Mid-Engine Cooling

[lkchris]

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.

[Gilles]

Originally Posted by lkchris

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...

[Gelbster]

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.

[lkchris]

Originally Posted by Gilles

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...

Comparing mixture characteristics and rpm is apples/oranges--assume proper mixture for any useful discussion.

So, I had a 1984 BMW motorcycle with an oil cooler with a thermostat controlling whether oil circulated through it. The only time it did was during high-speed riding ... never in traffic. If you don't like "burning fuel" how about "doing work?" Conversion of fuel to energy is a heat-generating process. More energy (work) equals more heat. It takes a LOT of energy to push a car to 100 mph and virtually none to sit and idle.

As I previously alluded, many of us are conditioned to remembering old-time engines overheating when idling. That's NOT because they are generating more heat--it's because the water pump-mounted fan is turning at idle speed and doing next to no cooling. For our Boxsters, there's no such thing as "without proper airflow" because the fans are electric.

This is just basic physics, and there's also no way running faster is better for an engine than running slower--just as there's no way a tire lasts longer at low mileage versus high mileage. Just add up the total revolutions.

[flaps10]

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).

[jaykay]

Originally Posted by flaps10

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 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

[JayG]

Originally Posted by jaykay

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

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

[The Radium King]

[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.

[jaykay]

[QUOTE=The Radium King;466261]

Originally Posted by flaps10

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.

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 I would think it provides some effect once the oil is already too hot.

[flaps10]

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?