Monaco Signature

[Kooldude3066]

What fuel burn(mileage) experence have other owners experenced and at what speeds, towing, load, ect.

[Mike Canter]

Which engine and what year? In my 2004 Signature with a Detroit Series 60 motor on a flat road with zero wind I get 8 mpg at 55 mph and for every one MPH increase my MPG goes down 0.1. That is towing a Jeep Wrangler. My Signature really doesn't even know the Jeep is back there (lol). The sweet spot of the Detroit Diesel is said to be at 1450 rpm which is right at 62 mph and that is what speed I normally drive which gives me a pretty solid 7-7.3 MPG.

Do you have a Signature or are you looking to buy one?

[Kooldude3066]

I'm looking at a 2002 with the 450 hp Cummings. It is a 45', and I think it may be to long for the type of traveling I intend to do.I am trying to find size and construction with out the complexity of the signature model. I have Friends that have Monaco's and like them. I have owned large off shore yachts (Nordhavn)and the less bells and whistles the better, but I do not want to buy a Winny Bunkhouse either.

Dave
Also an airedale beebe stacker

[cb5300]

I have a 2008 Signature with 31K miles on it. It has a Cummins 600 (ISX) motor in it with 4.33 gears. The sweetspot is 1600 rpm and that equals 70 mph. Towing a 2007 Ford Explorer yields an average of a hair over 6 mpg.

I agree with you that the Cummins 400 might be a little lite for a 45ft Sig, but I sure that you will love the coach.

[Mike Canter]

That is a little confusing because I thought the Cummins ISM-500hp was the standard motor back then in 2002 for the Signature. The 2002 Sig weighed in at 47600 lbs and needed at least 500 hp.

[jsabatinos]

How is the "sweet spot" determined? I have an 08 Dynasty 45 with ISM 500.

Thanks
Jim

[Mike Canter]

The "Sweet Spot" is based on the engines torque curve. I know for 18 wheelers they attempt to gear then to have the Sweet Spot at 65 MPH. I have know idea what they do for MH's. Since MHs have automatic transmission we always run in 6th gear so we should change the speed to try and be in the Sweet Spot. I do lnow the "Sweet Spot" is not always the same for a particular motor because of changes in the motors. 2007 was a big year for changes in motors because of emissions and it appears that the Sweet Spot after 2007 dropped about 150 to 200 RPM from pre 2007 Sweet Spots. The Sweet Spot for smaller diesels is s lot higher than for big diesels again it is based on torque.

[moisheh]

It is easy to find the best speed for any unit. Drive on a fairly flat highway without any wind. Watch your Allison read out. The best speed would be where the tranny has shifted into 6th gear and does not hunt. On our Dynasty that is 62 mph towing a full size Silverado. Driving slower will not save any fuel as the Allison will dowshift to 5th gear.

[lonestarace]

We've had 4 tag axle Signatures ranging from 42' to 45'. A 98, 99, 00, & 2002. The 98 & 99 had 450hp Cummins M11s. And our current 2 Signatures, 00 43' Caesar and A 02 45' Empress, have 500hp Cummins ISMs. They have ranged in weight, lightly loaded, from 35.5k Lbs to 40.5k Lbs(wo toad). At 60 mph our mileage varies from 10 to 8 mpg.

We hope this helps

[dashdriver]

I've got the Cummins ISM 450 in my HR Navigator (42'). I get between 7.5 and 8.5 (depending on wind and grade) and my speed is usually around 60-65 mph (no toad). My weight is around 36k lbs if I remember right from the last time I had her weighed on a long trip.

[Mike Canter]

I thought you all might find this interesting since it deals with several of the engines used in the Signature. The big thing appears to be the change to the engines in 2007 for emission. The 2006 and prior motors ran a higher rpm "Sweet Spot" than the 2007 and later.

QUOTE
Many '07-spec diesels run 50 to 150 rpm slower than '02 to '06 diesels, which in turn were as much as 200 rpm slower than pre- '02 engines, notes ArvinMeritor, a major axle supplier. Most fleets have stayed with the same size wheels and tires, but have made other changes. For instance, some linehaul operators switched from overdrive transmissions to more efficient direct-drive models, which require "faster" (lower numerical) ratios to keep engine speed down. In view of this trend, ArvinMeritor developed and released a 2.50 to 1 ratio for its RS23-160 axle family in late 2005.
Linehaul tractors and trucks that spend a lot of time on freeways and Interstate highways might be set up to cruise at 65 mph. This, in fact, is the speed often cited by many engine makers, who state what rpm their engines should be turning at 65.

