CAT 450HP engine fuel mileage

tiffinboy wrote:

Diplomat Don wrote:
tiffinboy......Mine is a 36' weighing in at about 29000 pounds. I run about 1490 rpm at 59 mph. My Monaco is a rear radiator and I replaced the engine fan with a Source Engineering fan which uses less power and increases HP by 25. I also run a DiGiCr engine chip which has provided a very noticeable increase in mileage. I add OptiLube at every fill up and I drive using my VMSpc computer. I'm constantly watching my instant mpg and change my driving habits as mpg changes, such as wind or hills.

I have a SmartWheel and do 90% of my driving by never touching the throttle pedal as I hate the feel of it. I enter freeway on ramps at a reasonable speed unless traffic requires a faster entry. Once I hit 45 mph on a ramp, I set the cruise and then throttle up a mile per hour every second or two using the SmartWheel. All of my freeway driving is done by thumbing the cruise control up and done with very little use of the throttle pedal.

If I take a short trip to a local park (95) miles away, I only average about 8.5 mpg since there is so much starting and stopping. The long trip we took was literally 6000 miles of highway driving at speed with few stops and starts. I track my mpg via my VMSpc and my wife does it on paper at every fuel stop. On trips that I don't tow where there is a lot of nonstop highway driving I can get 10 mpg.

I've been on this forum for over 8 years and have read a lot about the fuel mileage people get. I would have to say that yours is low for the speeds you're driving. I would question your driving habits. Your mileage is closer to what the people who drive 65-70 mph are getting.

go from reno to bishop and back and I bet u get 5.5.in what way does a smart wheel help fuel mileage?

I actually use my Smart Wheel the same as Diplomat Don.... set the cruise and bump it up slowly (if traffic allows). I, like Don, don't like to use my throttle pedal. Our coach weighs just over 40,000 lbs. and we average about 7.0-7.5.

When fueling, I always tilt the coach with the airbags towards the passenger side so that I can fill it to the brim. I can go at least 100 miles before the needle moves off of full.

MM.

Fishers exaggerate the size of their catch, golfers fudge their scores, motorists enhance their mileage reports, Motorhomers dream about coaches that get more than 10 mpg and handle effortlessly in a strong crosswind. Some report excellent results...but physics is physics!

tiffinboy wrote:

Ivylog wrote:
The Cat 3406 is a great engine. 10 yes, but not at 75. 14.6L geared to run 65 at 1300 rpms in a coach that weighs 34K maybe with a tail wind.

ok never knew his ratio was so much higher than mine.Iam 1650@62
also did not know it was 14.6L engine? that's huge compared to my 8.9

Thanks for the reply

Unless things changed a lot in 2001, our 2000 Patriot Thunder has a C12, not the larger CAT and gets 425 HP from it. According to our Silverleaf, our average fuel economy is ~8.5 mpg with some days as high as ~9 mpg and as low as ~7.5 mpg. Under extreme conditions we have been able to average >10 mpg for an entire day but that is rarely the case.

We weigh ~37,000 pounds with our toad.

tiffinboy......Mine is a 36' weighing in at about 29000 pounds. I run about 1490 rpm at 59 mph. My Monaco is a rear radiator and I replaced the engine fan with a Source Engineering fan which uses less power and increases HP by 25. I also run a DiGiCr engine chip which has provided a very noticeable increase in mileage. I add OptiLube at every fill up and I drive using my VMSpc computer. I'm constantly watching my instant mpg and change my driving habits as mpg changes, such as wind or hills.

I have a SmartWheel and do 90% of my driving by never touching the throttle pedal as I hate the feel of it. I enter freeway on ramps at a reasonable speed unless traffic requires a faster entry. Once I hit 45 mph on a ramp, I set the cruise and then throttle up a mile per hour every second or two using the SmartWheel. All of my freeway driving is done by thumbing the cruise control up and done with very little use of the throttle pedal.

If I take a short trip to a local park (95) miles away, I only average about 8.5 mpg since there is so much starting and stopping. The long trip we took was literally 6000 miles of highway driving at speed with few stops and starts. I track my mpg via my VMSpc and my wife does it on paper at every fuel stop. On trips that I don't tow where there is a lot of nonstop highway driving I can get 10 mpg.

I've been on this forum for over 8 years and have read a lot about the fuel mileage people get. I would have to say that yours is low for the speeds you're driving. I would question your driving habits. Your mileage is closer to what the people who drive 65-70 mph are getting.

The Caterpillar engine you mentioned is huge in comparison to your ISL. It will get ten miles per gallon because it has so much power and torque that it is just cruising with the weight of the 40 foot Beaver. I have seen it on big freight trucks going 75 mph, not sure about a Beaver or any other coach going that fast.

Yes he can get that mileage just before he wakes up from the dream that he's having! Even a coach that does get an occasional 10 mpg won't do it at 75 mph.

Here's what typically happens.....you have guys that never really tract their mileage, but will on occasion see that they didn't take on as much fuel as they thought they would at a particular fuel stop. They check their mileage and see they got about 9.8 and round it off to 10 mpg. What really happened was they were on an angle at the last fuel up and added an additional 5 gallons of fuel. Then they fill up angled the other way and take 5-7 gallons less than they normally would. So between the two fill ups they were off by over 10 gallons. If you drive 400 miles and take on 40 gallons you get 10 mpg. Now add in that 10 gallons of over and under fueling and you're now at 8 mpg.

The above happens often with the DP's since the tanks are almost 8' across and leaning in one direction or the other can really change how much they take. The Monaco tanks have metal pipe fillers welded on the top edge of both sides of the tank and are really susceptible to this.

We just returned from a 6300 mile trip. We started the trip and ended the trip by fueling up at the same station and in the same position. We then calculated the fuel mileage for the entire trip. We saw some 7 mpg's and some 11 mpg's, all caused by how the coach was leaning when we fueled up. We have a short and fairly light DP with a very economical ISL 400. We averaged 9.24 mpg over 6000 miles towing our truck at 58-59 mph (we only passed two other RV's). I can definitely say your friend driving 75 mph did not get 10 mpg.

Ivylog wrote:
The Cat 3406 is a great engine. 10 yes, but not at 75. 14.6L geared to run 65 at 1300 rpms in a coach that weighs 34K maybe with a tail wind.

ok never knew his ratio was so much higher than mine.Iam 1650@62
also did not know it was 14.6L engine? that's huge compared to my 8.9

Thanks for the reply

The Cat 3406 is a great engine. 10 yes, but not at 75. 14.6L geared to run 65 at 1300 rpms in a coach that weighs 34K maybe with a tail wind.