Modified Thermostat for higher MPG's...

[Mako]

Hottter engine temperature. Less cumbustion heat (Energy) is lost to a hotter cylinder wall and head, therefore greater economy.

Blue Tec range use higher temp "ThermoT" to increase fuel temperature. I think it's 60C as opposed to 30C.

 

[Scott_DeWitt]

would this mod work on a 09 CR and would it benifit me? also is there anyone out there that has tried it on a CR?

About the only advantage to Evans coolant (propylene Glycol) is that it operates at atmospheric pressure. It's coefficient of heat transfer is less than water/ethylene glycol and it's flammable, which is why many automotive sanctioning bodies will not allow vehicles to participate in events running Evans coolant and why OEM's don't use it.

Now a days factory cooling systems are well designed even at 2-3X the rated horsepower so any benefit of a cooling fluid change probably won't be realized.

 

[G3TDI]

Evans coolant is certainly a good fluid for heat transfer but it's highly flammable and explosive under the right conditions, one reason why OEM's have not used it..

My understanding about "highly flammable" is: "Highly Flammable liquid: A liquid that has a flash point of less than 21°C. Class IA flammable liquids have a flash point below 73 °F and a boiling point below 100 °F"

With that it's not "highly" flammable.

I can also find claims that "traditional" 50/50 coolant mix could be flammable, though I personally have doubts about that one.

 

[G3TDI]

About the only advantage to Evans coolant (propylene Glycol) is that it operates at atmospheric pressure. It's coefficient of heat transfer is less than water/ethylene glycol and it's flammable, which is why many automotive sanctioning bodies will not allow vehicles to participate in events running Evans coolant and why OEM's don't use it.

I guess you edited your post after I clicked quote but before I clicked submit got pre-occupied

In this context it has the benefit of higher boiling point, and I personally prefer the no/almost no pressure in the system.

Now a days factory cooling systems are well designed even at 2-3X the rated horsepower so any benefit of a cooling fluid change probably won't be realized.

I am not sure I follow what you are referring to here, but this whole thread is about improving fuel consumption with higher coolant temps (this is a fairly well established fact) and in conjunction with doing so (raising the temps) re-creating the same or increasing the margin between operating temp & boiling temp, as for that purpose EVANS works great IMHO.

Now yes I will not debate on the pros and cons, as with anything, when we alter our vehicles we are gaining something but loosing something else.

One concern I personally had, and still am not convinced this or that way is the viscosity difference of EVANS vs other traditional coolants.

One book I found interesting on all this is this book:
http://books.google.com/books/about/Engine_Cooling_Systems_HP1425.html?id=06TgJ1j119IC

http://www.amazon.com/Engine-Cooling-Systems-HP1425-Performance-ebook/dp/B002VRZPDC

 

[Tom W.]

50/50 water/conventional antifreeze will burn. I got into an argument w a local TDI guru about this, he said a diesel engine could experience runaway via water/antifreeze. he grabbed a pan he had drained some antifreeze/water into and set it on fire. case closed. I lost the argument.

 

[Tom W.]

An internal engine is a heat engine. Any time you can safely retain heat instead of loosing it (exhaust, cooling system, etc) you will improve the efficiency and therefore improve your MPG.
http://www.rtugroup.com/revolutionary-technologies/pseudo-adiabatic-technology

http://www.hotrod.com/techarticles/engine/hrdp_1009_what_ever_happened_to_smokeys_hot_vapor_engine/

https://www.sof.or.jp/en/activities/pdf/06_07.pdf

http://www.elsbett.com/gb/elsbett-diesel-technology/elsbett-piston.html

 

[josh8loop]

I've been running the higher temp gasser stat for over a year, I see 201-219 on scan gauge.
I've been killing fan control modules (3rd one now) in such a matter that the A/C compressor does not run anymore. I'm not in anyway sure that my electrical failures are related to coolant temps, or my swap wiring, dealer servicing until I owned it, or just a VW thing.
I'm just posting here to see if anyone else has similar issues.

