wallynm
Los Alamos NM
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Joined: 09/27/2000
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Most folks will say I full of it, but we ran our 2000 Suburban 5.3 L on the cruise control on a recent run from Albuquerque to Colorado Springs, to Frisco, Colorado and back to Albuquerque. We ran @ 65 MPH and the the RPMs were around 1800 and averaged 21.3 MPG. No a lot of wind but some in places and several changes in elevations that exceeded 10,000 ft.
Have a Cat Engine Yahoo Group or Cat RV Club Web Page
Have a Freightliner Yahoo Group or FCOC Web Page
wallynm@yahoo.com
2002 DSDP 3567 PUSHED BY KITTY KAT
THOSE THAT DO NOT KNOW HISTORY ARE DOOMED TO REPEAT IT
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jmadre
Elizabeth City, NC
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Joined: 11/10/2007
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alcolby wrote:Any engine has a sweet spot for fuel efficiency, find out what yours is, and that's where the best MPG is.
It is not necessarily "low RPM's"
Al C
joebloe wrote:All things beng equal(tire pressure, drivetrain health), mpg is about rpm. Keep your rpm down, your mpg goes up. That's the end of that tune.
I keep reading comments about lower RPMs equaling higher efficiency. I agree with Al. Our 5.3L Tahoe gets the same MPG at 2100 RPM out of overdrive as it does at 1500 RPM in overdrive. I use the Tow/Haul mode to switch between the two.
1994 Coachman Catalina 280RK behind a 2007 Chevrolet Silverado 2500HD 6.0L + Equalizer 10,000# + Prodigy brake controller
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JohnMo
Kentucky
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Joined: 11/09/2007
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alcolby wrote:Any engine has a sweet spot for fuel efficiency, find out what yours is, and that's where the best MPG is.
It is not necessarily "low RPM's"
This is true, and probably especially so for RVs. I travel a lot of secondary highways where the speed limit is 55 MPH. Even in my Corolla, you don't want to start out at the bottom of a hill at 55 MPH. The Corolla's been much happier in the 60-65 MPH range.
On very flat roads we could all probably maximize MPG by driving 45 or 50 MPH, but the road is a factor that has to be taken into account.
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JohnMo
Kentucky
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wallynm wrote:Most folks will say I full of it, but we ran our 2000 Suburban 5.3 L on the cruise control on a recent run from Albuquerque to Colorado Springs, to Frisco, Colorado and back to Albuquerque. We ran @ 65 MPH and the the RPMs were around 1800 and averaged 21.3 MPG. No a lot of wind but some in places and several changes in elevations that exceeded 10,000 ft.
I believe it. My '96 Suburban with a 5.7 and 160k miles on the clock routinely does 16 MPG without a lot of special effort. I've always thought that it might do 20 MPG if it were in top shape and speeds were held to <= 65 MPH.
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david_42
Oregon
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Joined: 04/08/2005
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I drive about the same way, but I don't use the resume function, because when I get to 40 mph, it goes to full throttle! Up to 40, it's nice & slow. Of course, with a diesel, higher throttle setting for acceleration makes sense, but I find the change-over disconcerting.
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BurmaShave
Minnesota
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Joined: 09/26/2001
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You will wear out your tires 10,000 miles sooner due to the higher pressure which will cost you $ 80 prorated for 4 tires.
The key to mileage is not rpm, it is throttle opening (BMEP). Driving in 5th at low RPM and lugging will burn far more gas than at a reasonable rpm like 1/3 of max
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wolfe10
Texas
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Joined: 10/08/2000
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BurmaShave wrote:You will wear out your tires 10,000 miles sooner due to the higher pressure which will cost you $ 80 prorated for 4 tires.
A 4 PSI increase over factory recommended PSI is unlikely to cause any grave issues. Remember, factory recommendations are generally based on COMFORT, not MPG, handling or tire wear.
Brett Wolfe
1993 Foretravel 36' U-240
Cat 3116, Allison 3060
Caterpillar RV Engine Owner's Club: www.catrvclub.org
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JohnMo
Kentucky
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BurmaShave wrote:You will wear out your tires 10,000 miles sooner due to the higher pressure which will cost you $ 80 prorated for 4 tires.
I'm not sure I buy that. Raising pressure reduces rolling resistance, which I would think would also reduce overall wear as the tires are scrubbing less overall. Might change where some of the wear occurs, but as long as you're under the max PSI listed on the sidewall, I don't see a problem.
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longhornheifer
San Antonio, TX
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Joined: 05/18/2004
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According to an article in the most recent MH or Good Sam magazine, you can get better mileage NOT using cruise control.
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Sully2
Cincinnati
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Joined: 01/20/2003
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JohnMo wrote:BurmaShave wrote:You will wear out your tires 10,000 miles sooner due to the higher pressure which will cost you $ 80 prorated for 4 tires.
I'm not sure I buy that. Raising pressure reduces rolling resistance, which I would think would also reduce overall wear as the tires are scrubbing less overall. Might change where some of the wear occurs, but as long as you're under the max PSI listed on the sidewall, I don't see a problem.
The inflation pressure stamped into the sidewall is the MINIMUM inflation pressure...to be able to carry the tires MAXIMUM loads...
2000 Country Coach Allure; Cummins ISC 330 HP; 71/2 - 8 MPG regardless
2002 Jeep Liberty
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