Karl
Moderator Emeritus
Generally speaking, racecar drivers know what the other fellow is going to do and doesn't have to worry about oncoming traffic or wild animals on the track (four-legged kind).
Lets talk fuel economy and ways to improve.
- Thread starter lakedawgs
- Start date
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Ian H
Well-known member
- Joined
- Mar 23, 2005
- Posts
- 248
I seem to remember something about water injection into the intake manifold years ago in the UK,don't know if that was in the fuel crisis days and was suposed to increas performance or gas miles
John From Detroit
Well-known member
There are several things that can be done to reduce the effect of the wind.. Resistance is one of them
First SLOW DOWN. There have been charts and graphs that have been produced using wind tunnel tests on selected vehicles. Where as some hot cars "Knife" through the wind, Motor homes Bulldoze And as it turns out air does not like to move faster than a given speed... Most coach designs start to "knee over" between 55 and 60 MPH So SLOW DOWN.. now dropping much below 55 won't make as much of an improvement in most cases. But slowing down TO 55 will.
Next we have actually wind resistance, the friction of the wind on the body.
WAX.. I mean SIMONIZE seems to help Now. I don't know about motor homes here. I know about 1977 AMC hornet hatchbacks, I used to own one.. Sticker said I'd get around 21MPG Highway (less in the city) never got that, Till I waxed it , When I waxed it the millage went from around 16 to around 20 for freeway trips. (The other thing that made a big difference was a new carb, unit shipped with a defective, a new one coupled with a wax job, and I broke 21MPG)
Anything you can do to "Streamline" the coach will help too.. This means don't hang a bunch of stuff off the sides. Off the back is OK.
Strangely (Not really) pulling a towed may help too.. IT "Spoils" the air flow at the rear of the coach, The trade off here is additional weight you are "hauling" which may offset or exceed the savings due to improved air flow
First SLOW DOWN. There have been charts and graphs that have been produced using wind tunnel tests on selected vehicles. Where as some hot cars "Knife" through the wind, Motor homes Bulldoze And as it turns out air does not like to move faster than a given speed... Most coach designs start to "knee over" between 55 and 60 MPH So SLOW DOWN.. now dropping much below 55 won't make as much of an improvement in most cases. But slowing down TO 55 will.
Next we have actually wind resistance, the friction of the wind on the body.
WAX.. I mean SIMONIZE seems to help Now. I don't know about motor homes here. I know about 1977 AMC hornet hatchbacks, I used to own one.. Sticker said I'd get around 21MPG Highway (less in the city) never got that, Till I waxed it , When I waxed it the millage went from around 16 to around 20 for freeway trips. (The other thing that made a big difference was a new carb, unit shipped with a defective, a new one coupled with a wax job, and I broke 21MPG)
Anything you can do to "Streamline" the coach will help too.. This means don't hang a bunch of stuff off the sides. Off the back is OK.
Strangely (Not really) pulling a towed may help too.. IT "Spoils" the air flow at the rear of the coach, The trade off here is additional weight you are "hauling" which may offset or exceed the savings due to improved air flow
cougar3514v
Well-known member
- Joined
- Sep 29, 2005
- Posts
- 290
We used water injection in the 70's, but it was to increase performance, not economy. It allowed us to run higher compression and keep the cylinders cool. BTW, all it takes is one glance at a piston from an engine where the owner didn't worry about the knocking to see how much damage that little ping can do. I've seen a piston melted so bad it looked like it had been made from Silly Putty.
I have found the best way to increase my MPG is to predict when I'm going to have to use the brakes. When I see a traffic signal turning yellow then red or when I see brake lights in front of me, I stay off the gas and coast so that I can hit the green and still have some forward momentum. Okay, most of my towing is done on the highway, but it works great even without a trailer hitched to my truck. It also saves on brakes, wear and tear on the motor, and tires. I keep the MPG display in my F-350 on all of the time and have found that my city driving mileage increases easily from 17 MPG to 18 MPG when I'm doing this.
I also like to travel about 3 seconds behind the vehicle in front of me. I am consistently plagued, however, by the drivers of the slammed and skated Hondas that zip in front of me reducing my trailing distance to about 5 feet. That blows my whole "predicting when to use the brakes" theory out the window. ;D
-Dave
I have found the best way to increase my MPG is to predict when I'm going to have to use the brakes. When I see a traffic signal turning yellow then red or when I see brake lights in front of me, I stay off the gas and coast so that I can hit the green and still have some forward momentum. Okay, most of my towing is done on the highway, but it works great even without a trailer hitched to my truck. It also saves on brakes, wear and tear on the motor, and tires. I keep the MPG display in my F-350 on all of the time and have found that my city driving mileage increases easily from 17 MPG to 18 MPG when I'm doing this.
