Gas vs. Diesel

[GlockWRX]

Avoid ALL of the new gen diesels. They all have issues.

Stick to the older diesels, you can get the power and fuel milage that folks think of when they discuss diesels. The new diesels get WORSE milage in a platform than a gasser will.

I wouldn't go that far. The newer diesels aren't as efficient as the ones from a few years ago, but they are still better than a gas motor especially when their output is taken into account. Only the Ford V10 comes close in power, but it will die trying to pull like a diesel over the long haul. The discontinued GM 8.1 with the Allison was close but still short of a strong diesel.

Of the post 2007 diesels with DPF systems, the Fords are the worst MPG wise. An in-law has a new F350 SRW and he gets 13-15 highway empty. My bro-in-law gets 17-18 highway empty in his 6.7L Cummins, and my 2008 GMC Duramax gets around 16-17 empty. In town is a good 3-4 MPGs less. My friend has an LBZ equipped GMC (basically the same motor I have without the DPF), and he gets about 1-2 MPGs higher than I do.

I will admit that the older diesels were more efficient. Plus they are easier to chip and tune than the new ones. Far less electronic interference from the computers.

I love my GMC Duramax, but if I was looking for a used diesel, I would look for this in order:

2007 GM's with the LBZ motor. Some of the older GMs are good, but the LBZ was the best of the pre-2007 motors (IMO). They also come with the excellent Allison tranny.
Ford 7.3's. I forget the years that these were made, but there are plenty of Super Duties and Excursions with this motor. Not as powerful, but responds well to tuning and is a good solid motor. Avoid the 6.0, as they are problem prone.
Dodge Cummins of just about any vintage as long as it has a manual tranny. The Cummins is an awesome motor. Powerful, robust, and a torque monster. It also turns automatic transmissions into dust. It wasn't until the lastest generation 6 spd that Dodge could put an auto behind it that would survive. The six speed manual trannies they used were pretty robust and lasted a lot longer than the autos.

[larry0071]

You've got some information mixed up. The 6.0 was not available until the 04 model year.

Hummers are cool, but not enough room.

I've thought about a 6x6 truck before, mostly because from what I have read they can run on lots of different fuels. Downside is from what I've read, they are not exactly reliable.

2003 was the transition year from the 7.3L to the 6.0L and in 2003 you could purchase both Excursions and SuperDuty trucks with one or the other. Once the 7.3L engines were used up in mid 2003, they were no longer available.

I own a 2000 Ford Excursion 7.3L that my wife drives. I took it this past weekend kayaking and put 3 kayaks inside it and 2 men and one 13 year old. I tow my 28 foot trailer with it, trailer and sled pulling truck and all the other junk on the trailer go about 12,000 lbs. It is nice to be able to tote the trailer and the entire family plus more in the rear storage area with my "SUV".

I also own a 2005 Dodge crew cab with 8' bed and a Cummins. I hate it with all my heart and soul. Both of my diesels are modded, the Ford has never missed a beat. The Dodge has melted two engines in 18 months. Did I mention I hate this thing?

[MarshallDodge]

The Dodge has melted two engines in 18 months. Did I mention I hate this thing?

You play, you pay.

I have never seen a 7.3 that could hold a candle to the Cummins in towing or longevity but it sounds like you are one of the lucky ones.

I have the Edge Juice/Attitude on my Dodge. It is not a serious box but I like the defueling feature = no meltdown.

[larry0071]

I agree the 7.3L is not as fast nor will make the power of the cummins, but the 7.3 seems to be an anvil of an engine.

I smited the first Cummins with a Smarty Revolution tuner and it was replaced under warranty. New crate engine. 6 months later using a BullyDog with the "Scary Larry" tune I melted that crate engine and I never took it to Dodge. I sleeved 2 holes, put in 120# Hamilton Diesel valve springs, stage 2 Hamilton cam, 100HP injectors, ballanced the rotating assembly and since then I have maybe put 3K miles on it. During this 18 month period I broke the input shaft and replaced it with billit, broke the output shaft and replaced both the intermediate and output with billit. I also wiped out 5 sets of over drive clutches, and that was in a built trans with Alto Red Eagle clutches, Dunrite valve body, and TCS triple disk billet convertor. Each trans failure cost me about a grand in parts, not counting the 3 shafts at $650 for input and about a grand each for intermediate and output shafts.

I have spent about 30 grand repairing this truck in less than 2 years. I'm scared to drive it now! I can't afford to fix it!

The Ford has been modded front to back since a week after I got it. I had to change 2 batteries and an alternator so far, plus 3 sets of ball joints.

[Nathan_Bell]

I wouldn't go that far. The newer diesels aren't as efficient as the ones from a few years ago, but they are still better than a gas motor especially when their output is taken into account. Only the Ford V10 comes close in power, but it will die trying to pull like a diesel over the long haul. The discontinued GM 8.1 with the Allison was close but still short of a strong diesel.

Of the post 2007 diesels with DPF systems, the Fords are the worst MPG wise. An in-law has a new F350 SRW and he gets 13-15 highway empty. My bro-in-law gets 17-18 highway empty in his 6.7L Cummins, and my 2008 GMC Duramax gets around 16-17 empty. In town is a good 3-4 MPGs less. My friend has an LBZ equipped GMC (basically the same motor I have without the DPF), and he gets about 1-2 MPGs higher than I do.

