160F Thermostat On 996 3.4 With California Smog

[ALLSPEED]

I have a 1999 996 C23.4 6spd. and seen a lot of threads of people going to 160f. I live in the central valley of California and it gets over 110f in summer. Cooler temps make things last longer but I couldn't find results from anyone with a California car where the government like their cars to run hot for smog. Mine stays dead on at 185f but wouldn't mind lowering it to make it last longer.Come on guys, fill me in. Thanks, Robert

[pk2]

1) Heat is not bad. If your car were actually running at 185 you would be perfect. If you were running at 160, that would be bad. The motors are designed to operate at peak efficiency of about 180ish.

2) By "Government", do you mean this and the 11 other states with strict state standards? Or the federal government with weaker standards? They're both irrelevant. All the motors in this country and I believe the world, run at the same temp as your motor.

3) The theory is that Porsche actually thinks they have to run these motors at 210 to pass emissions. So you don't freak out, they jigger the gauge to read a false 180ish when it's actually 210. 180 is good. 210 is to hot and shortens the life of the motor.

Little do they know, so the "160" theory goes and as I understand it, they could actually run them at a true and safe 180 (with a 160 thermostat), add years to the life of the motor and, still pass emissions. And so by extrapolation, after some 20 years developing this motor, they haven't figured that out yet.

So the theory goes.

Regards, PK

Edited April 2, 2010 by pk2

[JFP in PA]

Under EPA rules, Porsche has to build a car that will continue to pass emissions standards (those in place at the time of construction) for at least 80,000 miles. Raising the coolant temps has been a cheap band-aid in this effort since the late 1960's, and is practiced by just about all the OEM's.

Interestingly, Porsche does not use 185F stats in their most performance oriented engines; the GT2 and GT3's for example use a lower temp stat to maximize engine output and longevity. Dyno tests on an M96 before and after showed that the engine picked up a small, but measurable amount of HP and torque by using the lower temp stat (actual data was published on LN Engineering's website).

As for emissions, were I live you can be subject to either "advanced" testing (I/M Readiness via the OBD II port), or a sniffer, depending upon the location. I have several customers running the 160F stat in M96 variants, some for a long time, and all continue to regularly pass emissions testing. The DME's in these cars are more than flexible enough to adapt to the engine running cooler.

Perhaps of more interest is that cars with the 160 stat (and have oil temp readouts) also show lower oil temperatures, often 25-30F cooler, which is a big advantage. Comparisons of UoA's on the same M96 before and after switching to the 160F stat show the oil holds up better, as you would expect from the significant drop the oil's running temps.

After monitoring several cars for a couple of years, I see no downsides to the 160F stat………..

[ALLSPEED]

Thank you for answers with reasoning. So the temp. gauge is kind of like the speedo, not quite right? Can you think of a quick and easy way to accurately measure my coolant temp. Regardless I don't like the idea of it running anywhere close to 210F. It just seemed like 160F was pretty low and was not sure if car would accept the change. Sounds like a good project to start on. From what I've read on these threads the only one available was the LN with housing. Is that correct?

[Loren]

PST2 or PIWIS tester or Durametric tester will all measure all fluids accurately.

[JFP in PA]

PST2 or PIWIS tester or Durametric tester will all measure all fluids accurately.

As will any OBDII scanner with PID capture capability (Actron, etc.)..............

[JFP in PA]

Thank you for answers with reasoning. So the temp. gauge is kind of like the speedo, not quite right? Can you think of a quick and easy way to accurately measure my coolant temp. Regardless I don't like the idea of it running anywhere close to 210F. It just seemed like 160F was pretty low and was not sure if car would accept the change. Sounds like a good project to start on. From what I've read on these threads the only one available was the LN with housing. Is that correct?

The dash temp display is nearly a bad joke; it is both non linear and grossly inaccurate as well. Most M96's showing around 180F on the dash are actually running 205-210F.

LN has the only ones available in North America to my knowledge............

