60 or 65 M.P.H. ?
Hello,I have always tracked my fuel mileage at 65 M.P.H. maximum speed. The decisionfor this speed was I felt that it would be a fair speed in which to give you information regarding the fuel economy of the Cascadia. I’m aware that many of you drive slower or even faster in your own trucks. Recently, I had a driver ask me what fuel mileage could the Cascadia and Detroit Diesel obtain at 60 M.P.H? I replied, maybe I need to try it out at 60 M.P.H. This got me to thinking it might be interesting to see the results being the truck is set up to be optimal at 65 M.P.H.
I decided to get feedback from you, my readers and see what you think? If you have an interest in knowing the fuel mileage results, I will be happy to take a week or two and run at 60 M.P.H maximum speed to see what the end results would be. Click on the comment button and let me know if there is any interest on this issue. Till next time… be safe,
Henry
February 22, 2012 at 8:57 am
Sounds like an interesting study, particularly because you are geared to run 65. Could make the ” slower is better” theory a little more complicated, which is just what everybody needs Henry; more complications! Necessary none the less.
February 22, 2012 at 12:15 pm
Henry,
Greetings. Love reading your blog, and am very impressed with your overall fuel mileage. I would love to see your results at 60 mph.
What is your final axle raito?
I am in the process of an RFP for a new Cascadia, and want to get as close to your spec as possible, but targeting 60 – 62 mph as the optimal speed.
Thanks,
Corey
February 22, 2012 at 12:27 pm
Cory,
I have a 3.42 final axle ratio.
February 22, 2012 at 1:14 pm
Thanks Henry,
I was kind of targeting 3.36, or possibly a 3.21, but wanted to make sure the DD 15 could be properly programed, in conjunction with the Ultrashift Plus, for lower shift points without negatively impacting fuel mileage.
C
February 22, 2012 at 1:25 pm
Henry,
That would be great to see the comparison between 60 and 65 mph. Especially since 55 is the speed limit here in Oregon. You can get away with 60, but 65 will earn you a ticket. If you end up in an accident and they can prove you were going 65, you may also earn a careless or reckless driving citation.
On a different but related note, what have you noticed on your fuel mileage after adding the smooth panels under your trailer?
Thanks,
Craig
February 22, 2012 at 1:32 pm
Craig,
I got into winter blend fuel right after putting the panels on.so I did not see any change yet. The one thing I can say for sure is the panels have greatly reduced the rain spray from the tandems of my trailer tandems.
February 22, 2012 at 3:38 pm
I would love to see you run 3 entire fuel tank fillings at 60 mph and another 3 at 55 mph and then compare mpg between 65, 60 and 55 mph. Any chance you can do that ?
February 22, 2012 at 3:39 pm
Henry, I would like to see what kind of fuel mileage you could coax out of your Cascadia for a month staying as low as possible in over drive so the truck does not shift constantly. A month would be a better test as you could run a DDEC report which would be very interesting reading.
With your truck spec’d for 65 mph this will be a good test.
February 22, 2012 at 3:43 pm
What about 55? I mean, if 60′s good, wouldn’t 55 be even better?
I can’t wait to see your numbers.
February 22, 2012 at 4:02 pm
We run 62 and see an improvement. Give it a try and see how you do!! Look forward to seeing the results. Thanks Henry!!
February 22, 2012 at 4:25 pm
I’m with Linda, I think you need to do it for a month since you’re coming into a little warmer weather. I would like to see you at 60 mph so I can compare the Cascadia to the Classic. Good luck. It will be interesting to see how you like driving slower. It’s definitely less stressful.
February 22, 2012 at 4:29 pm
Miguel,
I already have a good record of 65 mph. 60 is very possible to do but 55 would be tough because it would put me too close to my shift point between 12th and 13th gear. Driving at 55 might work but I would have to have a really light load to pull it off. That being said I am not sure what would be proven of any relevance. What do you think?
February 22, 2012 at 5:22 pm
I agree with Linda – you need to run 60 for a month.
If you do this – I will wear my pajamas for the Health Walk at MATS…
February 22, 2012 at 5:35 pm
I’d like to see you do a month at 60 and also a month at 55. I’m just as curious to see the difference in the time it takes to do your runs at those speeds.
February 22, 2012 at 6:25 pm
Henry, great topic, foot or cruise at those speeds/?? great post
February 22, 2012 at 9:15 pm
Heney,I too would love to see a month at 60 and a month at 55. As curious about the time differances as I am about the fuel mileage. I believe those numbers will be surprising. What would happen with locking out OD ? I thought running in direct is more efficient .