I also like to travel about 3 seconds behind the vehicle in front of me. I am consistently plagued, however, by the drivers of the slammed and skated Hondas that zip in front of me reducing my trailing distance to about 5 feet. That blows my whole "predicting when to use the brakes" theory out the window. ;D
-Dave
John From Detroit
Well-known member
I gotta agree with you there Cougar, Those "Varroom-Screech" drivers (Race to wait for the next light) not only burn up more fuel, tires, trannies and such, but take longer to get there as well.
I sometimes tell of driving home with a bad clutch linkage... Had to time all the lights so I got there on Green, Did too
I sometimes tell of driving home with a bad clutch linkage... Had to time all the lights so I got there on Green, Did too
Gary RV_Wizard
Site Team
Not really. A denser air charge will support the use of more fuel and makes it possible to deliver more power, but the engine computer does not adjust fuel flow simply to match the incoming air temperature. If it did, all our vehicles would run faster n cold days than on hot ones! :
Fuel and air intake are both adjusted to meet the power demand on the engine, i.e. your foot on the go-pedal.
Karl
Moderator Emeritus
Gary,
Picky, picky, picky. What I should have said was "The computer senses the cooler air temp and/or the greater air density and adjusts the amount of gas accordingly to maintain the proper fuel air ratio. More/colder air; potentially more gas - depending on throttle position."
So there! ;D Geez, you try to keep things simple.....
Picky, picky, picky. What I should have said was "The computer senses the cooler air temp and/or the greater air density and adjusts the amount of gas accordingly to maintain the proper fuel air ratio. More/colder air; potentially more gas - depending on throttle position."
So there! ;D Geez, you try to keep things simple.....
rbell
Well-known member
I just started to run my Ford pickup on E85 this week. I'm going to use 3 or 4 tanks on normal use, then switch to regular again and run a comparable mileage test with it. I absolutly can't tell a difference in the way it runs so far. Although it smells different when it's running. Reg gas was $3.43 and E85 was $3.12 at the station I filled up at.
Time will tell.
Time will tell.
Karl
Moderator Emeritus
Dick,
You might be interested in reading this Comparison Test and see how it corresponds to your experience with E85.
You might be interested in reading this Comparison Test and see how it corresponds to your experience with E85.
F
Frizlefrak
Guest
Proper tire inflation is the cheapest and easiest way to boost fuel economy. Once that's done, let's look at the state of tune for your tow vehicle. Ensure that the air filter is clean, and adhere to the maintenance schedule in your owner's manual.
Now let's look at weight. If you're not boondocking, jettison that extra 30 gallons of fresh water left in the fresh tank. Keep a couple of gallons in it for roadside use of the potty, but anything extra is 8 lbs per gallon of dead weight. Also keep the grey and black tanks empty. Unload anything you don't need for your trip prior to leaving. It doesn't take much to add 500 lbs to your trailer. Same goes for the truck...leave behind anything not needed.
Use your cruise control when practical and safe. Don't run the tow vehicle's A/C unless you need it. And of course, drive at a sensible speed. Finally, try to plan your fuel stops in areas where there is a lot of competition...Costco or Sams/Walmart usually has the lowest fuel prices.
Ohhh....and leave the drafting to Jeff Gordon and Dale Jr.
Now let's look at weight. If you're not boondocking, jettison that extra 30 gallons of fresh water left in the fresh tank. Keep a couple of gallons in it for roadside use of the potty, but anything extra is 8 lbs per gallon of dead weight. Also keep the grey and black tanks empty. Unload anything you don't need for your trip prior to leaving. It doesn't take much to add 500 lbs to your trailer. Same goes for the truck...leave behind anything not needed.
Use your cruise control when practical and safe. Don't run the tow vehicle's A/C unless you need it. And of course, drive at a sensible speed. Finally, try to plan your fuel stops in areas where there is a lot of competition...Costco or Sams/Walmart usually has the lowest fuel prices.
Ohhh....and leave the drafting to Jeff Gordon and Dale Jr.
cougar3514v
Well-known member
- Joined
- Sep 29, 2005
- Posts
- 290
I have found that for the, uh, non-obsessive driver, cruise control is great. Cruise control, however, does not yet anticipate hills. To improve fuel economy, I usually get a little speed up on the down-hill side (still keeping it safe) just before making a climb. It's much better than waiting for the CC to kick in when it's already lost too much momentum.