[Blue-S]

Some people seem to think that the Boxster cruises at 180 degrees because the temp gauge needle typically sits between the "8" and "0" of the "180" label when at cruise. I don't think that Porsche labeled the gauge so that 180 degrees is indicated when the needle is in that position...even though they might have made it deliberately misleading. The temp gauge has a blue-tinged tic in the vicinity of the "100" label, then an unlabeled tic, then a tic above the left side of the "8" in the "180", then another unlabeled tic, and finally a red tic in the vicinity of the "250" label. That being the case, the common temp gauge needle position at cruise (between the 8 and the 0) might be inferred as 200 or maybe more. I suppose that the unlabeled tic to the right of 180 could be inferred as 225...

This topic was debated/discussed last August on the 986 Forum, so in response I grabbed a scan tool and did some road testing. One of the data lines available in the Generic scan tool mode is ECT (from the DME), so I was able to compare temp gauge readings, HVAC diagnostic mode coolant temp readings and scan tool ECT readings on my 2000 Boxster S 6-speed.

Key on, engine off:

HVAC = 31 deg C (88 deg F), Scan Tool = 91 deg F

Gauge needle exactly on the "tic" above the "8" in "180':

HVAC = 78 deg C (172 deg F), Tool = 181 deg F

10 miles on highway at 75 mph indicated, 83 deg F ambient temp & gauge needle straight up between "8" and "0":

HVAC = 91 deg C (196 deg F), Tool = 194 deg F

Idling:

HVAC = 100 deg C (212 deg F), Tool = 208 deg F

HVAC = 101 deg C (214 deg F), Tool = 210 deg F

HVAC = 102 deg C (216 deg F), Tool = 212 deg F (gauge needle near right edge of "0" in the "180" label)

Given these results, I can only conclude that (on my car, anyway) the HVAC panel diagnostic mode is reasonably accurate at typical cruise temps, and that when the gauge needle is "straight up" between the "8" and the "0" my coolant temp is 190 - 195 deg F. It is a bit odd that the HVAC diagnostic display ECT is cooler than the scan tool displayed ECT until approximately 190 degrees F coolant temp, then the situation reverses so that the HVAC display reads slightly higher than the scan tool reported ECT. The Bentley manual hints that the HVAC panel receives engine coolant temp from the instrument cluster, so maybe the cluster is re-scaling the ECT data to effect a slight change.

These results make a lot of sense to me, because a 10-11 degree C (18-20 deg F) coolant temperature gain through the engine is quite plausible under the conditions noted above. If the inlet side thermostat is 80 deg C, and the coolant exiting the engine is 90-91 deg C, then I'm quite happy with that.

[pk2]

Under EPA rules, Porsche has to build a car that will continue to pass emissions standards (those in place at the time of construction) for at least 80,000 miles. Raising the coolant temps has been a cheap band-aid in this effort since the late 1960's, and is practiced by just about all the OEM's.

I was hoping you would pipe JPF,

What's the exspensive fix? a reflash.

Interestingly, Porsche does not use 185F stats in their most performance oriented engines; the GT2 and GT3's for example use a lower temp stat to maximize engine output and longevity. Dyno tests on an M96 before and after showed that the engine picked up a small, but measurable amount of HP and torque by using the lower temp stat (actual data was published on LN Engineering's website).

This nags me, if an engine is running a 16o stat from the get go, I get can picture it. Hpwever, if a motor that has broken in at 219f for 50k ( worn to fit do a degree) is'nt dropping the temp 50 degrees all the sudden going to change all the tolerances due to a new coeifient of exspansion value. resulting in a refit of all internal components( I.E wear)?

I suppose you have had the oil anayze before and after a "stat" change on a high-ish milage motor?

Regards, PK

Edited April 2, 2010 by pk2

[steve_wilwerding]

Can someone explain to me how, at operating temperature, a low temp thermostat is better than a regular thermostat? Once they are both open, there is no difference in coolant temperatures.

I've talked to a few race shops, and they say that if you are having coolant temp issues, installing a third radiator helps a lot more than the low temp thermostat. All the low temp thermostat does is open sooner, which therefore takes the engine longer to get to operating temperature (which is not necessarily a good thing). You might get a few more minutes of "cooler" coolant, but I doubt that affects longevity much.

[Loren]

Can someone explain to me how, at operating temperature, a low temp thermostat is better than a regular thermostat? Once they are both open, there is no difference in coolant temperatures.

