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Fuel mileage question

Yahoo Message Number: 69917
I am buying a few lottery tickets and expect to win enough to upgrade to a newer CC in the next year or so. That said, I am curious as to the fuel mileage that coaches with the bigger engines (500+ hp) get versus the standard size (400 hp). I realize that the larger engines may be put in coaches that weigh more than the standard size engines and that will influence mpg. So, I have two questions: 1) Are the larger engines as efficient as the standard size ones? And, 2) Do the Cat engines get as good mpg as the Cummins of the approximate same size?
Everyone wants a large enough engine to produce sufficient torque to get up long, steep hills without undue struggling? (My 350 hp Cummins produces 1050 foot pounds of torque that only push my coach and pickup up a long hill like Black Mountain on I-40 in NC at 37 mph). However, I wonder if the 525 and 600 hp engines are more than needed and use more fuel, or don't work as hard and use the same or less fuel to get the job done. To be fair, one would have to consider if they are an aggressive driver (drive the maximum speed limit) or a conservative driver (I drive 61 mph even on highways with 70 mph limit to get the best mpg).
I have no clue as to the "average" fuel mileage of the larger engines. I haven't seen any discussion as to the difference between the Cat engines and the Cummins of similar hp, if there is any. With diesel prices already at nearly $4.00 a gallon in Texas and going up every week in every state, anyone considering purchasing a newer coach will want this information to be a part of their of their decision. Obviously, an exceptionally good price would make up the difference in mpg for a number of years.
While I wait for some input, I'll send Martha out to buy some lottery tickets. You can't win unless you buy them, and she is always has better luck than I do. With chances being at least a million to one, maybe I had better invest my $5 a week.

Gene Merryman

2000 Allure #30496

Re: Fuel mileage question

Reply #1 –
Yahoo Message Number: 69918
Gene,

The simple answer is larger engines are usually used in bigger, heavier coaches, so they get less MPG.
That being said. It takes xx amount of fuel to produce xx amount of power, regardless of what is doing it. There is a little more friction loss in larger engines. But from a math point the fuel used is equal to the power used. This is a very simple answer, there are a lot more formulas, etc that can be sued itf you want to really twist your heard up.
My coach is 46,000, not towing anything I average right at 6 MPG. Towing a 5500 lb toad it drops to about 5.6. TOwing my 22,000 lb 32' stacker I get about 4.5.

The coach has a series 60 DDA

Mikee

Re: Fuel mileage question

Reply #2 –
Yahoo Message Number: 69921
Gene...

Go to the CATRVCLUB forum and you will find polls on fuel mileage for most of the Cat engines...
As for me, 36foot '99 Magna with Cat C10 385hp, Allison HD4060 transmission... I get 8.3 MPG with GCWR of 42,000+

No problems pulling hills with or without toad...
I run the C10 at 1300 rpm, (in the "sweet spot", just abve max torque of 1250lbft) At that setting, the Ol' Magna is doing 60MPH which is fast enough for me... At higher speeds the mileage drops like a rock...

buck

k7wn, '99magna5653, Cat C10, Allison HD4060

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Re: Fuel mileage question

Reply #3 –
Yahoo Message Number: 69923
Gene, I agree with what Mikee and buck have already said. I have a C-13 CAT (525 HP, 1,650 torque), now at 41,000+ miles. My coach is 42,000 lbs loaded up and the toad 4,000 lbs. I drive about the same as you. We just returned from a 3,000 mile round trip and my overall average was 7.7 MPG. I pull the hills just fine, pass all the trucks going up and am mostly at 45 MPH+, except for the monster climbs.
I have the spread sheet buck mentioned and have put the numbers to a graph, which I will email you directly. If anyone else is interested in MPG that well over 100 CAT owners reported for a variety of engine sizes, let me know.

