Mid-Engine Cooling
 

Wow in this hot weather the M96 sure does cook in its own juices in the oven behind ones head. What are creative solutions are there out there to get more cooling air into the bay and cool fluids? Vented rear bumper cover, ram air oil cooler?

Redirect airconditioning ducts and blast the air to: radiators, engine bay and intake.

I'm sure there is a net gain in there somewhere.

don't need any of that
Its a lot hotter here than it is in Toronto and I have no cooling issues

That is a good one never would I have come up something like this! It's fun but a lot of pain for no gain as you mentioned

San Diego? It's almost cold there in summer 25 - 26 C daytime max. Ideal climate but not hot normally. TO has had some very bad summers lately but it's much warmer than SD.

In my opinion the boxster engine package runs waaay too hot (save winter) no matter where you are. Have a look at vented mid engine Ferrari bays and the like and you will see what I mean. It doesn't matter if your temp gauge is steady.

These cars really could use for better cooling.

If the fans kick on then the car does a good job of holding the temp but normal operating temp should be lower then it is.

City driving in 100+ weather gets the engine warmer then I would like for sure. So hot that you feel the heat from the intake and wheel wells when stopped at a red light with windows down.

After parking the car it makes the whole garage a few degrees warmer as it cools down.

My question for the more technical guys is... How on earth did the air cooled cars ever manage? It seems Porsche's first water cooled cars only do a mediocre job of keeping heat to a minimum, so how did air cooled cars fair? Particularly big bore turbo models later on like the 993.

Maybe off topic but my old aircooled Duc would boil the hydraulic clutch when stuck in stop and go traffic at 40C. Made for some interesting rides...
I would assume the aircooled 911s ran rich to keep cool. Emissions probably put and end to that.
Nice and cool 34C with humidex in the 40s this week here :) at least it's not snowing...

http://986forum.com/forums/uploads01...1439937458.jpg

Depends on where in San Diego you are. I am inland and it is often 10-15 warmer than the coast
Its been pretty frickin hot here many days over 100 F
I also take her out to the desert and have never had an overheating problem. The only time I have seen my temp gauge move higher than the middle of the 8 was at the track and then it went between the 8 and 0

Yeeeeeeeeees!

Yes just keep in mind that that a major part of the air cooled senario is oil cooling.....this is probably the best answer for the Boxster

I was thinking about the temps of the engine over the last couple of days also. Very hot and humid out here. I brought the car back from buying it in Toronto yesterday and all I could think was, "this car is just not happy in congested city traffic".
But out here in the country on the twisties with no traffic lights in sight, it was very happy and didn't run too hot.

G

I'm also concerned about how hot the 986 engine can get. Not suggesting these to anyone, but I have bypassed the fan relays and wired a switch for each fan so I can manually control them. Why two switches?? Each fan draws 40 watts. When I tried a single switch controlling both it got so hot it melted.
I turn the fans on when the water temp gets to about 170 (low temp T-stat is open). The car never gets above 190 now. :)

I can't say I've ever really had an issue with my 986's cooling, as I usually keep the A/C on (and therefore the radiator fans). I know that it warms up my garage, though. :D

Once I was stuck in very severe traffic in the 964 when just about every Interstate in town was backed up (due to one route being closed from a severe car fire). Sitting in that stupid congestion did not make it very happy (didn't overheat), but after slogging through surface streets to the open Interstate way north of town, once the air was flowing again all was right with the world.

On my Audi s4, there was an after-run circuit that would circulate coolant and run the fans for up to 10 minutes after the car was turned off. Some people would change the temperature sensor so it ran more often, however I jumped the sensor with a switch so if I knew I wanted the car to run the fans for the full 10min, I would just flip the switch before turning it off.

I wonder if we can change the sensor that turns on the engine bay cooling fan, or if there is a similar timer that if the sensor is jumped, wouldn't just run forever.

Yeah....I had my carpet off and man that firewall gets pretty toasty. Has anyone put insulation/gold leaf on the backside of the hatch...? If my engine comes out I think I might foil up the whole engine bay.


Back on topic: Assuming that engine oil cooling is the way to go ( for a dedicated track car: transmission?), I had envisioned a duct incorporated in the right side vent that directs cooling air to shrouded oil cooling heat exchanger. If there is enough room you could put in a duct for the trans. as well.