I've talked to a few race shops, and they say that if you are having coolant temp issues, installing a third radiator helps a lot more than the low temp thermostat. All the low temp thermostat does is open sooner, which therefore takes the engine longer to get to operating temperature (which is not necessarily a good thing). You might get a few more minutes of "cooler" coolant, but I doubt that affects longevity much.

+1

[ALLSPEED]

I'm getting some debate here. May I assume that my stock 99 3.4 has a 185f. Does anyone know what it closes at, realizing that it doesn't snap shut. By the way I am not having a cooling problem but do live in a warm climate and was wondering if there was an advantage, cheaper than a third radiator.

Edited April 3, 2010 by ALLSPEED

[pk2]

I'm getting some debate here. May I assume that my stock 99 3.4 has a 185f. Does anyone know what it closes at, realizing that it doesn't snap shut. By the way I am not having a cooling problem but do live in a warm climate and was wondering if there was an advantage, cheaper than a third radiator.

If your temp is reading 185 all the time even when the ambient temperate is cool , your ok as long as you cooling system is clean. In this case your temp gauge is probably off. If it runs at 180 when it's cool and 185 when it's hot, a third radiator would probably fix that. ( I believe you would need an "s" bumper to let the air in).

A 160 thermostat is just going to be the lowest your (warmed up) temp you will have, (correct me if I'm wrong JPK) But, if your cooling system can't hack the heat, It's still going to peek at 185 (according to the gauge.). You shoud have a thirds radiator (again, asumming your cooling systen is tip-top)'

In my opinion.

Regards, PK

Edited April 3, 2010 by pk2

[whall]

+2

Thanks Steve. I don't remember much from my college thermodynamics class but it seems to me - a casual observer - that a cooling system has just so much cooling potential regardless of a thermostat's opening temperature. The answer to more (better) cooling is a larger capacity cooling system (third radiator in this case). If that isn't enough, get Jake's oil sump expander (more cooling medium - oil) and the larger "S" oil cooler (more cooling capacity).

This would be a moot point if Porsche had marked the temperature gauge with C(old)..........H(ot) with a bar somewhere between the two indicating a "normal" operating zone.

Bill

Edited April 3, 2010 by whall

[JFP in PA]

Under EPA rules, Porsche has to build a car that will continue to pass emissions standards (those in place at the time of construction) for at least 80,000 miles. Raising the coolant temps has been a cheap band-aid in this effort since the late 1960's, and is practiced by just about all the OEM's.

I was hoping you would pipe JPF,

What's the exspensive fix? a reflash.

Interestingly, Porsche does not use 185F stats in their most performance oriented engines; the GT2 and GT3's for example use a lower temp stat to maximize engine output and longevity. Dyno tests on an M96 before and after showed that the engine picked up a small, but measurable amount of HP and torque by using the lower temp stat (actual data was published on LN Engineering's website).

This nags me, if an engine is running a 16o stat from the get go, I get can picture it. Hpwever, if a motor that has broken in at 219f for 50k ( worn to fit do a degree) is'nt dropping the temp 50 degrees all the sudden going to change all the tolerances due to a new coeifient of exspansion value. resulting in a refit of all internal components( I.E wear)?

I suppose you have had the oil anayze before and after a "stat" change on a high-ish milage motor?

Regards, PK

To respond to your first question, the expensive fix would have been to re-engineer the engine, with 'minor' upgrades such as DFI, etc. Problem is that once all the tooling and casting molds were done, no OEM is going to throw them away and start over if an easier but potentially compromising solution is available, like keeping the engine running way to hot....... Unfortunately, in the large scale production world, bean counters will always trump the engineers.

Yes, we have virgin oil analysis, UoA with the OEM stat, and UoA with the LN stat on the same brand and weight of oil and mileage used for multiple cars that began the sequence with more than 50 or 60,000 miles on them; and we have parallel data on low mileage cars as well. The oil definitely benefits from the lower coolant temps. None of the cars has demonstrated any issues (e.g.: increased oil consumption, etc.) as the result of the change. An interesting, but not fully documented change was that most owners noticed a small, but consistent improvement in gas mileage.

