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Topic: 100% Load (Read 664 times) previous topic - next topic

100% Load

Here's another for you diesel guys. Is there any advantage to pulling a hill at less than 100% load? I don't have VMS on this rig but on others I was able to watch the engine load percentage (always got a kick out of that). Anyhow, I would often pull hills at 100% while keeping RPMs up. Just wondered.

Interesting tidbit: Our last M11 was rated at 1400 pounds of torque (400 hp). The VMS would always top out at 1393. Always wondered where my other seven pounds went.
jor
93 225
95 300
97 270
99 320

Re: 100% Load

Reply #1 –
Quote from: jor –
Here's another for you diesel guys. Is there any advantage to pulling a hill at less than 100% load? I don't have VMS on this rig but on others I was able to watch the engine load percentage (always got a kick out of that). Anyhow, I would often pull hills at 100% while keeping RPMs up. Just wondered.

Interesting tidbit: Our last M11 was rated at 1400 pounds of torque (400 hp). The VMS would always top out at 1393. Always wondered where my other seven pounds went.
jor
Just my experiences with two m-ll's with vmspc and pyrometers. At 100% load, even at higher rpms, egt's will climb slowly to 1400 f. or so and stay there. In the short run probably no problem, but I normally backed off after a minute or so, to 80 or 90% where pyro temps were less than 1250 f.
Jim C.
coachfree, previous 1997, 1999, 2000, and 2003 Foretravels.

Re: 100% Load

Reply #2 –
There is no direct measurement of HP or Torque.  VMSpc uses torque and HP vs rpm curves and other bits to calculate those numbers.  As I understand it engine load is a reported number. 

I try to keep engine load under 100%.  If you can drop a gear and increase rpms the engine load will go down.  Every coach with the engine and transmission it has and the weight of the coach and toad has sweet spots where everything seems to come into a balance for performance, efficiency and driver comfort level. 
Roger Engdahl and Susan Green
2001 U320 3610 #5879 (Home2) - 2014 Jeep Cherokee or 2018 F150
Hastings, MN

Re: 100% Load

Reply #3 –
Diesels by design like to run excess air. If running at a point where increasing the throttle does not increase RPM's all the extra fuel is doing is adding heat...

Chris 1999 U320

Re: 100% Load

Reply #4 –
Quote from: squeezer –
Diesels by design like to run excess air. If running at a point where increasing the throttle does not increase RPM's all the extra fuel is doing is adding heat...


Many Semi's and some motorhomes have mechanical pyrometers and boost gauges stock from the factory. They will give a good indication of actual engine load and if it is producing full power.
Jim C.
coachfree, previous 1997, 1999, 2000, and 2003 Foretravels.

Re: 100% Load

Reply #5 –
Running at 100% load won't kill anything but it's not good practice.  If you are in 6th and at 100% load you are probably running at low RPM.  This won't hurt the engine unless it starts lugging.  You need revs to power the cooling fans and keep them up to speed, that's why you drop a gear when the trans, retarder or engine temps climb.  Also you have nothing left in reserve at 100%.  The coach will just feel right when it's at operated at it's best. 

Different engines have different operating parameters.  It used to be an absolute no no to lug an engine, revs were everything.  Then the fuel crisis hit and operating at low RPM's became the thing.  With Cummins newer engines they can operate happily at 1,000 RPMs.

Keith
Keith, Joyce & Smokey the Australian Cattle Dog
1995 U320 SE Extreme 40' WTBI Build # 4780, with a Honda CR-V hopefully still following behind.
Motorcade # 17030
FMCA # F422159

Re: 100% Load

Reply #6 –
The ability to lug and pull makes a vehicle easier to drive IMO.

Passed last year on a old low mile v8 luxury car because it was a revver. Dead off idle, 03 model.

Bought another brand low mile  08 v8 luxury car recently instead and it has both amazing torque and runs at 80 at 2,000 rpm and pulls well with light throttle. 

And I fairly fast if revved.  Hard to get both.

Took a lot of time (4 years)  to get our m11 coach to pull at low rpm versus downshift and still rev out well.




"Riding and rejoicing"
Bob
1997 U320 40' Mid entry, build 5132,  wtbi ce27, 4th owner
2007 Solara convertible
2 prodeco tech outlaw ss electric bikes

1095 watts solar
08 Ls 460 and a sc430
2000 Ford F-250 superduty 4x4
 

Re: 100% Load

Reply #7 –
Quote from: jor –
Here's another for you diesel guys. Is there any advantage to pulling a hill at less than 100% load? I don't have VMS on this rig but on others I was able to watch the engine load percentage (always got a kick out of that). Anyhow, I would often pull hills at 100% while keeping RPMs up. Just wondered.

Interesting tidbit: Our last M11 was rated at 1400 pounds of torque (400 hp). The VMS would always top out at 1393. Always wondered where my other seven pounds went.
jor
Rounding ERROR....