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Diesel swap for pure tow rig. Normal towing and best mpg options....?

My 5.3LT/6l80 half ton getting 12.5 and never lacking for power towing is why I thought of the LS/LT route. It did absolutely perfect. So I had kind of thought of going that way. I averaged 17.5 towing the 2800# trailer with all my camping gear and stuff in the bed, doing 75-80 out to Wyoming. Then 12.5 back doing 7-9% grades and winding around state parks and such mixed in there. Then 70 mph across south Dakota. With a CCLB k30 on the trailer.

So so far, the mpg and towing ability really isn't that different from the diesels.

Even on a winding 9% uphill coming back I had to watch my speed to keep from speeding. 10-11k is about all the trailer weight I should ever have. More like 9600 or so with the k30 on it.

I was really contemplating the 6.2lt/10speed auto idea before diesel started popping back into my mind.
And doing the DOD delete while it was happening.

I'm cornfused , and really can't decide.
Diesel being so much more than gas is also a factor I guess.
 
What does it cost to put a modern gas drivetrain in nowadays? I could do a damn nice 800ft/lb cummins swap in a 2wd for 7500-10000.
 
shady said:
My 5.3LT/6l80 half ton getting 12.5 and never lacking for power towing is why I thought of the LS/LT route. It did absolutely perfect. So I had kind of thought of going that way. I averaged 17.5 towing the 2800# trailer with all my camping gear and stuff in the bed, doing 75-80 out to Wyoming. Then 12.5 back doing 7-9% grades and winding around state parks and such mixed in there. Then 70 mph across south Dakota. With a CCLB k30 on the trailer.

So so far, the mpg and towing ability really isn't that different from the diesels.

Even on a winding 9% uphill coming back I had to watch my speed to keep from speeding. 10-11k is about all the trailer weight I should ever have. More like 9600 or so with the k30 on it.

I was really contemplating the 6.2lt/10speed auto idea before diesel started popping back into my mind.
And doing the DOD delete while it was happening.

I'm cornfused , and really can't decide.
Diesel being so much more than gas is also a factor I guess.
Click to expand...
The power and mileage of the Diesel more then offsets the artificially inflated price .

The LS/LT thing sounds good on paper until you have to pay to rebuild the 8 or 10 speed trans

The new 6.6 Gasser is pretty nice engine, may consider that into your options.
 
I could do the 4th gen LS and a 6l80 for 10k all rebuilt.
10spd I don't know. Haven't really priced one.
I don't really think I'd want to step into the LT realm because of the direct injection.
But then I said I'd never do an LS before and then went and did one lol.

The diesel thing has me intrigued because it's different, new things to learn, etc. The price of it possibly skyrocketing is a little scary, but I should know what it's gonna do before I start this build next spring or so.

I think the new 6.6 would be pretty pricey at this point still. Maybe more than I'd want to do even.
 
My inlaws have a 6.6 gasser. It's a 21 Chevy 2500, crew short bed. Pulling my last camper (38ft, 10k pounds) we average 7.5 to 8 mpg. In flat land Mississippi and Florida.
 
My experience with towing through the mountains with a 6.0L gas engine in a 2015 Chevy 2500 HD is 7-9 mpg with 10K car trailer and a squarebody regular cab 4x4 truck on the trailer. My current 2016 Chevy 3500HD dually with stock emissions restricted Duramax and the same trailer/load gets 12-15 mpg in the same terrain. Unloaded running empty, both get similar mileage around 15-16 for the gasser and 16-17 mpg for the diesel on flatter ground. The only way you save money with the Duramax in stock form is towing heavy over long distances and doing it often which is what I use my dually for. I also found the gasser would like to slow down more on mountain passes (often below 45 mph on steep grades) and didn't feel like it was made for the job compared to the Duramax truck.

However, both trucks have options for tuning and improving MPG and power. Deleting emissions and tuning the Duramax is on my list. My friend with a 2007 Duramax 2500HD did a delete and tune and gets 5-10 mpg average better than I see.

Recently, I bought a 14K tilt deck-over trailer that is heavier and puts the vehicle higher into the wind. I have noticed my MPG drop with the added wind resistance in a strong head wind while climbing a grade but otherwise fairly comparable to the 10K car trailer.
 