[JFP in PA]

Can someone explain to me how, at operating temperature, a low temp thermostat is better than a regular thermostat? Once they are both open, there is no difference in coolant temperatures.

I've talked to a few race shops, and they say that if you are having coolant temp issues, installing a third radiator helps a lot more than the low temp thermostat. All the low temp thermostat does is open sooner, which therefore takes the engine longer to get to operating temperature (which is not necessarily a good thing). You might get a few more minutes of "cooler" coolant, but I doubt that affects longevity much.

There seems to be some significant misconceptions on how this works. The stat does control the minimum operation temp of the engine by controlling when full coolant flow commences (the OEM stat begins to open at 185-187F, but is not fully open until around 200F; the 160 stat begins to open at 160F and is fully open by around 170F or so), but it also controls the minimum temperature the system can return to by "throttling" the flow if the system tries to overcool (this happens most obviously in the winter, but also occurs at warmer temps as well were it controls the temperature to which the coolant will return to after becoming hotter due to being stuck in traffic, etc. ). The basic cooling system in M96 equipped cars has more heat transfer capacity (coolant to the ambient air) than the car actually needs; other wise the car would not cool back down after being stuck in traffic, or when the fans kick in. If the radiators controlled the minimum operating temperature of the system, there would simply be no need for any type of thermostatic control.

The addition of a third radiator aid in the rate at which this cooling takes place by adding more capacity, but there is already more than enough capacity built into the car without the third radiator to accomplish it, albeit over a longer period of time. In a race car, because of the uneven demands being placed upon the engine and cooling systems, cooling rates are as critical as total capacity. On street cars using the LN stat, those with two radiators took longer to cool back down than those with the third unit, but both cooled back to the same baseline temps in the mid to upper 170's, while OEM stat cars came back to a 205-210 baseline. This is the "throttling" effect of the stat……

Edited April 3, 2010 by JFP in PA

[ALLSPEED]

Good input from everyone. I like it. The minimum temp. was the benefit I was curious about and JFP touched on that. Someone correct me if I'm wrong but if the car has sufficient cooling adding a 160F stat would possibly lower normal operating temp. I realize this depends on ambient temp., load, etc. but in an ideal condition. MORE INPUT APPRECIATED.

Edited April 3, 2010 by ALLSPEED

[Steve Tinker]

As a practical side to this discussion, I fitted the low temp thermostat last year and it has now completed a sub tropical summer and winter in Australia. Our temps are similar to Florida.

I replaced the coolant and thermostat together on my 2001 Boxster S which has the 3rd radiator & larger heat exchanger as standard. What I have found is that my front mounted cooling fans come on less and for shorter periods and I have only heard my engine compartment fan come on once since the thermostat changeout.

So not only does the oil get an easier life, but the cooling fans have it better too.

But note that in heavy traffic, the temperature gauge goes up and indicates the same as before the changeout (after all, a fully open themostat is a fully open thermostat), but on the open road the temp gauge now runs exactly at the 180 tick mark, where prevously it ran well above the tick.

[Stefan]

I agree with the above commentary that suggests the 160 degree thermostat is ineffectual. It would be nearly impossible to perform a controlled experiment that demonstrates that it is effective as there are too many variables that cannot be controlled. I think everyone is in agreement that it won't prevent your car from overheating as the stock thermostat opens fully before that happens.

Additionally, note that the 160 degree thermostat makes the car take longer to warm up which decreases fuel economy and increases emissions.

The moral of the story is that if your car is running at normal operating temps, the stock thermostat is fully open and you're getting 100% of the benefit that at 160 degree thermostat would give with none of the ill effects.

The rhetoric that suggests the stock thermostat doesn't actually open when it is supposed to is based on similarly uncontrolled experiments, whose results are worse than incorrect, they are misleading.

Save your money on the thermostat install and instead take your lady out to a nice dinner. You'll get more mileage that way.

Edited April 4, 2010 by Stefan

[JFP in PA]

I agree with the above commentary that suggests the 160 degree thermostat is ineffectual. It would be nearly impossible to perform a controlled experiment that demonstrates that it is effective as there are too many variables that cannot be controlled. I think everyone is in agreement that it won't prevent your car from overheating as the stock thermostat opens fully before that happens.

