Which dually - 8.1 vs pre-DEF 6.6?

[Grit dog]

The biggest issue you’ll find with older Duramax trucks or any older electronic injected diesel for that matter, is that many have been abused by kids who threw a tuner on dad/granpa’s already well-used old farm truck and ran the piss out of it with little to no maintenance.

Look at what you’re buying carefully if you go the diesel route, many of the drivetrain components are far more expensive than that of a gas truck and a “cheap truck” can turn expensive really quickly if you get one that’s bad enough.

Good points.
But from the flywheel back it’s apples to apples.
Not advocating diesel per se based on @Frankenchevy needs. And historically there is a pro-gasser sentiment from many in this forum, but even the mighty 8.1, new 6.6 GM gasser or 6.4 hemi or Godzilla motor will get absolutely walked by any new diesel or in this case an LB7/LLY/LBZ with a $300 tow tune. Add in altitude and slowing that load coming downhill and altitude will widen the gap made by the diesels skinny pedal. And an exhaust brake can be added for the other half of the arse whoopin.

 

[CheemsK1500]

One thing to keep in mind with a used diesel is the cost of the some of the individual components. A replacement turbo for a LB7 is around $800 from the cheapest vendor. Injectors will typically start around $1500 and go up from there. Fuel pumps are often $600+. As someone who has owned a 6.7 Cummins truck, I can confirm that the prices I’ve listed are reasonable by diesel standards and can be much more expensive depending on what particular engine you have.

Thankfully, you won’t have to be changing most of these parts on a regular basis, unless you are extremely unlucky or abusive to a vehicle. But, it is important to keep these potential costs in mind when shopping used since you don’t know how much life the existing parts have left in them.

 

[Frankenchevy]

I was surprised to find out that first gen dmax injectors are $300/each for Bosch or roughly $2400 to do them all. Cummins Bosch injectors run $3500 to do the 6 of them. Can’t remember if that’s with tubes and all. I did a set in my older Cummins as preventative maintenance. Don’t want one hanging open and washing down a cylinder.

 

[77Dmax]

Clean, stock diesel trucks are out there, you just have to know where to look. Stay away from the diesel forums, those are all beat like rented ******. The key is to buy them before the tuners get their hands on them.

I'd also venture to say most LB7/LLY/LBZ trucks at this point has had new injectors and or head gaskets done.

Also its a common misconception that all of the injectors need to be replaced at once. On an LB7 motor thats partially true because the labor sucks and the failure rate is near 100%. With my LLY I've replaced exactly one injector four years ago that I bought at carquest (GASP). It was in stock and has a good warranty. Zero issues so far. 300k miles and counting on that turd. Also the injectors can just be replaced. There is no need to tune or relearn.

The fuel filter isn't a big deal either. I buy the delco. I swap it once a year or so. Sometimes it's there for longer. Every oil change or every other is excessive and unnecessary.

Folks love to talk about the cost of maintaining a desiel to 300k and seem to forget the gas job also needs plenty of maintenance to survive. My work truck is a '19 one ton with a 6.0 gas.. thats had all sorts of work done to it with 195k on it, and I've put nearly every mile on it. Its never gotten better than 11 mpg, and drops to 6-7 with a mini-excavator on the trailer. The old dumpy LLY handles the load way better and gets that 11 mpg loaded.

 

[Grit dog]

^I will say though, gas engines have gotten cleaner under the hood and arguably easier to work on. (Not talking obscure, European or hybrid)
When I pop the hood on any newer rwd car or truck and compare to the rats nest of chit from the 80s/90s there’s less in the way.
Same cannot be said for diesels. Especially with emissions in tact. As much as I like diesels, from that standpoint alone, most are more expensive to work on. Even my 2016 Cummins. Had to do an exhaust manifold gasket a few years ago. It took every type of wrench I owned to get to all the bolts. And I mean every one and all the extensions, swivels etc.
That was in a deleted truck. It would have been twice as hard on a V8 diesel and especially a Flowerjoke.

