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Old 07-10-2009, 09:12 PM   #1
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Low temp thermostats....

Has anyone fitted a Raby Flat6 low temperature thermostat?
I've just ordered one and will replace my 8 year old original thermostat when I change the coolant.
Any thoughts on how your engine now operates (quicker warm up) or any apparent differences to the original 'stat.....


Last edited by Steve Tinker; 07-11-2009 at 12:01 AM.
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Old 07-11-2009, 07:48 AM   #2
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I recenty replaced mine with the LN part on my '02 S. Haven't drivin it enough to give feedback, but I trust what Charles and Jake state (plus the turbos and GT3s all came with low temp stats)...certainly appears to run cooler from the gauge.

I needed a coolant flush anyway; replaced with Porsche OEM coolant....car has 16k miles.
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Old 07-11-2009, 10:35 AM   #3
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I once did this on my 87 Camaro. I went from a 220 thermostat to a 180 thermostat and it cardoned up the heads/valves really bad. What temp is stock on the Boxstrer and what temp are you wanting to go to?

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Old 07-11-2009, 04:56 PM   #4
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According to Charles and the LN website, the stock t-stat starts to open at 186* and doesn't fully open until 210 or so. This creates some real hot pockets within the engine itself. The low temp t-stat starts to open around 166* and is fully open by 184*, IIRC. Lower coolant temp equates to lower oil temp, which in the long run, could save your engine.
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Old 07-11-2009, 09:46 PM   #5
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I live in the sub tropics - something like Florida I suspect - where it rarely drops below 5 deg C on a winter night while summer temps are around the mid to high 30 deg C. Considering the M96 engine runs hot out of the box, I will try the low temp thermostat and report any change (if any) to the daily running characteristics.
But I am looking more to the long term reliability more than anything - new coolant & thermostat coupled with 5000 mile oil & filter changes (5W40 Shell Ultra synthetic) hopefully will do the trick.....
I've a lot of money tied up in my Boxster S (they cost about 2 to 2.5 times more here than the US) so I'm hoping the Raby/LN Engineering boys know their stuff.
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Old 07-12-2009, 05:14 AM   #6
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Engines are designed with specific running tolerances in mind. These tolerances are dependent on certain material temperatures. If the temperatures are different, clearances and pressures in the nominal running state are not the same as what the designers had in mind. This will influence things like friction, oil consumption, combustion efficiency, fuel consumption, and oil pressure.

This is why a thermostat that works for one engine, like the GT3, may not be the best answer for another.

I don't know if lowering the water operating temp in the M96 is beneficial or not, but I do know that it's not what Porsche considered optimal when designing the engine.

Last edited by blue2000s; 07-12-2009 at 05:16 AM.
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Old 07-12-2009, 05:39 AM   #7
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It's been my experience that a cooler thermostat does nothing once it's past it's opening point. If your stuck in 110f traffic your going to heat up to the same point regardless off when your thermostat starts to open.

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Old 07-12-2009, 06:17 AM   #8
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It's been my experience that a cooler thermostat does nothing once it's past it's opening point. If your stuck in 110f traffic your going to heat up to the same point regardless off when your thermostat starts to open.

Regards, PK
A good point, the thermostat controls when the water starts to flow through the radiator, but the fans come on at the same temp as always and the radiators haven't changed.
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Old 07-12-2009, 06:23 AM   #9
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"I don't know if lowering the water operating temp in the M96 is beneficial or not, but I do know that it's not what Porsche considered optimal when designing the engine."

I'm sure Porsche took all optimal points into consideration when designing the M96 engine...like all the other weak points designed into it. I trust the "real world" experience of Charles and Jake over the factory hype and coverup. I wish for my engine to last and will do everything I can to make it do so.
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Old 07-12-2009, 06:45 AM   #10
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Quote:
Originally Posted by jmatta
"I don't know if lowering the water operating temp in the M96 is beneficial or not, but I do know that it's not what Porsche considered optimal when designing the engine."

I'm sure Porsche took all optimal points into consideration when designing the M96 engine...like all the other weak points designed into it. I trust the "real world" experience of Charles and Jake over the factory hype and coverup. I wish for my engine to last and will do everything I can to make it do so.
Don't you think Porsche tests their cars on the road extensively before releasing them? I saw a row of 996 Turbos outside of Vail about 6 months before the car was released.

I appreciate what Jake and Charles doing too. And I'm not saying the thermostat is a bad thing, but I do know it's a change from the way the design was intended.

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Old 07-12-2009, 08:14 AM   #11
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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..........
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Old 07-12-2009, 08:51 AM   #12
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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.

Last edited by blue2000s; 07-12-2009 at 08:58 AM.
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Old 07-12-2009, 09:55 AM   #13
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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………….


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

It doesn't, but feel free to believe whatever you wish..................
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Old 07-12-2009, 04:26 PM   #14
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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.
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Old 07-13-2009, 05:45 AM   #15
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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
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Old 07-13-2009, 05:57 AM   #16
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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.

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Old 07-13-2009, 05:59 AM   #17
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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?
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Old 07-13-2009, 06:14 AM   #18
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I'm not sure

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.
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Old 07-13-2009, 06:25 AM   #19
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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!
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Old 07-13-2009, 06:26 AM   #20
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Originally Posted by JFP in PA
I am a life-long SAE member, does that count?

Don't know. What is your specialty???? Engines design, etc.

Just asking, don't get testy on me.


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