Additionally, note that the 160 degree thermostat makes the car take longer to warm up which decreases fuel economy and increases emissions.

The moral of the story is that if your car is running at normal operating temps, the stock thermostat is fully open and you're getting 100% of the benefit that at 160 degree thermostat would give with none of the ill effects.

The rhetoric that suggests the stock thermostat doesn't actually open when it is supposed to is based on similarly uncontrolled experiments, whose results are worse than incorrect, they are misleading.

Save your money on the thermostat install and instead take your lady out to a nice dinner. You'll get more mileage that way.

OK Stefan, let's go take the "rhetoric" item by item....................

"I agree with the above commentary that suggests the 160 degree thermostat is ineffectual. It would be nearly impossible to perform a controlled experiment that demonstrates that it is effective as there are too many variables that cannot be controlled. I think everyone is in agreement that it won't prevent your car from overheating as the stock thermostat opens fully before that happens."

We employed commercially available data loggers, which were left in the test cars for periods ranging from five days to two weeks in order to observe how the vehicle's baseline temperatures responded in "real world" driving conditions. And, no one ever implied that a cooler thermostat was going to prevent a vehicle from overheating; only that it would run at a cooler baseline temperature, which it does when using the 160F stat.....................

"The rhetoric that suggests the stock thermostat doesn't actually open when it is supposed to is based on similarly uncontrolled experiments, whose results are worse than incorrect, they are misleading."

Not really true. To collect information on when the stats begin to open and are fully open, we employed a laboratory magnetic stirring hot plate and four liter glass beaker for our bench tests. The hot plate has a calibrated rheostat to control the rate of heating, and an independent speed controller for the stirrer to assure constant water movement. The test thermostats (all brand new) were all suspended midway down by a wire to prevent any uneven heating effects. Each type of thermostat was tested four times, and allowed to cool to ambient temperature before subsequent tests. Each test was begun with fresh tap water that exhibited a temperature of 52-54F (measured by a digital read out thermometer with its sensor tip at the depth of the middle of the thermostat in the beaker). The stirrer was turned up to a setting of "50", and the heat was then turned on with the rheostat set to "60% power". Temperatures were observed when the thermostat first began to open, noted as a gap appearing between the center plunger section and the outer housing, and when the center plunger stopped moving and was fully open. Because of the experimental design, the rate of temperature rise allowed multiple observers to independently note the start and cessation of plunger movement, as well as the temperatures. These observations agreed within 1-2 degrees. The results are as previously summarized in early posts.......................

"Additionally, note that the 160 degree thermostat makes the car take longer to warm up which decreases fuel economy and increases emissions."

Interestingly, as far as warm up, just the opposite seems to occur. The M96 is factory equipped with some coolant by-pass flow capability, which helps provide of heater output well before the thermostat actually starts to open. Because the 160F stat starts to open, and is fully open at a low temperatures, several owners have commented that they feel the car is warming up "more quickly", most likely a perception triggered either by warmer air coming from the heater sooner, or because they see movement in the dash gauge earlier. When the manufacture was asked about this observation, they confirmed that "It is a normal observation" for the 160F stat to be observed as warming up to running temps more quickly due to increased warm water flowing sooner. Unfortunately, because the "warm up rate" perception rests with the car owner, it has not been independently or experimentally confirmed, but has been noted by multiple owners.

As for emission, as mentioned previously, I operate in a state were "sniffer" emissions testing is common. To date, none of the cars, my own included, has demonstrated any problems passing state emissions testing. While I have only seen some of the actual test values (we are not licensed to provide emissions testing), but from what I have seen, there does not appear to be any significant change in the values (HC, CO, and NO in this state) before and after moving to the cooler stat, so there does not appear to be any detrimental impact on emissions. And, again as noted previously, owners (myself included) have observed slight (2-4MPG) increases in fuel economy durng longer trips; which have not been evaluated experimentally due to significant variances in driving styles, road types, weather differences, etc., etc

Now, if you have either experimentally sound, or even significant empirical data that supports another perspective, I for one, am always open to listening and trying to learn something new...... But, in any case, have a nice Easter..................

