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Old 08-18-2015, 11:47 AM   #1
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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?

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Old 08-18-2015, 12:17 PM   #2
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Redirect airconditioning ducts and blast the air to: radiators, engine bay and intake.

I'm sure there is a net gain in there somewhere.
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Old 08-18-2015, 12:26 PM   #3
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don't need any of that
Its a lot hotter here than it is in Toronto and I have no cooling issues
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Old 08-18-2015, 01:12 PM   #4
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Redirect airconditioning ducts and blast the air to: radiators, engine bay and intake.

I'm sure there is a net gain in there somewhere.
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
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Old 08-18-2015, 01:22 PM   #5
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don't need any of that
Its a lot hotter here than it is in Toronto and I have no cooling issues
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.
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Old 08-18-2015, 01:39 PM   #6
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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.
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Old 08-18-2015, 02:00 PM   #7
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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...
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Old 08-18-2015, 02:37 PM   #8
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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?
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Old 08-18-2015, 02:44 PM   #9
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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.
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
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Old 08-18-2015, 04:05 PM   #10
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Yeeeeeeeeees!
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Old 08-18-2015, 04:13 PM   #11
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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...

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
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Old 08-18-2015, 05:20 PM   #12
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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
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Old 08-19-2015, 01:18 AM   #13
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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.
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Old 08-19-2015, 04:21 AM   #14
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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.

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.
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Old 08-19-2015, 04:34 AM   #15
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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.
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.
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Old 08-19-2015, 06:16 AM   #16
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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
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Old 08-20-2015, 03:16 PM   #17
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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.
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Old 08-20-2015, 06:28 PM   #18
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Okay add fan packs to the backside of the hx
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Old 08-20-2015, 07:24 PM   #19
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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"

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Old 08-20-2015, 07:32 PM   #20
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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.

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