So hopefully the topic title catches a few interested ears to contribute...

This is not an IMMEDIATE project for me, it's more to stimulate some discussion, pick some brains, and see whether what I want is smart or foolish.

Specific planned thoughts:
- take a smaller displacement LS 4.8 or 5.3, literally focused on the cheapest and most common versions. The ones you see for $250-500 at most complete with everything. Anyone getting a 6.0 pays alot more, i'd rather just add a few psi since it sounds like if the stock internal parts aren't any stronger boost will get you to the same place.
- add some turbocharger boost focused more on TORQUE to get loads moving than big horsepower numbers.
- be relatively frugal (trying to avoid $10,000 builds here) and focused on RELIABILITY
- hopefully not destroy the life of the engine, i'm hoping it would go 100,000 miles preferably 200,000 miles, i'm aware higher power wears out things faster but it shouldn't be breaking in 10,000 miles just because you ran 10,000lbs up a hill in the rockies a few times. Duty cycle is intended more for other light trucks that 'tow occasionally', not the HD trucks that tow endlessly.

My goal is not to produce 900hp for 9 seconds at a time, it's more to produce torque up to the 450-550lb/ft range coming in strong even under 2000rpm for minutes at a time climbing up a hill, basically replacing a big block or the earlier duramax diesels. Just like the Ford Ecoboost is a V6 meant to replace V8 power, i'm looking for a smaller small block LS to replace big block Vortec 8100 and Duramax LB7 type power. Horsepower goal? Don't actually care - just want the torque. Curious, but don't want to sacrifice low end grunt - my eventual goal would be a Suburban 3/4 ton towing up to 10,000lbs cross country.

This might be a fools errand, it's probably simpler to just put in a big block, and the unladen MPG of a turbo small block might not actually be much better - I know i'm not too impressed with what I hear about the Ford Ecoboost for it's MPG (V8 power sure everyone raves about the power, but why call it ECOboost when it also has V8 economy from what I can tell - i'm not griping about anything except the name) but thats why I started with admitting this is a thought exercise, that if it gets good feedback might become a real project, and if universal feedback indicates it's foolish will probably die on the vine.

 

Do not know for sure but it might be that 333 ft-lbs of torque at 3000 rpm would be easier on an ls than the 500/2000 combo you are talking about. A 5.3/4.8 is not built like a diesel (keeping in mind the junkyard theme) and should be able to sustain 3000 rpm for a while.

 

That could well be, fwiw i'm not against something like replacing rods and pistons but when people say blocks and crankshafts should take 1000hp bone stock I was hoping no more than that should be necessary. I know torque kills parts in a way different than rpm, but i'd still like to round out the bottom end/focus on it more than most projects. Something like 40% more torque and 15% more HP is worth trying to build for me, if I went from the lowest LR4 4.8L with 255hp model to merely 293hp but the torque raises to 400lb/ft that's probably the least i'd consider worth the work. (plus altitude compensation if you've seen how engines lose power as you climb the rockies with a load, a big thing I really like about the Ecoboosts)

Should 40% more torque be an engine killer? It might be, but even stock rods and pistons used in later model or bigger displacement engines they seem to handle it - 335lb/ft in the LM7 5.3L, 370lb/ft in the LQ4 6.0L, not too far away now from "at least 400lb/ft" as a goal - just getting there with boost instead of displacement. An LQ4 with a 22% torque boost from a turbo would hit 450lb/ft, my original 'big block torque' goal... are the pistons/rods that close to dying at a constant heavy load? I don't know, it's just my thinking. If I upgraded those, would the rest of the engine handle 550lb/ft or would it all come apart?


Over on the GMT400 boards (88-98 chevy pickup) when people have voted on the best engine changes and upgrades the clear majority of people choose a 383 small block over the greater power of every LS swap often 100hp more. Why? Torque to get the loads moving and keep them moving without howling like a banshee at redline in 2nd gear going up hills - mind you this only matters to guys who drive trucks like trucks and not sports cars. Most guys here need 10 second quarters, not 10k towing! Even if we trade torque for rpm and shift slightly up from "diesel replacement" level i'd still like to focus lower than most builds and i'd like to open the floor for brainstorming of different ways to get there.

I'm aware a couple of broken parts may eventually happen - if built I accept there may be some experimenting here, i'm just trying to avoid known failures, like where people say engine parts known to fail at some levels like those brittle hypereutectic pistons and such.

It would also mean things like no chinese turbos - something that can run hard for minutes is best, heck maybe even the Cummins ones with a built in engine brake function, if the turbo map wouldn't be hopelessly wrong for a gas engine.

