Foretravel Owners' Forum For owners and Fans of Foretravel Motorcoaches September 14, 2025 ...

100% Load

June 20, 2015, 10:25:13 am

The thread on operating temps got me to thinking about another issue, max load. The scenario would be: Engine with a peak torque of 1250 and a governed speed of 2000 (my M11) pulling a long 7% hill, let's say in 4th gear. RPMs at maybe 1450 with torque and horsepower both pegged at 100%. Operating temperature remains below the upper limit, let's say it doesn't exceed 200.

I've seen a few posts here and elsewhere in which the poster states that he avoids pushing the engine to its max load point. I say, why not! Opinions? Thanks.
jor

Quote Selected

Re: 100% Load

Reply #1 – June 20, 2015, 10:42:15 am

If not overheating, no problem with WOT.

Quote Selected

Re: 100% Load

Reply #2 – June 20, 2015, 11:25:07 am

When I am climbing I am watching my VMS-PC.  I run at max load and torque- keeping an eye on temps.  If temps rise, I back off , gear down, etc to find the right spot- usually close to max torque and max load.  I believe that gives me the best side of using my power and fuel economy ( if you can call it that).

Quote Selected

Re: 100% Load

Reply #3 – June 20, 2015, 11:33:53 am

Jor,
The power chart for my M11 showed 400HP to 1700RPM. HP started to decline above that.
I found that 1700RPM in 4th gear worked well climbing those 7% grades out west.
I engaged the cruse and let the engine run.
Usually ran at something less than full throttle and never had a heat problem.
I talked to Cummins NW about that and was told that's ok. He said I could run the 2000RPM limit and would not hurt it, would just push a lot of fuel through it.

Quote Selected

Re: 100% Load

Reply #4 – June 20, 2015, 04:21:36 pm

One interesting thing: On our ISM, at full load the VMS indicated the rated torque which was 1450. On our M11 it pegs at 1343. Rating is 1350. I want my missing 7 pounds.
jor

Quote Selected

Re: 100% Load

Reply #5 – June 20, 2015, 05:14:45 pm

Quote from: jor – June 20, 2015, 04:21:36 pm

I want my missing 7 pounds.

I've got some I can spare 

Quote Selected

Re: 100% Load

Reply #6 – June 20, 2015, 05:15:07 pm

Do check your crank/cam position sensor.  My m11's oil soaked and misfiring the injectors.  You could hear the uneven firing standing behind the coach running.

Upgraded part available. Inexpensive

Quote Selected

Re: 100% Load

Reply #7 – June 20, 2015, 07:46:49 pm

Higher RPM for the same speed circulates coolant better and lowers EGT on hills. Just because the temp gauge does not go over 200 does not mean that there are not hotter areas in the cylinder head coolant passages.

Pierce

Quote Selected