Engine swap for street and towing

[Curt]

Also I might add that the Duramax’s 20mpg is unloaded.Haven’t towed with it yet.And my best guess on my 84’s fuel mileage towing through mountains was 4-6,maybe.I could actually watch the gauge go down.Probably the biggest hinderance of all,even with 42 gallon reserve tank.

 

[Vbb199]

Here we go. "No oil burners" @Vbb199 , is uninformed.

diesels do burn oil there is no misinformation there.

 

[jaredpears]

@jaredpears , you say your daughter is young and you have time.........I call BS....in a minute you'll turn around and she'll be out of school!!! TIME FLIES my friend!!!!!!!!

I know trust me, these 2 years have already flown by!

 

[jaredpears]

The 6.0 isn’t exactly great on fuel. Towing is kind of an equalizer. Yes a 454 will get 11-12 unloaded, yes a 6.0 will get 13-14 in the same circumstances, or 15-16 with a fuel injected 350; but you throw a 6500-7500lb mid-sized bumper pull airstream behind the vehicle, they’re all getting 10ish mpg.

Only way around 10ish mpg pulling a decent size bumper pull is a diesel swap. The 5.9 Cummins is the most logical option. 12 valves are pretty good mileage, awesome power/tq potential and are the “go-to” diesel swap for good reason. HO 24v from 03-04 are the king of efficiency, but obviously more complex to swap.

@jaredpears , I would advise against a 6L auto trans. I hated towing with my ‘19 Silverado because of that tranny. In tow haul mode it would violently downshift on downhill sections and everywhere else, it was slower than sleepy Joe at making up its mind on which gear it wanted to be in. I’d go with the 4l80 over the 6l80.

Maybe get a blueprint 383…

Side note: my BIL and I towed identical trailers on our Utah trip. We were towing 70mph average, with some sections 75mph. He has a 2013 vortecMAX 1500 Silverado with the 6.0 and we took our 2004 crew cab long bed Cummins on 35s with a small lift. He got right at 10mpg sometimes less and we were stopping for fuel quite a bit. I got over 15mpg and was in the fast lane on all the grades.

Long story short, towing will equalize gas engines fuel efficiency within a small margin. I haven’t checked the fuel economy on the freeway on that truck, because it is almost always hooked to my wife’s horse trailer nowadays, but I remember it being around 20mpg on the freeway at 65ish mph. Not sure how much the nv5600 6 speed contributes to fuel economy, but my wife feels like a tractor trailer driver rowing through the gears and really likes it.

I have only had good experiences with my shops 09 2500 6.0 6l80 towing 19’ and 30’ scissor lifts on a tilt bed trailer. And while a 12v would be an awesome swap, and my brother knows them like the back of his hand, I’ve heard they’re a tight fit and aren’t good for the k10 frames

 

[jaredpears]

I think the 454 is taking the lead in my mind because it’ll bolt in, I can pick up the vortec for pretty cheap from the junkyard, seems like the best bang for buck. Does anyone know if the Quadrajet off the 350 can be tuned for the 454 or would I just need to get a new carb?

 

[Frankenchevy]

My (sold) 2012 6.7 Cummins did 12-14 on hwy,stock engine,unloaded.

That is pretty bad. They must’ve changed something, then went back after realizing the mistake. Our 2020 longhorn Laramie crew cab long bed 3500 did 22mpg on a flat highway trip on the factory ht tires based on the LOM.

I have only had good experiences with my shops 09 2500 6.0 6l80 towing 19’ and 30’ scissor lifts on a tilt bed trailer. And while a 12v would be an awesome swap, and my brother knows them like the back of his hand, I’ve heard they’re a tight fit and aren’t good for the k10 frames

I’ve read the same thing about 12v and k10/20. A 12v not turned up at all isn’t much different than a healthy 454 torque-wise. It must be torque delivery or perhaps the weight.

Maybe the programming on the 6l80s was different based on the year or being 2500 vs my 1500. Either way, I believe the consensus is that the 4l80 is the more robust option, but I don’t know much about automatics other than what I read or do/don’t like based on operating one.

 

[Grit dog]

That is pretty bad. They must’ve changed something, then went back after realizing the mistake. Our 2020 longhorn Laramie crew cab long bed 3500 did 22mpg on a flat highway trip on the factory ht tires based on the LOM.

The 07.5 - 12 models were and still are far and away the worst for fuel economy out of the lineup. If it was still saddled with OEM tuning and emissions. '13 was a big year, restoring "most" or even all of the lost fuel economy between the early 6.7s and the late 5.9 CR engines.
@Curt 's mileage is maybe a tad low (but no mention of how fast "on hwy" was), but that era of engines sucked fuel compared to all before it and after it due to the frequent regens burnign alot of fuel, as the only means to keep the exhaust, exhaustin'.

