Community Forums

Crasher · 10-10-2020, 09:23 AM

I had always run in the normal mode and rarely went into economy mode. This last trip from WI to AZ, 2,000 miles, I went into eco mode as soon as I started up. I liked how the trans shifted up at lower rpms keeping the engine near the peak torque of 1450. I was also surprised that the coach could climb long inclines and not shift out of 6th gear till near the top. Once the rpm got down under 1500, it just seemed to lug it's way up the hill. The OAT was in the upper 70's to upper 80's and the engine temp would run up to 205 with an occasional 210 when the fan would go into high speed and pull the temp back down below 200. A couple times, on a hill, I took it out of eco mode and all that happened was a higher rpm with no speed change. My coach weighs 40,000 and I tow a 6400# Avalanche. The first day we had strong winds and stopped when we turned west at Fargo for a crosswind and the gusts hit 50 mph. Only got 6.5 mpg. With no wind days, it ran 7.5+ running 65-68 mph. Overall, I was pleasantly surprised how well economy mode performed. We are leaving tomorrow for Sand Hollow UT with our rock buggy on a trailer that weighs 8,000# and will see how it goes with a heavier load. What do some of you DP owners run in?

**Petro** · 10-10-2020, 09:33 AM

I usually operated my Horizon in economy mode on average terrain in Wisconsin. When I was traveling in mountain area I turned the economy mode off. I could not gain any additional MPG in the mountains and it felt to me the engine had to work much harder.

Don

**Lt Dan** · 10-10-2020, 09:37 AM

I normally leave mine in normal mode but will switch to Econ on flat terrain. I prefer it to downshift a bit sooner when climbing. Just my $0.02 worth. I have not seen much difference if any in mileage between the two modes.

Skip426 · 10-10-2020, 09:39 AM

I run in Economy mode 95% of the time , as you've mentioned the short shifts keep the engine in it's torque band and I feel it accelerates faster . Also the shift to 6 th gear happens a few mph lower and that keeps me closer to the towing speed in CA.

96 Wideglide · 10-10-2020, 09:39 AM

I'll turn it on in flat, or rolling terrain. Turn it off in the mountains. Don't want to lug the engine.

Old Scout · 10-10-2020, 09:41 AM

….not sure econ-mode makes that much difference in MPG....suspect it a good option on flat terrain....lugging a diesel on inclines is not your friend unless you can watch/manage coolant and exhaust manifold temps....most new rigs don't have pyrometers as OEM so prefer to manage RPMs rather than lug the engine--IMHO...

Crasher · 10-10-2020, 11:03 AM

I didn't mean to imply that the mpg was higher in economy. I don't think it has much if any impact. Maybe on flat or rolling terrain, keeping the rpm's lower might use less fuel, but only marginally. I think it climbed long inclines better when pulling in or near the peak torque rpm. My silverleaf showed a maximum of 1175# of torque @1400 (rated at 1250), and only 390hp (rated for 450) @2000-2200 rpm. Of course as the rpm's go above 1400 , the torque level goes down. If the Silverleaf is accurate, the engine is not developing maximum power. I could have it tweaked up, but where it's at leaves a safety margin for EGT and load on the transmission rated for 1250# torque.

wolfe10 · 10-10-2020, 11:07 AM

No single answer to MPG improvement in economy mode. On flat ground, it makes ZERO difference (think I 10 across Louisiana). Continue west to the Texas hill country with its short, steep ups and downs. Here, it can make a significant difference.

And, counterpoint to taking it out of economy mode in mountains. IF, repeat IF you want more control, leave it in economy mode and use the down/up arrows to select the proper gear.

Yes, you can leave it in "D", but a smart driver is PROactive, where the Allison can only be REactive-- reacting to what happened behind you.

96 Wideglide · 10-10-2020, 11:13 AM

Climbing grades, I want to be near peak HP. Not peak torque!

Ray,IN · 10-10-2020, 11:16 AM

Go to this website,scroll down to economy mode operation.That is verbatim what Allison says for operation of their RV transmissions.
My SIL is maintenane manager for a nation-wide trucking company. I asked about economy mode when we bought the MH. He said to use it all the time, as it resulted in slightly better fuel mileage and was easier on the engine. He recommended I have Allison re-program the TCM to make economy mode the default instead of power mode.

Crasher · 10-10-2020, 11:58 AM

[A modern turbo inter-cooled diesel is much more efficient at low RPM high throttle settings. This is NOT my opinion. It is stated in just those words in the Cat Owner’s Manual and likely the Cummins manual as well.]

This is an excerpt from the article Ray referred to. Add to that that Allison recommends running in economy mode unless higher rpm is needed for cooling. A diesel engine is designed to run at peak torque for best efficiency. At least that is what I have heard over the years.

Gary RVRoamer · 10-10-2020, 03:06 PM

In 10 years of widespread travel I never found any advantage in using Econ Mode; no mpg gain on the flats and certainly no advantage on grades. Just left it in the normal mode.

Ray,IN · 10-10-2020, 04:51 PM

Gary, that article also says driving style determines fuel mileage results. I do not see nay mileage difference either, as I'm a foot on the floor guy from a stop and climbing grades.
Allison has a relatively new feature FuelSense 2.0.