75 v. 83 thermostats for 87-94 cars
#16
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Erik: my main issue is living in a very humid and nearly year round HOT climate, is there an advantage to running the lower
thermostat. they made the 75' for the earlier cars, and those used the same temp switch as later cars: same switch from 87-95.
I feel confident, that in Florida, my oil temps are never on the low side.
thermostat. they made the 75' for the earlier cars, and those used the same temp switch as later cars: same switch from 87-95.
I feel confident, that in Florida, my oil temps are never on the low side.
However...I would first make sure everything is perfect stock. I've flushed out a couple radiators from cars that were otherwise in great shape, you would have been surprised to see the gunk that came out from various forward and reverse flushings.
Issues at low speed / idle can indicate fan issues, doesn't seen to be the case here.
Running lean can also cause engines to run hot. I don't think this is very common with 928's though, but still a possibility.
Clogged CATS, but if they were that bad I'm sure you would feel it with the power. Also not a terribly common reason for 928's to run hot.
The t-stat installed could be faulty and / or the seal behind it.
I'm sure I'm missing a few things to check.
I'm not a big fan of modifying things unless I've verified everything is 100% perfect.
#17
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if it was a good idea to run a 75C thermostat do folks really think Porsche would not have worked that one out? I cannot comment on other motors but my motor needs to get warm before it feels "loose" and that seems to happen when the gauge indicates 80C or greater so it makes no sense to try to run cooler.
I have tried a 75C thermostat and in really hot weather it makes no real world difference but in cooler season weather it does make a difference and it is not a "good difference" as I am concerned.
I have tried a 75C thermostat and in really hot weather it makes no real world difference but in cooler season weather it does make a difference and it is not a "good difference" as I am concerned.
#18
Three Wheelin'
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if it was a good idea to run a 75C thermostat do folks really think Porsche would not have worked that one out?
#20
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FWIW: this is from the 928 motorsports online parts list:
Application: All Porsche® 928 1978-1995
The Problem: The Porsche® 928 is susceptible to overheating as the radiator ages, or when modifications are made to increase its HP (and heat) output. This is especially true if the car is kept in hotter climates.
The Solution: Replace the stock 83°C thermostat with this brand new thermostat at 75°C. The lower temperature opens the t'stat earlier, and lowers the operating temp of the engine. Made in Germany for Porsche®. A new o-ring to seal the housing is included!
Application: All Porsche® 928 1978-1995
The Problem: The Porsche® 928 is susceptible to overheating as the radiator ages, or when modifications are made to increase its HP (and heat) output. This is especially true if the car is kept in hotter climates.
The Solution: Replace the stock 83°C thermostat with this brand new thermostat at 75°C. The lower temperature opens the t'stat earlier, and lowers the operating temp of the engine. Made in Germany for Porsche®. A new o-ring to seal the housing is included!
#22
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Hotter engine = more efficient, better gas mileage & emissions.
#23
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FWIW: this is from the 928 motorsports online parts list:
Application: All Porsche® 928 1978-1995
The Problem: The Porsche® 928 is susceptible to overheating as the radiator ages, or when modifications are made to increase its HP (and heat) output. This is especially true if the car is kept in hotter climates.
The Solution: Replace the stock 83°C thermostat with this brand new thermostat at 75°C. The lower temperature opens the t'stat earlier, and lowers the operating temp of the engine. Made in Germany for Porsche®. A new o-ring to seal the housing is included!
Application: All Porsche® 928 1978-1995
The Problem: The Porsche® 928 is susceptible to overheating as the radiator ages, or when modifications are made to increase its HP (and heat) output. This is especially true if the car is kept in hotter climates.
The Solution: Replace the stock 83°C thermostat with this brand new thermostat at 75°C. The lower temperature opens the t'stat earlier, and lowers the operating temp of the engine. Made in Germany for Porsche®. A new o-ring to seal the housing is included!
#24
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I dunno, i'm not the the engineer that decides those things. And i'm still learning that when I overthink how things should be, I end up discovering that I shouldn't be thinking about it.
You asked if they're the same..they're not.
You asked if they're the same..they're not.
#25
#26
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FWIW: this is from the 928 motorsports online parts list:
Application: All Porsche® 928 1978-1995
The Problem: The Porsche® 928 is susceptible to overheating as the radiator ages, or when modifications are made to increase its HP (and heat) output. This is especially true if the car is kept in hotter climates.