You would fashion an opening the side vent shroud to accept a bell mouth / velocity stack with a duct leading to the shrouded oil cooler. I think setrab makes some small stuff that may fit in the engine bay and I believe I have seen them used for Boxster trans coolers.

With this arrangement you would get a seamless cold air intake for oil cooling. The engine bay fan along with ram air from the side vent would provide for superior heat exchange.

Not sure about how to properly mount the heat exchanger in the bay....without welding mounts. Unfortunately all this may have to done with engine out

I don't know if that solves the original problem: engine getting hot when sitting still.

Once you are moving, there is plenty of air moving up front for the coolant to do its job inside of the oil cooler. When you are sitting still, the engine bay fan activates and moves air over the whole area of the oil cooler.

I think a foolproof way to keep everything COOLER than it is with a stock setup is a bigger oil cooler and a user controllable engine bay fan.

Okay add fan packs to the backside of the hx

Interesting subject but suggest we divide it into at least 2 parts:
1. engine cooling (and trans)
2. engine bay cooling
The engine and trans cooling has been discussed already .
The engine bay cooling obviously concerned Porsche hence the engine compartment fan. Heat soak also an issue. Logically just increase the size/efficiency of the engine compartment fan+ducts.
See post #5 in the link for ideas but be wary of causing codes.In theory you could wrap the exhaust to reduce radiant heat in the engine compartment &/or reposition the engine compartment temp sensor to a hotter location so it comes on sooner/stays on longer ?
High speed fan relay hack/mod - 996 Series (Carrera, Carrera 4, Carrera 4S, Targa) - RennTech.org Community
"Engine Compartment Fan Connect a wire to the ground of the relay located in the relay carrier behind the passenger seat, driver’s side. Relay #8. . Feed this wire to where your switch will be located. I simply fed the wire along the driver’s side of the car and under the door sill. Connect the wire to one side of the switch. Connect another wire from the other contact on the switch and connect the other end of this wire to a chassis ground point. With key on, this switch will now immediately turn on the fan drawing air into the engine compartment. When you turn the key off, the fan will continue to run for about 5 seconds until the relay shuts down. Your fan operation remains normal when the switch is off. This mod helps keep the engine compartment much cooler when driving around town and is particularly beneficial to any engine that draws its intake air from inside the engine compartment, such as the EVO SC. If you are adventurous, you can automate the operation of these switches so they will switch off at a specific speed, or operate when vacuum is present only, etc. You can choose any style switch you want and even use Porsche switches. I simply used 2 toggle switches that I installed in the batwing, Jim"

I've thought about this. But:

The stock fan is loud AF.

Once you go to the level of controlling fans yourself, the car becomes something that 'needs help' to accomplish something so simple and be self sustaining. It's like having a high maintenance partner. I refuse to go there. Now my Autöcar sensor suite is a different story since I am monitoring things, and to control something would be autonomous.

END DIATRIBE

The 3 page thread linked below may be useful, Issues with polarity reversal in the wiring for example. Yes it is 996 but the concept and execution are very similar.
Engine Compartment Fan Question - Rennlist Discussion Forums

Coming late, I'm curious about whether the taller oil cooler(S oil cooler, 996-107-025-59-M6) would be fitted to surrounding air inlet of the base pre-00 Boxster.
I got following reply today from Bod Tindel, senior technical advisor of Pelican;
"Sorry, but we don't have anything to indicate that this cooler could be fitted to the base Boxster engine. If it would fit, I think we would have gotten some input from our customer base, or from Porsche."

If way possible, enlighten me!

CK

I think it safe to assume Boxster cooling was thoroughly tested by Porsche.

Good to understand that a sustained high-speed Autobahn run will get the engine hotter than any other sort of use. Basically, it's more fuel burned equals more heat. Not a lot of heat generated idling, but plenty generated at sustained high rpms. Electric fans are lots better than the attached-to-the-water-pump fans of old mericun iron---where the fan runs at idle speed, too. Apples and oranges.

