To get the most out of a piece of equipment, you need to undertstand how it works. Once you understand that, you can optimize conditions to get what you want.

In reading an earlier coversation, I wondered what role temperature had to play in fuel efficiency in a diesel engine.

A gas engine works best around 180*. It's most efficiant with the lowest intake temp you can get.

But a diesel is a very differant animal, and maybe the same rules don't apply? I'm a scientist at heart, and wanted to design some kind of a test that might get me some answers; or at least some clues.

I had to drive from Ogden, UT, to Colorado Springs, CO, yesterday. That was the perfect oppurtunity. The big trick in any experiment is to normalize as many variables as possible. In this test, terrain, altitude, and vehicle speed (78mph) all remained fairly constant. I was driving east on I-80. I started the first test in Evanston, and ended the third test west of Laramie, where the altitude really starts to climb. The 4th test was heading south on I-25, south of Chayenne - relativly flat terrain and light traffic.

Fuel mileage reported on the overhead display. Previous trips have shown the display to read 0.5mpg over actual calculated mileage. Not totally accurate, but certainly good numbers for comparison.

Truck is bone stock except for Smarty Jr, set to Economy, PoD60. Temps obtained from BullyDog Outlook Monitor.

1. Winter cover on, flaps closed. Air temp 50-55*
2. Winter cover on, flaps open. Air temp 50-55*
3. Winter cover removed. Air temp 40-45*
4. Winter cover back on, flaps closed. Air Temp 36-48*

.................. 1 ......2.......3......4
Water temp..195....195....192..195
Trans temp...115....80......52...110
EGT (avg)....725...650....600...725
Miles driven...76......78.....81....80
Mileage ....... 20.2..19.1...19.0..21.0

It would appear that the colder the operating temps, the worse the fuel mileage.

I wonder what would happen if I left the cover on during the warmer days of spring?

For my next experiment, I wonder if a colder air intake charge really makes enough of a differance to bother with. I want to do the Home Depot air box mod. I have enough materials lying around the house to do the mod without spending anything. Block it off and go for a drive. Then open it and do the same drive.

Adding a pyrometer to the intake horn is looking like a good idea, too.

 

Im pretty interested in what the warmer temps is gonna bring to your testing. Keep us posted.

 

Make sure you get the proper temp sensor, I am not sure a Pyro is the best idea, I think it's parameters are to high and is not accurate for lower temps. BUT, I am not 100% on this.

Max

 

Here is a text written to explain why you would want to increase the operating temps of a diesel motor. This text was written as it applies to a Powerstroke but should equally apply to diesel motors in general and may be of some use to you.

http://www.dieselsite.com/pdffiles/h...nginetemps.pdf

I have seen the test results for tests done on IAT and they showed improvement with lower IAT. Can't find that PDF at the moment.

 

Do this.

Install Evans NPG coolant.

Instal a 210 degree thermostat.

Have engine fan turned up to where it doesnt kick on till 220*.

Will see a 10% gain in mpg's.

Diesels need to run hotter but cant because of the limitations of antifreeze.

Thats been changed.

Evans coolant wont boil till over 300 degrees. So, it doesnt cavitate and will not boil and turn to gas the way antifreeze does up against the liner of the cylinder.

You will have no pressure in the coolant at 210* No high pressure rad cap will no longer be needed.

Go read Evans NPG website.

I know of a guy playing with this in a 8.3 cummins. Upped the operating temp 15 degrees. Fuel mpgs are gained by 10% across the board.

This will spark another war here. Im known for that.

Just go read evans website. Youll learn.. http://www.evanscooling.com/

Ive ran the stuff in my dirtbikes for years. Makes my engines last forever. My 2 stroke piston last forever. Generally they need replaced each season. Cools way better by always staying in contact with what its trying to cool.

Read the whole website. I will have to write another 5 pages of arguements to make what they easilly say. If your a scientist you will catch on quickly. Spend an hour on evans website. It will take that to understand the abilities of this product.

Carey

 

Why isn't the factory thermostat 210* or so? Why does the fan come on so early? These are simple things that can make big differances. Especially the fan on temp, that's a free change at the factory level. There must be a down side to running at 210*.

 

Factory is like 192* Downside to 210* is the antifreeze isnt up to the task long term. We have enough cavitation as it is. Using Evans there is no cavitation so you are able to safely run hotter temps and not hurt the engine.

One could fool the temp sensor with a resistor so fan would come on later.

This is all new for our lil engines, but trucking companies have been using evans for years and getting .3-.6 tenths better mpgs using it.

This is something that an electronics wizard would need to mess with on our trucks to figure all the electronic details out.

Could be safely done though.

