I just came back from Florida with my Vista V-10, going down I drove at 61/62 mph and it was based more on comfort than anything else, I averaged 6.6 mpg pulling a Jeep Liberty. Coming home I was in more of a hurry and drove at 65/67 mph still got 6.6 mpg average on 4 fill ups. However, I didn't feel comfortable at that speed and will go back to 61/62 mpg and be able to relax. Also, all the way down, apx. 1200 miles, I passed only 3 trucks and never got to the point that I was tailgating someone, it was a very relaxing speed.
I have an 06 Phaeton, with a 350 CAT and pull an 2003 Honda Pilot SUV. At 65 MPH on flat land the tach reads 1750 consistently. I often wonder if this is a good thing or a bad thing??
John S. wrote: My coach shifts into 6th gear at 62 mph. So, 65 is my sweet spot as I can set the cruise and stay in 6 th gear for the best fuel milage and distance covering.
IMHO, you'd get better mileage by driving slower in 5th gear.
I'm thinking you are not correct on this one. Diesels are a different animal than gassers. Depending on the final drive it's probably turning fewer RPM's at 65MPH in 6th gear than it would at 55 MPH in 5th gear.
There are 24 hours in every day - it all depends on how you choose to use them.
Bruce & Jill Brown
2008 Kountry Star Pusher 3910
kitch251 wrote: I have an 06 Phaeton, with a 350 CAT and pull an 2003 Honda Pilot SUV. At 65 MPH on flat land the tach reads 1750 consistently. I often wonder if this is a good thing or a bad thing??
Jij
Thats not bad. Assuming it's a C7 Cat I think you'll find the published peak HP to be at 1600 RPM's, the peak torque around 1450 RPM's. A little taller tire or a little longer gear ratio might help a little with the MPG's, but you're not in a bad spot at all.
goufgators wrote: I've read posts about a vehicle's "sweet spot" with the OP usually citing a given MPH speed such as 55, 60, etc. I suppose that is the speed that gives, in the opinion of the poster, both optimum power and gas mileage. My question is: how is that "sweet spot" determined? Of course, I can determing the speeed at which best MPG is achieved but do not know how to associate that bit of information with determining best power range. My MH is an '05 gas Itasca. Thanks for any input... Larry
I go just fast enough to keep it in OD most of the time, which for me is 51 - 53mph. We're not in any hurry with driving a 10 ton behemoth and there's plenty of lanes for the rest. Any faster has to burn more fuel or defy the laws of Physics.
"We are often so caught up in our destination that we forget to appreciate the journey."
1998 36ft. National Tropi-Cal Model 6350 on a 1997 Chevy P32
Chassis_7.4 Vortec Engine_4L80E Tranny_slide_tag axle.
Our 425hp ISL Cummins has a 6 speed Allison that shifts into 6th gear exactly at 55 mph. If there is not too much of a demand on the engine, it will stay in 6th until about 51 mph then shift to 5th gear. In 6th, the RPM's are running about 1,500.
Over 52,000 miles of checking my mpg's.... 55 mph is absolutely the best. I try to stay between 55-60 mph which will give me 7.5-8.0 mpg. I check my fuel economy at every fuel stop as I'm just a numbers person (accountant).
MM.
Mr.Mark
2008 Monaco Dynasty, 42.2 ft., 4 slides, 425 hp clean-air Cummins diesel
2013 Honda CR-V EXL, AWD, w/Nav, SMI Air Force One vacuum-assisted braking
Our C-12 Cat seems to give the best economy at about 1350 rpm or so. 6th gear at 63 or 5th at 55 although the jury is still out on which is better as it's very terrain and wind dependant so I need a lot more driving to figure it our. I've seen as high as 14 at 55 while in OR but not often.
The Silverleaf is spot on for mileage but of course does not take any genny or Hurricane usage into consideration.
The Cat performs best when lugging the engine so I tend to use economy mode whenever practical.
Dick
2000 40" DP Beaver Patriot Thunder Cat C-12 425 HP, 1550 Tq
1997 Jeep GC Limited ---toad
2008 Toyota Tundra Crew Max Limited TRD (Retired)
2009 Cougar 268 RLS ~8700 lbs road wt (Retrired)
2006 Jeep Liberty Turbo Diesel.....TV in Training
John S. wrote: My coach shifts into 6th gear at 62 mph. So, 65 is my sweet spot as I can set the cruise and stay in 6 th gear for the best fuel milage and distance covering.
IMHO, you'd get better mileage by driving slower in 5th gear.
I'm thinking you are not correct on this one. Diesels are a different animal than gassers. Depending on the final drive it's probably turning fewer RPM's at 65MPH in 6th gear than it would at 55 MPH in 5th gear.
The major factor in fuel/gas mileage is drag created by wind resistance. Higher speed more drag.
Sarver, PA/Crystal River, FL/Shelocta, PA · W3TLN · FMCA 335149 · Mystic Knights of the Sea
2005 Suncruiser 38R · W24 chassis, no chassis mods needed · 2012 Honda Accord EX-L · 2008 Honda Odyssey EX-L
We used to travel at the speed limit, but we found that dropping down to max of 62-64 mph improved mpg and reduced driver stress significantly. We often will seek roads where 50 to 55 mph is the limit to further reduce stress and improve mpg. On the Natchez Trace Parkway when rolling along at 50 mph (the limit) we were at 3000 RPM in 4th. took the speed up to 52 and RPM dropped to 2200 in fifth and the road speed felt comfortable to us.
Sweet spot for us is the mix of mpg and driver stress, I guess the latter got more important a few years ago when we started drawing Social Security. Of course when we get our DP I will have to revisit much of this, but I cannot imagine pushing over 64 mph for any length of time, I don't even drive the tow'd any faster these days, what's the hurry?
Paul
Trucking down the road in our new Phaeton 36QSH on Freightliner Chassis with a Cummins 380 pushing it. 2011 Cherry Red Jeep Wrangler Rubicon with US Gear Unified Tow Brake System. Check out my blog
FMCA 352081 SKP# 99526
My 8.1L gaser seems to like between 60-62 mph in 6th gear. If I'm in slightly hilly terrain (not huge mountains) and driving 55 in cruise control, I notice the rpm's dropping off and it gets close to hunting; it doesn't do that at 60-62mpg.
I only check total trip gas mileage as a curiosity, I've never checked it to look at the sweet spot.
Eric
2009 Holiday Rambler Admiral 33SFS (34' 3")
2008 Jeep Liberty - North Edition (4x4 auto)
FQCC/Camping Quebec, KOA, Good Sam, Coach-Net
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