Having towed with a Cummins and an LS, there’s no way in hell I’d ever build a tow truck with an LS. If I did it would be a stroked and forged 6.2 with a 3.0 whipple, 4.30 gears, and a full exhaust. My 14 Silverado with the 5.3//6l80e with a tune//intake//full exhaust couldn’t hold 70mph on flat ground towing a 6k lb camper without constantly gear hunting. My 2020 Silverado 5.3//8l90 stock can’t do it either towing the same load. Sure I could lock them both in 5th//7th gear but why? I could take a stock diesel of any form in the past 20yrs and set the cruise at 75 and never think about it.

For a swap, hard to beat a 12v Cummins of any flavor. I’d think the dmax would be awesome but you’ll blow your 10k wad on the engine and electrical alone. I’m a fan of the common rail stuff but they are stupid expensive. $1500+ for injectors ain’t chump change and the lb7’s usually need them replaced at some point.

Definitely do the zf6 if you can. That’s a sweet shifting transmission.
 
See I had different results with my 15 Silverado. Towed amazing and had more than enough power for the 10k. But that's the LT not an LS so that may be different for sure.

I still like the diesel thing. If Cummins is what everyone suggests, what do I look for for a 12v ve... What years and such did they come in, etc.?
My knowledge of Cummins is they're diesel, 5.9 or 6.7, and 12v or 24v.... That's about it.
 
91.5-93 is intercooler ve pump. 89-91 is non intercooled ve pump. I wouldn’t pass on a 94-98 p7100 though.
 
Mine are LTZ. I attributed the 14’s issue to having larger tires on it but the 20 was on factory tires. TBH, half tons are for soccer dad’s that want to pretend to do stuff in my opinion. That’s why they are my wife’s vehicle.

Anything from 89-98. And even then, you find a VP engine (98-02) those are easily converted to a p7100 and you get the better flowing head.
 
So 92-98... That gives me search parameters... I do a little one, and they're fuggin GOLD here :doah:
A rusted out engine that looks like it's been used as an anchor , laying on a pallet is $3500. Only running truck was 6k , 300k+ miles , and needed a rebuild due to 2 cylinders being bad.

Cummins looks to eat up the budget quick too lol
 
centexk5 said:
Mine are LTZ. I attributed the 14’s issue to having larger tires on it but the 20 was on factory tires. TBH, half tons are for soccer dad’s that want to pretend to do stuff in my opinion. That’s why they are my wife’s vehicle.

Anything from 89-98. And even then, you find a VP engine (98-02) those are easily converted to a p7100 and you get the better flowing head.
Click to expand...
Meant LT as in the engine family. The direct injection stuff is great on torque and mpg
 
shady said:
So 92-98... That gives me search parameters... I do a little one, and they're fuggin GOLD here :doah:
A rusted out engine that looks like it's been used as an anchor , laying on a pallet is $3500. Only running truck was 6k , 300k+ miles , and needed a rebuild due to 2 cylinders being bad.

Cummins looks to eat up the budget quick too lol
Click to expand...
Go price out an LB7.
 
Haven't gotten there yet.

I had a 2wd Ford with a 7.3 and manual lined up for $2500 a couple years ago. Didn't jump on it.. then just kind of quit looking at diesel stuff for it.

I know about the lb7 injectors, and I'd be fine with replacing them before it went in if I went that way. Seems most people like the Cummins though.
 
Check govdeals.com for school busses well maintained most retired due to time friend got one here for 2500 running drove it home pulled engine Trans sold rest for 600
 
The LS/LT engines tow pretty well with the 6+ speed transmissions, the whole low end torque argument is based on old school transmissions with only a few gears. Sure, it matters a lot with a heavy truck, horsepower that starts with a 1, and a TH350 or SM465, but modern stuff with a bunch of gears and lockup converters really keep the engine in it's happy spot whenever.

The 12V Cummins is a great choice too. Easy to fit, easy to plumb, one wire to run. The VE pump won't make as much power as a p-pump but 500hp/1000tq at the crank is easy even with a VE pump. That's still lots of tow rig motor. Dump the stock turbo and turn up the fuel and a 12V Cummins makes an awesome tow rig engine and they're as simple and reliable as they come.

I have two rigs with 6.0L LS type engines and one with a 12V, the Cummins is the slowest but is by far the best tow rig and definitely more efficient. I'm a big fan of the Cummins for this kind of thing.
 
Not sure about the swap but my stock auto trans 2002 7.3 gets 12 hucking my K5 to Moab from Vegas.
 
I have a spare 1996 12V Cummins (VE pump) with a 6-speed Allison that came in a junk diesel pusher RV that was stripped of interior. I only had to haul it away / friend deal. My current plan is to use it in a future tow rig build using the 1949 Chevy panel body. I just need to get through a few other projects before I can start on it.

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