 

[bucket]

Good points.
But from the flywheel back it’s apples to apples.
Not advocating diesel per se based on @Frankenchevy needs. And historically there is a pro-gasser sentiment from many in this forum, but even the mighty 8.1, new 6.6 GM gasser or 6.4 hemi or Godzilla motor will get absolutely walked by any new diesel or in this case an LB7/LLY/LBZ with a $300 tow tune. Add in altitude and slowing that load coming downhill and altitude will widen the gap made by the diesels skinny pedal. And an exhaust brake can be added for the other half of the arse whoopin.

I don't know about getting "walked on". Power is power, a lot of people have it in their mind that if something does a job at 2500 rpm, compared to 5000 rpm, that automatically means that it does it better. Just because an 8.1 or other gasser is winding out in rpm, doesn't mean it has a hard time while doing it.

The power between the two really is comparable. Yeah, the Duramax is going to make a little more power, but I sure as hell would hope so... it has a turbo for cripes sake. Also I will point out, the more one is tuned, the more it is going to eat parts. I would never ever buy a Duramax truck that has been tuned and hot rodded.

And just to put it out there, I am NOT pro-gasser. I am just realistic with that can be done for the money. There's two different Duramax trucks in the company that if the owner decides to offload them, you can bet your sweet biscuits that I'll have dibs on them. Hell, there was even an '09 F350 that I loved and it got sold off many years ago. If I could have afforded it at the time, I would have bought it.

Clean, stock diesel trucks are out there, you just have to know where to look. Stay away from the diesel forums, those are all beat like rented ******. The key is to buy them before the tuners get their hands on them.

I'd also venture to say most LB7/LLY/LBZ trucks at this point has had new injectors and or head gaskets done.

Also its a common misconception that all of the injectors need to be replaced at once. On an LB7 motor thats partially true because the labor sucks and the failure rate is near 100%. With my LLY I've replaced exactly one injector four years ago that I bought at carquest (GASP). It was in stock and has a good warranty. Zero issues so far. 300k miles and counting on that turd. Also the injectors can just be replaced. There is no need to tune or relearn.

The fuel filter isn't a big deal either. I buy the delco. I swap it once a year or so. Sometimes it's there for longer. Every oil change or every other is excessive and unnecessary.

Folks love to talk about the cost of maintaining a desiel to 300k and seem to forget the gas job also needs plenty of maintenance to survive. My work truck is a '19 one ton with a 6.0 gas.. thats had all sorts of work done to it with 195k on it, and I've put nearly every mile on it. Its never gotten better than 11 mpg, and drops to 6-7 with a mini-excavator on the trailer. The old dumpy LLY handles the load way better and gets that 11 mpg loaded.

Agreed. I put new injectors in our '03 many years ago, but not a single one has needed replacement since then.

However, a 6.0 gasser has no business in this discussion imho, lol.

 

[bigcountry78]

Aside from repair costs (injectors and pumps). The rest of this is largely conjecture or lack of knowledge about diesels.
Hasn’t been a diesel engine in a truck in the last 25 years or more that you “crack lines” to prime.
But it is a good way to make a big mess or cause serious injury.

I’m just drawing on my own experience, growing up around diesel tractors on a farm. I also made the mistake of buying a 2005 f250 with the 6.0 power stroke. That was a terrible decision that I have yet to live down. For me and my experience, a gas engine in a pickup makes more sense. Diesel for tractors, sure.

 

[Craig 85]

One thing to remember in all this @Frankenchevy lives in California and whether it’s gas or diesel he probably won’t be able to tune it.

I left CA 3.5 years ago and emissions have only gotten worse since leaving. My understanding is if you do have a tune, it has to be a CARB approved tune. They won’t pass the emissions testing if it’s not.

 

[77Dmax]

I don't know about getting "walked on". Power is power, a lot of people have it in their mind that if something does a job at 2500 rpm, compared to 5000 rpm, that automatically means that it does it better. Just because an 8.1 or other gasser is winding out in rpm, doesn't mean it has a hard time while doing it.

