The easiest way to reduce oil viscosity at the critical spot...the bore walls where the piston rings are rubbing...is to increase coolant temperature to the 220-280 degree range.

There is another slight MPG benefit in that hot bore walls and cylinder heads don't "leak" as much heat when they are at higher temperatures. Your engine is a pressure machine where the high pressures are generated by the heat of burning fuel in air, so not leaking heat is an efficiency improver as long as you don't break something else.

The Cummins 'Physics of MPG' white paper talks about this briefly.

http://www.cummins.com/na/pdf/en/pro..._Whitepape.pdf

There is a company called "Evans Cooling" that markets a non-water coolant that is mostly propylene glycol and it claims that diesel engines have gained a bit of fuel economy by operating at high temperatures with its coolant.

If you do a Google search you can find that most of the engine manufacturers are trying to develop engines with ceramic components so that they can run at much higher coolant temperatures. Your tax dollars are being spent at the High Temperature Materials Lab at Oak Ridge National lab in TN to develop ceramic engine parts.

One big 'fly in the ointment' for these kind of MPG improvments is the EPA's insistence that NOx pollution be greatly reduced. In general anything that raises peak combustion temperatures also increases NOx. This is why the new Cummins diesels like the 6.7 I6 all must suffer 'water cooled EGR' this model year, which is hurting the MPG to the tune of 5-10%

It is very hard to improve the fuel economy of any engine and not increase NOx....except perhaps for DaimlerChrysler's "pee in the exhaust" system called "Bluetec" that puts urea in as an after treatment.

 

HankL,

Your post is right on all counts. The best thing to do to increase MPG is to ease away from the stoplights, don't make black smoke and keep the freeway speed to 60-70 MPH. I find that I can improve my average MPG by 20% by backing off on the throttle. It sucks, but with diesel @ $3.00/Gal. in CA it makes a big difference in my monthly fuel bill. I pull a long grade at least twice a month towing a chemical, equipment, or race-car trailer, so I am able to keep the injector tips burned clean. My freeway milage (no trailer) will go from 20.2MPG @65 MPH to 16.1MPG @80 MPH at long steady cruse, both ways, hand calc.. On a 600 mile round trip I save $23 by driving @ 65. I save about the same amount of $ if I tow @ 55 instead of @ 65-70(with an eye out for the CHP,also the Radar Detector and CB on). By easing off on the speed, I am saving about $170 per month, based on 3,000 miles per month.

Ralph

 

I think I'd rather spend the 23.00 and have fun driving rather than to have to restrict myself.

 

It's not the money mayfair, its self control.

[IMG]local://upfiles/30416/31769E369D1A485EAFCA4003F2675EAF.jpg[/IMG]

 

I was thinking about slowing down to 65on my trip to family reunion but it would add 2 hours to the trip, 10 hours Vs 12 hours to do 740 miles.

 

At 60 I get 19mpg, if I do 63 I get 17mpg, if I do 65 get 15mpg, and if I do 70 I get 10mpg so I don't really go over 60.

 

Im 80-85 all the time on the Highway. I really dont travel that much but I just cant drive 55 LOL. Seriously, something about driving at 60-65 just seems way too slow to the point that I want to fall asleep. If I kick it up a notch to around 80, all is well. Im not rich by any means but to save $20 its just not worth it to me....

 

ULSD (ultra low sulfur diesel)
is making it extra tough to keep MPG.

You have to find ways to improve MPG about 7% just to stay even.

My brother runs a trucking company using Kenworth T600s with Cat diesels.
He told me the other day that he calculated the 1st Quarter fuel consumption for paying state road taxes and found that his fleet average MPG had fallen about 7% from its usual 6.2 down to 5.8 with the only difference from past quarters being the ULSD fuel.

That also means the EPA has caused everything hauled by a truck to go up in price.

That also means the EPA has caused every diesel truck in the USA to emit 7% more CO2 gas because of a very questionable effort to get rid of a small amount of NOx gas.

 

Wow Hank that's pretty wild !!

Do you think someone with intelligence will take notice to this and react accordingly, or do you think they'll stay the course even though it's rediculious?

 

The problem with them is NOx and soot. the 2007 emissions crap is to get rid of mainly the soot (ulsd, doc, and dpf will help with this) and very little of the NOx (egr, ecm strategies, and pistons to help with this). In 2010 emissions will step up and try to get rid of nearly all the NOx.