Rear fender oil cooler mount details, How I did it Options

[IronHillRestorations]

After I made a post about my alternate location for an auxiliary oil cooler, I thought more details would be helpful.
First let me say that this was a piece of cake for the current project, as the right rear quarter panel was removed for rust repair and chassis stiffening. Due to the difficulty in properly locating the forward mounting holes, I don’t know how feasible this is for a car with the engine installed. When I put a (slightly smaller) cooler in this same area 25 years ago, I made no notes or kept any of the measurements, I just made it work, but at that time it was done with the engine out of the car.
After trial and error fitting of a cardboard mockup, I picked a Mocal 34 row, 235 matrix cooler, which measures 260mm by 280mm, or roughly 10 5/16” x 11 1/8” which doesn’t include the -12AN fittings. This is what I think to be the largest cooler you could get in that area ahead of the right rear wheel. This cooler has a capacity of .75 quarts, which is .20 of a quart more than the kit BAT offers to upgrade a 911 front oil cooler. This is a case where bigger is definitely better.
Since airflow in the rear quarter panels isn’t as good as the front fender , I added a 7” Spal puller fan that will be mounted directly to the oil cooler with a plastic mounting tie kit, which are very sturdy round zip tie fasteners that make it easy. The fan will be wired with a relay to a switch on the dash or an automatic inline switch (to be determined later). On my old install I tried to make the fan automatically switched, but it ran too much and the fan died. A testament to this set up is that I never knew the fan died, and oil temps never got over 220* even in the hot Tennessee summers. Since this is going to be a widebody hot-rod with flared rockers, I’m toying with the idea of incorporating a scoop in the rocker flare, but that too is undetermined.
Here’s a hardware list, that doesn’t include any oil lines, thermostat, or relay wiring for the fan.
1 Mocal A34A12 34 row -12AN 235 oil cooler
2 Mocal/Setrab ABKT-235 oil cooler bracket for 235mm core
1 BAT ABKT1 cooler/fan mounting tie kit
1 M8 x 1.25 x 60mm fully threaded cap screw (13mm hex)
2 M8 x 1.25 x 50mm fully threaded cap screw (13mm hex)
12 M8 washers
8 M8 x 1.25 nylon insert nuts
1 M8 x 1.25 weld nut

Even with the fender off it took more than one attempt to get it in the optimum location, which is as far forward as possible without interfering with the outer suspension console. Using the suspension console as the baseline level plane, the cooler is tilted down at the back about 5* give or take a degree.


Just for reference

Here's what the cooler looks like mounted. It's pretty big.


I wanted to make sure the cooler could be installed and removed with the fender on, I made sure there was no interference. I had the fender on and off several times during the test fitting process.
With the fender off it was easy to use the bracket as a reference where to mark and drill the 5/16” front mounting holes, which are 70mm apart.

[Tdskip]

Great discussion.

If the look cooler works without a fan wouldn’t a more conventional radiator work without one? OR, if going to trouble to mount a conventional radiator the fan is a while-we-are-at-it thing anyway?

[mepstein]

Great discussion.

If the look cooler works without a fan wouldn’t a more conventional radiator work without one? OR, if going to trouble to mount a conventional radiator the fan is a while-we-are-at-it thing anyway?

I think it depends on how much cooling you want and how much stop and go traffic you might run into.

My thought is if you can fit a loop cooler in that spot then why not go with a small modern cooler and a low profile fan pack. A loop cooler is going to do very little if you are sitting in traffic on a hot summer day. Especially when the blacktop is radiating 140 degrees up into the rear quarter.

[horizontally-opposed]

Great discussion.

If the look cooler works without a fan wouldn’t a more conventional radiator work without one? OR, if going to trouble to mount a conventional radiator the fan is a while-we-are-at-it thing anyway?

Have seen a few ways to add an external oil cooler on a 914, including a center front, paired front coolers at the corners, under the rear trunk floor, and now Perry's insanely clean & cool install. All of these were radiator style, I think? Have thought about a loop cooler for the front fenders—narrower than the 911 due to the car's design but doubled with two lines going across whether inside or outside of the front trunk. Even if the loops are very small, hard lines would add a lot of oil (and surface area) on the way forward, through both loops, the connections across the car, and the way back.

I've never thought about, much less seen, a 911 loop cooler in a 914's rear fender, or that it might fit.

Can see why Perry's setup would need a fan, as there might not be much if any airflow in there without a vent or ducting. Suspect the area above/behind the rear wheels sees a lot more air circulating than the area in front of the rear wheel, even if it isn't nearly as much as a front cooler would see.

[Tdskip]

I think it depends on how much cooling you want and how much stop and go traffic you might run into.

My thought is if you can fit a loop cooler in that spot then why not go with a small modern cooler and a low profile fan pack. A loop cooler is going to do very little if you are sitting in traffic on a hot summer day. Especially when the blacktop is radiating 140 degrees up into the rear quarter.

Makes sense - delta of effort is small enough to just include a fan.

Thanks

[willieg]

Perry
Great documentation. Thank you.

[stevesc_us]

Yet another option to consider. I never tracked my 6 in all the years I owned it, but this engine lid set up fabricated by Henry Schmidt at Supertech always provided sufficient cooling with my 3.2 motor transplant.

[JmuRiz]

Always wondered where that car ended up. Does it have an on-cooler thermostat or a separate one?

I'm still hemming/hawing about where to put my cooler for my 2.8 6-conversion.
Under rear trunk, front cooler....or that engine lid one. I have a GT style lid that might work with the dual oil cooler fans (IMG:style_emoticons/default/idea.gif)

[stevesc_us]

She is now owned by Freeman Thomas, who as you may be aware is a well-known car designer that worked at the Zuffenhausen factory in the 1980's and was the original designer of the Audi TT. The best part of this tid bit of history is that his inspiration for the TT was none other than the 914-6! Couldn't have asked for a more worthy caretaker to carry on the stewardship of cherishing my sweet 6 after my 25 years of ownership.

[vitamin914]

Although it seems we may spend more time under our cars than driving them the problem I am running into with my Aux. oil cooler location is ROAD CRUD.

The tires kick up everything on the road, water, sand, stones, bubble gum. Locating in the wheel well means the fan motor is going to be destroyed a lot quicker and the fins are going to be fouled up. I just yanked the failed horn the PO put in the front wheel well directly ahead of the front tire. A pound of dirt must have fallen out it when it hit the ground. Best place for the oil cooler has to be the front or under the engine lid, worst anywhere near a tire.

My oil cooler is almost behind the rear wheel and I am forever cleaning it. I don't need another job of relocating it either. Maybe an angled Lexan deflector to keep it cleaner?

[914werke]

I like that loop cooler but at nearly $600 Im sure you can get a decent traditional cooler, fan & lines for that!
Oh & kudo's Perry, sano setup!

[colingreene]

Not that anyone asked, This is what i did for my 2258cc motor that always ran on the hot side.
I used a Setrab Oil cooler sandwich adaptor with a thermostat in it to some -12 lines.
the lines run out and around the motor back to the cooler. the fans are controlled by a thermostatic switch to keep oil temps regulated.

I made some mounts to hang it off the back of the tin and the front of the trans mount so when I remove the motor it all comes out as one part.

[Tdskip]

Thanks for posting that @colingreene