-Dave
-Dave
Carl L
Moderator Emeritus
Frizlefrak said:
I would make one exception to your excellent advice for travel trailers: a full fresh water tank when the tank is forward of the axles is a good way to increase hitch weight. Increased hitch weight, up to 15% of the trailer weight, can contribute to the stability of the trailer-truck system. That contribution can be valuable with a tail heavy trailer (hitch weights 10% on down) or in bad crosswind situations like last weekend in Banning Pass near Los Angeles.
Especially in light of what happened to Dale Sr.
F
Frizlefrak
Guest
Carl L said:
Good point. A tail-heavy trailer can get quite squirley. I'll opt for safety over economy any time.
glen54737
Well-known member
When I was towing a TT i put a cap on my pickup this reduced the drag and i saw about a 1 mpg difference aven when not towing.
carson
Well-known member
Let me add a bit of info re "drafting" behind a truck/trailer.
A little while ago the show "Mythbusters" did an episode in this regard. The tried to 'scientifically' prove the 'Myth".
They used a regular car behind a semi/trailer at 55 mph. They measured each try using a measured amount of fuel and calculated the saving in percentage of fuel usage.
The results:
Distance behind the truck:
100' saving ~ 11%
50' ~ 20%
20' ~ 27%
10' ~ 39%
2' ~ 35% (inconclusive)
I am going to forgo the attempt to save any fuel that way. In the RV I'll be using the 10 second rule.
FWIW, carson FL
A little while ago the show "Mythbusters" did an episode in this regard. The tried to 'scientifically' prove the 'Myth".
They used a regular car behind a semi/trailer at 55 mph. They measured each try using a measured amount of fuel and calculated the saving in percentage of fuel usage.
The results:
Distance behind the truck:
100' saving ~ 11%
50' ~ 20%
20' ~ 27%
10' ~ 39%
2' ~ 35% (inconclusive)
I am going to forgo the attempt to save any fuel that way. In the RV I'll be using the 10 second rule.
FWIW, carson FL
Ron
Moderator Emeritus
I agree it just isn't worth jeopardizing safety to try to save a little fuel even at todays cost of fuel.
Frank B
Well-known member
lakedawgs:
Though perhaps not exactly what you are looking for at the moment, I have found my diesel GMC truck to be much more economical than my previous Chev 350 (5.7 liter) gas truck. I got 10 mpg with the gas truck, and get 14-16 with the 6.6 liter diesel. THAT is a tangible saving of some 50%.
Previous comments about cost of fuel vs depreciation are valid here as well. I am in a situation similar to yours where the diesel pickup is seldom used other than when pulling the trailer. More money invested in the truck means more money lost in depreciation if percentage depreciation remains the same. However, with that said, diesels hold their value much better, and a low-mile diesel commands a very strong resale price.
I will never go back to a gas truck for pulling. The massive torque of the diesel is made to pull. Now, even after almost a year, I can hardly believe how good that diesel is.
Frank.
Though perhaps not exactly what you are looking for at the moment, I have found my diesel GMC truck to be much more economical than my previous Chev 350 (5.7 liter) gas truck. I got 10 mpg with the gas truck, and get 14-16 with the 6.6 liter diesel. THAT is a tangible saving of some 50%.
Previous comments about cost of fuel vs depreciation are valid here as well. I am in a situation similar to yours where the diesel pickup is seldom used other than when pulling the trailer. More money invested in the truck means more money lost in depreciation if percentage depreciation remains the same. However, with that said, diesels hold their value much better, and a low-mile diesel commands a very strong resale price.
I will never go back to a gas truck for pulling. The massive torque of the diesel is made to pull. Now, even after almost a year, I can hardly believe how good that diesel is.
Frank.
The other day I was driving on a fairly level section of freeway with our new Honda van. It has a computer that give an instantaneous fuel milage read out. At 55 mph, it was reading about 18 mph. As all the traffice was passing me, I increased my speed to 65 and the reading went up to 25 mpg. I have noticed this before but I drove a few more miles this time to see if it repeated. It seems somewhat surprising that going a bit faster would improve the milage. The van was in the same gear at both speeds. The van shuts off 3 cylinders for economy when crusing at a steady level pace and in both cases was running on 3 cylinders. Maybe there is a "sweet" spot or maybe the milage computer isn't all that accurate.
