Jump to content

Huge difference, large mpg loss 65 mph to 70 mph. Any idea what may be causing it, my gears?

TXGREEK

By TXGREEK
in Engines & Drivetrain

 Share

Recommended Posts

TXGREEK Senior Enthusiast

TXGREEK

Posted
  • Author
Posted

I wonder if I did get new gears, they’d help ?


Sent from Above

  • Replies 38
  • Created
  • Last Reply

Top Posters In This Topic

Popular Days

Top Posters In This Topic

Popular Days

Popular Posts

Mike GMC
Mike GMC

Wind direction, grade, engine temperature may all contribute, but it looks like you found the sweet spot of your set up.  We have a highway here that seems pretty flat, but going south, I get 16.x and

muddkatt
muddkatt

Run the same route again, but this time run 70 in the direction you ran 65 and run 65 in the direction you ran 70.

TXGREEK
TXGREEK

Ok, I believe I’ve figured it out, it’s definitely the wind cause today I was heading beck on the same road and low and behold This was yesterday coming back and this is today coming back ITS

Wiggums Senior Enthusiast

Wiggums

Posted
Posted

Maybe it's the grade..  go to Google Earth, put your mouse on top of where you were and the place you went, Even going up 1,000 ft can be a 15% reduction in fuel economy.

TXGREEK Senior Enthusiast

TXGREEK

Posted
  • Author
Posted
Maybe it's the grade..  go to Google Earth, put your mouse on top of where you were and the place you went, Even going up 1,000 ft can be a 15% reduction in fuel economy.

 

I’d agree but I’m returning on the same exact road. Only thing I believe it would be is the wind like huntr1117 mentioned

 

 

Sent from Above

 

muddkatt Senior Enthusiast

muddkatt

Posted
Posted (edited)

Run the same route again, but this time run 70 in the direction you ran 65 and run 65 in the direction you ran 70.

Edited by muddkatt
typonese
  • Like 2
TXGREEK Senior Enthusiast

TXGREEK

Posted
  • Author
Posted
Run the same route again, but this time run 70 in the direction you ran 65 and run 65 in the direction you ran 70.


Heading back next week, on the way to Pasadena


Sent from Above
TXGREEK Senior Enthusiast

TXGREEK

Posted
  • Author
Posted

Ok, I believe I’ve figured it out, it’s definitely the wind cause today I was heading beck on the same road and low and behold

This was yesterday coming back
9731e6a879f4c0465ef6aeb12a2369f1.jpg

and this is today coming back
af061b00e9757a853066f894c89c2a4b.jpg

ITS THE WIND! It’s got to be, WOW! Yesterday I did notice it was very windy and today not as much, some great ideas though, huntr1117 nailed it!

It’s crazy to think a good strong head wind would affect me so much. I wonder, getting new gears would help? I do typically drive 75-80 outskirts of town. Would new gears help or decrease mpg’s? I don’t want to sacrifice mpg’s for get up and go cause it’s very quick with just 323’s and a tune.


Sent from Above

  • Like 2
Snowcamo Senior Enthusiast

Snowcamo

Posted
Posted
Ok, I believe I’ve figured it out, it’s definitely the wind cause today I was heading beck on the same road and low and behold

This was yesterday coming back
9731e6a879f4c0465ef6aeb12a2369f1.jpg

and this is today coming back
af061b00e9757a853066f894c89c2a4b.jpg

ITS THE WIND! It’s got to be, WOW! Yesterday I did notice it was very windy and today not as much, some great ideas though, huntr1117 nailed it!

It’s crazy to think a good strong head wind would affect me so much. I wonder, getting new gears would help? I do typically drive 75-80 outskirts of town. Would new gears help or decrease mpg’s? I don’t want to sacrifice mpg’s for get up and go cause it’s very quick with just 323’s and a tune.


Sent from Above

I hear you guys are under a " wind advisory on that side of tx" likely your issue.

Sent from my LG-G710 using Tapatalk

  • Like 1
dieselfan1 Senior Enthusiast

dieselfan1

Posted
Posted

Just leave it and drive it. You can afford the gas ??.

A few weeks ago I towed my smaller 6x14 enclosed cargo trailer on a 240 mile round trip.

I filled up in Buffalo MN at the Murphy's at Walmart. I got around 10 mpg and used almost the whole tank.

A week later I did the same run same trailer with about 700 more lbs. this time.

I filled up at BP this time and got almost 14 mpg. Same conditions light wind around 70 degrees.

So obviously the gas is the difference in this case and what a difference.

  • Like 1
CadillacLuke24 Enthusiast

CadillacLuke24

Posted
Posted

The wind can be insane. I live in Casper, WY, and the wind can get atrocious. Back in October of 16 we had 70 mph gusts out of the SW. WY 220 heads southwest out of town, so I drove that for 50 miles, stopped, and returned. On the way out I got 15.4 MPG, and on the way back I got 36.4 MPG. 

  • Haha 1
KARNUT Senior Enthusiast

KARNUT

Posted
Posted

Even with my Camry, the difference between 72 and 75 MPH is 2-3 mpg depending on added wind.


Sent from my iPhone using Tapatalk

flyingfool Senior Enthusiast

flyingfool

Posted
Posted (edited)

dont waste your time getting new gears, get another rear diff and swap it in or out until you find the right combo. you'd be surprised after bolting on speed parts that you'll find out the stock set up was best.

People just need to learn to drive slower these days 65mph!!!. when civilians and grandmas can buy a 300hp Toyota Camry, that was the end of calm decent drivers. I miss the old days when hondas only made 90hp , you could blow the doors off of 90% of the drivers on the road. now old ladies leave me in the dust!

