I am well along with the 3.0 liter engine swap on my 1970 914-6. I am aware the 3.0 liter 911 engine will need an external oil cooler. I am aware that Patrick Motorsports sells a 914-6 GT style front mount oil cooler kit with all the plumbing and front spoiler. I would prefer to do something that won't be visible on the outside of the car. I am wondering if anyone sells an oil cooler kit based on a compact plate style heat exchanger with a fan. Could something like this be mounted under the rear trunk? Has anyone done something like this?

Also, does anyone still sell a front spoiler with the rubber lip vs solid fiberglass?

I have a brand new front spoiler with the rubber lip I could sell
Still in the packaging. Never installed
But I don’t know a cost effective way to ship it

Lots of oil cooler locations are used.
Other -6 have used under the trunk
It’s less effective that frontal air
So it depends on how much cooling you need

Late 70's 911 had a "trombone" cooler in the passenger wheel well. Might be some sort of work around there.

Do a search, but a lot of people have mounted one with a fan under the rear trunk on the passenger side. The aluminum block 3.0 and 3.2 run super cool. My 3.2 with front cooler does not run hot except when I’m stuck in traffic. This is in so cal in the middle of summer when it’s triple digits.

I’m not running an extra cooler on my 3.0. Had the modified OEM unit refurbed and modified to fit the car. Figured that’s what the original engine had for cooling. So far it’s fine in the PNW region. Just use the car on tours and an occasional drive. Won’t use it on the hottest days but without air conditioning I don’t want to take it out. Maybe I’ll add one later, but want to add air at the same time.

I'm also not running a cooler on a 3.0 but I'm collecting parts and plan to add one.

Another option is to add a cooler to the engine lid.

Perry had success with one in the right side quarter panel.
Mine used a cutout in the front valance, through the stock holes behind the bumper and then out the two large holes in the floor where the two access holes are covered.
Anything not in direct cool airflow is a compromise.

There are lots of threads on here discussing this topic. Short summary is that the consensus is that the front mount is best, and I agree with that, but if you do not want to cut your car there are three options:

1) under trunk floor with fan
2) in the right wheel well with fan
3) under the engine lid (no fan needed)

All of these have been made to work to provide some additional cooling. No consensus on which is best, or on wether they work well enough in high stress application.

I spent A LOT of time engineering and building an under trunk cooler using a fan to pull air from the passenger side wheel well. It worked ok until it split the cooler because of a cold start with no warm up bypass. It is disconnected and my cooling is fine on my mag case 2.4 for my recreational short road trip use.

If I were doing it again I would probably try the under the engine lid installation. Simplest install but you have to work out the thermostat bypass issue for which there are several options.

Good luck

Oil temps depend also on motor condition
Worn motors will run hotter than fresh ones

And high compression motors will also create more heat
(more hp creates more heat)

You could always do the conversion, get the car running and then revisit oil cooling as needed.

The 911 loop coolers are wide for the 914's front fender IIRC, but this concept is the right solution for street car drivers who don't want to cut the front end, don't want to modify a 914's outer appearance, do want to keep all functionality, do want a spare tire in the frunk, etc. The late Bruce Anderson also preferred loop coolers to radiator style, at least in the U.S.

I've long wondered if someone with a pipe bender could copy the idea but for the 914's RF fender, then mirror it for the LF fender and connect the two with pipes across that are hidden by the front bumper or valance, or just behind an LE spoiler. Would add a lot of oil capacity and heat sink—and there are already good options for getting the oil from the engine up to the front…

What I don't know is whether this is something that makes sense to do as a custom job, or something that requires a production run to make sense.

I thought about a custom loop cooler under the bumper/valance with a a blind GT opening and some holes in the bottom of the valance.
But any kind of cooler in the valance like above or done like a RSR would be destroyed if you ever hit a curb.

911’s also have metal hard lines up the longs. The loop coolers are often replaced for superior modern coolers with many times the surface area. It’s also easy to direct air into the 911 front fender while the 914 fender won’t get air without modifications.

People have made the alternatives work but if you do a search on this site you can see it’s been discussed to death and the traditional front cooler location is the clear winner if you want the best working system to cool your oil.

Most oil coolers located in the rear of the car out of the air flow are a compromise. Such compromises may be enough, but if you are planning on some spirited track driving or high altitude (thin air) driving, you will find a compromise may be a disappointment.

My car has a GT style cooler from Patrick Motorsport, and without the cutaway bumper or spoiler openings. Stock LE front spoiler is fitted. With the air available through the various stock clearances, and the opened up holes in the front bulkhead, the 2.6L stays cool in our Texas heat. The only deficiency is maintaining 70mph in 90+ degree ambient the engine temps do creep up to 220 due to insufficient airflow at those speeds and RPMs. I do plan on doing a GT style cut bumper in the future.

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On the 2.4L engine, I put a 911 3.2 Carrera cooler with a fan in the right rear of the car, mounted vertically between the motor mount and the pinch weld. It won't fit with a stock muffler, but an aftermarket muffler that mounts to the left side of the car leaves room for a cooler there. I put a 190 degree thermo switch in the cooler, and wired it through a fog light relay with an integral fuse holder. Grounded it to the same location as the ground strap, and hooked the power to the battery cable post on the starter. The fan will run independent of the rest of the car's electrical system, and will keep running after the engine is off.

