New to the board, New to a PSD... MPG Question??

[Mile High Stroker]

Hi! I have been lurking on here for the last couple months taking in all the good info. I bought an '04 F-350, CC LB, FX4 almost two months ago. So far I have a Rough Country leveling kit (with 4" blocks in the rear) and 4" turbo back MBRP. I love this truck!!

My question is about MPG... I just made a road trip from Denver to Flagstaff, AZ and only averaged 14 MPG... I thought I would see an improvement with the exhaust, but noooo.

Is this MPG to be expected? What can I do to improve it?

Thanks!

[Goose350]

Thats about average. Do you have bigger tires? Put a custom tune on that thing and it will help a good bit

[Mile High Stroker]

Thanks Goose! This board has been a great source of info.

The tires are a little larger... not much though. I figured my speedo is 2.5% off on miles by checking mile markers for 100 miles.

Oh, I drove 77-80 mph at 2250 RPM. Maybe that's it??

[Mile High Stroker]

OH! Another quick question...

When I first start the truck with the new exhaust it sounds AWESOME. Very deep tone. Then, after like 30 seconds, it sounds VERY restricted. The whistle starts (which I know is the turbo), but all the deep tone is gone. The tone comes back if it is under load or if I get the RPMs up to 2K or above, but just not the same ... Although it is still pretty sweet sounding like a jet on the tarmac

The guy who put on the exhaust says it is the waste gate valve??

[Goose350]

Originally Posted by Mile High Stroker

Oh, I drove 77-80 mph at 2250 RPM. Maybe that's it??

That is definitely it. Anything over 2000 rpm kills fuel mileage.

[semmens21]

the best mpg ive seen were when my rpms were below 2000

[Goose350]

Originally Posted by Mile High Stroker

OH! Another quick question...

When I first start the truck with the new exhaust it sounds AWESOME. Very deep tone. Then, after like 30 seconds, it sounds VERY restricted. The whistle starts (which I know is the turbo), but all the deep tone is gone. The tone comes back if it is under load or if I get the RPMs up to 2K or above, but just not the same ... Although it is still pretty sweet sounding like a jet on the tarmac

The guy who put on the exhaust says it is the waste gate valve??

Its the turbo. Waste gates are on a 7.3l

[Raul@Stealth Automotive]

you wont see an increase with just the exhaust... you need to get a custom tuned SCT... but there are alot of factors to MPG like tire pressure, elevation, temperature, and what RPM range your in

-Raul

[epc303]

I absolutely concur regarding the 2000 rpm.
Last year, I traveled from Denver to El Paso, and back in my F-250, as part of a military convoy (in GSA vans) so we were restricted to 55-60 mph on the highway per gov't regulations. I got 21-22 mpg on this 1200 mile trip. On different "non-military" trips of similar distance and terrain when I traveled a more reasonable 65-70 mph my mileage drops off to 18-19 mpg. In a couple of instances when I had a particularly heavy foot and averaged more like 75-80 mph, the mileage really drops off. I have wanted to plot this on a graph but haven't got around to it, but I think the mileage drops off exponentially at speed above 55 mph. One key is keeping an eye on the turbo psi - if the turbo psi starts to rise, your fuel economy is going to drop. Under no-to light-loads (i.e. not accelerating, not going up a hill, not towing, etc), the turbo psi is a essentially 0 below 2000 rpm.

Ethan
Denver, CO

2005 F-250 CC, 6.0 L, 6-speed manual, 4x4, 90K miles
2007 Ford Freestyle Ltd, 30K miles
2006 Kawasaki KLR-650, 6K miles
1995 Kasasaki Concours (ZG-1000), 30K miles
1982 Jeep CJ-5, 133K miles

[04strokin6.0]

There is alot of great knowledge lurking in this forum good luck and have fun