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    Globespy is offline Porsche Activist
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    Thermostat Modification to Lower Temps

    I was considering changing the thermostat on my boxster to one I had seen for sale (I think LN Engineering) - it was to lower the running temperature of the thermostat, and that of the coolant system. Makes sense.

    Then I got to thinking that thermostats are pretty basic things and went searching for ways to modify it's operation.
    I found the following site - a guy who has solved his climate related cooling problems on his older diesel Mercedes. Ignore the car he's working on and instead focus on the simplicity of a thermostat and it could well be a possible option for those who want to keep coolant temps down particularly in racing conditions. Maybe you could keep your stock thermostat for winter and use the modified one for summer/racing conditions? It makes sense to me!

    Thermostat Replacement and modification


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    Re: Thermostat Modification to Lower Temps

    Do you have a specific reason to lower the operating temperature of your engine? Or, to put it another way, what problem are you solving?

    Yes, thermostats are pretty basic things, but the all of the systems in your engine are not. In modern cars, they are all computer controlled and all expect each of the other systems to be doing their part. Coolant temp, engine temp and even the temp in the engine bay are all tightly controlled these days. The ECU, when it modifies timing, fuel, etc, expects the engine to be at a particular temperature. Change that temperature, and the ECU won't be able to optimize your engine. Lower the temperature and the ECU might keep the engine in warm-up mode, where it richens the fuel mixture. At the best, this will hurt your mileage, at worst, you could burn out your catalytic converters.
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    Re: Thermostat Modification to Lower Temps

    Does your state have a smog law? Auto inspection? Can your car pass with this mod?

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    Globespy is offline Porsche Activist
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    Re: Thermostat Modification to Lower Temps

    Quote Originally Posted by downshift View Post
    Do you have a specific reason to lower the operating temperature of your engine? Or, to put it another way, what problem are you solving?

    Yes, thermostats are pretty basic things, but the all of the systems in your engine are not. In modern cars, they are all computer controlled and all expect each of the other systems to be doing their part. Coolant temp, engine temp and even the temp in the engine bay are all tightly controlled these days. The ECU, when it modifies timing, fuel, etc, expects the engine to be at a particular temperature. Change that temperature, and the ECU won't be able to optimize your engine. Lower the temperature and the ECU might keep the engine in warm-up mode, where it richens the fuel mixture. At the best, this will hurt your mileage, at worst, you could burn out your catalytic converters.
    Hmmm...there is a part available from Pelican Parts and (I think) LN Engineering that claims to do the following:

    "This thermostat begins opening at 160 deg F. and features a calibrated, German-made 160F thermostat pre-installed in a new, OE Wahler thermostat housing and gasket. It is calibrated to allow thermostat opening a full 20-25F degrees earlier than the factory thermostat. That means that the the low temperature thermostat is designed to be fully open by 180-185F, allowing for full flow to the cooling system to maximize cooling potential."

    The purpose of my post was to bring attention to a DIY solution - perhaps not as 'specific' as the above option, but let's face it - if the engine computers have to adapt to a new thermostat that specifically begins at 160 versus say a modified one that starts around 160-170, what's the difference? The goal is lower start temps to maximize cooling potential.

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    Re: Thermostat Modification to Lower Temps

    Again, what problem are you solving? Your existing thermostat will open fully to maximize cooling potential already. What problem does lowering the tempertature it starts to open solve?
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    Globespy is offline Porsche Activist
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    Re: Thermostat Modification to Lower Temps

    Quote Originally Posted by downshift View Post
    Again, what problem are you solving? Your existing thermostat will open fully to maximize cooling potential already. What problem does lowering the tempertature it starts to open solve?
    I'm attempting to prevent a problem from happening - that's the idea, sorry if that wasn't clear.
    If the car is driver very hard either on the road or at the track, then temperatures are all higher. Lowering the operating temperature(threshold) of the coolant will maximize it's effectiveness.

