CAT 450HP engine fuel mileage

[tiffinboy]

I have a friend that claims he gets 10.5 MPG at 75 mph in his 2001 450HP Cat 40Ft beaver PT motorhome and his average is 9.5??
I only get 7.5 in my ISL425 and I only drive 63MPH ?
Is this believable or?
Hes pretty smart guy about facts and figures?

[Two_Jayhawks]

tiffinboy wrote:

Two Jayhawks wrote:

tiffinboy wrote:
I have a friend that claims he gets 10.5 MPG at 75 mph in his 2001 450HP Cat 40Ft beaver PT motorhome and his average is 9.5??
I only get 7.5 in my ISL425 and I only drive 63MPH ?
Is this believable or?
Hes pretty smart guy about facts and figures?

Your friend is stretching the truth a bit I think. My equipment is almost identical to your friends except I bet his weighs 5K more. I can return slightly over 10 all day long every day if I limit speed to 55-60. Done that over thousands of miles. At 75 I'll be 8.5.

ok so he says 9.8 average and u say 10 all day long so whos stretching the truth then?

Not to quibble but I can only achieve slightly over 10 by driving 55-60. Your friend is able to make 10.5 mpg driving 75. Big difference. He must have air tabs. 😉

[DSDP_Don]

tiffinboy......You originally asked if we thought your friend could get the mileage he was claiming. Several came on here, said he couldn't and explained why. Others told you what they were getting and how they achieved those numbers, but you have criticized or made fun of almost every response. Either you're a Troll or have the need to argue everything.

You state that you drive from Reno to Bishop and get no where near what others are getting....duh! If I drove back and forth over the Grapvine ten times and no where else, I would probably only see 3-5 mpg.

If you're goal is to argue or criticize every answer you get after asking a question, maybe you should find something else to do.

[Mr_Mark1]

gswcgi wrote:
I have a 36' Safari DP. How do you tilt the coach to one side or the other with the air bags. On mine all air bags deflate at once.

Gswcgi, our leveling system can be set in auto or manual mode. I can manually adjust all four corners of our coach on the 10 airbags or with the hydraulic levelers. When I pull into the diesel pump area, I hit 'manual' on our leveling pad and I hold down the 'lower' button for the right front and right rear. It automatically chooses air leveling as I have to specifically hit 'hydraulic' if I want to use the level legs. The coach starts releasing air from the airbags and I start leaning towards the passenger side. Instead of using 'lower', I could hit 'raise' on the driver's side (front and rear) and the coach will rise which will, again, lean me over to the passenger side.

Sometimes, the 'twisting' light will illuminate on the pad and I'll stop the front and/or rear, most of the time it won't twist (all depends on the angle). Once I'm done, I start the coach and hit 'travel' and we level-out and are ready to go and my fuel tank is tip-top full!

There is also a 'raise all' and 'lower all' button if I want to raise or lower the WHOLE coach manually on the airbags.

Mark

[tiffinboy]

RayChez wrote:
What Mr Marks posted is about right for a coach weighing 40K lbs. It takes every bid of that ISL 425 hp 8.9L to move that weight. While the Beaver 40 footer with the big Cat 14.6L should be cruising with that weight. So like many have posted here before that the more power an engine has the better fuel mileage it would get. There is a lot of difference between a 8.9L and 14.6L engine.

its not 14L its a 425C12 which is 11.9 so still huge compared to 8.9L though

[Two_Jayhawks]

tiffinboy wrote:
I have a friend that claims he gets 10.5 MPG at 75 mph in his 2001 450HP Cat 40Ft beaver PT motorhome and his average is 9.5??
I only get 7.5 in my ISL425 and I only drive 63MPH ?
Is this believable or?
Hes pretty smart guy about facts and figures?

Your friend is stretching the truth a bit I think. My equipment is almost identical to your friends except I bet his weighs 5K more. I can return slightly over 10 all day long every day if I limit speed to 55-60. Done that over thousands of miles. At 75 I'll be 8.5.

[gswcgi]

I have a 36' Safari DP. How do you tilt the coach to one side or the other with the air bags. On mine all air bags deflate at once.

[Mr_Mark1]

tiffinboy wrote:
Mr mark we have almost identical coaches weight and engine wise.I have never seen 9.8 average ever.I have seen 8 maybe but my trips involve a lot of hills and mountain passes so that hurts at around 1.5MPG so perhaps if I was to go 1000 miles on flat freeway I would see 9.5 or better iam sure.I installed the
adjustable Electronic Fuel pressure regulater and that seems to help under normal throttle and gives better power.adds around 40-60HP

Tiffinboy, when I say '9.8', it happened on one tank of fuel (actually maybe 2 or 3 times) but it was a perfect low wind day probably driving east as the wind usually blows West to East (in the southwest) and the terrain was probably almost flat. If I remember correctly, my Aladdin computer system states that our total average is 7.3 mpg over the almost 65,000 miles I have on the coach.

On edit: I generally run 400-600 miles before I fill up so I get a good run for figuring fuel mileage. Only a few times have I let my tank get down to 1/4, normally I fill up at about 1/2 tank.

Mark

[tiffinboy]

Mr mark we have almost identical coaches weight and engine wise.I have never seen 9.8 average ever.I have seen 8 maybe but my trips involve a lot of hills and mountain passes so that hurts at around 1.5MPG so perhaps if I was to go 1000 miles on flat freeway I would see 9.5 or better iam sure.I installed the
adjustable Electronic Fuel pressure regulater and that seems to help under normal throttle and gives better power.adds around 40-60HP

[Mr_Mark1]

tiffinboy wrote:

Mr.Mark wrote:

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.

ok u say smart wheel(wrong term) I simply say I use cruise control
I average 7.8 last trip lots of passes.I looked at the mileage chart and fuel used of the Cat 425HP friend and he got 9.7 from Edmonton to las vegas

Tiffy, I was using your term 'smart wheel' but we both know we are talking about the cruise control. I certainly wasn't referring to blinking my marker lights! LOL!

Over the 65,000 miles I've driven our coach I check the fuel mileage with pen and paper. I've gotten 4.5-9.8 mpg (we tow 99.9% of the time and I usually travel at 58-60 mph). I also make note on the receipt of how much generator time and or Aqua-Hot I've used if I really want 'real' numbers.

Mark

[RayChez]

What Mr Marks posted is about right for a coach weighing 40K lbs. It takes every bid of that ISL 425 hp 8.9L to move that weight. While the Beaver 40 footer with the big Cat 14.6L should be cruising with that weight. So like many have posted here before that the more power an engine has the better fuel mileage it would get. There is a lot of difference between a 8.9L and 14.6L engine.

[Mr_Mark1]

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.

[wilco]

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!

[docj]

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.

[DSDP_Don]

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.