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Old 09-18-2020, 01:30 AM   #1
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Join Date: Jul 2015
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Cummins 450 HP loss of power going up hill

I just switched from a 2014 40ft with a Cummins 450 HP to a new Allegro Bus 45 OPP with the same Cummins 450 HP, my problem is I lose considerable speed go up any grade greater than 2%.
The 2020 has about 4500 miles on it and I have done both, manually shift and let the transmission do the shifting.
I know the 2020 is about 9000 to 10000 pounds heavier than the 2014.
I pull the same 2015 F150 Ford Truck with both vehicles and the speed below are speeds with both vehicles pulling the F150 and fully loaded.
When I first took delivery of the 2020 in Southern CA, went north on I15 from Riverside and was able to climb out of the valley at a max speed of 49 mph, which was close to my 2014 which did the same climb at 54 mph.
But since then I have noticed the power drops off a little more each time I climb a good hill or now even on the small shorter hills.
Leaving Denver on I70 west bound, in the 2014 I would climb it between 45 and 50 mph. In the new 2020 I slowed down to 26 mph in the first 25% of the climb and never got over the 26 mph (I started at 70 mph).
Last week leaving Steamboat Springs going east on US 40 up Rabbit Ears Pass which about 11 mile climb, I started at 65 mph and by the time I got to the first bend I was down to 38 and finally down to 31 within another 1/2 mile.
I have made the same climb numerous times in my 2014 and never got below 52 mph.
The 2020 has about 4500 miles on it and I have done both, manually shift and let the transmission do the shifting.
I know the 2020 is about 9000 to 10000 pounds heavier than the 2014.

Any suggestions on what the problem might be since it seems to be getting worse.
2020 Tiffin Allegro Bus 45OPP
2015 Thor Tuscany 40RX -Selling (I hope)
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Old 09-18-2020, 02:39 AM   #2
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Join Date: Jul 2008
Location: Pennsylvania
Posts: 299
9,000-10,000 lbs
That’s it, bingo.

My 43 ft Winnebago (450ISL) weighs 43,500lbs loaded with fuel pulling my Jeep. ( MH =40,000 & Jeep Liberty =3,500 )
If I fill the water add another 800 lbs.
It climbs ok. Took it to the Black hills and the White Mountains of New Hampshire already. But the technoform laminate in my MH weighs much less than the wood in your MH
My CCC is 8,000 lbs. which I will never get close to.

BTW I would expect it to struggle a bit if I did a trip to Breckinridge or Steamboat. I think I’m just on the edge weight wise for serious mountain climbing. I don’t do too much here in the East. 2000 maybe 3000 feet in New Hampshire. That’s not much.

What’s the weigh of your MH with a full tank and your toad?

Here is mine

2020 Winnebago Horizon 42Q
Maxum Chassis, 450 ISL
99 Storm 30H, 04 Southwind 32 VS, 07 Ellipse 40FD
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Old 09-18-2020, 05:12 PM   #3
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Posts: 530
25-26 MPH is pretty slow. I would not be happy with that. It may be the extra weight but I was having a similar problem just before I lost my #1 injector line. I was gradually loosing power on the hills. The 2020 would have the most current injector lines so it probably would not be that but you may want to make sure your fuel system is up to par.

My scale weight and driving experience is very close to 2cyber71. I'm a little heavier because of my Jeep is 5,800 lbs. I drove all the way across the country and back this summer and I think my slowest speeds were around 48 mph when it was running right but I was not on 70 through Denver.
2015 Winnebago Tour 42QD
Cummins 8.9 ISL 450
Freightliner XCL W/IFS
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Old 09-18-2020, 05:57 PM   #4
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Location: Cen Il.
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Since it’s gradually getting worse I would throw a new fuel filter in it. Cheap and the easiest thing to try first.
2014 Fleetwood Providence 42p
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Old 09-18-2020, 06:09 PM   #5
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I agree, dosn't seem right. What is your boost showing. Should be 25-30 lbs.
Bigjon & Sandi
99 Monaco Executive M-450
2002 Suzuki Toad.
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Old 09-18-2020, 06:29 PM   #6
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Posts: 900
Both post #4 and #5 are probably on the right track. I would change filters and make sure they are using the Fleetguard Statapor filters, and on the next hard pull or accerlation look at your boost. Should be making close to 30psi. A small boost leak or a clogging filter will reduce power.
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Old 09-26-2020, 06:18 PM   #7
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We weigh just under 45K lbs loaded and we're not a speed demon either. I've had a couple of gassers towing a toad pass me.
Joe & Ro
2020 Dutch Star 4328 w FL Chassis
2018 Jeep GC Limited w Ready Brute Elite towbar
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cummins, loss of power, power

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