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    Re: Thermostat Modification to Lower Temps

    Typically lower temp thermostats are most beneficially when adding a power adder, adding boost to an FI engine, running "hotter" (higher lift or longer duration) cams, significantly increasing rev limits, limiting the air flow to the cooling components, or making changes to part or all of the cooling system. There will be little to no benefit to a substantially stock motor or body work but there could be a detriment in cold weather or if it is set to open to low and prevents components and fluids from reaching optimal operating temps during warm up in a track setting where you might get to high revs quickly.
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    Re: Thermostat Modification to Lower Temps

    Quote Originally Posted by Globespy View Post
    I'm attempting to prevent a problem from happening - that's the idea, sorry if that wasn't clear.
    If the car is driver very hard either on the road or at the track, then temperatures are all higher. Lowering the operating temperature(threshold) of the coolant will maximize it's effectiveness.
    Sure, you can get higher temperatures on the track or even in hot weather. Say you reach 190 in these conditions. If the factory thermostat opens fully at 180, and the aftermarket fully opens at 170, where is the improvement? Both will be fully open at 190, and cooling will be maximized.
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    Globespy is offline Porsche Activist
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    Re: Thermostat Modification to Lower Temps

    Quote Originally Posted by downshift View Post
    Sure, you can get higher temperatures on the track or even in hot weather. Say you reach 190 in these conditions. If the factory thermostat opens fully at 180, and the aftermarket fully opens at 170, where is the improvement? Both will be fully open at 190, and cooling will be maximized.
    Well I am glad that I did not spend $175 on the thermostat that comes on at 160 instead of 180!! However, I believe the aftermarket one topped out at a lower temperature so I would imagine it would keep the overall temp lower particularly during higher stress conditions (track). So perhaps the modification I saw (int he first post) would not work out...but the aftermarket one might?
    I was hoping it would send my 987 into warp-mode.....dang it!
    It seems that modifications fall into the 'opinions & butt-holes' bucket.

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    Re: Thermostat Modification to Lower Temps

    Dedicted track cars often run without a thermostat at all. This opens up the coolant passages even more, so more coolant can flow to the radiator. But this is not recommended for a street car, due to the issues mentioned above.
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    Re: Thermostat Modification to Lower Temps

    Quote Originally Posted by downshift View Post
    Sure, you can get higher temperatures on the track or even in hot weather. Say you reach 190 in these conditions. If the factory thermostat opens fully at 180, and the aftermarket fully opens at 170, where is the improvement? Both will be fully open at 190, and cooling will be maximized.
    I'll just point out that the factory thermostat doesn't start opening until 186F and isn't fully open until 205-210F (varies). The low temperature thermostat starts opening at 160F so it is fully open by 185F. The idea here is to have full flow earlier, to try to control hot spots. There is plenty of capacity in the cooling system to allow for a lower temp thermostat. On a dedicated track car you can even go further to remove one or both fans to allow even more air through the radiators. If you don't see a drop in temperature with it, likely it's because you are sitting in traffic (no airflow) or your radiators need cleaning.

    Emissions testing is a non-issue. Any car with the low temperature thermostat will pass smog and won't run rich. The ecu has target parameters for fuel and timing and will adjust accordingly to ensure proper tune.

    There are lots of misconceptions and nay sayers but that said, there are several Porsche models with lower temperature thermostats, i.e. DFI cars, which run similar real-world coolant temperatures to an M96 engine equipped with one of our low temperature thermostats.
    Charles Navarro

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    Re: Thermostat Modification to Lower Temps

    Quote Originally Posted by downshift View Post
    Dedicted track cars often run without a thermostat at all. This opens up the coolant passages even more, so more coolant can flow to the radiator. But this is not recommended for a street car, due to the issues mentioned above.
    You actually won't want to run without a thermostat. It's double sided with two "plates" for lack of a better term that block off two separate orafices. One is thermostatically controlled and the other is sprung to be affected by operating pressures. Remove the thermostat and you defeat the normal operating flow of the cooling system. The cars tend to actually run hotter without them and have hot spots.
    Charles Navarro

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