I believe that burning fuel, actually helps to keep the engine cooler, and a lean mixture will quickly overheat an engine (and put a hole on your piston..), this is a well known fact on aviation engines

Also believe that be cruising at top speed is much better for the engine than sitting in a traffic jam on the middle of the summer with the AC on and without proper airflow.

However, this conclusions are from my own observations and I am no an engine expert by any means...

Agree but remaining problem is heat soak in extreme conditions.
Simplest,reversible solution (detailed previously) is to relocate the engine bay temp sensor to a hotter location.

Cherry picking this thread in no particular order. Typing quick and not proof reading. Please don't anyone take offense if something doesn't come out right. None intended, just trying to contribute what I know.

Gold foiling the engine compartment will hold heat in, which is not the desired effect.

I installed the taller oil cooler (heat exchanger technically) in my S model when I had my engine apart. I see no reason why it wouldn't fit a non S car and could likely be done without even having to remove the intake manifold (keep in mind, I only own an S and don't know how different the intake manifolds are).

To the guy running two fan switches because one melted, you do realize that the job of a relay is to control high current devices with low current switches, right? You could probably patch one switch into the relay and not cook anything.

The idea of running A/C air into the engine compartment is funny. The act of creating cooled air with A/C creates additional heat than you started with (no such thing as a 100% efficient process, i.e. you can't open the fridge door and cool your house off because there will be even more heat pouring off the back of the refer). Where does it go? Well, the condensers which expel the heat to the outside world are positioned in front of the radiators, which would make them hotter. Circulate that a while and you'll exceed the capacity of the A/C system and you'll just be dumping tons of heat into those radiators. No bueno.

Back when my A/C wasn't functioning I could provoke the fans to run by turning on the A/C (which didn't 'know' it didn't work), just like the above user with the manual fan switches. It definitely worked in low speed traffic or sitting. Now that my A/C is recharged and working it doesn't really dip the needle at all.

My engine compartment fan expels hot air out the side of my car, not blowing cold air into it. It does not blow air clear across the engine compartment and through the "oil cooler". It would need a long duct in order to do that.

To get heat outside the car and on the way you would want to use a base plate like I've seen marketed by Pedro and run an external oil cooler outside the engine compartment. Ideally it would have a fan blowing on it, but could run a snorkel or in place of the rear spoiler. It wouldn't do much when sitting without a fan. It would also need to retain the stock heat exchanger (duh).

Again, I'm pretty sure there is room for the taller oil cooler AND the external oil cooler adapter plate.

My car heat soaks my garage. So does my VW Touareg V10 or any automobile with a large hunk of hot metal.

The part about high speed operation generating the most heat is totally true. Run any "super" car at WFO for not even very long and it will build up heat it can't get rid of. Witness what happened when Frederich Peich proposed the requirements for the VW Pheaton (186mph with a 72 degree cabin even at 122 degrees F outside, caused many of his engineering staff to walk out - so the story goes).

I have installed an oil cooler as described above into my track car to keep the trans oil temps under control. I ran a 3" flexible brake duct from the right side vent scoop to a small heat exchanger with a 5" Spal fan attached. It is mounted directly to the rear trunk floor in a small space next to the gearbox on passenger side. I will post pics when I get the car back on the lift.

Great to see Bob is as useless as ever!!

Pelican Parts.com - Boxster S Oil Cooler

When I attempted to "Upgrade" my 986 "S" clutch disc with a Pelican sourced 987 "S" disc as suggested in the 101 projects book, I discovered the input shaft spline is different & incompatable. NoOne I could get on the phone was of any help. I suggested they ask SSF their supplier to compare the 2 discs side by side, but they wouldn't. Finally I had to buy a 986 disc & wait over the weekend to get it. A week after I first reported the problem Bob e-mailed me & said if I would send him the paperwork & explain the problem AGAIN, he would "look into it" Too lazy to ask any of his 3 co-workers I had already talked to! :mad:

I thought the AC thing was just fantastic too!

