high temperature coolant systems

[zyewdall]

Has anyone ever tried the waterless coolant systems in the VW diesels?  It seems like it is targeted mostly at semi trucks, but I was wondering if would increase the efficiency of the smaller ones (without causing any sort of undue harm). It seems that the gist of the idea is to use straight propylene glycol to give a much higher boiling point, and therefore allow a high temperature thermostat to be used without increasing coolant system pressure and cavitation problems.  The higher operating temperature in turn gives better efficiency.  Someone quoted a change from 6.5mpg to 7.5mpg.  If a rabbit got the same percentage improvment, it could go from 45 to 52mpg.

http://www.evanscooling.com/html/NpgPls_D.htm

Any ideas?

Zeke

[ricosuave]

ive thought about using it too, never got past that stage though...

rico

[Northern RD]

Has anyone ever tried the waterless coolant systems in the VW diesels?  It seems like it is targeted mostly at semi trucks, but I was wondering if would increase the efficiency of the smaller ones (without causing any sort of undue harm). It seems that the gist of the idea is to use straight propylene glycol to give a much higher boiling point, and therefore allow a high temperature thermostat to be used without increasing coolant system pressure and cavitation problems.  The higher operating temperature in turn gives better efficiency.  Someone quoted a change from 6.5mpg to 7.5mpg.  If a rabbit got the same percentage improvment, it could go from 45 to 52mpg.

http://www.evanscooling.com/html/NpgPls_D.htm

Any ideas?

I used Evens stuff in my Fox in South Afrika while living there(the equivalent here is the A1 Jetta) and even wit the temps in the mid to high 30`s celsius outside i never had a boil over even after flogging the engine.
 I use it currently in my `83 Jetta and RZ 350 race bike, works great.    

Zeke

[Northern RD]

Well, the first thing to understand is that VW diesels aren't subject to cavitation, that only occurs on wet sleeve engines.

My understanding has always been that no coolant transfers heat more efficiently than water, and that the lower percentage of coolant in the system, the better the heat transfer. Customary wisdom is to use as little antifreeze/coolant as needed to prevent freezing in the climate in which the vehicle is operated.

VW diesels are very susceptable to cooling system temperature. Changing from a 180°F thermostat to a 160°F will impact fuel mileage noticibly. A defective thermostat which never allows the coolant to reach operating temperature can halve fuel mileage.

In fact the sort cavitation referred to above has nothing to with wet or dry liner engines but rather to the coolant circulating through the engine. As the coolant circulates it passes by localized hot spots, boils, and injects gas bubbles into the coolant. Inasmuch as gas is less efficiant than liquid when it comes to transferring heat, then engines` overall ability to shed heat is reduced and the inevitable boil over results. The early ABA-into-the-A1 swaps were bad for this, particularily as regaurds the coolant paasssages in the head. There was also a series of articles in Europian car called "Lurching to Success' dealt with this in detail.

[zyewdall]

I used Evens stuff in my Fox in South Afrika while living there(the equivalent here is the A1 Jetta) and even wit the temps in the mid to high 30`s celsius outside i never had a boil over even after flogging the engine.
 I use it currently in my `83 Jetta and RZ 350 race bike, works great.    

Do you run the stock thermostat, or use a higher temperature thermostat like the semi's do with this?

[Northern RD]

Never had any luck with aftermarket thermostats so I went with the stock item from VW. I should point out that this car had a 1.6L gas engine.
In addition the coolant system was air tight becouse the Evens stuff IS flamable,...

[ricosuave]

so, how do you get it in there, and how do you get the air out?

[Northern RD]

so, how do you get it in there, and how do you get the air out?

A poor choice of words on my part: I just meant that the coolant system has to be absolutly leak free as the stuff from Evens is flamable. If it were to hit say, the exhaust manfold, it would likly catch fire.
As for purging the system of air, that`s an intresting question. The Bentley A1 and A2 manuals make no mention of getting air out of the coolant system, while the Bentley manual for the Fox spends several paragraphs on the procedure. I`ve never received a satisfactory answer for that one,... :?  :?  :?

[ricosuave]

well, i still think i will help.

id be interested in hearing if anyone else has used it in a diesel application first though

[zyewdall]

well, i still think i will help.

id be interested in hearing if anyone else has used it in a diesel application first though

You mean in a VW diesel application.  Semi trucks are diesels too