Edited April 4, 2010 by JFP in PA

[Stefan]

data loggers, which were left in the test cars for periods ranging from five days to two weeks in order to observe how the vehicle's baseline temperatures responded in "real world" driving conditions

The issue with this test is that you are comparing the data collected with likely relevant differences (external temp, humidity, barometric pressure) in driving conditions. Additionally, it is a normal phenomenon for people with recently modded cars to drive differently to "test" out the mod and that itself skews results.

no one ever implied that a cooler thermostat was going to prevent a vehicle from overheating

That is true. I just wanted to point out to the casual observer that if their car tends to run hot, this part won't do anything to remedy that.

we employed a laboratory magnetic stirring hot plate and four liter glass beaker for our bench tests

Ironically, this test fails to determine the truth almost for the opposite reason the first one does: by eliminating possibly relevant variables found in real-world testing you also invalidate the test results. Such relevant variables are difficult to predict but they could possibly include non-uniformity of heating of coolant or the part itself, other external forces, vibration, turbulence in the fluid flow, etc.

several owners have commented that they feel the car is warming up "more quickly"

While this is interesting, the reports of biased people cannot be used as reliable scientific evidence.

the manufacture was asked about this observation, they confirmed that "It is a normal observation" for the 160F stat to be observed as warming up to running temps more quickly due to increased warm water flowing sooner

I'd like to hear more about the theory of why it would warm up more quickly. Increasing the cooling capacity of the system earlier should dissipate more heat early, which should cause the temperature to rise more slowly.

none of the cars, my own included, has demonstrated any problems passing state emissions testing

State emissions tests are done at full operating temperature at which time the 160 deg thermostat performs identically to the stock thermostat. So this does not surprise me. It is during warmup I am suggesting the emission will be higher.

---

What this all amounts to is that it is really tricky business to design a test that gives meaningful results. Trained scientists make errors doing this all of the time. That is why we read that X causes cancer then later that X prevents cancer. While I appreciate carefully thought out experiments I just do not see the above as demonstrative of a benefit.

Edited April 5, 2010 by Stefan

[JFP in PA]

"data loggers, which were left in the test cars for periods ranging from five days to two weeks in order to observe how the vehicle's baseline temperatures responded in "real world" driving conditions

The issue with this test is that you are comparing the data collected with likely relevant differences (external temp, humidity, barometric pressure) in driving conditions. Additionally, it is a normal phenomenon for people with recently modded cars to drive differently to "test" out the mod and that itself skews results."

Unfortunately, you and I totally disagree on one blatantly obvious contradiction to your position: If a car consistently demonstrates a baseline operational temperature of 175-177F with one type of thermostat, and 205-210F with the other; over multiple drivers, driving conditions, weather patterns and across a protracted time frame, one of the thermostats is letting the car run at a cooler baseline temperature. Somehow, I still find that point inescapable.

"we employed a laboratory magnetic stirring hot plate and four liter glass beaker for our bench tests

Ironically, this test fails to determine the truth almost for the opposite reason the first one does: by eliminating possibly relevant variables found in real-world testing you also invalidate the test results. Such relevant variables are difficult to predict but they could possibly include non-uniformity of heating of coolant or the part itself, other external forces, vibration, turbulence in the fluid flow, etc."

You originally questioned the validity ("The rhetoric that suggests the stock thermostat doesn't actually open when it is supposed to is based on similarly uncontrolled experiments, whose results are worse than incorrect, they are misleading.") of how the opening points and full open temperatures were determined; yet when I provide you with a precisely controlled bench experiment, designed to remove any complicating outside influences, you question those results simply because they constitute the controlled environment you said was lacking. Stefan, you can't have it both way, unless of course your object is to create an endlessly circular argument that can never reach any conclusion……………. And, by-the-by, the method used exactly parallels the procedures that have been used for about 50 year to determine the opening temperatures for automotive thermostats………hardly what I would describe as "misleading".

"the manufacture was asked about this observation, they confirmed that "It is a normal observation" for the 160F stat to be observed as warming up to running temps more quickly due to increased warm water flowing sooner

I'd like to hear more about the theory of why it would warm up more quickly. Increasing the cooling capacity of the system earlier should dissipate more heat early, which should cause the temperature to rise more slowly."

