97 m11 upgrade test report
I never felt our m11 drove correctly power wise. Too many other high line coaches I have driven had a less revvy higher torque feel to them versus this coach.
But never having driven another m11 myself and being out of the Rv biz by 1997 made any driving opinion suspect.
But never felt "right" somewhat disappointing.
So I started going through every part in the engine compartment. If everything was as good as it could be that would be fine but sad.
52 months later I finally got what I like/wanted in the driving power of the coach.
Originally the coach would downshift every time at large throttle inputs. Revvy. Wrong for a large Diesel engine IMO.
Hmmm. And as it revved out it was not faster. Typical large Diesel engine is where the torque makes the coach accelerate faster than the rev out hp does. Not this one.
Hmmm.
Had to fix the bad stuff first. Winn system. Cam position sensor. Altitude sensor upgrade. Adjust valves and injectors.
Still down on power on the cummins dyno in Los Angeles. No blowby.
Limited power upgrades on a m11 celect plus. Too old. Replaced by the ISM.
the help and info here made my project possible. Thanks to everyone.
I have no idea for sure what of my changes could be eliminated and not alter the results but I doubt that the results would be the same if any steps skipped IMO.
Had the local cummins shops expert welder remove the oem muffler and install and 5050xl resonantor. Beautiful expensive job.
Helped but not done yet. Added a Donaldson blue foam airfilter after the Pittsburg power guys mentioned it helped on their web site in these.
Intermittent large RMPG increases on flat non windy roads got my interest up. Why?
Turns out Foretravel opted for a low temp hydraulic fan controller. Full max fan speed at 180 degrees. 40 or more hp continiously drawn off the engine if warmed up.
Never got a straight answer from the cummins guys as I think they do not know the answer to my temp questions.
My thought was that the engine will not produce full torque if not fully warmed up. No one to ask on 20 year old stuff.
Found a beaver owner selling a new 199 degree hydraulic fan controller off his c15 cat on Craigslist.
Had the cummins shop install the controller. And had the alternator rebuilt as the LN had a bad diode and bearings.
Less power off the motor.
270 watts of solar make the alternator work less when driving during daylight. No residental refer.
Left Orange County bound for sequoia Sunday. Two electric bikes on a rear rack and a Toyota Solara convertible tow car and full water and fuel. Full gvwr.
New Michelin xza-3+'s at 90 rear/100 front. No alignment issues. No dead spot. No truck sway at all.
No brake pad drag.
Ahh. Coach now torques harder in each gear. Pulled in the mountains at lower rpms without downshifting.
Agressive throttle made the coach accelerate in the higher gears without downshifting. Wow. Real torque.
At 7,000 feet in the Sierras the coach would accelerate up grades without downshifting and at medium throttle. Never floored.
Totally different drive.
Also like every big Rv I have driven I think this was was not broken in yet.
Sounds crazy but the truckers mentioned that their m11's did not fully seal up until 150k miles.
That's at 80k weight.
Round trip mpg was 7.6 and I mostly was at 68 mph.
Flat ground at 68mph showed 9.5 RMPG. S!ight downhill, on I99 out of Bakersfield headed towards Los Angeles showed 10 RPMG.
Full power up grapevine showed 52-54 mph with trans in non mode operation.
Engine temp never hit 220. 92 degrees ambient. Engine temp is noticeably lower. I assume the oem muffler made it run hotter from the high back pressure.
Yes it's noisier. Sharper toned.
Better mpg, lower temp, much better torque,
If I was not towing and no wind sucking bikes on the coach I think it would get 10mpg pretty easy.
Funny enough the RMPG got better at 68 or 69 versus low 60's. I think the engines torque and hp curves and Foretravels rear end gearing are perfect at 70.
Yes I know that's not possible as you lose 1 mpg from 60 to 70. Unless the motors more effecient at 1450 rpm than at 1300.
Tested this a half dozen times. At 60 I got 8.5 RMPG. at 68 I got 9.5. You tell me.
All the pieces together worked out.
The exhaust work may be part of this as the welder used better flowing curved sections versus flex hoses. Maybe.
Not sure why and what contributed, slightly higher temp allowed the ECM to allow more torque? Less loss at norms temp from the lower power consumption from the fans higher temp max speed?
Less restrictive air filter? Lower power consuming tires?
How does my numbers match up with other owners is necessary.
Quite possible every other one always drove like mine does now? No way to know.
No reason to ever sell this one.
25 pounds max boost revved hard.
I assume the turbo and injectors are ok. But who knows for sure. Not worth the time and money so far to have them checked.
Hope this helps someone. Almost said nothing. My secret.
Topic: 97 m11 upgrade test report