I ended up disabling my fans for stage 1 since I wanted my engine temps to run in that range. Here are those temperatures for the ALH anyway:

Stage 1
Switch on .......................197-206 deg F(92-97 DegC)
Switch off........................183-195 deg F(84-91 Deg C)

Stage 2
Switch on ........................210-221 Deg F(99-105 Deg C)
Switch off.........................195-208 Deg F(91-98 Deg C)






The only thing that operates my fan is Stage II and the AC system when it's turned on. I could imagine with a fully functional fan stage 1 and your higher temp T-stat your fan would be essentially fighting what the higher temp T-stat would be wanting to do. Maybe the increased On-time of your fan is contributing to the premature FCM failure?

 

[dremd]

I ended up disabling my fans for stage 1 since I wanted my engine temps to run in that range. Here are those temperatures for the ALH anyway:

Stage 1
Switch on .......................197-206 deg F(92-97 DegC)
Switch off........................183-195 deg F(84-91 Deg C)

Stage 2
Switch on ........................210-221 Deg F(99-105 Deg C)
Switch off.........................195-208 Deg F(91-98 Deg C)

Thanks for the reply.
I found the source of my FCM failures.
My drivers side fan draws 37 amps on high, which is just low enough to not blow the fuse, but high enough to bake the FCM.
As a temporary fix I cut the wire to the high speed.
My fans / radiator are still 1.8t so I'm going to have to sort out my options.

 

[SilverGhost]

Hmm, thanks for that insight. That might explain why I noticed the fans running for a few moments after I stop. Never used to do that before I put the higher temp thermostat in.

Jason


Sent from my iPhone

 

[Kristofk]

Anyone have any intermittent problems with warming up time?

Now, I may have flexed the smaller spring a little bit by handling the thing and positioning it correctly.

So, couple miles out going up a hill constant speed/load (50 mph) and wouldnt warm up, then barely warmed up later when I came to a stop at a fuel station. Although it was a cool day, it took a lot longer to warm up than my 192F thermostat. On hotter days, stop and go in the city, warms up normally.

Could be airflow to radiator not letting it warm up? Anyway, Ill check again next week, and report back. <-duh, always airflow. nevermind. must be the thermostat, but how?

 

[Jesse_Boyer]

My experience thus far:
.
First car, 2001 5sp:
Thermostat built per this thread's recommendations and I noted upwards of 212-214°F via a knockoff Scangauge. I figured this was appropriate as the temp leaving the head would be 8-10F higher than the thermostat controlled temperature (allegedly 205°F.) I do not have a before temperature, unfortunatley. Poor documentation on my part. If I'm not mistaken, the temperature reported was from the temp sensor on the back of the head which should be the same temperature reported via VCDS. More on this later. Regarding MPG's, I'd say it improved a bit, but I don't remember right off hand. Again, poor documentation on my part.
.
Second car, my '02 Wagon 5sp:
I just built the 'stat two nights ago and the height is virtually the same as the stock 'stat; 32mm +/- 0.5mm via my caliper. While the gauge reads 190°F (realizing its an idiot gauge and will read 190°F from ~167°F to 217°F,) VCDS gives an entirely different reading... upwards of 110°C. Yes, upwards of 230°F. I pulled over, checked the rad hose connected to the stat to see if there was ANY water flowing and it did feel slightly warm. Note, the water leaving the head is 230°F, but the water leaving the radiator would be FAR cooler (it was around 55°F ambient.) Thus, slightly warm would be appropriate (to me.) If this 230°F is accurate, I would assume even the idiot gauge would indicate a greater temperature than 190°F.
.
I pulled the stat again last night and watched it open in a pot of water VERY close to 205°F. Thus, its working as expected; maintaining 205°F at the thermostat. However, I did change to a different water temp sensor to see if there was an error of any kind. (I'll report back after I get a little more time to drive at a steady-state down the road.)
.
Regardless, if this isn't the warmest anyone has run an ALH head, I'd be shocked (if the temperature reported by the original temp sensor and my spare, knock-off temp sensor is correct.)

 

[79TA7.6]

I am assuming you have a thermometer since you were able to determine when the t-stat opened in the pot of water. Use this thermometer in the overflow bottle and see what temp is there. Of course it will be different than what VCDS will read, but it should not be 25° different.