Of course, it all begins with the engine, and the chosen make and model's characteristics should be studied so the match with the rest of the drivetrain will be a good one. Sweet spots and operating ranges vary by engine make and model, and we list them below. Another number often cited by engine makers is desired rpm at 65 mph, though that engine rpm might also be used at another road speed for other operations. Read and heed:
• Caterpillar – 2007 Cat C15s, including Multi-Torque models rated at 1,750 pounds-feet or more, should be geared for 1,325 rpm at 65 mph. C15s making less than 1,750 pounds-feet should run slightly faster – 1,400 rpm at 65 mph. And the C15 Heavy Haul, for rigs grossing 90,000 pounds or more, should spin at 1,500 to 1,650 rpm at 65 mph. As with the 2004 ACERT engines, operators of 2007 Cats have a wide operating range, with peak torque at 1,200 rpm but luggable to as low as 1,100 rpm. In high-range gears, transmissions should be upshifted at 1,500 rpm to get maximum fuel economy.
Cat's other heavy-duty models should turn at these rpm at 65 mph: C13 Multi-Torque with 1,750 pounds-feet, 1,325 rpm; C13 with 1,650 pounds-feet, 1,400 rpm; C9 with 1250 pounds-feet or more, 1,550 rpm; C9 with 1,150 pounds-feet or less, 1,650 rpm. Cat's medium-duty C7 should turn 2,000 rpm at 60 mph, or 2,200 rpm at 60 mph if better low-end startability and performance is needed.
• Cummins – The ISX's sweet spot is 1,400 to 1,500 rpm at 65 mph for linehaul applications. In vocational trucks, the ISX should run between 1,600 to 1,900 rpm at intended cruising speed. The ISM should run 1,500 to 1,600 rpm in linehaul and 1,700 to 2,000 rpm in vocational trucks. The ISL should operate between 1,600 and 1,900 rpm in linehaul and vocational trucks. For the higher-speed midrange ISC, it's 2,000 to 2,150 for steady 65-mph cruising and 2,150 to 2,300 for P&D and other urban applications. The even faster-running ISB, used in medium and light trucks and as the Dodge-Cummins Turbo Diesel, should cruise at 2,100 to 2,400 rpm at 65 mph.
• Detroit Diesel – For 2007 the Series 60 is only offered in a 14-liter size, and its sweet spot is 1,450 rpm. For vehicles grossing up to 80,000 pounds, the suggested engine cruising speed is 1,450 to 1,550 rpm, which would require a lower numerical axle ratio compared to an 2006 spec with a cruise rpm of 1,550 or more. The 2007 variable-geometry turbocharger and a torque curve extending down to 1,100 rpm make the S60s very driveable at lower engine speeds.

[boaterok]

Mike, since yours is a 04 Sig with DS60 5?? hp what do you see your sweet spot being on your unit? Would you assume yours would be the same as mine with a 05 Ex DS60 515hp, if you would advise I will try it. I expect my new trailer next week which will be a foot shorter and v nosed and weigh in 6k pounds less unloaded. I am axious to pull it to see what the mpg is with it. Roger

[Mike Canter]

Well if I believe the article and the guy seemed to know what he was talking about. (Knew more than me on sweet spots) then our Sweet Spot is at 1550 RPM which is around 65-66 mph. I believe that is where Monaco designed it to be. The problem is that there are really three types of driving conditions; steep grades which doesn't count because you have no choice but to keep it around 1800 rpm for horsepower, slight to medium hills and flat and level. I think my Sig with the S-60 runs better on slight to medium hills at 65 MPH because it is better positioned on the torque curve but on flat level there is no doubt that the slowest you go in 6th gear is going to give you the best MPG. I find the best compromise is 62 mph which is the 1450 rpm, below 57 mph it is going to drop into 5th gear and at 55 mph I am going to fall asleep. I find it tiring to drive so fast that I have to keep pulling out and passing people and at 62 I can stay in the right lane with my VORAD on and can drive a long time. If somebody gets in my way the VORAD just slows me down until they wake up then I speed back up. In metro areas I get out of that left lane and stay in the middle lane because of the local blind drivers.

[boaterok]

Thanks I concur with you rpm sweet spot of 1450 as I to find thats just about right to be out of 5th on flatland. Do you know what programming your motor has I think they call it DEC 7,8,9 or something?