6-February 03 From: Pleasanton, CA Member No.: 257  |
(IMG:http://www.914world.com/bbs2/html/emoticons/agree.gif) If 220 is the highest you see, skip the cooler.
Demick |
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| Eric_Shea |
Jul 14 2005, 09:45 PM
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#10
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PMB Performance Group: Admin Posts: 19,275 Joined: 3-September 03 From: Salt Lake City, UT Member No.: 1,110 Region Association: Rocky Mountains  |
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. Attached thumbnail(s) 
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| brant |
Jul 14 2005, 10:39 PM
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#11
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914 Wizard Group: Members Posts: 11,623 Joined: 30-December 02 From: Colorado Member No.: 47 Region Association: Rocky Mountains
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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 |
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| Joseph Mills |
Jul 14 2005, 11:15 PM
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#12
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on a Sonoma diet now... Group: Members Posts: 1,482 Joined: 29-December 02 From: Oklahoma City, OK Member No.: 39 |
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? |
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| jhadler |
Jul 15 2005, 09:37 AM
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#13
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Long term tinkerer... Group: Members Posts: 1,879 Joined: 7-April 03 From: Lyons, CO Member No.: 529 |
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! (IMG:http://www.914world.com/bbs2/html/emoticons/biggrin.gif) 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- (IMG:http://www.914world.com/bbs2/html/emoticons/wacko.gif) ), so it would have to mount somewhere else besides under the grille when inside the engine bay... -Josh2 |
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| brant |
Jul 15 2005, 09:41 AM
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#14
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914 Wizard Group: Members Posts: 11,623 Joined: 30-December 02 From: Colorado Member No.: 47 Region Association: Rocky Mountains
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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 |
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| Demick |
Jul 15 2005, 09:55 AM
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#15
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Ernie made me do it! Group: Benefactors Posts: 2,312 Joined: 6-February 03 From: Pleasanton, CA Member No.: 257 |
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 |
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| davep |
Jul 15 2005, 10:28 AM
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#16
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914 Historian Group: Benefactors Posts: 5,141 Joined: 13-October 03 From: Burford, ON, N0E 1A0 Member No.: 1,244 Region Association: Canada |
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. |
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| maf914 |
Jul 15 2005, 11:09 AM
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#17
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Not a Guru! Group: Members Posts: 3,049 Joined: 30-April 03 From: Central Florida Member No.: 632 Region Association: None
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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. |
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| Joseph Mills |
Jul 15 2005, 03:43 PM
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#18
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on a Sonoma diet now... Group: Members Posts: 1,482 Joined: 29-December 02 From: Oklahoma City, OK Member No.: 39 |
I appreciate all of your insight, comments and predictions. (IMG:http://www.914world.com/bbs2/html/emoticons/rolleyes.gif)
Threads that wander a bit like this always bring a lot of good extra info to the table. I thank you! (IMG:http://www.914world.com/bbs2/html/emoticons/pray.gif) 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. (IMG:http://www.914world.com/bbs2/html/emoticons/beer.gif) |
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| brant |
Jul 15 2005, 04:21 PM
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#19
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914 Wizard Group: Members Posts: 11,623 Joined: 30-December 02 From: Colorado Member No.: 47 Region Association: Rocky Mountains
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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 |
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| Dman |
Jul 15 2005, 05:27 PM
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#20
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Member Group: Members Posts: 163 Joined: 18-February 03 From: Sacramento CA Member No.: 311 |
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. Attached image(s) 
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