FORDTRUCKS777

I get TERRIBLE mpg in my 1999 5.4. About 11 mpg on average. I was thinking that a 5.9 cummins (24v) diesel might give me better fuel economy. Most of them are around 17-20 mpg, and diesel around here is about $4.10-$4.15. Gas is about $3.80. What do you guys think?

PS...please dont tell me stick with the 5.4 just because your a die hard ford fan

gone postal

The amount of work involved makes it prohibitively either expensive or time consuming.

Kamison

the diesel is so heavy compared to the normal 5.4 that your front end wont be able to sustain the weight very long. especially if you offroad or hit a big enough pot-hole.

depami

I think he's talking about a Dodge. The Cummins part might be okay but I don't think I could tolerate the Dodge part. Every one I've ever been in wreaked cheap.

11 MPG with a 5.4 is horrible. Something must be wrong. My 2001 has a lifetime average of 15.1 at 176,000 miles.

PJB

My brother had an '05 Ram 2500 and it was getting 22 mpg.
Don't forget that diesel is much more expensive than gas so despite getting a few more mpg youre paying more at every fill up.


Maintenance is also higher for a diesel truck, even oil changes due to capacity. Parts cost more due to being heavier duty.


My brother's Ram liked to eat u-joints, shocks and other front end parts. Dodges also have weak transmissions (his was replaced at 95k). The body was pretty shot on his truck too, rust all over the wheels and rockers and cab corners.

FORDTRUCKS777

But with the brand, body, and upkeep set aside......Could I be saving a couple dollars more in gas? The way i figured it was, if I filled up 25 gallons in my 5.4 it would cost $95 @ $3.80, but if I paid for 25 gallons if diesel in the cummins then i would pay $102.5 @$4.10. Wouldn't that $7 increase for diesel allow me to get a few more miles before filling up again? The 12v cummins can get up to 22-25 mpg with very few "mods" and the 24v is around the 17-19 mpg area.

depami

17 – 19 = 18 Average
$4.10 / 18 = $0.227 per mile.

$3.80 / 11 = $0.345 per mile.

$0.345 - $0.227 = $0.118 per mile savings.

$0.118 X 1000 miles per month = $118.00 per month savings on fuel.

gone postal

Mea Culpa, I thought this was another cummins swap into an F-150 thread.

The $118/month savings on the cummins in fuel would be eaten by the additional upkeep and maintenance costs. 11MPG doesn't even sound close to correct for a stock truck with a 5.4.

Adam013085

Do some maintenance on your truck and you should net a few more MPG. There is something wrong with yours only getting 11 MPG.... Also remember you are using winter gas too so that will cut MPG down 1-3 from my experience. My 4.6 is getting 14 MPG winter and I plan to do quite a bit of maintence the next Saturday my wife is off so she can watch the kids.

Zrock

How can you set the upkeep aside? Everything diesel is 3-4x more expensive. I just got rid of mine because the price of fuel and the cost of upkeep outweighed the benefits. Just some simple examples. Oil change gas-$30 diesel-$100min, Waterpump Gas $50 Diesel-$300. Even a simple u joint is 3x the price of gas.

How are you calculating your fuel usage? and is everything stock on your truck including tire size?