I have a kdx dirtbike and when I used regular antifreeze at high 10-12k elevations it would overheat and perculate. It would ruin the piston about every 25 hrs.

I switched to evans and it no longer even makes any water pressure no matter the altitude.

5 years later Im still on the same piston. I just replace the rings each winter.

One other great thing about evans is no water pressure in the engine. So no water pump failures, blown hoses, or blown head gaskets. It totally takes a load off the cooling system.

6.0 ford engines that blow lots of head gaskets would no longer have a problem if they used evans.



Carey

 

It makes sense to me but what will come is how a dealer or manufacture will take it if there's a warranty issue. Only because you have to change the standard operating temp up by both temp sensor and T-stat and if not thru the ECM. So now you have made a non factory change. Non warranty trucks who cares right but we are all in that box of anything over the instilled in our brains of 210-215 or shes going to blow. I feel that if you have a non water base type coolant (good) and thus keeping the vapor factor out, which is going to happen with any water base anything. Even at standard operating temps is going to keep them at or below longer normal temps thus less the fan is working = less you will see in slight mpg gains.
Now I went from factory Tstat running 210 all the time or higher and replaced with new on that works normal(old one wouldn't open all the way) and now I'm seeing 190-200ish and no difference in mpgs. Oh Running 50/50 mix. this summer will tell the tail though.

 

I admire your post. However don't overlook the possible aerodynamic differences between having the radiator covered up vs open and causing drag under the truck.

Your transmission temp also took a dive when the radiator was opened up and I'd suspect your oil pan temps dropped about the same also. Colder oil equals thicker oil. In your transmission that means greater parasitic losses.

You need to find a way to raise the water temp, while still keeping the other variables the same like aerodynamics and other fluid temps.

 

^^ Right on. 78mph is fast and there is a lot of aerodynamic drag. Aero drag increases with the cube of the speed. Change Tstat and run tests over a longer period of time keeping as many variables constant.

On the right track with hotter being more efficient, in general. Aside from thining the oils and reducing friction, more heat in the components lessens the losses of combustion heat to the iron and gives more temperature gradient to the turbo's hot side, which if re-matched, could do great things. Back to the oil thining, that may not be good. Top ring turnaround temp is the highest momentary oil temp seen in the engine so too high a temp could increase top ring and bore wear at the top. Run a good synthetic is sustained high coolant temps are to be experimented with.

Higher incylinder temps contribute to NOx emissions so there is a trade off between efficiency due to higher temp and loosing efficiency due to having increased EGR and retarded timing, to offset greater NOx at higher temps. 180 is considered a good minimum temp to drive off moisture and light ends that might collect in the crankcase. Above that it is emissions versus efficiency and a whole lot of variables to trade off. Charge air density suffers a little too.

I would really like to see a controller company crack the injection event sequencing and get back to a single injection event or possiblly a very small initial event and a big secondary event. The third event is a total waste of fuel in my opinion and it is there to produce EGR along with the cam timing. EGR is basically an inert in the engine that separates the air from the fuel and causes slow burning and lower peak pressures and temps for emissions driving efficiency in the wrong direction.

 

I thought about aerodynamics. The differance between closed cover and no cover I think would be noticable. But the differance beween closed and open flaps would be a lot less. Especially since the rest of the truck is about as aerodynamic as my garage.

In most engines, oil is heated by rpm's. And oil temp tends to run about the same water temp. Since water temp didn't change a whole lot, I wouldn't expect the oil temp to change much.

The trans temp is another issue. I'm surprised that there's that much variance, since it goes through a heat exchanger. That should have kept the temps a little more stable. Of course, with the colder fluids, that would create a little more drag. Not much because trans fluid is thin, and tends to maintain stable viscosity throughout it's temp range.

My other thought is to place some card board behind the intercooler, and in front of the radiater. Try to heat the water a little but keep the intake charge cool.

Changing the fan temp would be pretty easy. Install a manual switch. Or install an automatic temp switch in the ground wire to close the circuit at 210* or so.

Changing the thermostat is another story. I'v not been able to find a 210* thermostat.

Evans coolant has been around for a long time. I considered putting it in my race car, but then considered the cost. During the change out, you have to make sure all water and glycol fluids are completly removed. All of it. That means flushing a couple of times. Gets expensive.

 

Evans makes a fluid to run thru it to dry it out.

Youd need to drain the block drains, then remove the tstat, Then hook a shop vac to the lower hose. set it to blow or vacumm would work to. Leave this running for 1/2 day.

The engine will be bone dry inside.

On the tstat youd need to find one that is the same diameter and that would work fine. Pretty doubtfull youd find a cummins 210 tstat.

Semi truck guys do the same, they just match up a tstat that is the same diameter.