Speed and fuel

[chetjester]

When I drove for Davekc, he told me that there was a chart/graph that showed how much more fuel was being burned as the truck speed increased. Does anybody know where I can find that information? When I drive, I have a tendency to drive as fast as I'm allowed, which may not be the most economical decision.

Good advice accepted.

Thanks.

 

[davekc]

I actually have several. This is one

http://www.goodyear.com/truck/pdf/brochures/brochure_factors.pdf

and the other is
http://kec.kansas.gov/chart_book/SpeedVsFuel.pdf

Last one is pretty simple.

Those are a couple I remember, and I am sure there are others. I looked through my files and my other ones are for marine applications.












Davekc
owner
23 years
PantherII
EO moderator

 

[LDB]

I don't know where to find the chart but basically every 1 mph increase above 50 is a .1 mpg decrease so if your truck gets 10 at 50 it's about 9.5 at 55, 9 at 60, 8.5 at 65 and 8 at 70. It isn't exactly linear and isn't exactly .1 to 1 but that's close enough for government work as the saying goes.

Leo Bricker, 73's K5LDB
OOIDA Life Member 677319, JOIN NOW
Owner, Panther trucks 5508, 5509, 5641
EO Forum Moderator
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Support the entire Constitution, not just the parts you like.

 

[chetjester]

You're right. The second one is easier. Guess I should stay around 60 mph. Now how can I tell my foot that?

 

[joebob1_30132]

great info Dave turned you on too. I stayed at 60 mph whereever i may have roamed, left early p/u early delivered early.(whenever i was allowed)

 

[rollnthunder]

I would have to disagree.Every engine should have sticker on it that tells you what rpm the peak hp and what not is made.In my freigtliner with the 9 speed if i keep the rpm around 1500 to 1800 i get over 10 mpg at that rpm he Mph is 63 to 68.The key is not to go over the max rpm where your engine is making power.Stay a few hundred rpm under that and you will get the best MPG.

 

[ATeam]

The speed/fuel economy equation has less to do with engine RPM and more to do with wind resistance. It does not matter what you have under the hood. As truck speed increases, so does wind resistance. The higher the wind resistance, the lower your fuel economy.

You will notice that the .1 mpg/1 mph formula that Leo offered does not start until 50 mph. That is because wind resistance below 50 mph is less of a factor.

That helps explain why conventional-nose trucks get about 1 mpg less than aerodynamic trucks. That figure comes from Kenworth, a company that makes both kinds of trucks, and from a host of industry writers that are informed on the topic.

Regarding the foot question, sit your foot down for a heart-to-heart talk with your wallet.

 

[chetjester]

Phil, I think you are right. I need to have a "come to Jesus" talk with that heavy heavy foot I have when I get back into a straight truck Monday.

I'm coming back to a mighty powerful straight truck after driving an 18-wheeler that required me to press that pedal as hard as I could as I maneuvered the hills of PA.

We will have that talk.

 

[nightcreacher]

the sweetspot of your engine depends on gear ratios tire size and the engine its self
most trucks get their best mileage at 55,and loose .1 for every mile over 55
thats my 2 cents

 

[60MPH]

60 mph always works for me I know in my express van with a duramax I get 24.5 to 25 mpg at 60 mph. I know if I drive 70 I only get 19 to 20 mpg, thats 5 mpg loss in only 10 mph increase in speed. So I only drive 60 and I always get to where I am going on time.


60 MPH ALL DAY-EVERY DAY

 

[kangar0085]

It's crazy how these sprinters get ridiculously high fuel mileage.

 

[easyrider2697]

>It's crazy how these sprinters get ridiculously high fuel
>mileage.



Its almost as crazy as the sticker price on them too!!

 

[Turtle]

My Sprinter gets its best fuel mileage at 63 MPH. It's generally right around 24.4 MPG at that speed, but of course heavy headwinds and crosswinds will have a pronounced effect on that. So do tailwinds. Depending on traffic, routing, scheduled delivery times, etc., I'll usually drive at or near the posted speed limit, which gives me an overall MPG of 21-22.

On long and relatively flat roadways, if the rest of the traffic, especially the big trucks, are mostly running at 65, like on the Turnpike, I'll sit back and Cruise at 63, which accomplishes two things. One, it's the best speed for fuel mileage, anyway, and two, the "long distance drafting" effect I get by having other vehicles pass me and then pull me along , increases the 24MPG I get to often stoopid numbers, like the 28.8 I got last night across Ohio and Indiana.

Slow and steady, even in expediting, wins the race - Aesop