 

[josh8loop]

My experience thus far:
.
First car, 2001 5sp:
Thermostat built per this thread's recommendations and I noted upwards of 212-214°F via a knockoff Scangauge. I figured this was appropriate as the temp leaving the head would be 8-10F higher than the thermostat controlled temperature (allegedly 205°F.) I do not have a before temperature, unfortunatley. Poor documentation on my part. If I'm not mistaken, the temperature reported was from the temp sensor on the back of the head which should be the same temperature reported via VCDS. More on this later. Regarding MPG's, I'd say it improved a bit, but I don't remember right off hand. Again, poor documentation on my part.
.
Second car, my '02 Wagon 5sp:
I just built the 'stat two nights ago and the height is virtually the same as the stock 'stat; 32mm +/- 0.5mm via my caliper. While the gauge reads 190°F (realizing its an idiot gauge and will read 190°F from ~167°F to 217°F,) VCDS gives an entirely different reading... upwards of 110°C. Yes, upwards of 230°F. I pulled over, checked the rad hose connected to the stat to see if there was ANY water flowing and it did feel slightly warm. Note, the water leaving the head is 230°F, but the water leaving the radiator would be FAR cooler (it was around 55°F ambient.) Thus, slightly warm would be appropriate (to me.) If this 230°F is accurate, I would assume even the idiot gauge would indicate a greater temperature than 190°F.
.
I pulled the stat again last night and watched it open in a pot of water VERY close to 205°F. Thus, its working as expected; maintaining 205°F at the thermostat. However, I did change to a different water temp sensor to see if there was an error of any kind. (I'll report back after I get a little more time to drive at a steady-state down the road.)
.
Regardless, if this isn't the warmest anyone has run an ALH head, I'd be shocked (if the temperature reported by the original temp sensor and my spare, knock-off temp sensor is correct.)

This is not the first time we have had reports of inconsistency from unit to unit. I have heard of the 234 Deg F before and it was posted about in the preceding pages. That seems like too high a temperature to me. Mine ranged from 205-214 IIRC. Could be a result of temperature differences between thermostat to thermostat and have nothing to do with the assembly process itself. If a guy were going to experiment with this it might be prudent to buy a couple 205 thermostats and choose the one that gives the most acceptable temperatures or find a way to achieve the same results with a higher initial quality thermostat(Behr or other OEM brand for instance). Glad to see that you seem to think you gained FE on your first build-your results tract along with what I have experienced with mine.


One thing I wanted to mention is that the ALH temperature probe has two different temperature elements contained within. One I believe goes to the cluster, and the other goes to the ECU etc. One of the two could be bad or just off a bit. Would be worth replacing the temp sensor before experimenting with temperature modification just for piece of mind if the temperature sensor is on the older side. BTW the temp sensor reads the temperature of the coolant leaving the head so it should read the max outlet coolant temps.

 

[Jesse_Boyer]

Agree on all of the above. I might find another 205F 'stat, but that unit is technically performing as its designed. I verified it starts to open very near 205F, which is does. Taking a pot of water and observing the thermostat open while very, very slowly increasing the temperature seems like the most logical way of proving the functionality. For what its worth, my two stock, OEM thermostats both seem to open near 85°C and are rated for 87°C.

I swapped the temperature sensor and will attempt to check it tonight at highway speed. I intend to check the probe's accuracy with an IR temp gun (provided I can find it.) If the second sensor reads the same as the first and both match the IR, upwards of 110°C, I'm likely to find another option. Perhaps the 195°F will suffice.

 

[josh8loop]

Since our ALH's regulate temperature on the inlet side of the water pump it is a fair assumption that what ever thermostat initial actuation temperature plus 10 deg F would be representative of the actual engine operating temperature. I just revisited a video I made of a 195 Deg F stock thermostat and it initially began travel at around 205 degrees-that temperature plus 10 degrees gives my actual operating temperatures which is what I have witnessed. Perhaps the guys building this "Hybrid" T-stat should pre-select the 205 thermostat based on some travel vs. temperature experimentation to ensure that a proper operating temperature is reached?