The power between the two really is comparable. Yeah, the Duramax is going to make a little more power, but I sure as hell would hope so... it has a turbo for cripes sake. Also I will point out, the more one is tuned, the more it is going to eat parts. I would never ever buy a Duramax truck that has been tuned and hot rodded.

And just to put it out there, I am NOT pro-gasser. I am just realistic with that can be done for the money. There's two different Duramax trucks in the company that if the owner decides to offload them, you can bet your sweet biscuits that I'll have dibs on them. Hell, there was even an '09 F350 that I loved and it got sold off many years ago. If I could have afforded it at the time, I would have bought it.




Agreed. I put new injectors in our '03 many years ago, but not a single one has needed replacement since then.

However, a 6.0 gasser has no business in this discussion imho, lol.

Yeah the 6.0 is what it is.

Another thing to consider is the availability of an 8.1 truck. I'm pretty well immersed in the biz, I've only seen a handful of them in the wild and that was yrs ago. Up here in the rust belt those years are all but gone too.

 

[bucket]

Yeah the 6.0 is what it is.

Another thing to consider is the availability of an 8.1 truck. I'm pretty well immersed in the biz, I've only seen a handful of them in the wild and that was yrs ago. Up here in the rust belt those years are all but gone too.

I don't know how to spot them in the pickup trucks, without looking under the hood. They are easy to spot in the 2500 Suburbans though. The 6.0 burbs got the semi floating 14 bolt. But the 8.1 Burbs got the full floating 14 bolt and that can be spotted when following behind one. If I had to guess, every 2nd or 3rd 2500 Burb I see has the 8.1 under the hood.

And yeah, I'm that weirdo that bends over in the hardware store or Wal-Mart parking lot to see what rear axle lurks beneath a Suburban, lol.

 

[Grit dog]

I’m just drawing on my own experience, growing up around diesel tractors on a farm. I also made the mistake of buying a 2005 f250 with the 6.0 power stroke. That was a terrible decision that I have yet to live down. For me and my experience, a gas engine in a pickup makes more sense. Diesel for tractors, sure.

I can understand the sour taste if you had a 6.ohno.
Also can understand if you’re comparing to some select old finicky diesels.
But both of those are like comparing a newer LS to an 80s smog choked Chebbie with a worn out carb and all the emissions stuff going bad. Or _______ insert some other notoriously finicky or unreliable engine. Like a 6.4 Powerstroke! Lol

Example, in the late 80s we had a few diesels where I worked. They were all gutless wonders and not super reliable (that’s subjective because some of the junk we ran, it was a miracle it ran). But had a idk probably 86-87 Kubota diesel tractor. Stone reliable.
Diesels have in general gotten much better on all fronts. Save for the early Tier IV and missions years and honestly still a bit of an issue. But ya trade DEF issues for collapsed lifters in a new LS. Ain’t no vehicle perfect.

 

[Grit dog]

One thing to remember in all this @Frankenchevy lives in California and whether it’s gas or diesel he probably won’t be able to tune it.

I left CA 3.5 years ago and emissions have only gotten worse since leaving. My understanding is if you do have a tune, it has to be a CARB approved tune. They won’t pass the emissions testing if it’s not.

The era of Duramax he’s contemplating is as easy as plug in, instant tune. Unplug before emissions. Almost Instant compliant. Not an issue.

 

[77Dmax]

I don't know how to spot them in the pickup trucks, without looking under the hood. They are easy to spot in the 2500 Suburbans though. The 6.0 burbs got the semi floating 14 bolt. But the 8.1 Burbs got the full floating 14 bolt and that can be spotted when following behind one. If I had to guess, every 2nd or 3rd 2500 Burb I see has the 8.1 under the hood.

And yeah, I'm that weirdo that bends over in the hardware store or Wal-Mart parking lot to see what rear axle lurks beneath a Suburban, lol.

8.1s in trucks have the AAM rear. There's no mistaken that diff.

 

[bucket]

8.1s in trucks have the AAM rear. There's no mistaken that diff.

Right, but so does the Duramax. Stock for stock, it's hard for me to tell between the two unless I can hear them, lol.