 

It depends on if your budget is for the complete swap and how much work you are able to do yourself.
The right size turbo will easily add 100-150ftlbs over stock on a 5.3 although I think I would bite the bullet and buy a 6.0, I can get 6.0's at my local pick and pull for less than $400 but it takes multiple trips to find one before someone else gets it. Even in the $1000 range I still feel it's a better starting point.
A 6.0 with a small turbo or PD blower will be a pulling monster with a few mods.

 

Its not a true 1:1, but, I have a gen 2 LT1 383 with a 7675 and that will go from vacuum to 15psi in about 1.5 sec while cruising if you punch it.

I am not sure how well it would handle sustained heavy loads ECT and IAT wise, but the idea is doable for sure.

 

I think you'll get better mileage towing if you can make enough torque to keep transmission from downshifting. But you'll want to play with rear gear ratios so engine isn't lugging at low RPM.

I have a 3.5 EcoBoost Max Tow with 3.73 gears, tune, downpipes, intercooler. All the torque is in by 2000 RPM on dyno, and that's right where it cruises on the freeway. And it has a very aggressive transmission 1st gear ratio (4.17). That's why it tows so effortlessly.

LS by nature is a higher revving engine than the EcoBoost. Just work with what it wants to be.

 

Saab I think used to have an idea they called the Light Pressure Turbo - the idea was a combination of a low end torque optimized turbo would give V6 power to a 4cyl, allowing one to use steeper gears, but effectively giving the same or even better MPG because medium loads are often the best for Brake Specific Fuel Consumption figures. I don't know if it worked as advertised but the idea always intrigued me.

I posted a thread elsewhere about wanting to play with an LS hooked to a 5R110 transmission - because of a lower first gear for some of the same reason, and that cores for this 5 speed are much cheaper than any modern 6 to 10 speed while being super tough unmodified and having a nice wide total range of ratios. (1100ft/lbs sustained rating, after the torque converter anyway and you can lock that converter even in 2nd) Especially in a gas engine i'm not convinced even 6 gears are necessary.

Vs EcoBoost torque by 2000rpm - if I can't achieve the same, maybe 2500rpm then. Just something lower than the usual "howling on the freeway in 2nd gear going up a medium hill when you have a load" if possible. LS's seem highly tuned for the midrange - i'm not trying to fight physics, i'm just seeking the complete opposite of the guys with their top end turbos for the track. If more than pistons and rods are at high risk of failure the idea might be moot.

Towing truck duty breaks lots of things. But these engines are rated for a certain HP and torque output - not too far below what I want - and I thought that it was basically the same rods in the higher power 6.0 as there was in the 4.8 and 5.3 - if not as I said rod/piston swaps aren't out of the question, as long as that's all that it is. I'm fine sticking with iron heads - anything for reliability, make the power with the turbo.

LT1's have been rated to tow 7000lbs and more with no turbo with the right setup and my understanding is LS stuff is stronger yet so I thought things weren't too far out of line.

I know I can do it with cubic inches - I guess I wanted something that could be replicated by anyone using the lowest HP common cheaper engines. If the stock con rods and pistons are basically the same strength across the LS family, then a few more psi on a smaller engine still hits the same limit - engine strength - regardless of cubic inches. I feel safer doing this with an LS because of the reputation of the block, block-to-head sealing, and crankshaft being so dang tough and so much stronger than older small block and arguably even big block use.

Budget is mostly enough to fix known points of assumed failure, rods and pistons for an LS are so common swapping them isn't the end of the world, but more than that might be. Does anyone think other parts would be failing at 400-550ft/lbs for minutes at a time duty cycles?

 

Thought this might be similar. Not trying to be a search ****, promise.

5.3 for towing thread

 

You can make more torque with more cubes and less boost and sustain it longer and in the end it probably won't add much to the overall cost of the build.
The issue at that power level isn't the crank/rod/piston/block strength , The issue I see you running into when trying to make more power with a smaller engine is all going to come down to keeping heat/detonation from becoming a problem.
It's doable with a 5.3 but the harder you push an engine the more it hurts long term reliability. A small engine isn't going to last as long as larger engine built to the same standards. A smaller engine has to work harder either by feeding it more boost or turning more rpms or a combination of both to do the same work as a larger engine.
I don't see 1000,000 mile reliability on a junkyard 5.3 with chinese turbo setup used for towing, I'm not even sure a junkyard 6.0 is the best option in stock form but it would be hard to swing the cost of a rebuild and forged pistons and not spend a little extra money for a 6.0 core.

Are you prepared to run E-85 or a large dose of Meth/water because that is the end result.