I would do this with a digital thermometer and a dial indicator based fixture like I did in my video. Would be a good idea to thermocycle the prospective thermostats a half dozen times to break it in a bit as well.

I should also mention that the thermostats I tested have quite a bit of hysteresis meaning that stroke length vs temperature for increasing thermostat temperatures are not the same for stroke length vs temperature for decreasing thermostat temperatures. I also notice that it takes a higher initial thermostat temperature spike to get initial movement and after that it seems to be well behaved.

 

[Jesse_Boyer]

I just revisited a video I made of a 195 Deg F stock thermostat and it initially began travel at around 205 degrees

This is strange to me. The 'stats I've tested have moved very close to the rated temperature, not +10°F of the rated temperature.

 

[Jesse_Boyer]

update: I swapped to another temp sensor (new VW) and read roughly the same temps; 107°C at the head. The first OEM read as high as 109.8C and the chinese unit read just 104C (I had all of them but the new one, so not a great deal of expense to mess around.) For the record, the chinese unit read incorrectly at the gauge as well and did not indicate 190F as it should. Its junk and its in the trash.

Essentially, I've chickened out with my really high 'stat for now. While I heated it a pot of water and I can see the 'stat start to open around 95C, the water picks up nearly 15C by the time it leaves the head. I may switch back later, but I have a family road trip this weekend and I don't feel like worrying about the experiment the entire time.

 

[G3TDI]

update: I swapped to another temp sensor (new VW) and read roughly the same temps; 107°C at the head. The first OEM read as high as 109.8C and the chinese unit read just 104C (I had all of them but the new one, so not a great deal of expense to mess around.) For the record, the chinese unit read incorrectly at the gauge as well and did not indicate 190F as it should. Its junk and its in the trash.

Essentially, I've chickened out with my really high 'stat for now. While I heated it a pot of water and I can see the 'stat start to open around 95C, the water picks up nearly 15C by the time it leaves the head. I may switch back later, but I have a family road trip this weekend and I don't feel like worrying about the experiment the entire time.

I wouldn't be too concerned, I see anything between 105-108c on a regular basis with my scan gauge, a little while ago upon crossing a little pass at around 1800ft I had this:

No issues yet, granted this is a fully rebuilt engine bored and head studs etc so yeah everything is fresh *AND* I am running EVANS COOLANT!

P.S. Ignore the IQ message just a glitch in the BETA VCDS mobile...

 

[Jesse_Boyer]

well that's toasty-warm.

I may get adventurous later

 

[G3TDI]

well that's toasty-warm.

I may get adventurous later

But like I said this is the coolant I am using (so no water in my system):

http://www.evanscooling.com/products/high-performance-coolant/

 

[SkeeterMark]

But like I said this is the coolant I am using (so no water in my system):

http://www.evanscooling.com/products/npg

Curious why you would use that.

 

[G3TDI]

Curious why you would use that.

Well I read a lot about the coolant (and learned a lot) as to why we use water in our cooling systems for instance. Two reasons cheap and relatively abundantly available.

Now why do we have the system pressurized? The only reason is to raise the boiling point of the coolant/water mix, so this in itself told me this was a compromise in order to be able to use water in there.

I was extremely skeptical to this stuff first off, as I am to most "magical" auto chemicals , but the more I read the more it made sense.

So for my personal application I wanted it due to these benefits:

"Evans Waterless Coolants have a boiling point above 375°F and will not vaporize, thus eliminating overheating, boil-over and after-boil."

Now the no pressure in the system is just an added plus if you ask me. Not that you should (need to) open your coolant system when it's hot but I can with this stuff at any time. I also personally believe (totally subjectively yes) that my coolant components might last longer as they don't have to operate under pressure at all times.

I ran across the info about it through Leno's Youtube channel first off:

http://youtu.be/t7PykrgzWPQ

http://youtu.be/KRLXKW2ph0w

Yes those are indeed as much commercials as they are anything else so take it that into account!

