Low temp thermostats....

[JFP in PA]

OK, let's put this one to bed: The LN thermostat will lower the point at which the coolant flow starts by about ~25 F. Considering that the dash gauge is inaccurate as Hell (when it reads between the "8" and "0" on the "180", the car is actually at about 205-210F), dropping the full flow point allows the engine to run (steady state cruise speeds) in the mid to high 170's. Considering that the M96 engine has a significant number of "hot spots" (places with the cooling system where flow restrictions cause much higher than average coolant temps), and that these engines use a laminar flow oil to water oil cooler to keep the oil temp under control, reducing the coolant temps by this amount significantly lowers average oil operational temps, usually by 20F or more. That alone is huge in protecting the engine, regardless of what oil you run.

So (from practical testing and longer term running experience) here's what you get:

• Significantly lower average coolant temps.

• Significantly lower oil temps and longer oil life.

Here's what you don't get:

• Problems.......You still have plenty of heat in cold (0F) ambient temps, no impact on the emissions system (no codes, no inspection rejects, etc.)

I really fail to understand why so many people balk at this concept..........

[blue2000s]

Originally Posted by JFP in PA

OK, let's put this one to bed: The LN thermostat will lower the point at which the coolant flow starts by about ~25 F. Considering that the dash gauge is inaccurate as Hell (when it reads between the "8" and "0" on the "180", the car is actually at about 205-210F), dropping the full flow point allows the engine to run (steady state cruise speeds) in the mid to high 170's. Considering that the M96 engine has a significant number of "hot spots" (places with the cooling system where flow restrictions cause much higher than average coolant temps), and that these engines use a laminar flow oil to water oil cooler to keep the oil temp under control, reducing the coolant temps by this amount significantly lowers average oil operational temps, usually by 20F or more. That alone is huge in protecting the engine, regardless of what oil you run.

So (from practical testing and longer term running experience) here's what you get:

• Significantly lower average coolant temps.

• Significantly lower oil temps and longer oil life.

Here's what you don't get:

• Problems.......You still have plenty of heat in cold (0F) ambient temps, no impact on the emissions system (no codes, no inspection rejects, etc.)

I really fail to understand why so many people balk at this concept..........

I dont' see how this puts anything to bed.

Lower oil temperatures aren't always a good thing and the lower temperature alters expected operating tolerances. The designers didn't care what the gauge read when they were designing the engine. They didn't use that gauge so it's really not relevant.

But like was stated above, it's really just changing when the radiators start to see flow, extending the warm-up time. The engine will run to the same temperature it would have anyway eventually.

[JFP in PA]

Originally Posted by blue2000s

Lower oil temperatures aren't always a good thing and the lower temperature alters expected operating tolerances. The designers didn't care what the gauge read when they were designing the engine. They didn't use that gauge so it's really not relevant.

Actually, you are wrong about lowering oil temps; it is one of the most critical things you can do to extend engine life. And in this case, more than likely the designers were overruled by the accountants in the OEM configuration; both the coolant and oil run very hot the way the cars are delivered………….

Originally Posted by blue2000s

The engine will run to the same temperature it would have anyway eventually.

It doesn't, but feel free to believe whatever you wish..................

[blue2000s]

Originally Posted by JFP in PA

Actually, you are wrong about lowering oil temps; it is one of the most critical things you can do to extend engine life. And in this case, more than likely the designers were overruled by the accountants in the OEM configuration; both the coolant and oil run very hot the way the cars are delivered………….

It doesn't, but feel free to believe whatever you wish..................

Actually, I've read a study that found low temperature operation can form acids in motor oils, and high temperatures can cause oxidation. There is an optimal temperature where both effects are minimized at about 90C, or 194F. So there seems to be a "too low" range and a "too high" range for optimum oil longevity. I don't believe I'm wrong at all, but I'd be happy to be educated on the subject.

I'd also like to understand from you how an engine that runs the coolant in the 200F range under steady state would notice the difference between a thermostat that opens at 160 vs one that opens at 180F.