Lee
--

Lee Zaborowski

07 Intrigue 12153, Cat C-13

Re: Fuel mileage question

Reply #4 –
Yahoo Message Number: 69928
Thanks, Lee! I know Mike would appreciate receiving that graph. Our Cat-9 sometimes gets up to 7.7 but it also can be less. We rarely drive over 65 mph and pull most hills fine too. Before our last trip of about 4500 miles, Mike removed the mud flap from the back of the coach per several suggestions on our forum here, and we saw a little mph improvement.

Mike Frederick
06 Inspire 51784

Re: Fuel mileage question

Reply #5 –
Yahoo Message Number: 69929
I'll put in my 2 CENTS WORTH. I have ISL 400 in my Intrigue 42' Ovation, 40,000 lbs loaded. I get better fuel milage than my old Allure with ISC 330 at 31,500 lbs at 63 mph on the flat and level. I can keep up with any prevost with the 515 Detroit on any grade. If I play my cards right I can keep up with any 45' Magna or Affinity with the 525 CAT. These guys with the 505 in my same coach, or the tuned up 505's in the Magnas and Affinities, putting 530 HP on the ground and the 600 and 650 Cummins and CATS leave me in the wake of their dust. Grades where I am running 45 in the Cascades, the Sierras, in Colorado, or the Grape Vine in CALIF. ; they are easily doing 60 + mph no matter what they are hauling. As to milage as I found out at CC owners conference before a factory rally CATS average a mile to mile and half less than a Cummins which averages less than a Series 6 Detroit at similar horse power ratings. If you go back and read reviews in FMCA Magazine etc, you will see Lexas and big Affinities getting 5.5 to 6mpg. I have had owners with 525 Cats tell me the same thing. They also say they picked up some milage with the newer Cats after reprograming. The Cummins 600 seems to get anywhere from 6,5 to 7.2 depending on how you drive them. I drove a 2008 Magna on a loop and the Silver leaf said I got 4.6 driving through downtown Eugene to Springfield, but ended up averaging 6.7 circling around to Harrisburg and back to JC where I started.I can get 8.6 to 9.3 driving 55 on the flat and level with my ISL down to 6.9 running up and down Wolf Creek Pass, Monarch pass, or 75 mph between San Antonio and El Paso, with a Spring headwind. A challenge is the western approach to Eisenhower tunnel on I-70 west of Denver. With a head wind I was down to 35 mph and was getting ready to hop in the Honda and push. I had the local Cummins people replace my charge air cooler and reposition a leaky sensor on the crossover pipe 5 years ago. So the last time on the Dyno I was putting 360 hp on the ground about 44o HP at the flywheel in 4th gear. TWI 20045 Intrigue 11731

Re: Fuel mileage question

Reply #6 –
Yahoo Message Number: 69931
gene nailed it . it's all in how you drive. if you feel the need to be first all the time, you'll pay at the pump. when i trucked i had a 425 Cat 4.25 mpg average for a year. my gross weight was 160,000lb on 11 axle rig. running Michigan train. now with my '02 Magna & my enclosed car trailer loaded with '53 hornet + stuff i average 7mpg. bob '02 magna 6028(C12-425hp Cat)

Re: Fuel mileage question

Reply #7 –
Yahoo Message Number: 69932
gene nailed it . it's all in how you drive. if you feel the need to be first all the time, you'll pay at the pump. when i trucked i had a 425 Cat 4.25 mpg average for a year. my gross weight was 160,000lb on 11 axle rig. running Michigan train. now with my '02 Magna & my enclosed car trailer loaded with '53 hornet + stuff i average 7mpg. bob '02 magna 6028(C12-425hp Cat)
 

Re: Fuel mileage question

Reply #8 –
Yahoo Message Number: 69941
I'm getting what seems to be better than reported mileage in my Lexa.
My first major stint (Seattle to Phoenix) in my Lexa with 515hp Cat C-15, averaging about 59mph, was 7.15mpg. This was with a crack in the Charge Air Cooler, giving my 17psi max boost.
The return trip, with new radiator and fixed charge air cooler (getting 24psi max boost), was 7.22mpg, but I averaged 68mph (needed to make it back in two days, also had new 75mph Michelins).

Jim