It brought the temps on the engine down 40 degrees F on a Texas summer day.

Clay

You could put a bunch of finned tubing in a big loop inside the right rear quarter.
Behind the latch post, in front of the tire.
There is a good bit of space there and a scoop at rocker level could provide
cool air when in motion.

An option for additional oil cooler

Clay, that sounds great. Could you post some pictures of the cooler install. Thanks, Mark

Loop coolers have their limitations, with more efficient systems out there I would not waste any time with a loop cooler. I could not get my 930 temps in check with the stock loop cooler here in so cal heat. Any bit of traffic would cause the rise in temps. I replaced with a fender mounted radiator cooler (Elephant Racing) along with a pull through fan mounted on the backside. My temps hold steadily at 180, rises to 200ish with hard driving on a hot day.

You said it so well in that thread:



No doubt a front/radiator cooler is best, and needed in a high-horse application (say, 230-325 hp).

There are a lot of six conversions out there that don't need "best," but would benefit from more than the 914-6 oil cooler. More capacity and a cooler of some sort will do that. And loop coolers sure worked for a lot of flat sixes for hundreds of thousands of miles…with many of them being this side of 3.2s on up. Which is a lot of six conversions.

If there was an "improved loop cooler" for the 914 that used both front fenders and two lines connecting them exposed to air one way or another, I would be very interested. I am not over 210 now, but Clay's words about engines as they age, and wanting a bit of reserve (and not loving the idea of adding heat near the 901...), have me interested. The downsides of a front cooler (spare tire relocation or deletion, which is also a safety issue in a crash), less frunk space, cutting the car, etc etc are real for some, less concerning for others. If I was racing my 914 or had a big six (3.4 and up), I'd view a front cooler as a must.

My 914-6 came to me with a 3.0 with Webers. It had a somewhat crude home made oil cooler system made from 1/2" copper pipe that ran from the engine up the passenger side long, behind the rocker cover, and then went to the front of the car and if I recall it ran in the wheel well to the front nose panel. Then it ran across the nose panel along the upper nose and then turned down and then returned along the bottom of the nose to the passenger front fender and then ran back to the engine behind the passenger rocker cover. All soldered. It looked OK except for the somewhat butchered front nose panel, of course it was covered by the front bumper. The previous owner said the car never overheated. I never drove it with that set-up. But there is no reason that would not be an effective cooler for a 3.0 engine. Simple and probably pretty inexpensive.

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My car now has a 3.2 and I went with a PMS front GT style cooler with shroud and hardline running up/down the driver's side rocker. I have a modified front valance to allow air to pass through the valance and enter the cooler through 5 of the large black body plugs in the nose which we left out. The front bumper is stock. Very low profile cooler venting if you ask me. The 3.2 runs nice and cool, typically in the 190-205 range depending upon weather. I sat in stop/go traffic for about 10 miles on a day when it was 108 degrees out and my temperature climbed to 220. As soon as I got in clean air it dropped to 190 very rapidly. I would rather have over-kill on air cooled cars so I love my oil cooler system.

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My 2.7 RS MFI spec engine only has the onboard cooler, but it's a high efficiency unit from Stoddard. Been running it around this summer in Oregon where we hit the 90's at times.

With normal driving, it sometimes hits 95C or 203F....more than safe enough to run without a 2nd cooler. I will likely never add the additional cooler as the car will not be tracked or pushed that hard for extended times on the street.
I think the 8.5:1 compression ratio on the engine helps a lot in keeping the engine temps down.
If it did get too hot, I'd try adding the GT engine lid with the extra ventilation first.

Just my experiences.....

I have mine under the trunk with fans. Never driven over around 80 mph at 100 degrees F though, although some of that has been going uphill crossing the great divide. I see three points on the temp gauge. Temp goes up and hangs till the internal t-stat opens. Then goes up and hangs till the 911 external t-stat opens. Then goes up and hangs till the fans turn on. Never have gotten beyond that point yet.

Here is from an old post. A sheet of steel and there you go.

Your car continues to be one of my all-time faves, and neat to see these "before" pics. It even looked cool then!

Very interesting to see this system, and if done to a (significantly) higher level of execution, it's along the lines of what I was thinking. More capacity, more heat sink, and possible sufficient for 2.2-3.0 engines of 180-250 hp driven on the street—without the need to move the spare wheel/tire or alter the usability of the front trunk (other than it staying cool...). My guess is total length is quite a bit longer than the factory loop coolers for 911s, and those worked well for a lot of cars up to and over 200 hp.

I guess the key in a 914 would be smaller loops in each narrow fender and then where to go across—either just behind the forward torsion bar mounts (but: low), through the trunk in front of or behind the spare tire, or a mix of the front trunk and behind the bumper. I think you are right: A custom job would be the way to go…I'd just want to find someone meticulous.

Your new cooler is beautifully executed, by the way!!