Engine swap for street and towing

[jaredpears]

This will be no time soon, just want the information for research and part gathering. I’d like to build my 83 suburban to be decently fun to drive on the street and be able to tow smoothly, as eventually I’d like to get a smaller airstream to take my daughter on trips in. She’s only 2 so there’s no big rush. Anyways, I know that the 350 “can” tow but I’d like to be able to tow comfortably at around 70 mph without it really struggling. So far I’ve tossed around a carbed vortec 454, 4bt cummins, and I’ve even done some research on the Mercedes om606 diesel converted to manual injection, even one of the bigger ls’s. What’s everyone’s opinions on options for something like this?

 

[Catbox]

Mine would be to carb the L-29 Vortec 454.
When you can afford, swap it over to an aftermarket fuel injection system.

This is what I have planned for my truck.
Rebuild the 454 with a bigger cam and drop it into the truck with a carb and a matching 4L80 transmission.
Once it is sorted and the funds are present, I will inject it.

I don't plan on towing with it, but I will be driving it all over the place.

 

[Bextreme04]

That's what I did for mine for driving around and towing.

1997 Vortec 454/4L80e

I kept the stock injection and converted to OEM LS style ignition and computer control.

 

[Bextreme04]

You must be registered for see images attach

You must be registered for see images attach

 

[Vbb199]

Theres no reason a decently built 350 cant do the work, as im doing it now with my suburban. 7-8k behind it.

BUTTT, here at GMSB we always encourage bigger displacement.

454!!!

Please no oil burners under the hood

 

[jaredpears]

The 454 is taking the lead in my mind for simplicity, fuel mileage isn’t supercritical to me as I have driven a big block with a very very worn out ignition that was getting 7 mpg(also a vortec 454 in my old 99’ k2500) If I do the vortec 454 it’ll just get an oval port manifold and an hei and I don’t plan on changing any internals just to keep it simple. My old truck that had it was still kicking damn strong at 188k with the only major malfunction being the stock plastic distributor. I put it through the rigors, up to and including blowing the water pump by it downinshifting into 2nd gear going up a hill while towing, accidentally freezing the block because I put too much water in it, 4low pulling a pole truck out of the mud, which my dumb*ss still had the parking brake on. This is why I’m partial to the vortec vs over the older mark 4. Oh and getting a serpentine belt over the v-belts

 

[jaredpears]

You must be registered for see images attach

You must be registered for see images attach

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

 

[RecklessWOT]

454 is the way to go for sure.

With that being said, I have towed many vehicles through the mountains with my 350. Less than the ideal setup, but a loaded car trailer also weighs a lot less than an airstream. Would a 454 be a heck of a lot better? Of course. But not like you have to switch if you don't want to. Unless you're doing heavy hauling on a regular basis, hell a 305 could tow a camper easy. Especially in Texas, not like you're climbing steep mountain passes at super high elevation or anything

 

[jaredpears]

454 is the way to go for sure.

With that being said, I have towed many vehicles through the mountains with my 350. Less than the ideal setup, but a loaded car trailer also weighs a lot less than an airstream. Would a 454 be a heck of a lot better? Of course. But not like you have to switch if you don't want to. Unless you're doing heavy hauling on a regular basis, hell a 305 could tow a camper easy. Especially in Texas, not like you're climbing steep mountain passes at super high elevation or anything

While texas is relatively flat, I have a lot of family stretching from California all the way to Illinois and New York, so it would be nice to take her up there when the time comes, which is mainly why I said a comfortable towing situation haha

 

[RecklessWOT]

While texas is relatively flat, I have a lot of family stretching from California all the way to Illinois and New York, so it would be nice to take her up there when the time comes, which is mainly why I said a comfortable towing situation haha

Hah, fair enough. Living in a part of the country where the states are so small and I'm all over the place, while knowing how big texas is I was just kind of under the impression people from Texas never left that state lol. If you're planning on cross country road trips with a 454 though, you're gonna wanna think about gearing or OD transmissions. A nicely built 350 might be the best of both worlds. There's nothing like BBC power, but they also get like 9mpg whether you're towing or not. In the right situation, with a 350 on a long road trip you can get almost double that, and still have enough power to tow around the country. I have had my 'burb cross country several times and while the big tires, tall gears, and 700r4 have left me wanting more on occasion, if set up properly I know it can do a hell of a lot better. Don't get me wrong, I LOVE a big block and would never talk someone out of one, I'm just saying you probably don't need one for what you have in mind. You'd be surprised

 

[jaredpears]

I’ve been heavily looking into a 6l80e, depending on how cheap I can find one, I know it needs some specialized stuff to make it work behind the older motors, it’ll make it so much nicer to drive, I love it behind the 6.0 in one of the work trucks. I understand a 350 can be built to more than likely do what I want, but now while I do all my own wrenching, I don’t really want to tear into a motor much. I’ve taken heads off before but I’ve never dived into the rotating assembly and cam, so the swap just sounds easier to me if we’re being honest

 

[SquareRoot]

Here we go. "No oil burners" @Vbb199 , is uninformed. I was in that boat until I bought a Duramax. In your situation I'd probably swap in a 6.0 lq9 and be done with it. Modern small blocks produce the torque of yesterday's big blocks with better efficiency. Otherwise the OEMs would still make them. Like the 8.1s they have gone the way of the dinosour.

 

[Frankenchevy]

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.

 

[idahovette]

@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!!!!!!!!

 

[Curt]

I towed my 28’ bumper pull this past elk hunt through some mighty steep mountains.Healthy 383,4 speed manual,4.10 gears.

That’s a experience.I’m doing it again and again.However,had it not been for the SM465,not really sure if I could of done it,not with no small block.440 foot pounds from 2500 through 4000rpm.

On the flat I kept up with all the new diesels.70-75 all day long.

I would definitely go big block and fuel injection.That’s what I want,but we’ll see.If money was no object,I’d absolutely go Duramax.I have a 2023 with a 10 speed Allison that does 20mpg easy(I was and am still amazed).910 foot pounds.

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

After you’ve towed with a newer diesel,towing is different with a old truck.I still enjoy the experience even if it’s a little nerve wracking.Nothing gives assurance like a exhaust brake tow mode