I will admit that the older diesels were more efficient. Plus they are easier to chip and tune than the new ones. Far less electronic interference from the computers.

I love my GMC Duramax, but if I was looking for a used diesel, I would look for this in order:

2007 GM's with the LBZ motor. Some of the older GMs are good, but the LBZ was the best of the pre-2007 motors (IMO). They also come with the excellent Allison tranny.
Ford 7.3's. I forget the years that these were made, but there are plenty of Super Duties and Excursions with this motor. Not as powerful, but responds well to tuning and is a good solid motor. Avoid the 6.0, as they are problem prone.
Dodge Cummins of just about any vintage as long as it has a manual tranny. The Cummins is an awesome motor. Powerful, robust, and a torque monster. It also turns automatic transmissions into dust. It wasn't until the lastest generation 6 spd that Dodge could put an auto behind it that would survive. The six speed manual trannies they used were pretty robust and lasted a lot longer than the autos.

The 6.7 Cummins has massive computer/sensor issues. I swipe one when I have to tow Heavy loads and it has not made it through a trip without throwng a light on. Guy I grew up with is a Cummins certed Dodge dealer mechanic and he has more hours working diagnostics on the post '07 motors than he has on the 12v or the 24v 5.9L. Half the time he cannot find anything wrong to have triggered the computer blues. My buddy who owns his has the paperwork history to get it lemoned, but of course Chrysler is not bound by that any longer so he will run it till the warranty is gone and then rip all of the BS off and run it till it dies.

The 6.4 PS has QC issues through out it. Less sensor issues, but there have been numerous stories of valve train issues and EGR. Also have heard some DPF issues, the system goes into regen and will not come out until dealer level computer is hooked to it.

The Duramax's I have never really paid much attention to. I know two folks who have them one loves his, one wants to burn his to the ground. He is currently trying to get Chevy to buy his back, but he assumes that they will go the way of Chrysler RE Lemon Laws.

For a BOV light duty truck I would go 5.9L Cummins 12V; 7.3 that has the 444e fuel system on it, get rid of the deadhead cylinder; 5.9L Cummins 24V; All are stone simple for a diesel wrench to diagnose and fix.

RE: Milage put less than 6k behind them and the gassers will be cheaper to run for most hauls. Break that level and the diesles still are going to do better but not as well as once was the case.
My '02 250 got 16.4MPG that is with a 6" lift and 36" tires on it. It also put 350 rwhp down. Neighbor's '05 Dodge with the same amount of lift and about 375hp would get 18-19mpg. YOu do not get that factory now. Put a 10k load behind mine and it dropped to 14 mpg. we put 12k behind the '07 dodge and it got 9 mpg.
I can go into these same motors being used in medium duty applications and being fuel sucking boat anchors as well.

I stand by my statement to avoid all new gen diesels for a vehicle that you would bet your survival on.

My BOV has a 352 CID TD in it. Other than the 44mm socket needed to turn the damned driveshaft to set the valves, any diesel tech can wrench on it and have the tools to do so.

[MarshallDodge]

I agree the 7.3L is not as fast nor will make the power of the cummins, but the 7.3 seems to be an anvil of an engine.

I smited the first Cummins with a Smarty Revolution tuner and it was replaced under warranty. New crate engine. 6 months later using a BullyDog with the "Scary Larry" tune I melted that crate engine and I never took it to Dodge. I sleeved 2 holes, put in 120# Hamilton Diesel valve springs, stage 2 Hamilton cam, 100HP injectors, ballanced the rotating assembly and since then I have maybe put 3K miles on it. During this 18 month period I broke the input shaft and replaced it with billit, broke the output shaft and replaced both the intermediate and output with billit. I also wiped out 5 sets of over drive clutches, and that was in a built trans with Alto Red Eagle clutches, Dunrite valve body, and TCS triple disk billet convertor. Each trans failure cost me about a grand in parts, not counting the 3 shafts at $650 for input and about a grand each for intermediate and output shafts.

Larry, you make it sound like it's the Dodge/Cummins fault but you nearly doubled the output of the motor with mods and obviously ran the EGT's through the roof. I guarantee that your 7.3 isn't making nearly the power. Did you upgrade your turbo while you were at it? I would have gone with twins at that point. More fuel needs more air.

My neighbor has the newer 6.7/6-speed auto Dodge and loves it. The DPF catalytic system "fell off" and he put an Edge box on his. He pulls a massive three axle toy hauler with it.

I agree that the old 12V motor was a reliable workhorse, I am looking for one for my son to drive.

[larry0071]

The first engine that died was as follows:
Straight pipe 4" exhaust
AFE Intake
CFM+ Intake Elbow
Smarty Revolution programmer
Quadzilla digital guage system
Snow Performance Water/Meth injection (Stage 2 system)

Nothing hot, and I use the Snow system to fight EGT's. I dropped a valve in #2 and split that piston in half. I was at OEM redline.

Engine #2 seen a change from the Smarty to the Bullydog Triple Dog. No other changes. Still a mild build. I was at 1335°F when that engine locked up and burnt holes in pistons #3 and #4. This did a best of 12.7 in the quarter.

This latest build has the Hamilton Diesel valve springs, stage 2 camshaft, and a Industrial Injection Silver 64 with +100 HP injectors. I expect to see about 700 rear wheel HP when I get to a dyno. I expect mid to low 12's.... and if it shocks me... maybe high 11's.... but I expect I will need a shot of drugs to get 11's out of this pig.