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-   -   What's Your Engine Temp? (http://986forum.com/forums/showthread.php?t=17246)

Jaxonalden 06-20-2008 11:36 AM

What's Your Engine Temp?
 
In a post on Performance Talk someone said their engine was running hotter than normal after installing a set of headers. The explanation was that the O2 sensors were picking up more hydrocarbons because of no CATs and the ECU was compensating by leaning out the mixture.
If it was running warmer the thermostat would open more and the coolant would flow more and the radiators would do what radiators do and you would not see a change on the gauge, right?

What I do notice on my car is that my engine runs cooler than any other vehicle that I drive. It will read about 182 degrees no matter what. I know you can buy performance thermostats that open at 180 degrees, thus fooling the ECU into thinking the engine is cold and compensating that by adding a little extra squirt. So I was wondering about the rest of you, what are ya'll running for engine temp?

pbanders 06-20-2008 11:46 AM

FWIW, my water temp runs slightly over the 180 deg. F mark once warmed up, with essentially no variation regardless of how hard I drive the car or the outside temperature (which was about 112 deg. F yesterday). Stock w/Tip.

Lil bastard 06-20-2008 12:38 PM

The Tip S cars do run a little cooler (maybe 3°-5°F) because of their added air/coolant transmission cooler.

This is basically a 3rd (or 4th for the 'S') little radiator on the same circuit as the engine coolant.

The Tranny does add some heat, but the transmission cooler (in conjunction with the main radiators) more than compensates causing the coolant to flow just a little cooler.

FYI, those with '00 MY or earlier cars can access a digital readout of the actual coolant temp (as opposed to a somewhat inaccurate needle arcing across a mostly non-graduated gauge face) by putting the Climate Control Unit into diagnostic mode and reading the value for code 6c.

Tom Blue 06-20-2008 12:43 PM

I have a 2002 S which runs just a little over 180. Like pbanders, no variation with speed or outside temp.

CJ_Boxster 06-20-2008 12:53 PM

I noticed that when i didnt reinstall my plastic cover near the engine after i repaired my engine mount, my coolant temps have been down ever since... I think as im driving, alot more engine heat is able to disapate quickly without that last plastic cover installed.

rick3000 06-20-2008 01:13 PM

I've had some coolant issues, but since then the needle has not passed the edge of the zero. Unless you get a flashing light or are always significantly past the zero I wouldn't worry.

CJ, what plastic cover are you talking about? Do you have a picture of it?

Quickurt 06-20-2008 02:42 PM

My 987S runs dead square on 175 degrees, like above, no matter the outside temp or how hard I run it.

CJ_Boxster 06-20-2008 03:00 PM

Quote:

Originally Posted by rick3000
I've had some coolant issues, but since then the needle has not passed the edge of the zero. Unless you get a flashing light or are always significantly past the zero I wouldn't worry.

CJ, what plastic cover are you talking about? Do you have a picture of it?


This is the cover circled in red that i removed.

rick3000 06-20-2008 04:00 PM

Thanks! I wonder if drilling some holes in it would help with lower my temps. Not that they are bad, but I would prefer to see them lower, especially when it's 100° outside. :cheers:

chitowndad 06-20-2008 06:11 PM

Word to the wise
 
Guys,
A long time ago I had an 80's Camaro that would always run in the 220 degree range. Wanting better performance I dropped in a cooler thermostat 180 degrees and the car did run faster because the air going in was cooler, etc. After a year of running the cooler thermostat (below the mfg specs) the heads were badly carboned up and it cost a lot to regrind the heads...

My advice is stick with the stock thermostat. Opening the engine bay and removing plastic parts might be ok, just don't change the thermostat.

My 2001 Boxster runs 182 consistently!

-Steve

Lil bastard 06-20-2008 06:12 PM

Don't know as if I'd want to remove or drill any holes into the plastic covers under the car, or remove them.

Aside from playing a role in the car's aerodynamics (which probably have little effect at legal speeds anyway), these covers are designed to direct airflow to the proper places, ie around the engine bay.

The primary source of cooling for the engine is the oil and the coolant, not ambient air, probably like 95%.

But, consider that the only source for cooling ancillaries like the alternator, AC compressor, drive belt pulleys and tensioners is the airflow through the engine bay. Loosing a few degrees on the temp gauge (which is nonetheless operating in the OK range) may not be worth compromising the service life of these components.

Jaxonalden 06-20-2008 08:02 PM

Thanks for all the replies, looks like 182 degrees is the overall winner. Man that sure seams cold when thinking about engine temperature. I've always been taught that proper engine temp is in the 200-215 degree range. At that temp all the different metals in the cylinder wall, piston, rings and valves are all properly expanded and sealing the combustion chamber.

Porsche must ether be using special metals or someones been lying to me.

2000SoCalBoxsterS 06-21-2008 12:19 PM

My 2000 S runs slightly above 180 degrees.

Lil bastard 06-21-2008 12:45 PM

Quote:

Originally Posted by Jaxonalden
Thanks for all the replies, looks like 182 degrees is the overall winner. Man that sure seams cold when thinking about engine temperature. I've always been taught that proper engine temp is in the 200-215 degree range. At that temp all the different metals in the cylinder wall, piston, rings and valves are all properly expanded and sealing the combustion chamber.