Your side vent fan should be drawing air in to cool.....probably exits past the trans. somewhere. If it is blowing out there is something amiss...you can check it with a sheet of paper

[QUOTE=flaps10;466254]I installed the taller oil cooler (heat exchanger technically) in my S model when I had my engine apart. I see no reason why it wouldn't fit a non S car and could likely be done without even having to remove the intake manifold (keep in mind, I only own an S and don't know how different the intake manifolds are).[QUOTE]

so, the 986 Boxster S oil cooler is the same as the one used on all 996 cars. also the same as the one used on base 997.1 cars. the 997.1 S model has a different part number - it appears to be a direct fit to the m96/97 block as well as taller ie, bigger volume) - is this the oil cooler you fit on your car? if so this is a very cool mod, and confirms that there is space under our intake manifold for it to fit (the 986 intake manifold isn't as tall as the other cars).

this got me searching and I found this ...

997 GT3 Water/Oil Cooler/Heat Exchanger on a M96/97 - Rennlist Discussion Forums

it appears that the gt3 oil cooler is the same height as the 997.1 S oil cooler, but that the adaptor would add an inch or two to the overall height. what's your take on this fitting?

to the original question, I think fitting a taller 986 S/996 oil cooler on base 986 cars is a standard mod done by spec racers all the time.

Nice glad someone has actually done this....seems to be the best packaging solution. Were you able to incorporate the intake right in the existing side vent rubber plastic duct for an ultra OEM look? You would also get a boost effect with the fan when it runs. Don't know how the heck you mounted the heat xcr though...my imagination / vis skills can't picture that...I would guess an edge is facing up..so get air flow. Do you have a manual fan switch?

I take it that cooling the trans take care of everything else including engine oil. Any data?

Pictures would be much appreciated!

[QUOTE=The Radium King;466261] I have always wondered whether this thing actually provides oil cooling to any large degree. What is the differential temperature profile of coolant vs oil in there. I hope it's not hot coolant there:cool: I would think it provides some effect once the oil is already too hot.

Some good discussion going here.

I'll double check the flow direction of my engine compartment fan. I remember hearing it running when I was standing next to the car once and put my fingers over it because I was curious about the flow direction, and thinking the result was odd.

Moving on..

I refer to the oil cooler in quotes below because it is technically just a heat exchanger. It is exchanging heat from the oil into the coolant which carries it forward and attempts to get rid of it. Sure, some heat radiates off the exchanger but most is carried off in the coolant. Truth is, we really don't want it just radiating into the engine compartment. We want it pumped overboard.

The oil cooled cars I've owned rammed massive amounts of air through the oil cooler at all times using the engine fan. And they worked damn good even in hot weather in the desert - assuming all of the cooling tins were in place. The quickest way to make me walk away from a prospective air cooled car is to see any tin shrouds missing. The air flow is intended to be very directional and with missing shrouds it tends to recirculate very hot air.

And to answer an early question, yes they ran a bit rich and that is what killed the air cooled vehicles in this country.

First I've heard of a tranny cooler on a manual transmission car. Do you have a transmission temp gauge? Are all three of the scoops attached to your triangular shaped belly pan, which serve to direct air at the transmission?

the vent on the drivers side (left) is cool air intake for the engine

transmission coolers are also standard issue on spec racers - the small 5-speeds need all the help they can get. the caymans often also need tranny coolers at the track - again, a smaller, lighter unit than the 986 6-speeds so need other ways to ditch heat. LSDs are also a big heat maker.

Transmission Gearbox Oil Cooler System - 996 - 997 Trans By Patrick Motorsports Porsche & Mid Engine Performance Specialists

BYprodriver..
haha. Thanks

Thanks
 

Cool responses , and I'm getting more refined insights in our troubled lovely cars.
Thanks to gentlemen

You are in Korea Bachmoza?
I am guessing there are not that many Boxsters there

Yup. Boxsters are rare, but Big brothers not..:(

------------------
99 tip base, LN IMSB
Mazda MX-5 NB6C
Jaguar XJ3.2

The car is loaded into the trailer for a trip to the track this weekend. When I get back I will get it on the lift and take some pics. I use some of the same components in the Patrick kit and I added a small fan to pull the cold air coming in from the right side engine compartment vent through the cooler. Fan is switched to come on with the pump through a separate relay. Trans oil temps with back to back drivers (wifey drives it as well) get up to 260 degrees. Just had a full rebuild on the box partially due to hot temps (and 5 years of track abuse)