 

[Curt]

That is pretty bad. They must’ve changed something, then went back after realizing the mistake. Our 2020 longhorn Laramie crew cab long bed 3500 did 22mpg on a flat highway trip on the factory ht tires based on the LOM.

I’ve read the same thing about 12v and k10/20. A 12v not turned up at all isn’t much different than a healthy 454 torque-wise. It must be torque delivery or perhaps the weight.

Maybe the programming on the 6l80s was different based on the year or being 2500 vs my 1500. Either way, I believe the consensus is that the 4l80 is the more robust option, but I don’t know much about automatics other than what I read or do/don’t like based on operating one.

Yes sir,it was bad.What was worse is I loved that truck…no DEF.

I didn’t look at Ram before I bought mine this year,but I’d have to think they also added a new multi gear trans?I know the Chevy and ram both sport a 31 gallon fuel tank,my range full is over 600 miles,with my 2012 I was lucky to get 400.I think that truck was a 6speed

 

[Curt]

And now,diesel is maybe not the hottest choice for a upgraded engine or new truck.

I guess if you did the bio route on a 12 valve.

I think the 454 is taking the lead in my mind because it’ll bolt in, I can pick up the vortec for pretty cheap from the junkyard, seems like the best bang for buck. Does anyone know if the Quadrajet off the 350 can be tuned for the 454 or would I just need to get a new carb?

yes,the carb would work.no electronics is nice,but altitude changes can greatly effect your carb.Fuel injection is becoming somewhat more reasonable in costs.

 

[Frankenchevy]

Yes sir,it was bad.What was worse is I loved that truck…no DEF.

I didn’t look at Ram before I bought mine this year,but I’d have to think they also added a new multi gear trans?I know the Chevy and ram both sport a 31 gallon fuel tank,my range full is over 600 miles,with my 2012 I was lucky to get 400.I think that truck was a 6speed

We have the Aisin 6 speed, being a 1-ton with the HO engine. We got the 50-gallon tank. Puts our freeway range around 1,000 miles unloaded.

 

[Bextreme04]

How did you mount those coils? I do love the coil per plug setup when money would allow

One side is an L21 valve cover and the other I drilled the stock cover and riveted on mounts for stock LS coil pack mounts.

 

[1984dually]

For me the 8.1l 496 is a better option. Bolts right in and you can use your drive train as is. Use 454 exhaust manifold. Upgrade to a 4l80E and cruise at 70 no problem. Kodiac or van front drive would be nice but not totally needed. There is aftermarket brackets available. 6.0
ls engine would be good but would work but nothing like peak torque at 3000 or so than 4500. Did that swap about 8 yrs ago and been happy with it.

 

[peats]

Save yourself a lot of time and money and find a 400sbc and rebuild it. Flat top pistons if you want, rv cam, quadrajet, long tube hedders, stock heads and make sure you use a big block rad. Gear it around 330 to 370 . You will be amazed at the torque these engines make. No need to change connecting rods.It won't make much power above 4,000 rpm but will be outstanding up until then. I've had a couple of these combos and still have one in my '72 k5. you won't get tired of the torque!

 

[Matt69olds]

Don’t bother with the 6L90. It’s hard to beat a 4L80 for comfort, durability, and ease of use. Gear the differential so at 65-70 mph the engine is starting to come onto its torque curve

Go with the big block. And since torque is the name of the game here, don’t limit yourself to big block Chevy. A 455 Buick or olds swap, or even a 500 Cadillac is a fairly easy project. Before I had my diesel Ram, I used my dads 455 olds swapped 81 GMC to haul my car to the various races. It’s a basically stock 71 455, the truck has 3.08 gears and the trailer loaded weighs around 6500-7k. It has zero problem pulling the trailer and interstate speeds.

Diesels are hard to beat, but with the cost of diesel fuel the added fuel economy isn’t nearly the advantage it use to be.

All Q-Jets are capable of at least 750 cfm. The small block carb will need some calibration changes for the bigger engine. Get with a Q-Jet specialist, they can provide the expertise and parts to get the carb right.

 

[Big Ray]

I'm building a l29 with a XR276HR cam.
Richard Holdener on YT got 515 foot lbs at 3500 rpm and 428 hp with it and a holley 750.
For my travel 'burb.

Piss cutter put out a video with a 388 stroker making over 500 ft-lbs.
At a sensible rpm.