 

[SkeeterMark]

I ask because their site says it's not for daily driving. Do you have an odd application for your vehicle, or just figure if it's good for racing, etc., it would be good for a regular car (for the reasons you listed)?

 

[G3TDI]

I ask because their site says it's not for daily driving. Do you have an odd application for your vehicle, or just figure if it's good for racing, etc., it would be good for a regular car (for the reasons you listed)?

Well my goal is best possible MPGs:
http://forums.tdiclub.com/showthread.php?t=305898

Yes it is a daily driver but with plenty of "features" most would not want in their daily driver, such as really NO interior whatsoever aside from front seats and top part of the dash.

I am surprised they would say it's not for daily driving? Maybe because of the cost of using it, since you should flush your system with their special liquid and then use it (and it's not cheap either) but since my engine had been a part for like 2 yrs when I finally assembled it and I decided to use all new coolant hoses and radiator and coolant bottle and water pump I never bothered to flush anything, there wasn't a drop of anything in any of my system anymore anyhow.

One more thing this is the exact stuff I am using (can't seem to locate it on their website any more!?)

[EDIT] seems like they replaced what I use with this stuff
http://www.evanscooling.com/products/high-performance-coolant/
Earlier link was NOT correct, sorry about that! Was just going by the "NPG+" name that's on my container.

(yes blatantly hijacked pic)

 

[SD26]

One more thing this is the exact stuff I am using (can't seem to locate it on their website any more!?)

[EDIT] seems like they replaced what I use with this stuff
http://www.evanscooling.com/products/high-performance-coolant/
Earlier link was NOT correct, sorry about that! Was just going by the "NPG+" name that's on my container.

I was gonna ask you about that...

I've got NPG+, which has the new name now, in all of my vehicles: a motorcycle, a gas car, two TDI's. Haven't gotten it into my Ford 6.0PSD van yet as I haven't had the time and I need to install my coolant filter.

Works fine in street applications. Some of the other advantages...if it does freeze, it contracts rather than expands. If you have a leak in the cooling system, it doesn't have the expansion of a regular coolant...so, when you're on a long trip trying to get home with an irritating pinhole leak someplace, one can open the degas bottle cap and operate under zero pressure (there is a little air that wants to expand too) while cooling and reducing the leak to a dribble or maybe eliminating it for that time. Regardless, you get home. Experienced this a couple of times in my Ford bus pulling an enclosed auto hauler over long distances.

 

[Tom W.]

I've used Evan's in various vehicles since 1996. All daily drivers. The high boiling point and no pressure features have saved a couple cars from overheating. Also because there is no water, there is no corrosion in the system. Plus you don't need to change out the coolant. Ever.
I finally sold my 1996 Chevy Astro last year, had 236,000 miles on it. Still had the original Evans in it.

 

[nick-w]

Temperature is not holding steady

I tried to read through as much of this form as I could its so long. I just installed my hybrid thermostat part number 13379 and 13352. Came apart and went together easy.
But I'm having temperature fluctuations, takes a long time to get up to temperature once it's in 190 if I go down a hill goes down to 150.driving over a long hill I got temperatures of 220 then coasting down the other side back in the hundreds.
Is anyone else having the same trouble temperatures going up and down? I have Vcds but I'm just reading the temperature with scan gauge when driving.

 

[aNUT]

I ran Evans coolant & a Wahler 92C t-stat in my ALH a while back. Result was 12 cracks in the head in about 30K miles. Do not recommend. Replaced head, been running 87C & G012/13 coolant w/ zero issues for 50K.

 

[nicklockard]

I've been searching for a hotter thermostat for my wife's Merc' E430 with no luck at all. Stock is 80C. I think we could squeek out better mpg with a 90 C. Any ideas?

 

[SD26]

I ran Evans coolant & a Wahler 92C t-stat in my ALH a while back. Result was 12 cracks in the head in about 30K miles. Do not recommend.

That's interesting.

I have more miles than that individually on two ALH's with no issues. I've also used Evans and a hotter thermostat on two 7.3PSD's with no issues.

I'd think you have another issue that caused the cracks or is was a bad head in the first place.

.