The Solution: Replace the stock 83°C thermostat with this brand new thermostat at 75°C. The lower temperature opens the t'stat earlier, and lowers the operating temp of the engine. Made in Germany for Porsche®. A new o-ring to seal the housing is included!
Application: All Porsche® 928 1978-1995
The Problem: The Porsche® 928 is susceptible to overheating as the radiator ages, or when modifications are made to increase its HP (and heat) output. This is especially true if the car is kept in hotter climates.
The Solution: Replace the stock 83°C thermostat with this brand new thermostat at 75°C. The lower temperature opens the t'stat earlier, and lowers the operating temp of the engine. Made in Germany for Porsche®. A new o-ring to seal the housing is included!
So a cooler thermostat cleans out the old radiator returning it to as-new performance levels?
...think about that. If (the vendor stated problem) you're overheating because **** radiator, why will moving energy into it _faster_ make it also cool better?
Why would a 500Hp car on stock hardware have no problems then?
#27
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LOL - Ok, back on point here guys.
It is funny though.....
It is funny though.....
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if it was a good idea to run a 75C thermostat do folks really think Porsche would not have worked that one out? I cannot comment on other motors but my motor needs to get warm before it feels "loose" and that seems to happen when the gauge indicates 80C or greater so it makes no sense to try to run cooler...
I have never used anything but the 83oC thermostat, per Porsche's suggestion. If you don't have a sharktuner, you should come borrow mine so you can drive around for an hour, log the data, and you will see that the coolant temperature varies between 179 and 187 degrees regardless of the thermostat and whether you're cruising at 2800, doing WOT blasts, or doing stop-start through town. Then you can put a big piece of duct tape over your temp gauge and stop worrying about it..
The faster you get to the right operation temperature, the better it is.
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Under some conditions a 'cooler' thermostat may prevent the core engine temperature from reaching the designed operating temperature.
... and thus 'longer' becomes 'infinitely-long.'
There is of course a corollary:
If your car's engine is operating at a temperature in excess of the designed operating temperature, fitting a cooler thermostat will not lower the operating temperature.
You do, however, raise the nuances of this topic to the foreground.
If you fit a 75-degree thermostat then, yes, of course the core temp will be a bit lower because you are adding heat exchange capacity.
But, even at 185 degrees the 928 engine isn't 'completely' warm yet and thus you're running the engine at a temperature lower than what Porsche intended.
On the subject of what Porsche intended, I looked through the TSBs, Service, info, etc and didn't find a reference to a thermostat change. And, my 15-year-old version of PET that would show the part numbers before supersession is non-functional. I don't disbelieve a change for '89 from '87-88, but I'd like to know the provenance. If at any point I knew about this change I have purged it from memory.
I did multiple tests - ... the temp needle never got past the initial white mark unless I was on the track and only after a couple laps @ WOT.
If you don't think changing the t-stat will effect the steady state operating temp, install a 110C / 230F thermostat and tell me it doesn't run warmer.
Unless someone can show that the 75-degree thermostat allows more water to flow from the radiator to the water bridge than the 83-degree thermostat when they are both fully open, then the only possible effect of a 75-degree thermostat is to keep the engine below its designed operating temperature for a longer period than the 83-degree thermostat.
Let's face it: this topic almost always comes up because someone has an issue with the cooling system and thinks a lower temperature thermostat will fix the problem. It won't. At best it will postpone the observance of the problem by a few minutes or until the weather gets hotter.
Last but not least: All you folks that are using your cluster gauge as a way to determine if your changes to the cooling system have an effect - Stop it. Use an IR thermometer or, better yet, a contact thermometer. With the pre-'89 spade connectors to the cluster sender you can change the 'calibration' by unplugging the connectors and plugging them back in. ('cause you're scraping-off the green oxidation on the connectors and changing the resistance.)
As for why Porsche decided to change to 83-degrees the likely answer is 'emissions.' A cooler engine is a dirtier engine and the faster you warm it up the quicker is your exhaust cleaner.
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I have never used anything but the 83oC thermostat, per Porsche's suggestion. If you don't have a sharktuner, you should come borrow mine so you can drive around for an hour, log the data, and you will see that the coolant temperature varies between 179 and 187 degrees regardless of the thermostat and whether you're cruising at 2800, doing WOT blasts, or doing stop-start through town. Then you can put a big piece of duct tape over your temp gauge and stop worrying about it..
All the modern Porsches run ~210 (IIRC) unless you click sport mode, in which case the core temperature drops (over the course of minutes) to 194-196.