Edited by flyingfool
swathdiver Senior Enthusiast

swathdiver

Posted
Posted

The gears would make fuel usage more consistent, the truck better able to maintain speed.  It would bring your one way averages closer together.  Is that really necessary?  To each his own.

  • Like 1
TXGREEK Senior Enthusiast

TXGREEK

Posted
  • Author
Posted
The gears would make fuel usage more consistent, the truck better able to maintain speed.  It would bring your one way averages closer together.  Is that really necessary?  To each his own.


It’s amazing just how much mpg’s change with a 5 mph difference. I’m not stressing over it and I’m keeping my trucks gears as is.


Sent from Above
  • Like 1
BB&Chiveon Enthusiast

BB&Chiveon

Posted
Posted

According to studies backed by the department of energy, the average car will be at its advertised MPG at 55 mph. But as the speed increases:

      - 3% less efficient at 60 mph
      - 8% less efficient at 65 mph
      - 17% less efficient at 70 mph
      - 23% less efficient at 75 mph
      - 28% less efficient at 80 mph

  • Like 2
flyingfool Senior Enthusiast

flyingfool

Posted
Posted (edited)
2 hours ago, BB&Chiveon said:

According to studies backed by the department of energy, the average car will be at its advertised MPG at 55 mph. But as the speed increases:

      - 3% less efficient at 60 mph
      - 8% less efficient at 65 mph
      - 17% less efficient at 70 mph
      - 23% less efficient at 75 mph
      - 28% less efficient at 80 mph

yeah  and headwind is not calculated, this is all ground speed. doing 60mph with a 15 mph headwind puts you close to 25% efficiency loss.. holy smokes!

Edited by flyingfool
  • Like 1

Create an account or sign in to comment

You need to be a member in order to leave a comment

Create an account

Sign up for a new account in our community. It's easy!

Register a new account

Sign in

Already have an account? Sign in here.

Sign In Now
 Share
Go to topic listing

  • Latest Articles

  • Posts

    • KARNUT
      OCI, not when but why?

      By KARNUT · Posted

      What’s missing in all this is patience and investment in the future. Buy a 170K starter home. Ten years later sell it invest in a more expensive home. Eventually you’ll have a 600K home and pay starter home payments. Buy a starter car. Maintain it well. Save the payments after it’s payed for then buy an expensive car if you desire. Buy a tumbler make your own coffee, pack your lunch. Cook your own dinner. Most importantly take care of your car.
    • Atlas
      OCI, not when but why?

      By Atlas · Posted

      People mislead themselves. Statistics are highly useful indicators.   Here's the tie-in to this thread. If an oil sample tests shows a wear indicator of 7 using cheaper ACDelco oil, and a wear indicator of 2 (lower = less wear) using a particular brand of Mobil oil, and wear has a linear relationship with engine lifespan, anyone could assume that Mobil is reducing wear by more than 50% (let's just say a 200% reduction for you red state people trying hard to do math) which leads to increasing engine life by 2x. Perhaps, in a vacuum, by itself, when dreamed by AI.   Yeah?! That's what the statistic is saying, isn't it?   No, it isn't. It didn't come out and say engine life is doubled. That's a very bad assumption, and a case of severe myopia by assuming something potentially untrue about the only data point in focus.   Average cost of a new car is 50k. You bet it is.   The median cost of a new car is more like 35k. Expensive cars are skewing the perception that "average" now means a $50k price of entry for a very average automobile. And that's not true. People who don't understand statistics twist the living heck out of them to mean all sorts of things they don't actually mean.   "Average" new car payment is $1000/month. Yep, it is. And in that number are all the $35k new car buyers who bring significant equity, and the $25k new car buyers who finance the car for a month just to get a rebate, and then pay it off. Know what isn't in that number? All the payments made by people who don't finance a car.   Picking one's own data point (don't have a car payment, never paid $50k for a new vehicle, my house cost $170k, I afforded a middle class lifestyle on $4.50/hr) is just a data point. Just like earning $25/hr in an area where the median home price is almost $1 Million is a data point. In fact, it's a lot of data points given that 80% of the US population lives in/around major cities. They're not idiots; the vast majority of them do it to make a living because that's where the big money is.   The highs have become higher, lows have become lower, and how your personal mileage varies is not truth for an entire country. At the same time you can't NOT acknowledge the data. While it doesn't paint YOUR personal picture, it certainly tints the reality that you also live in, as does your single data point.    
    • ShotgunZ71
      Poll: Does your truck have the rear window leak?

      By ShotgunZ71 · Posted

      Glad you had success with it. I did as well, but about 5-6 months later it returned. Tried again, same result. This was after the dealer made several attempts and never even got it to slow down.
    • KARNUT
      Gas Prices

      By KARNUT · Posted

      3.15 Kroger’s in Montgomery Tx
    • TheGeek
      Will not stay in Reverse

      By TheGeek · Posted

      I have a LTZ and it has the shifter in the console, which I like, but, every now and then, it will not stay in Reverse. I go through all the motions, hold the button in, push the shifter forward and watch the dash.  The big red R comes on and also the back up camera.  Then, it just pops out of Reverse with the shifter all the way forward.  So then the game begins.  Back and to Drive, Reverse.  This goes on 8 - 10 times. Very frustrating. Had it back to the dealer and they replaced some kind of computer, but it is now happing again. It is so bad, my wife will not drive the truck, she is afraid of being stuck somewhere.    Anyone else with this PIA problem? 

  • GM-Trucks.com Clubs

  • Popular Contributors

×
×
  • Create New...