RV wind deflectors do they work we will see

[cj99]

Ok , So as we know the current cost of fuel ( 5 to 6$ ) for diesel it is more important than 1 year ago to try and save fuel. so things I would not have bothered with due to pay back time are now on the table again.
So I have bought ( but not gotten yet ) a wind deflector for the RV ( goes on the back/top of the truck ) . I have been reading and watching videos about them and it seems a very mixed bag. some people claim 1.5 to 3 MPG while others seem to have even seen a loss in MPG.
Most of the reviews that claimed a loss were on trucks that pulled TT and I believe the issue is with the distance between the top of the truck and from of the TT, typically feet away like close to 5 ft. while on a 5th wheel the top of the back of my truck to the front of the RV is maybe 2 ft ? I have to believe they work or you would not see them on big 5th wheel trucks ( tractor trailer setups ) But most people even ones who seen little to no improvement say it did cut way down on bugs on the front of the RV. That alone has value to me and if there is no bugs then were did they go ? They had to go up and over or around the RV which kind of tells me it must work !
Now I am getting ready to travel about 2000 mile on my next trip so even if I get half of what they claim ( 1.5 MPG ) that's 200$ at 5 dollar a gallon price . This almost pays for the air deflector . And if I sold it for half of what I paid for it then I'm ahead right there.
I will try to record data and post it here. Ill do 65 MPH on flat road with it down for 50 miles or so then try it with it up and see what the old MPG gauge says .

[Veebyes]

Close enough, there are 5 US quarts to an imperial gallon.

As far as the wind thinghy goes, JMO but an awful lot miles will have to be driven to get a payback on that deflector.


I drive a bone stock truck. I have not reset to mileage computer in about 10 years. I think that I have a good ideas of what the truck is doing & that average is a little over 10mpg. All loaded up the 5er is over 12,000lb. It is rare that I cruise at over 65mph. I drive more on engine RPM than speed. It just so happens that 65mph is turning close to 1,900 RPM in top gear. A sweet spot.

[pianotuna]

cj99 That's why Ford uses metric parts in USA?

[cj99]

fj12ryder
your funny! but I agree lets not talk liters , or British pounds, or Chinese yen.. we are in America! we use regular gallons and miles per hour

[cj99]

Johnny G1 wrote:
US gallon =3.78 ltr, Can gallon =4.54 ltrs and when I said I got 16.3 ltrs per 100 that is 17 .177 mpg and that was pulling with 3.55 gears. 10 litrs per 100 = 28 mpg. Usually pull @ 1600rpm, and keep it in top gear.

I thought you said 3.51 gears now its 3.55 ?

[fj12ryder]

Johnny G1 wrote:
US gallon =3.78 ltr, Can gallon =4.54 ltrs and when I said I got 16.3 ltrs per 100 that is 17 .177 mpg and that was pulling with 3.55 gears. 10 litrs per 100 = 28 mpg. Usually pull @ 1600rpm, and keep it in top gear.

It makes no difference to me how you figure it, I'm not going to believe anyone will average over 11 American miles per American gallon. And 16.3 liters per 100 kilometers is 14.4 mpg, the way I figure mpg.

[HTElectrical]

JRscooby wrote:

TravelinDog wrote:

fj12ryder wrote:
Okay, that makes a bit more sense since the Imperial gallon is about 20% larger than the US gallon. That translates to around 11 mpg. I can believe that.

Nope. An imperial gallon is equal to 1.20095 U.S gallons so it is smaller.

I don't know snot about imperial gallons. I did not spend much time in school, and it has been a long time.

But if you think 1+ .2 is bigger than 1+0, there is a problem with education system.

1 + .2 is bigger than 1 + 0.
1 + .2 = 1.2
1 + 0 still = 1

[Johnny_G1]

US gallon =3.78 ltr, Can gallon =4.54 ltrs and when I said I got 16.3 ltrs per 100 that is 17 .177 mpg and that was pulling with 3.55 gears. 10 litrs per 100 = 28 mpg. Usually pull @ 1600rpm, and keep it in top gear.

[fj12ryder]

TravelinDog wrote:

fj12ryder wrote:
Okay, that makes a bit more sense since the Imperial gallon is about 20% larger than the US gallon. That translates to around 11 mpg. I can believe that.

Nope. An imperial gallon is equal to 1.20095 U.S gallons so it is smaller.

That statement contradicts itself. 🙂

[cj99]

TravelinDog wrote:

ivbinconned wrote:
My Ram is a 16. Have been pulling for 45 years. I think I know what I’m doing and not interested in debate.
We carry 100 imperial gallons which is bigger than the US gal.
Many times we have pulled 1400 plus miles before filling.
I pull between 60 and 70 mph.

So if you're comparing Imperial gallons to U.S. gallons perhaps you're also measuring kilometers traveled and KPH.
So those 1400 "miles" you claim to have gotten only equal out to 869.91 actual miles. That I can believe.

sounds about right you if think about it

[JRscooby]

TravelinDog wrote:

fj12ryder wrote:
Okay, that makes a bit more sense since the Imperial gallon is about 20% larger than the US gallon. That translates to around 11 mpg. I can believe that.

Nope. An imperial gallon is equal to 1.20095 U.S gallons so it is smaller.

I don't know snot about imperial gallons. I did not spend much time in school, and it has been a long time.
But if you think 1+ .2 is bigger than 1+0, there is a problem with education system.

[TravelinDog]

ivbinconned wrote:
My Ram is a 16. Have been pulling for 45 years. I think I know what I’m doing and not interested in debate.
We carry 100 imperial gallons which is bigger than the US gal.
Many times we have pulled 1400 plus miles before filling.
I pull between 60 and 70 mph.

So if you're comparing Imperial gallons to U.S. gallons perhaps you're also measuring kilometers traveled and KPH.
So those 1400 "miles" you claim to have gotten only equal out to 869.91 actual miles. That I can believe.

[TravelinDog]

fj12ryder wrote:
Okay, that makes a bit more sense since the Imperial gallon is about 20% larger than the US gallon. That translates to around 11 mpg. I can believe that.

Nope. An imperial gallon is equal to 1.20095 U.S gallons so it is smaller.

[cj99]

2 wheel drive will get a little better fuel and 3.51 gears are good for mid loads as long as your not doing a lot of uphill
I have 373 in F350 and that seems to be a good gear for this truck as long as I don't go over 70 MPH or 2000 RPMs

[fj12ryder]

Cummins12V98 wrote:

fj12ryder wrote:
Hey, if you say so. I pulled a 12,000 lb. 5th wheel with a 2001 Dodge dually six-speed, and got 12 mpg at times. Never saw 13 mpg, let alone over 14 mpg. Just color me very skeptical.

That truck with the 6 speed stick is about the most fuel efficient truck out there. I assume you had 4.10's?

Nope, 2-wheel drive and had the 3.51's. It did need to be in 5th below 60. 🙂 The best mileage I ever got with the 15,000 lb. trailer in tow was a touch over 14 mpg. I was coming downhill from Albuquerque to Amarillo, and had an honest 35 mph tail wind. Filled up in Amarillo and used pencil and paper to come up with 14.1 mpg or so. I don't even remember what the lie-o-meter said. 🙂