[JFP in PA]

Originally Posted by blue2000s

Actually, I've read a study that found low temperature operation can form acids in motor oils, and high temperatures can cause oxidation. There is an optimal temperature where both effects are minimized at about 90C, or 194F. So there seems to be a "too low" range and a "too high" range for optimum oil longevity. I don't believe I'm wrong at all, but I'd be happy to be educated on the subject.

Well, we've been running the LN stat in six different customer's cars for over a year now, regularly checking a variety of parameters, including running full UOA's, and the oils (2,500 to 10,000 miles between changes) continue to look very good. And, by-the-by, the normal oil operational temps on these cars, even with the LN stat, are typically well over 200F.............the major difference being that with the low temp stat, they are staying 20-25F cooler than they were with the OEM stat………………


I'd also like to understand from you how an engine that runs the coolant in the 200F range under steady state would notice the difference between a thermostat that opens at 160 vs one that opens at 180F.

Simple, actually, the stat controls the minimum engine temp as well as at what temp the cooling system has full flow (stats open gradually in response to temp, not all at once). The LN stat is at full flow in the low 170’s, while the OEM unit does not see full flow until nearly 210 in most cars. As the result, a car with the OEM stat will run (steady state cruise on a 72-74F ambient day) about 210-215. The same car (and day) with the LN stat, the car cruises at 177-179F coolant, and the oil temp dropped over 20F as well. Tiptronic equipped cars also saw a concomitant drop in their ATF temps as well. Because higher engine operating temps are focused on emissions, not performance; lowering the operational temps improves volumetric efficiencies, not unlike using a cold air intake to improve charge density. A cooler engine also allows the DME to use more timing advance without detonation issues; which is an additional benefit to those running remapped DME’s. On Charles Navarro’s otherwise stock base (Tiptronic) Boxster, changing the thermostat from the OEM to the 160 netted an increase of 5 HP and about 4 Lb Ft. of torque at the wheels during back to back dyno runs using 93 octane fuel………volumetric efficiency does matter

[Brucelee]

I doubt you two will get into agreement so be careful not to escalate.

If there is an engine engineer around, he MIGHT be able to address this.

For what it is worth, unless the engine is showing signs of overheating, personally, I would stick with the stock thermo temp.

Invest the time and money in Red Line oil.

Which of course, starts another argument.

[JFP in PA]

Originally Posted by Brucelee

I doubt you two will get into agreement so be careful not to escalate.

If there is an engine engineer around, he MIGHT be able to address this.

For what it is worth, unless the engine is showing signs of overheating, personally, I would stick with the stock thermo temp.

Invest the time and money in Red Line oil.

Which of course, starts another argument.

I am a life-long SAE member, does that count?

[blue2000s]

Originally Posted by JFP in PA

Simple, actually, the stat controls the minimum engine temp as well as at what temp the cooling system has full flow (stats open gradually in response to temp, not all at once). The LN stat is at full flow in the low 170’s, while the OEM unit does not see full flow until nearly 210 in most cars. As the result, a car with the OEM stat will run (steady state cruise on a 72-74F ambient day) about 210-215. The same car (and day) with the LN stat, the car cruises at 177-179F coolant, and the oil temp dropped over 20F as well. Tiptronic equipped cars also saw a concomitant drop in their ATF temps as well. Because higher engine operating temps are focused on emissions, not performance; lowering the operational temps improves volumetric efficiencies, not unlike using a cold air intake to improve charge density. A cooler engine also allows the DME to use more timing advance without detonation issues; which is an additional benefit to those running remapped DME’s. On Charles Navarro’s otherwise stock base (Tiptronic) Boxster, changing the thermostat from the OEM to the 160 netted an increase of 5 HP and about 4 Lb Ft. of torque at the wheels during back to back dyno runs using 93 octane fuel………volumetric efficiency does matter

I appreciate the explanation. It's interesting info.

- Are there UOA results for both the standard and low temp t-stat for comparison?

