Anthem pulling power

[SDM1]

Marc,
i will agree it was not setting speed records by any means. I just geared the coach down as needed to stay the 1400 to 1500 range and let it pull. true enough i lost probably 10 MPH on the long 2/3 mile incline but it pulled just fine and actually maintained the 10MPG on that specific trip! The fellas at Entegra shop told me to just try that type of drving on the way home and they sad i would be impressed with fuel economy, true enough i was impressed! Besides, the RV lifestyle is to see the country right, what better way than going slow with a panoramic view out the windshield of an RV!!!! LOL!!!

[Steve Ownby]

Originally Posted by MRUSA14

I can't agree with that. My ISL engine is rated for max torque at 1400 RPM. Trying to climb a 6-7% grade at 1400 RPM will get you nowhere.

There are two issues at play here:
1. Max fuel economy is achieved when the engine is held as close to torque peak as possible.
2. Ascending a grade without losing any more momentum than necessary. This requires keeping the rpms up close to hp peak. This will also contribute to heat management.

[bill2011]

This thread is very informative. Thanks to you knowledgable guys for sharing this information. I suspect if winter ever ends here I may be able to drive our coach a bit more efficiently.

[SDM1]

Originally Posted by Steve Ownby

There are two issues at play here:
1. Max fuel economy is achieved when the engine is held as close to torque peak as possible.
2. Ascending a grade without losing any more momentum than necessary. This requires keeping the rpms up close to hp peak. This will also contribute to heat management.

Steve, you are correct on #2. If t is a long ascending grade you need to monitor engine temp and do not LUG( as we call it ) the engine which will cause overheating. Sometimes fuel economy is not the best to worry about! Torque moves weight and HP gives you speed! Sometimes you have to figure out how your own coach will perform at it's best and safest!
I tested the theory and had good luck with the torque RPM on hills, great on fuel that way. But i work in the oil industry and dont mind supporting my job by increasing rpm most the time! I just offered my experience with the driving habits that Entegra mentioned for me to try to get the fuel economy i was told the coach like mine could achieve!

[Steve Ownby]

Originally Posted by SDM1

Steve, you are correct on #2. If t is a long ascending grade you need to monitor engine temp and do not LUG( as we call it ) the engine which will cause overheating. Sometimes fuel economy is not the best to worry about! Torque moves weight and HP gives you speed! Sometimes you have to figure out how your own coach will perform at it's best and safest! I tested the theory and had good luck with the torque RPM on hills, great on fuel that way. But i work in the oil industry and dont mind supporting my job by increasing rpm most the time! I just offered my experience with the driving habits that Entegra mentioned for me to try to get the fuel economy i was told the coach like mine could achieve!

No disagreement from me. I read a white paper published by Cat at a Cat engine seminar years ago which made the same point. Cat did a number of study's regarding all the factors influencing fuel economy.

My intent was to point out to new DP drivers the other issue on long grades. Without the ram air coming through the radiator that a front mounted engine gets a DPs cooling package depends on the velocity of coolant through the engine to keep heat rejection up. Most of the time, in the east, where you can see the crest of the grade from the bottom, you're ok. On a five to ten mile 6% grade, cooling will become an issue at low rpm.

I see your home is Pigeon Forge. I'm over on the east side of Gatlinburg out 321. Got stuck here this winter as my wife had to have some dental work done that started in January. Bad year to stay in the mountains. Good news is that I'm now very confident in the insulation of my coach.

Safe travels.

[DSL417]

SDM1,

I guess I'd like to understand how you're increasing you milage from the 6-7.5 MPG that most of us are getting to the 10 range. That's a lot of difference, particularly if you're getting it in the mtns. Pls, more detail.

[SDM1]

Originally Posted by DSL417

SDM1,

I guess I'd like to understand how you're increasing you milage from the 6-7.5 MPG that most of us are getting to the 10 range. That's a lot of difference, particularly if you're getting it in the mtns. Pls, more detail.

DSL417,

Sorry for the long delay on response. As i had mentioned above, on a factory repair trip in early 2013 I had discussed fuel mileage with some of the Entegra tech's! One of them told me to give the coach a try on the way home( from Indiana to Pigeon Forge Tennessee) of doing the best I could to keep the coach at max torque RPM when pulling grades, BUT in doing that to keep close eye on the engine temp also as to not overheat the engine with to low of an RPM. If engine temp climbs over drivers comfort level then rev it up for max cooling. In driving the coach as instructed i DID get 10 MPG on the trip home without any overheating issues, this was pullng a 4x4 tahoe also. Granted i did drop speed pulling the grades coming through Kentucky, but i was not in a hurry anyway and really wanted to test the theory. IT WORKED on the trip as tech told me it would. NOW, do i drive the coach that way all the time, of course not. To maintain the 10mpg the driver must constantly monitor upcoming road conditions and planning to hold a certain rpm and downshifting as required etc. So in attempting to stay at that , to me it makes driving the coach way to demanding and non enjoyable.
Maybe some others can test the ideal out and see if it works for them. Maybe it was a freak event for me. When i drive the coach again i will test it one more time to confirm and post results.

Safe and happy travels to all as the season is getting close upon us!!!

Tony & Stacey

[MRUSA14]

Driving up a steep grade at 1400 RPM, wouldn't that be "lugging" the engine? Isn't that bad for the engine?

