Chevy 5.3L vs 6L for towing

I have a '94 2500 left to me by my grandfather. He charged my dad and I to take care of it and every can use a free truck right?

Its been faithful with its terrible 305 and I think 4L60 but I can hear the main bearings knock on start up, yet it still tows well. The front two cylinders oil fouled the plugs about 15k miles after the first tune up we did on it, but at 144k 30k miles later hasnt quite done that again.

Enter the proper ls swap. I've been trying to find a 6L LQ4. Dad passed on one at picknpull because some one pulled the spark plugs out and "theres rust in the jugs and your grandfather is rolling over in his grave for suggesting using a crappy engine". Yet I was wanting to rebuild it and then use it....

Everything seems to be $1800+ for just engines, and I missed a wrecked van for $1600. Do I keep looking for a van or should I look for 5.3s? I've heard they get similarly terrible towing mpg like the 9-11mpg my dying 305 gets.

So GRM the bottom line is...do I need a 6.0 to tow if so any one got a lead on on here in Ohio? or can I use a 5.3?

~Alex

How much do you need to tow? I think the 4L60e will be the weak point in the system with either engine. I think 5.3 will be plenty for you.

The 6.0L is a pulling animal (when coupled to its stock trans). Lots of torque- one of the best towing trucks I've ever owned.

It also sucks gas. Mine got about 9 mph with no load on it.

Not sure how hard an LS swap is in these trucks, but why not slap in a mildly built crate 350?

The 5.3 is a better engine than any factory 350 truck motor.

5.3L will be fine. The 6.0L was a fuel sucker from the factory. A few tight-lipped guys seem to have unlocked a tune that at least keeps it proportional for its size, but in factory tune they burn more fuel than you would expect compared to the 4.8/5.3 versions.

5.3L is plenty, and since folks don't think the 5.3 is big enough, they're much cheaper than 6.0L. If you poke around, you should be able to find a decent 6.0L for not crazy money. I got a 6.0L LQ9 (the 345hp high-output version of the LQ4, found in Escalades, SS trucks, etc) with 80k, wiring and ECM for $1300. They had it pulled, palleted, and ready to load on my truck. I think what kept that one less expensive was the fact that the accessory drive was busted in the wreck, so it came with water pump and alternator, but no brackets or other accessories. Since I'm putting it in a car, I need a modified F-body drive anyway so it was no issue for me. The LQ9 has the 317 heads, which are basically LS6 heads with slightly larger chambers (since the LQ9 is 6.0 and the LS6 is 5.7).

But 5.3L truck motors are as plentiful as bacteria and more than enough for towing. You'll run out of truck capability before you run out of torque.

Your old 4L60 will physically bolt up to the LS, but there are two bolt holes that won't line up. You'll have 5 which is plenty. The problem you'll have is compatibility. The 5.3L ECM will need some custom hacking to get it to run the old 4L60E. I would either build a whopper 700r4 and program the ECM as a manual transmission version to ignore the transmission, or just get the 4L65E that was behind the 5.3L.

I will, however echo what Junkyard Dog and Kenny said: The 5.3L will be a better motor all around than an old-school 350, however, a 350 will be 80% as good for a tenth the work and money. Don't get me wrong... I'm all about taking what you have and making it what you want, but you're looking at investing 5 times what the truck is worth that can't be recouped if you take it out and sell. But I've received that advice a million times and ignored it because its what I want so please don't think I'm being critical.

Consider this: A good running Vortec 350 from a junkyard = $500. Take the vortec heads off, have them cleaned and magnafluxed and sell them for $200. Sell the intake for $100. Buy a set of $600 aftermarket vortec heads with thicker castings from Jegs/Summit. Buy a used aluminum 4-bbl vortec intake that someone took off a ZZ4 crate motor or a marine engine for $80. Find the TBI from a 454. (454 TBIs are like a 4-bbl version of the 350 TBI). Swap over the dizzy and accessory drive, use a Melling RV-type cam, burn a chip, and now you are set up with 275-300 easy and cheap HP, and its basically a bolt-in right down to the sensors and wiring harness. That way you're getting more oomph than a 5.3 without all the hassle. You won't win MPG contests, but you'll be surprised at how much it doesn't guzzle.