Porsche must ether be using special metals or someones been lying to me.


You're confusing coolant temp with engine temp. The coolant keeps the engine within the proper operating temp range.

If you use an infared thermometer and check temps on the engine at several places and average it out, you're likely to find those temps in the 500° - 600° range, and of course, the combustion chamber temps reach upwards of 1200°-1300°.

Lil bastard 06-21-2008 01:00 PM

Just an observation, there does seem to be a lot of obsession about coolant temps by Boxster owners - just do a search to see how many times this issue has been brought up.

I've owned several 50's and 60's brit and '70's japanese cars which were notorious for overheating and never saw a degree of obsession amongst their owners as I see here.

Given the inherent inaccuracies between gauges and the number of variables which can affect slight increases and decreases of the gauge, so long as you're operating in the OK range, you're not adversely affecting anything.

Individual engines all have their own 'unique' operating temps within a range and a 3°-10° variation means nothing.

Quickurt 06-21-2008 01:09 PM

I have to agree with LB, geez. I just can't call him by his chosen name (!) but I don't think watching your temp guage like a hawk can head off any catastophic engine failures. I'm also not familiar with what the onboard computer monitors, but if red lights and warning bells go off on the dash read-out to make you "consider your remaining range" just because you're down to 63 miles of gas remaining, I would hope it would do at least the same if your over temp, before the engine :barf:

Jaxonalden 06-21-2008 09:14 PM

As I said in my original post "my engine runs cooler than any other vehicle that I drive" and that's all I was getting at. I'm not being obsessed with my coolant temp or watching it like a hawk, I was making an observation that was out of the norm and was just wondering if everyone else had the same temp. Big deal!

BTW, coolant temp is engine temp. If your going to sell the argument that you can use a pyrometer and see greater temps around the engine and then average them for engine temp is ridiculous. The coolant system maintains the engine at a set temperature by the OEM and my point is that Porsche runs their engines cooler than any other manufacture that I know.

An added benny to the 180 degrees means the oil and tranny fluid are also being cooled better.

Lil bastard 06-21-2008 11:02 PM

Hate to disagree, but coolant temp is NOT engine temp - proper combustion could not take place in a 180° environment.

The coolant, flowing through the water jackets does NOTHING to cool either the main, conrod or camshaft bearings - this is carried out by the oil, not the coolant ! The oil sheds this heat through the sump and oil cooler which, in the case of the Boxster, means to the coolant.

In fact, fully 60% of engine cooling is accomplished by the oil - not the coolant !!

The coolant extracts heat from mainly the combustion chamber and the head - cooling the valves in the process.

But, the major components of the engine - the Block, Crank, Pistons, etc. typically run in the 500°-600° range as previously mentioned.

If what you say were true - that coolant temp = engine temp, then no pyrometer reading should exceed 180°- 185° (except maybe the headers/exhaust manifold), which is certainly not the case.

That's not to say the coolant doesn't perform a critical role, it certainly does. But to obsess about it does not accomplish what many mistakenly believe.

Quickurt 06-22-2008 04:50 AM

Actually the size of the water cooling system is calculated to keep the coolant at a usable temperature. It carries off heat from much hotter areas to be dissiminated into the air through the heat exchangers (radiators). The coolant is simply the vehicle used to transfer internal heat to the air. The oil does the same, and in fact in the air cooled engine oil was the only vehicle. Air cooled the cylinder sleeves directly through cast fins, but the heads were cooled by oil, as well as the internals of the crankcase. The air cooled engine also ran much hotter, overall, and was one reason why they had oil seapages. They expanded and contracted more as the temps rose higher and dropped more with the higher operating temperature and oil seal material had to withstand higher operating and aging temps.
As LB points out above, the oil is also cooled via the water in liquid to liquid heat exchangers, so the coolant acts as the vehicle to carry the heat absorbed by the oil out into the air.
I don't know if any are still used, but some industrial and ship engines used steam as the coolant because it allowed higher operating temps than when the coolant could not rise above the boiling point. The reason cooling systems are pressurized is the raise the boiling temp of the coolant (water).
By the way, a simple physics question. If the engine and the coolant are of uniform temperature, how is heat absorbed from the engine, into the coolant, and then released into the air through the radiators, to return to the engine and absorb more heat?

Quickurt 06-22-2008 05:00 AM

By the by, please don't think this is "lecturing."
I can only speak for myself, but I feel it helps everyone understand their cars better, if they understand what everything is really doing.
The main reason European cars have always handled better than American cars is due to a basic philosophical difference between the two industries.
The europeans understand the purpose of the suspension system is to keep the tires in as close to perfect position and loading at all times, to maintain near perfect adhesion between the tires and pavement. Ride comfort is compromised in favor of control.
American manufactures understand the purpose of the suspension system is to give the car as smooth a ride as possible over any type of pavement surface. Control is compromised in favor of ride comfort.
Who's right?
I think the Europeans, Lincoln Town Car owners cheer for the Americans! :cheers:
The more we all know and understand, the better decisions we should be able to make.
:dance:


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