[loisjop]

One more thing! If that is such a good idea why don't they program the econo side of the transmission to do that? There are many programs for the tranny and I tried to get mine programmed closer to what you're talking about and Spartan wouldn't let them do it. As our transmission are set up now you can't tell any difference between econo and regular. Noel

[757driver]

Here is an interesting and informative post from the Allison Forum.

Econo mode operation
This is a post from Brett Wolfe from Diesel Rv


ALLISON MODE BUTTON

There are TWO TOTALLY DIFFERENT "LET THE TRANSMISSION CHOOSE THE CORRECT GEAR" MODES/PROGRAMS in the Allison ECU which is the "electronic brain" controlling shifting and other functions.

In ECONOMY MODE, the transmission will not downshift even at WOT (Wide Open Throttle) until the engine pulls down to peak torque RPM in some application and 200 RPM lower that "regular mode" in others.

In REGULAR MODE, the transmission WILL downshift much earlier (to maintain higher engine RPM).

ONLY at higher throttle positions is there any difference, so on flat ground you will NOT notice any difference (except accelerating from a stop IF you are at or close to wide open throttle).

It can make a BIG difference in rolling hills. If you are in rolling hills and regular mode (particularly with the cruise control on), it is common for the transmission to shift down to 5th on the uphill and back to 6th on the downhill. Repeat this process hundreds of times. In economy mode, you will stay in 6th gear unless the hill is so steep or so long that the engine can not pull it without dropping below peak torque RPM. If you can pull a hill in a higher gear (lower engine RPM) AND the engine does not overheat, THAT IS WHAT ALL ENGINE MANUFACTURERS RECOMMEND FOR THE MOST ECONOMICAL WAY TO CLIMB A HILL with a modern turbo, after-cooled diesel engine.

If you know you will need a lower gear because of the steepness of the grade and/or are engine temperature is rising higher than the thermostatically controlled temperature, while driving in economy mode, use the down arrow to drop a gear (this is what I do) or switch out of economy mode. Be sure to switch back into economy mode (or shift up) when past the steep section, or agree to pump extra fuel at the next fill-up.

IF your engine begins to overheat, your HP/weight ratio is low OR if it irritates you to loose a few mph on a hill in the name of saving fuel, in the hills, by all means drive in regular mode.

It confuses me to hear people advocate driving in economy mode only on flat ground, as there is not 1% difference in shift RPM's between regular and economy mode on flat ground, excepting accelerating from a stop if you use WOT.

Every time you start the coach, the transmission is in regular mode. This is the default setting. IF you push the mode button, it goes to "economy mode" AND the light illuminates.

There is no "absolute" on how much difference in fuel economy driving in economy mode will have. On flat ground where you will be in 6th gear irrespective of what mode you are in, there will be ZERO difference. The MOST difference in mileage will be in rolling hills, where in regular mode, particularly if on cruise control you will start up a hill in 6th gear, go to WOT in 6th gear, downshift of 5th gear still at WOT (WHERE IT IS USING A LOT MORE FUEL). After the hill is crested, the transmission will up-shift to 6th, then likely coast a little in 6th gear (unless you are driving with the exhaust brake on-- if you are it then applies the exhaust brake AND downshifts TOWARD the pre-select gear which is generally either 2nd or 4th).And so on 6-5-6-5-6-5-6-5.......

A modern turbo inter-cooled diesel is much more efficient at low RPM high throttle settings.

Note: In either mode, you are free (and welcome) to use the up and down arrows to PRO-ACTIVELY choose the correct gear. You can not screw anything up-- even if you down-arrow to 1st gear at 70mph, the transmission understands that you meant "please downshift to the next lower gear as soon as the engine RPM will not exceed the pre-set amount. Then downshift again when safe....."

By the same token, you can shift between regular and economy mode as often as you want with the transmission in any gear when you make the change.

OPINION: I drive in economy mode 99% of the time, including in REAL mountains, but use the up and down arrows to choose the proper gear. I use regular mode ONLY when I am willing to say, "I am willing to throw a lot of fuel away to gain a little performance." When passing on 2 lane roads, THIS IS the case.


« Last Edit: November 15, 2011, 08:05:51 AM by Brett Wolfe »




__________________
Art
1999 Trade Winds 7371 W/ Cat 300hp
1990 D 250 Dodge Ram Cummins Turbo

[MRUSA14]

That's a really good post and Brett Wolfe knows his stuff. I personally think that these things have poor enough uphill performance and I don't want to make it worse. I will pay the extra money at the pump for what I perceive to be a better trip. Others may choose to save the money and that's okay too, unless they are in front of me in a no-passing zone. If I had a Cornerstone I might feel differently.

[loisjop]

The above is true if they choose to program it that way. Mine makes absolutely no difference what mode you're in, it shifts the same. I ask for mine to be programmed differently and Spartan said due to the torque and h.p. being so close to max,on the Cummins 450, for the Allison 3000 they won't program the economy mode differently.

[MRUSA14]

Originally Posted by loisjop

The above is true if they choose to program it that way. Mine makes absolutely no difference what mode you're in, it shifts the same. I ask for mine to be programmed differently and Spartan said due to the torque and h.p. being so close to max,on the Cummins 450, for the Allison 3000 they won't program the economy mode differently.

That explains why I see little to no difference in economy mode. As for climbing mountains at 1400 RPM, if I wanted to go that slow I could have saved a ton of money and bought a gas-powered coach.

[Ann n Gene]

Another good advantage of the Cornerstone, the Allison 4000 tranny.