I used to build these for trucks and boats, except I tried to keep it cheap and I kept stock vortec heads and a Qjet or Holley. The one I built for my boat dynoed at 290 hp at 5300 and I forget the torque, but it was lots. I put one like this in a 79 Caprice (with a Qjet) with a TH350 and 2.73 gears and it could do 18-20 mpg on the highway. I know that holds no comparison to a truck with 3.73s towing a trailer, but I didn't think that was too bad.

yeah, just build a 350. Then again a ring and bearing job in the 305 won't cost much at all.

I can add in here.

I JUST (last weekend) finished my lq4 swap in my 1989 k2500 4 speed manual.

Here is my 2 cents and actual numbers

Total cost for the swap: ~$2700

Total hours (drive in the garage then drive out): 5 weekends at 10-16 hours or so a weekend. Make sure you have all the parts sitting there waiting, I collected parts for 8 months and used ebay to keep the costs lower.

Best part is that it is so simple I literally drove it out of the garage, bled the coolant, went to gas station, filled it up and took it on a 180 mile little road trip. No issues and its got 400 miles or so on it now and gets me 15-16mpg.

Havent put it to a trailer yet, but im expecting good things. Ive got a huge parts list with part numbers I can give you of that helps. Ill add a photo or two later.

the 5.3 tows fine in my avalanche, but i also have the optional 4.10 gears. they're very good gears for towing with a 5.3.

Build a 350 or even 383 with some cheap aluminum heads, spend the money you saved on gas that you would have spent just the same with a 5.3 or definitely a 6.0..alot less headache

curtis73 wrote: Find the TBI from a 454. (454 TBIs are like a 4-bbl version of the 350 TBI).

I'm not trying to doubt your wisdom (because I know it's deep), but I have a TBI body from a 454, and it's definitely a 2-bbl; just with bigger bores than the 350(&305?).

snagged from teh interwebs:

In reply to RealMiniDriver:

I'll hazard a guess that the 454 unit flows about twice as much as the smaller one.

I've already towed tons of stuff with the 4L60, I figured I'd replace with a 65 or 80 with the new engine, I forgot to mention that. I was going to try and get it from the same truck.

After I rebuild the engine, rebuild the trans (Ive had low oil and metal on the dipstick before) and tune for a 350 or dumb 383 build which isn't an option I'd be pretty much at a 5.3 or 6.0 swap.

Catapulkid- So you like it then? Would you recommend a 6.0 or a 5.3? Thats exactly what I'm looking for in all of this work.

One thing I saw was the Ly6 was not too different in price verses a LQ4 at least on ebay. I guess its time to try and see what I can find for deals on a 5.3...Either way though I'd get a tune...

~Alex

I'm not dealing with TBI. Its part of the archaic 50s design I hate about the 305/350 these trucks came with.

Multiport EFI is the future!

My 1996 C1500 with the 350 Vortec has 260hp stock, and gets 20mpg on the highway, and 12-13mpg towing an open trailer with 2,000lb Miata (and a bed full of race stuff). It has 255k on it now.

The aftermarket heads, and marine intake/tbi seem like a lot of work for a potential of only 15hp. It would seem you could find that in other ways, no?

All of this because the 305 needs an intake manifold reseal?

I would suggest you get the 5.3. I was thinking about this swap also with my 91 Camaro for a while. The 5.3 will be much cheaper and easier to find, which will make the process less stressful. A negative that I can think of is that there won't be very many relatively low mileage engines since the vehicles are heavy use DD status.

The most recent copy of Car Craft showed up in my mailbox a couple days ago. Highlighted on the cover was a 350 built for low money. Made 320hp & 400lb/ft of torque at the flexplate. Vortec 350 and a Street Demon carb. So a bit different from your 305 but you'll have a lot of the right accessories to get the swap done. It'll be a bit more complex getting the factory TBI/ECU setup happy but I'd go that route.

Racerfink- Yeah a newer more efficient v8 is a better way for that. I'm not really after horsepower, just efficiency. Which is what the newer engines like the 5.3 is good at, after all its a smaller engine replacing your 5.7/350.

