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I'm working on getting the MPG's on my 2001 Excursion with the 7.3L up after deployment. I'm looking at 4" turbo back catless, mufflerless exhaust, a tuner and an intake. we'll see where we are after that. I've also considered a meth injection setup for those trips from Virginia to Texas. lol
 

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I'm afraid none of your mods will do jack for MPG.

Check out the MPG forum. We've posted stickies on what works and what doesn't.
 

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Check out the MPG forum. There are stickies there that go exhaustively through what works and what doesn't.
 

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I guess I'm pretty lucky then. I have an 01 extended cab short bed. Just hit 300,000 miles. I get pretty good mileage. I have a TS6 and always keep it on 6, S&B cold air intake, stock gears, 35" tires in aluminum wheels, always add cetane booster during the summer and winterizer in the winter, synthetic oil, and change fuel filter at every oil change. I live in Indianapolis and I drove to Lansing, MI to see my aunt. I drove 3 and a half hours at 82 mph and got an average of 20.3 mpg. I haven't done much but it works.
 

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I'm afraid none of your mods will do jack for MPG.

Check out the MPG forum. We've posted stickies on what works and what doesn't.
Check out the MPG forum. There are stickies there that go exhaustively through what works and what doesn't.
Okay, I'll bite. Where is this MPG Forum? :confused:
 

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The only engine mods I haven't tried is a common rail injections system. Yes, I have done single shots.That does seem to help the Cummins and Duramax a lot.

Maybe if I hit the lottery and could bribe ol' Swamp Donkey to try again, I understand they did try this about ten years ago, but it disappeared from the scene. Maybe it didn't make enough HP. for racing purposes, but maybe it would work out OK for a 300 HP daily driver.

Failing that, I'll have to keep working on aerodynamics.
 

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The only engine mods I haven't tried is a common rail injections system. Yes, I have done single shots.That does seem to help the Cummins and Duramax a lot.

Maybe if I hit the lottery and could bribe ol' Swamp Donkey to try again, I understand they did try this about ten years ago, but it disappeared from the scene. Maybe it didn't make enough HP. for racing purposes, but maybe it would work out OK for a 300 HP daily driver.

Failing that, I'll have to keep working on aerodynamics.
Dave, how do you like the gear vendors? I know a while back it was giving you problems. Is it still a hassle?
 

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Lt. Dan (re: Post #69)

My initial problems with the GV were not due to the GV unit itself but rather a cheap-Charley electrical connection supplied with the GV unit.

I took the truck to a local avionics shop and they substituted a connector used for military aircraft (Don't ask - I've long since forgotten the details) Since then it has worked flawlessly. Mechanically it has been bulletproof. I can tow a Bobcat with no trouble.

As I've gotten older, my heavy tow missions have tapered off and I used the GV as a virtual seventh gear. I have used it as a splitter but it seeems a little clumsy for my tastes. I'm sure a professional trucker used to splitter would feel right at home. As I reported before, the GV ain't cheap (about $5000 for a 4x2 kit and you need to shorten the drive shaft) so you better be driving a lot to justify it. My truck has 345,000 miles on it and most of that with the GV.

My drive train - ZF6-650/GV/3.08 gears - has been trouble-free since I fixed the connector.

With my set I can nail it consistently at 1,325 RPM @70 MPH every time. To a great extent, that's where my MPG comes from.

Hopefully, this year i can spend some effort on the truck. My hard, flat tonneau was destroyed by a 60 MPH tailwind gust, soi right now I'm running open bed. 25 MPG in January. 26+ in warmer weather. When I had my homemade rubber and plywood fastback bed cover it easily and consistently ran 28+ MPG empty. So if I can put another "fastback bed cover on it, my MPG would go back over 28. I've thought about thee MVS bed cover but as I am not Jeff Bezos $4,000 for a bed cover seems a bit salty.

I'm also looking at getting some custom wheel skirts (I do zero off-roading) to further clean up the aero package, and prettying up my bizarre-looking air dam.
 

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Back when the 7.3 was state of the art, a racer advised me to keep the EGT under 600 degrees F for best MPG.

This has been excellent advice. Low engine RPM (at a given speed) and low EGT keeps the ol' 7.3 right at thee most efficient part of its BMSFC vs RPM map. You can tell when you are at your most efficient - you are are on the ragged edge of lugging.

The experience of the Cummins with mechanical injection vs common rail injection (with more or less the same long block) indicates to me that a usable common rail might improve 7.3 MPG by 3-4 MPG.
 

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The big downside to operating at low EGT/low RPM is that it will eat any non-Allison automatic transmissions. We're talking spectacular failures - lots of blue-tinted parts scattered down the road.

You need either to do an Allison conversion of a manual conversion to operate this way.

55 MPH is about the slowest I can drive with the GV engaged with th ZF's overdrive. Below that, the engine lugs like crazy.
 

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I also participate in a pure MPG-oriented web form called ecommoder.com. Pure MPG fanatics. They make me look like a dilettante.

Visit their forum and look for a guy who calls himself "aerohead" He is THE guru of pickup truck aerodynamics. He has a Japanese pickup that gets outrageous MPG at the limit. It looks like a Bonneville racer. In fact he has driven it to Bonnevile, put salt tires on it and tried some timed runs. he does OK but he has done zero mechanical mods to the truck and Bonneville has a way of finding mechanical weakness. He has an extensive library of engineering papers on motor vehicles and even prop-driven planes. (Jet aerodynamics are not relevant to pickup truck aerodynamics due to the much higher Reynolds numbers).

From there, I came up with an absolutely accurate (but not quick) means of measuring MPG. I used the truck odometer, the fuel pump, and a calculator. the Ford odometer is dead-nuts accurate if used with OEM diameter wheels and tires. You can get the computer re-programmed to account for non-OEM diameter wheels and tires. I've checked the odometer with GPS and police speed radar. The state certifies fuel pump delivery. Without an onboard dynamometer and scientific-grade flow measuring systems, I can't do any better.

I use four fillups (about 1,600 miles) to average out any variation in how i fill the tank and weather conditions. My daily commute is roughly one-third 70 MPH Interstate driving, one-third 55 MPH state two lane roads and, one-third urban/suburban traffic. The terrain is flat as a pool table, so uphill/downhill is not a factor. Unlike the Cummins MPG-nuts who test at 40 MPH, I stick to the posted limit. IMHO, driving slower than the limit is being dishonest with the averagee driver. In the city I drive along with the traffic. Because of this method my MPG is as honest as I can measure it.
 
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