Air flow to fender oil cooler and after market bumpers

[Dueller]

I am installing after market front rs style bumpers on my 87 carrera. Car is equipped with fender oil cooler and fan. I've never had a problem with oil temps. I know the factory had a small cut out under the bumper on the passenger side to facilitate fresh air flow.

Anybody noticed elevated oil temps after going to one piece after market bumper s? Anybody make an air duct for increased fresh air?

[Flojo]

think again... does it make sence to delete air flow to a cooler? no.
so whatever your up to, do alittle search and find out according to pictures what others have done (bore wit leading pipe to cooler maybe).

or, more "simple", relocate the fender cooler to the mid-front section, real RS style ;-)

[kuehl]

Jim,
If this helps you think through this:
I have a 87 cab, was a 3.2, is now a 3.5, 9.5:1,
stock gas, 8 psi of boost (supercharged),
stock oil cooler, removed stock fan,
attached 2 fans, installed lower temp electronic thermostat,
stock bumpers and valance,
oil temps are fine.

There is so much air in the front pocket the fans never
have issues finding it. And, unless you are going to build
a 1' x 2' tunnel for ram air to it, you don't need anything else.

[Targalid]

Front oil cooler air scoop

Porsche 911 (1974-1989) - Bumpers, Doors, Latches & Lids - Page 12

[TheSt|G]

Originally Posted by Targalid

Front oil cooler air scoop

Porsche 911 (1974-1989) - Bumpers, Doors, Latches & Lids - Page 12

This item is remarkably effective.

[Dueller]

Originally Posted by Targalid

Front oil cooler air scoop

Porsche 911 (1974-1989) - Bumpers, Doors, Latches & Lids - Page 12

I am familiar with that scoop for stock bumpers. Never had need with stock set. What I was curious about is when I add one piece front rs fascia which won't have center oil cooler opening as I am modifying to eliminate opening similar to an SC RS front. Thought about a naca duct on right side of bumper.

[will hung]

Can we get a pic of what you are starting out with?

If you are using an IROC front bumper to start, couldn't you just have the same opening at the bottom of the "blade" as the Carrera's had?

or

If using an IROC front bumper, couldn't you keep the passenger side circular hole and duct it to the cooler?

[Dueller]

Originally Posted by will hung

Can we get a pic of what you are starting out with?

If you are using an IROC front bumper to start, couldn't you just have the same opening at the bottom of the "blade" as the Carrera's had?

or

If using an IROC front bumper, couldn't you keep the passenger side circular hole and duct it to the cooler?

Sure, Will.but I am using brake cool ing ducts for....brake cooling with hose attached. I may be worrying for naught. But essentially front will only have ducting for brakes. Also thought about modifying glass bumper with a 964 duct on right side.

[Rodsrsr]

Interesting how these "cookie cutter" parts (even something as simple as a FG bumper) quickly turns into something that requires modification and re-design, or in other words "custom one off" lol.

[mnez]

I put on a RSR style FG bumper with a closed front oil cooler area. I sealed the area between the fender cooler and bumper with aluminum sheet, directed the air from the round brake cooler opening to the cooler, as well as cutting a rectangular opening in the underside of the bumper area, similar to the stock opening. The air has to go through the cooler since there is no other exit.
It has worked quite well, even on the track.
However we don't get southern US temps, but it works well for our summer temps in Ontario.
Brakes are cooler by the scoops attached to the bottom of the control arms.

[911pcars]

An oil cooler in the front fender is the same as sitting inside a car with the windows closed on a hot day. I exaggerate, but not by much. Within the available air space, your body perspires to radiate heat; the oil cooler radiates what it can. Not ideal nor efficient.

If you have no overheating issues, you're good - the variables are all working in harmony; ambient air temp, operating conditions, vehicle speed, altitude, engine size and state of tune, etc.

If the oil temp ventures close to or into the "9 o'clock" region of the gauge (some say 220ºF +), some remedial responses are in order - one or more of the following:

- Direct more air to the cooler (air scoops/deflectors, electric fan, relocate cooler to high pressure area, minimize air flow resistance through cooler, etc.)
- Provide for adequate airflow when vehicle speed doesn't provide it (electric fan)
- Reduce air temperature (save this for track/competition)

MHO,
Sherwood

[bugstrider]

Originally Posted by 911pcars

An oil cooler in the front fender is the same as sitting inside a car with the windows closed on a hot day. I exaggerate, but not by much. Within the available air space, your body perspires to radiate heat; the oil cooler radiates what it can. Not ideal nor efficient.

If you have no overheating issues, you're good - the variables are all working in harmony; ambient air temp, operating conditions, vehicle speed, altitude, engine size and state of tune, etc.