- What your explaining on the t-stat operation is that the engine won't run hotter than the fully opening temperature during cruising, which is essentially steady state at 72-74F. Keeping everything else equal, the water temp should go up linearly with air temp, so at 84F, the water will be 10F hotter, right? What temperature do the fans come on? Does the car run at a temperature independent of the t-stat at non-steady state like at an autocross or mountain road driving?

I definitely am not in this for a p*ssing contest, just to understand what's going on. I was an SAE member as well when I had my papers published there in in-cylinder flow simulation. I'm haven't been working in the auto industry for about 10 years so the membership expired a long time ago.

[JFP in PA]

Originally Posted by blue2000s

I appreciate the explanation. It's interesting info.

- Are there UOA results for both the standard and low temp t-stat for comparison?

Yes, we have installed several of these stats, including one in my own car, and run UOA's before and after. The actual test results are the property of the car owner's (they paid for them) so I can only provide summary info without their permission. We did not any see evidence of acid formation related issues, and we also did not see increased fuel dilution (another "old wife's tale" about lower the stat temp). In general, the oil looked like it had seen a lot less mileage that it really had, particularly in the cars that get the Hell beat out of them on a regular basis....

- What your explaining on the t-stat operation is that the engine won't run hotter than the fully opening temperature during cruising, which is essentially steady state at 72-74F. Keeping everything else equal, the water temp should go up linearly with air temp, so at 84F, the water will be 10F hotter, right? What temperature do the fans come on? Does the car run at a temperature independent of the t-stat at non-steady state like at an autocross or mountain road driving?

At any ambient temperature, the "steady state cruise" temp is a function of the ambient temp, air flow, radiator condition, air flow obstruction, etc. etc......as well as the full flow open temp of the stat. As you are an engineer, none of this should be news to you. On a hotter day, in bumper to bumper traffic, or under hard use, a car with the LN stat will still get warm and will eventually cause the fans to kick on (the function of which is controlled by the DME). But, when the increased airflow (either from the fans or movement of the car), the temps drop back down; the major difference is to where they go. In fact, one customer comment is that they notice that their fans do not seem to cycle as much as they did before the change. On my personal car, I saw the coolant temps rise yesterday (while stuck in traffic) to over 215F when the fans kicked in. As soon as I clear the traffic and was back to 65 MPH, the temps dropped back down into the high 170's low 180's range (ambient temps were in the 85F range). Note that I monitor the oil and water temps via a display from an aftermarket data logging system connected to the OBD II port rather than the dash displays, which are notoriously inaccurate and non linear on just about all Porsche models. To address your questions, yes higher ambient temps will result in higher coolant and oil temps, not necessarily in a linear fashion, but they will both be lower than when the OEM stat was used in the same vehicle under the same or similar conditions. When a car equipped with the low temp stat enters an adverse environment (traffic, track usage, etc.), it will start from a lower coolant temp and tend to take longer for the fans to come on, and will cool back down to the lower operating temp once the load condition returns to normal.

I definitely am not in this for a p*ssing contest, just to understand what's going on. I was an SAE member as well when I had my papers published there in in-cylinder flow simulation. I'm haven't been working in the auto industry for about 10 years so the membership expired a long time ago.

..................................................

[mikefocke]

I'd want to be citing the Porsche engine designers intent/knowledge as the reason for not changing the thermostat's characteristics.

After all these are the same people who brought you slipped sleeves, d-chunks, IMS and RMS problems, not to mention filler caps that went through how many revisions, AOSs that went through how many...I could go on and on.

[JFP in PA]

Originally Posted by mikefocke

I'd want to be citing the Porsche engine designers intent/knowledge as the reason for not changing the thermostat's characteristics.

After all these are the same people who brought you slipped sleeves, d-chunks, IMS and RMS problems, not to mention filler caps that went through how many revisions, AOSs that went through how many...I could go on and on.

Mike, while you are talking to them, also ask them what kind of thermostat they put in the GT2/GT3 and RSR cars.......................you might be surprised!