You misinterpret what was described. The perception is that the cars warm up more quickly, probably due to earlier observed movement of the dash gauge and greater heater output. But this is a perception, not an experimentally confirmed fact. The dash display is well known for its lack of accuracy and linearity, so even using two cars and stopwatches to try and measure the difference in gauge movement is questionable, which is why it was described as a perception, not a fact.

Again, the thermostat does not alter the capacity of the cooling system; it alters the minimum baseline temperature at which the engine will return to under equivalent circumstances.

"none of the cars, my own included, has demonstrated any problems passing state emissions testing

State emissions tests are done at full operating temperature at which time the 160 deg thermostat performs identically to the stock thermostat. So this does not surprise me. It is during warm-up I am suggesting the emission will be higher."

I have no idea what the emissions levels are during warm up for any vehicle, but then I do not believe the testing authorities do either, or would trust such data points as particularly meaningful. From my understanding of EPA and state testing methodology, which appear to mandate emissions testing under the conditions at which vehicle will spend most of its operational life span, namely full operating temperatures, I would say that comparing "sniffer" results is both appropriate and valid.

"What this all amounts to is that it is really tricky business to design a test that gives meaningful results. Trained scientists make errors doing this all of the time. That is why we read that X causes cancer then later that X prevents cancer. While I appreciate carefully thought out experiments I just do not see the above as demonstrative of a benefit."

Stefan, why don't we just agree that we disagree on this topic? At this juncture, I do not see any form of experimental testing or empirical observations that would dissuade you from your opinion………….

[Stefan]

The one thing we do agree on is that we disagree.

For those who don't want to slog through the entire post, I will summarize my position:

This device is worse than stock and the vendors have concocted invalid, biased, experiments that mislead people into believing that it benefits them. It attempts to solve a non-existent problem and offers no real-life benefit other than to lighten your wallet.

The whole thing reminds me of monster cable for which nobody has claimed a longstanding independently offered $1 million reward to prove its superiority.

Caveat emptor.

[JFP in PA]

The one thing we do agree on is that we disagree.

For those who don't want to slog through the entire post, I will summarize my position:

This device is worse than stock and the vendors have concocted invalid, biased, experiments that mislead people into believing that it benefits them. It attempts to solve a non-existent problem and offers no real-life benefit other than to lighten your wallet.

The whole thing reminds me of monster cable for which nobody has claimed a longstanding independently offered $1 million reward to prove its superiority.

Caveat emptor.

If that is the case, they should also know that I am not the vendor for this product, but a satisfied customer that has personally observed its benefits, as have many of my shop's customers………………….

[Cefalu]

So why isn't anyone discussing the radiator fans involvement here? While the thermostat regulates the minimum temperature coolant parameter, the cooling fans regulate the maximum temperature parameter, which is what most people are concerned with.

The coolant temp sensor signals low speed fan operation to begin at 206 deg F. and high speed is triggerd at 216 deg F.

With inadaquate airflow over the radiators like you would experience in slow traffic or worse yet a smog test, both thermoststs will be fully open and dependant on fan airflow to control engine temperature.

Have you ever had your electric fan fail? I have. Even on a cool San Francisco winter morning, you won't last 5 to 10 minutes in traffic with a failed electric fan before your coolant temp light goes on.

However, if you were not stuck in traffic and you were moving along with sufficient airflow over the radiators, the 160 deg F thermostat would lower engine coolant temperatures below the stock thermostat. And that bothers me. I would rather see my motor have a consistent coolant temperature than one that swings from 170 to 216. Is that wide band good for the motor?

In my opinion the only way the 160 deg thermostat can be helpful is if the fan sensor temps are changed to signal operation at lower temperatures. But new sensors are just part of the solution, you also need that 3rd radiator, otherwise the fans will be on all the time leading to premature fan wear or worse, potential fan failure.

So what is really needed is a kit that includes a reduced temp thermostat, new coolant temp sensors that operate at lower coolant temperatures and a 3rd radiator to reduce the load on the cooling fans.