If the oil temp ventures close to or into the "9 o'clock" region of the gauge (some say 220ºF +), some remedial responses are in order - one or more of the following:

- Direct more air to the cooler (air scoops/deflectors, electric fan, relocate cooler to high pressure area, minimize air flow resistance through cooler, etc.)
- Provide for adequate airflow when vehicle speed doesn't provide it (electric fan)
- Reduce air temperature (save this for track/competition)

MHO,
Sherwood

Don't want to jack the thread but I do have a question relating to the "(9 o'clock) position. I removed the trombone cooler and swapped for 28 tube brass. I will see the temps climb to the 9 position or slightly above on a curvy road on warm days when stuck behind a slow mover or sitting. Will anything be gained by mounting a circulating cooling fan to mitigate airflow since the 28 tube acts as a heat sync in these conditions? Have already installed the air scoop too.

The car, 78 911SC 3.0L is currently sitting pending a distributor replacement. Could a failing distributor affect the temps by possibly causing the timing to oscillate affecting ignition prior to total failure?

[Josh D]

Originally Posted by bugstrider

Don't want to jack the thread but I do have a question relating to the "(9 o'clock) position. I removed the trombone cooler and swapped for 28 tube brass. I will see the temps climb to the 9 position or slightly above on a curvy road on warm days when stuck behind a slow mover or sitting. Will anything be gained by mounting a circulating cooling fan to mitigate airflow since the 28 tube acts as a heat sync in these conditions? Have already installed the air scoop too.

The car, 78 911SC 3.0L is currently sitting pending a distributor replacement. Could a failing distributor affect the temps by possibly causing the timing to oscillate affecting ignition prior to total failure?

First verify your actual temps against what the gauge is reading with an IR thermometer. It could be that you're due for a new temp sending unit. Also check to make sure your long oil lines under the car aren't partially crushed.

I'm running the 28 row brass cooler and the only times I see temps that high are at the tail end of a 30 min commute in 110* ambient and running the A/C. If you're seeing 220*-230* on just a spirited drive, you might have other issues.

[IROC]

In my experience, the bumper itself doesn't make much difference if you're using a fender-mounted cooler. The air pulled through the cooler does the vast majority of the heat transfer.

I had the stock trombone cooler with my 2.7 and factory bumper. Worked OK, but track temps were higher than I liked.

I installed a Mocal front cooler (with a fan) to keep my stock 2.7 cool with a fiberglass IROC bumper. I wired the fan to a switch in the dash (no thermostat). With the fan off (ambient temps 90F+) the temperature would climb above 90C pretty quickly (street driving). Turning the fan on brought the temps down to 80C or so within a couple of minutes. Track temps would run no greater than 100C with the fan on.

I then installed a 3.2 and the Mocal worked fine for street use, but oil temps on the track would hit 120C. Yikes. I tried ducting air to the cooler and it didn't help. I ended up mounting a bigger Setrab cooler in the front opening of the bumper and that completely eliminated my compulsion to glance nervously at the oil temps all the time.

Not exactly applicable to your situation, but I wouldn't worry about the bumper itself relative to getting more air to the cooler.

[86 911 Targa]

Originally Posted by Dueller

I am installing after market front rs style bumpers on my 87 carrera. Car is equipped with fender oil cooler and fan. I've never had a problem with oil temps. I know the factory had a small cut out under the bumper on the passenger side to facilitate fresh air flow.

Anybody noticed elevated oil temps after going to one piece after market bumper s? Anybody make an air duct for increased fresh air?

^^^^^
I installed one of these.
Fan-on=210f
Fan-off=197f

The factory thermostat engages the fan @248f.

Good luck,

Gerry

[KTL]

The two cars in this video are running a stock 3.2 with the stock fender cooler and no modifications to the IROC bumper. Air can get under the bumper and find its way to the cooler. But I doubt there's much benefit to that airflow path. Some is better than none though.....

https://www.youtube.com/watch?v=--Br8BWBTmE&list=UUHJMEWT4gFl2ZdNW7zqeFaw

All that we did to help the oil cooler is wire the existing oil cooler fan to the fog light switch. The wiring mod allows us to turn on the fan manually (need to have the headlights/parking lights on) but in all honesty I really haven't seen any measurable effect (on the temperature gauge) by switching the fan on.

My red car would run a bit hotter than his for some reason at around 220 or 230 on really hot days. Buddy's silver car runs 210 all day at the track. I find it surprising that these 3.2 engines would run only a bit hotter running wide open on the track vs. cruising down the highway.

My point of sharing isn't to show off the video. Just pointing out that we ran the aftermarket bumpers which appear to provide less airflow to the cooler and still had no major effects.

I rode with silver guy last weekend at Road America and I made a point of looking at his temp gauge during the ride. It was a fairly hot day (low 80s) and temp was 210 and no hotter, which really surprises me. Honestly I think the gauge accuracy is off. Doesn't seem plausible that he could run hard for 20 min. on the track and still see only 210 on the temp gauge. I know the factory oil cooler is a good one. But it seems like without a good amount of air flow across the cooler, the temps should climb pretty high