Bentwrench- No the 305 burns oil, has main bearing knock on start up, makes 86hp and 100ftlbs, gets 8-9mpg while towing. However it still runs, thats the only impressive thing it does.

I also need to fix the ac, rebuild the trans, rebuild the engine, and other things I'm forgetting. All the same things that get changed with a newer engine swap.

OP seems to want to spend a LOT of money on a truck that isn't worth anything.

I can't really make any suggestions as he seems determined to go ahead with this even though it will cost a lot more than he thinks (go look at the GRM "actual LS swap cost" article a little while ago). Good luck finding an aftermarket standalone controller for the 4L60E in the newer vehicles (its well over $500).

The 350 vortec engine which will be approximately free and run with the TBI setup you currently have is the way to go. Spoiler alert: it makes more torque down-low then the 5.3L does, and while the 5,3L does get better "mpg", you won't see those savings add up until years down the road... when the truck is worth less than it already is.

The GRM bottom line is either swap a cheap TBI/vortec motor in (brand new goodwrench crate motors from GM are like $1500-$2k) or buy a whole 'nother damn truck.

For $3k, you could probably get into a rough-around-the-edges 2000-ish 2500... of course, a 1500 from 1999 or newer with the 5.3L is rated to tow more than the 94 2500, and you can definitely get one of those with higher miles but it nice shape for around the $3k mark.

RealMiniDriver wrote:

curtis73 wrote: Find the TBI from a 454. (454 TBIs are like a 4-bbl version of the 350 TBI).

I'm not trying to doubt your wisdom (because I know it's deep), but I have a TBI body from a 454, and it's definitely a 2-bbl; just with bigger bores than the 350(&305?). snagged from teh interwebs:

You're right... I was speaking metaphorically since it flows more like a 4bbl, but it is a 2bbl. The SBC TBI flows about 390 cfm wet with nozzles mounted. The BBC TBI flows more like 675.

Rustspecs13 wrote: I'm not dealing with TBI. Its part of the archaic 50s design I hate about the 305/350 these trucks came with. Multiport EFI is the future!

Amen. My fingers burned after a typed a recommendation for using a TBI on anything, its just that it would be an easy thing for this build

In reply to Rustspecs13:

I do. I recommend it and priced everything out to the nut and bolt both ways, even a caddy 500 was priced out for epic torque. Money is about the same and i didnt have the time to play with building a motor to cut some costs. I decided to go new when i found this lq4, with 83k complete for 900 bucks. Deals are out there. I had orginially planned a 5.3 and it woulda worked if you have the gearing.

It is so crisp and modern feeling compared the old tbi, not to mention the power.

Part of the problem is the truck was from my grandfather. My dad won't get rid of it. Its a 3 seater cab 8ft bed 2500 from florida so the chassis is solid. I kinda like it because its simple and no abs/excessive chassis electronics to fail or cause problems.

I'm never buying a crate tbi engine, nor would my dad. So that leaves junkyard engines, or craigslist deals. I can pull 3 5.3's and 2 350s from a local yard, and the 350s look like E36 M3 and the more complete not open to element one is 260k miles. Yeah, no. Same money gets a more powerful, more efficient engine, and with all the other repairs the rest of the stuff needs its almost the same money for a 5.3 or 350, only things after that is stuff like a fuel pump and AC lines.

Oh and I've looked at $3000 trucks around here (ohio) and they are rust buckets. Plus what else will they need? My truck has lots of maintenance done and I know what it needs. I love how it tows and I've way over loaded it before too and it hasnt been that bad...

In reply to Rustspecs13: Are you sure it's mainbearing knock? My 1997 350 has a knock on start up that sounds deep and serious It's the wrist pin and it's been knocking for about 250,000 miles (I have 343,XXX miles on it so far) Only 4 repairs to get that far. Total spent is under $1000 Never let me down. Always gave me sufficient warning to fix the problem before it left me stranded..

Oh and it get's 19MPG on the hwy and 17 in town.. That's in a 4X4 with most of the whistles and bells..