February 22, 2012 at 10:15 pm
Rich,
You are correct on the fact of direct drive being more effciant. The reason for my use is due to the gears that where availible for the 23,000 lb axle used in a 6×2 axle configuration. The gears where not avalibile for my driveline and the 6×2 had more to offer in regards to fuel mileage. Having the direct drive transmission and the tag axle would be the very best setup but it was not availible at the time the truck was being built.
February 22, 2012 at 10:18 pm
ELH,
That is a good question on use the foot or the cruise control. I might have to use the cruise at first just to get used to running at 60 instead of 65. Old habits die hard after all so we will have to see.
February 22, 2012 at 10:20 pm
Rich,
It will be interesting to see not only the time difference but also the savings to see how much MONEY was made in the extra time spent.
February 22, 2012 at 10:22 pm
PAJAMAS??? Now I know what to do. If I try 55 will you have Steve there in pajamas as well?
February 22, 2012 at 11:51 pm
Henry,
I think a month at 60 mph with a DDEC report for comparison would be awesome. Thanks for offering to do this.
February 23, 2012 at 7:43 am
Henry ,
YEP! You do 55 for a month and Steve and I both will wear our pajamas for the walk!
February 23, 2012 at 12:07 pm
I double dog dare ya to run 60 mph for a month. I’d love to see the numbers. You already defy physics by getting better mpg at faster speeds. Slower is intriguing. After those numbers come in maybe we can get you to run 57mph like Bob, Linda and I.
February 23, 2012 at 12:07 pm
Pam,
Lets get the 60 mph done first then we will talk about 55. So Steve is safe for now.
February 23, 2012 at 12:56 pm
Hello Again Henry,
I once drove a 2009 Volvo Vn670, 450 hp Cummins engine with 10 speed Autoshift transmission. I cant remember any other specs. It was governed at 70 mph, and if the display was close to accurate it would average 7.5 to 8.5 mpg.
Does this sound close to being possible with the increased speed, and if it is, would you consider it ?
Thanks, Bob
February 23, 2012 at 4:08 pm
Henry, do 55 for a month or I’ll do the walk NAKED ! You DO NOT want to subject your friends to that !
February 23, 2012 at 9:22 pm
Bob,
It sounds like it would be tough to hit those fuel mileage numbers at those speeds. I think my truck might be able to hit the 7.5 mark at 70 mph . One of the reasons for my staying at 65 is tire wear because wide base singles pick up bad wear patterns at higher speeds. The other factor is I dont need to run that fast to make my appointments and going faster would just be more time waiting. I will give the 70 mph speed some thought though.
February 24, 2012 at 2:26 am
Would love to see the results at 60 Henry……but I’d buy you a cup of coffee to see the results in 12th at 55. I’d think as long as you kept the rpm above 1225 you mileage should improve. Below 1225 rpm with any load would be, IMO, counterproductive. Miguel…what say you on this theory?
February 24, 2012 at 12:25 pm
Henry,
It really looks like you struck a “nerve” with this very important subject. It certainly will be interesting and informative to see the results of the tests between you and the Caffees’ when testing is complete. As you and I have discused, with the rapidly rising cost of fuel playing into the Fuel Surcharge, MPG really has an important impact on the bottom line of whoever is paying for the fuel consumed by each and every truck out there right now; I’m sure you will keep us informed ! ! !
February 26, 2012 at 5:25 pm
Henry -
if you find that your tranny ends up shifting to frequently when cruising at 55 mph, then by all means speed up. Basically trying to find the lowest possible cruising speed without impacting the shift frequency is what you want to do. This may end up being 56 or 57 or … you get the point. It would be interesting to see your average mpg at that lowest practical cruising mph.
Good luck !
Miguel
February 27, 2012 at 2:50 pm
Henry,
The Caffee’s sent this to me. I hope you are doing well: I never got to see you on Family Day here at the plant!!! I am excited to see the results of your test: it should be pretty interesting since you already have a baseline of great fuel economy already. Are you going to MATS this year?
Hope to see you sometime soon!
Pam
February 27, 2012 at 6:43 pm
Pam,
Yes I will be at MATS . This little test should be VERY interesting to see how good the DD-15 can do. The engine already done very well at a mainstream speed of 65 MPH so I am excited to see what kind of mileage can be achieved at at economy minded speed of 60MPH