Same engine and transmission.. I generally have it on... Does not make any difference on flat terrain but will be a help in terms of fuel economy for rolling hills. Since what it will do is keep it in 6th gear longer...
JohnnyT wrote: Same engine and transmission.. I generally have it on... Does not make any difference on flat terrain but will be a help in terms of fuel economy for rolling hills. Since what it will do is keep it in 6th gear longer...
Johnny
Like JohnnyT, I have made it a habit of turning it on, so when we get to the hills and mountains, it is working. Found that on the average, it increased our MPG by 1, so it is worth running in the economy mode.
Bob & Betsy - USN Ret'd '78 & FL LEO Ret'd '03 FMCA #F203528 '05 HR Endeavor, 40PRQ (Our Home) w/400 Cummins - With -'05 GMC Sierra SLT, CC Z-71, the pusher- With -
'07 Arctic Cat 500A & Wilderness Kayak, riding in the pusher - Our Current Location
JohnnyT wrote: Same engine and transmission.. I generally have it on... Does not make any difference on flat terrain but will be a help in terms of fuel economy for rolling hills. Since what it will do is keep it in 6th gear longer...
Johnny
Like JohnnyT, I have made it a habit of turning it on, so when we get to the hills and mountains, it is working. Found that on the average, it increased our MPG by 1, so it is worth running in the economy mode.
I fully agree with The Texan, and JohnnyT, but when entering mountainous areas with steeper, longer grades you will probably want to turn it off. I drive a lot of miles in the mountains and find shifting to 5th a little earlier (econo mode off) to be a big advantage to maintaining the proper rpm's, and speed loss is minimized.
Driving under the different terrain extremes, you will soon learn what works best for you.
On for rolling hills but off when serious climbing and descending is necessary. The mode button delays downshift 100-200 RPM and climbing requires RPM to be high for good cooling.
John
2008 Tiffin Allegro Bus 40' QSP
2006 Chevrolet Colorado Toad
BlueOx Aventa LX Tow Bar
SMI Air Force One toad brake
Copilot Live Laptop 10 GPS
JUrban wrote: The mode button delays downshift 100-200 RPM and climbing requires RPM to be high for good cooling.
John
This might be true for rear radiator cooling systems but doesn't make any difference with side mount radiators.
The mode button allows the trans to up shift at a lower RPM. With it in mode, you should be able to get into 6th before you hit 55MPH.
I have been experimenting with the mode on and off when climbing. So far all I have seen is a little slower in reaching the top. Temps run the same as on flat ground, at the lower RPM, say 1750 to 1900, mileage is higher that if you run at 2200.
If you have a Silverleaf and monitor your coach, you will see that when the RPM jumps to 2200 in 5th gear while climbing, your torque goes out the window as does mileage.
JUrban wrote: The mode button delays downshift 100-200 RPM and climbing requires RPM to be high for good cooling.
John
This might be true for rear radiator cooling systems but doesn't make any difference with side mount radiators.
The mode button allows the trans to up shift at a lower RPM. With it in mode, you should be able to get into 6th before you hit 55MPH.
I have been experimenting with the mode on and off when climbing. So far all I have seen is a little slower in reaching the top. Temps run the same as on flat ground, at the lower RPM, say 1750 to 1900, mileage is higher that if you run at 2200.
If you have a Silverleaf and monitor your coach, you will see that when the RPM jumps to 2200 in 5th gear while climbing, your torque goes out the window as does mileage.
Sorry, but According to Cummins and Freightliner, it DOES make a difference. My side radiator Cummins ISL does not run the fans at full speed until it reaches approximately 1900 RPM. If I allow the transmission to program the RPM down to the 1450-1550 it's reaching for, I am not getting maximum airflow, and not getting maximum cooling. My engine monitor temperature readings confirm this completely. In addition, by looking at Cummins fuel consumption curves when joined with the 3000 transmission, slower speeds and higher engine RPM's does not result in poorer fuel mileage. In most operating ranges we usually see in RV travel, even though it downshifts to a lower gear and the RPM increases, fuel used per mile decreases. Travel time is increased for sure, but economy is not compromised. By the way the ISL's max RPM is 2200, not the 2400-2450 seen in many Cat's.
JUrban wrote: The mode button delays downshift 100-200 RPM and climbing requires RPM to be high for good cooling.
John
This might be true for rear radiator cooling systems but doesn't make any difference with side mount radiators.
The mode button allows the trans to up shift at a lower RPM. With it in mode, you should be able to get into 6th before you hit 55MPH.
I have been experimenting with the mode on and off when climbing. So far all I have seen is a little slower in reaching the top. Temps run the same as on flat ground, at the lower RPM, say 1750 to 1900, mileage is higher that if you run at 2200.
If you have a Silverleaf and monitor your coach, you will see that when the RPM jumps to 2200 in 5th gear while climbing, your torque goes out the window as does mileage.
Sorry, but According to Cummins and Freightliner, it DOES make a difference. My side radiator Cummins ISL does not run the fans at full speed until it reaches approximately 1900 RPM. If I allow the transmission to program the RPM down to the 1450-1550 it's reaching for, I am not getting maximum airflow, and not getting maximum cooling. My engine monitor temperature readings confirm this completely. In addition, by looking at Cummins fuel consumption curves when joined with the 3000 transmission, slower speeds and higher engine RPM's does not result in poorer fuel mileage. In most operating ranges we usually see in RV travel, even though it downshifts to a lower gear and the RPM increases, fuel used per mile decreases. Travel time is increased for sure, but economy is not compromised. By the way the ISL's max RPM is 2200, not the 2400-2450 seen in many Cat's.
John
Sorry, I don't agree here. If you have a Silverleaf to watch, do the following:
Head up the hill at 55MPH and allow the transmission to shift itself. You will see that the RPM will stay pretty constant as will the speed. MPG in my case will be in the 3 to 3.5 range. If I allow the RPM to go to 2200, the MPG will drop to 2 to 2.2.
Speaking of temps, at the same time the trans will run 196 to 198. The coolant temp will remain steady at 198. Then again I do not have a Freightliner.
The Cummins engineer that checked our engine said to always use mode. He said it could increase MPG by about 1/2 mile per gallon and that the engine is designed to run most efficiently in mode.
I havebeen running with the "mode" switch on most of the time since I put the Banks system on due to it's much wider power/torque band (1200 ft lbs from 1400 to past 1700) rather than 1050 at 1400 and then the torque going down. In fact I have more than 1050 ft lbs from 1200 to 2100 rpm, only from 2100 to 2200 does it get lower than than 1050 and is still 250 ft lbs higher than the stock engine at that rpm. Now, what does that do to my mileage? I don't know but I do know that Cummins says that modern turbocharged diesels get better mileage when under low rpm and high boost pressures. Need to see if Banks has a fuel usage chart and see what rpm is best. So far I've been using the same as the stock, which would be 1600 rpm (about 60 mph) since the old torque peak was 1400. Will hook up the VMSpc next time out and do some experimenting.
Deen - Vancouver, WA
'02 Dutch Star 4090 (41+', triple slide)
435/1200 ISC Cummins/Banks PowerPak
'08 Honda Civic/dolly
'05 Honda Odyssey/dolly
NRA Benefactor Life Member
FMCA f47302s, Life Member: Good Sam, Newmar DP Owners Group
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