One more thing, A properly built big block will run circles around a little boosted 5.3 or 6.0 but in stock form they are not very efficient so mpg suffers, When it comes to the torque of an older Duramax you may come close to it power wise but not power and durability and they are actually fairly decent on fuel, I used to drive a 2005 Silverado 2500 and it got 22mpg pulling a flatbed trailer with no load and 17mpg pulling a fully loaded trailer.

 

I would think 6 psi and gears would be safe. Seems he would be happy if it just stayed in 3rd gear on the hills.

 

It’s doable I have run a 3.5 ecoboost tuned with a ton of modes done to it ,it makes well over 400rwhp with stock turbo’s & I’ve seen them make 620rwhp with upgrades turbo’s and pull like a freight train still..

don’t let anyone tell you a 5.3 can’t be used to tow, if you are up to building the motor, adding ARP studs everywhere needed, and you match the correct size turbos to the engines CI & CFM flow etc then set the tune correctly so it’s not set on kill, then install a really good cooling system for engine the the trans and then a good INTERCOOLER for the turbos, getting 200k shouldn’t be a issue as long as your not using cheap turbos, go with a brand the car manufacturers use like Borg warner..or garret..
good luck your not the first to do this ,plus you can drive with 600tq & 500hp all day easy ,& still be able to turn up the power with either a programmer or a dial a boost

 

In the end it might be better to pay the diff bet a 5.3 and 6.0, do a refresh (rings, bearings, and yes cam bearings)
which can be done cheap, based on your ability. A small RV cam, rear gearing, 80E trans, good trans cooler, and a decent converter, specd. for your goals. Or better yet, 6.2 and let it eat, lol.
A supercharger could give you the low end grunt you want, but then you are getting into the big bucks-remember anything you add on that has moving parts, is a fail point, lol.
I towed for years with a 4.8, watched the 18 wheelers wiz past me on hills, as I was wound up in 2nd, lol.
Your results may vary.

 

If Ford does it with a 3.5, why not Chev with a 5.3? Just spec the combo for the rpm range and go tow.

 

Because the EcoBoost era half tons are twice the truck of a decade earlier. It's when the OEM 1/2 ton wars got heated and trucks got super beefy.

Anybody can make power these days, that's not the trick. Towing is a game of endurance under distress. I'd keep the boost mild, and ease the load on the transmission with rear gears. The truck just wasn't born with the right hardware to work extra hard.

 

My concern is that most of the damage to these engines revolves around peak torque and associated timing.

 

there shouldn’t be a concern about it if the set up is correct and the combo spot on, which isn’t hard to do, there isn’t a Secret sauce to air,fuel & timing heck you can buy self tuning systems even, but LS tunning nowadays is pretty easy to find a good even a great tuner, considering your looking for a towing set up which are generally a mild set up, & your not trying to get ever ounce of power out of it , it’s a easy build…
you can use a 24 degrees a zero boost and remove 1 degree for every degree of boost so your at 14 Degrees @ 14 psi if your going that high, using a 9:5 to1 compression, you can add or remove timing from that point, but as long as your fuel is there this will always be a safe tune..if you replace the stock pistons & rods with some good used forged units ,install good bearings and add ARP studs all around, heck even look for a good tow/boost cam to help produce the big low/mid TQ numbers you want..there’s plenty of used or even good cheap new cams around..but again most importantly build the entire engine right, tune it mildly,& install a good turbo kit, not some cheap set which will fail and forced feed your motor chunks of eBay China at 5k Rpm..install the right coolers I’d say even go over sized, for the trans,radiator,couple big CFM fans,good oil etc..with twins you can go smaller CFM helping build better low end power, 600RWTQ is a no brainer with a 5.3 TT all day, with the right stall a good trans like a 4l80 the right gearing you can wave to the truckers as you pass them and keep on going..
ive seen plenty of LSTT 5.3’s smoke Diesels towing,plus you can always turn it up if you just want to play..

 

I thought we're talking engine power plant. If a 3.5 can be done, a 5.3 can too. What did Ford do to make a 3.5 work? The same approach works on a 5.3 or whatever flavor you like. Need IC, cooling system, TC, trans cooler, rear diff (GM 8.625 isn't big enough) with correct gear ratio that all works. Put a 6L80 behind 5.3 is basically the same as a 6R80 behind the 3.5. Personally, I wouldn't use anything less than a 3/4 ton for towing.

 

Where's peak tq on Ford 3.5? How does Ford make it work for 200K (Sorry, 100K)? All in the tune.

 

There is a little discussion on FB about this, one shop/tuner buddy just suggested the guy (LS GM Express Van) just add a PD blower.

 

S366 type turbo at 5psi or so, a big intercooler, and big transmission cooler.
It's never, ever, going to be a diesel in disguise, but it would certainly be better than a stock naturally aspirated setup.

http://www.performancetrucks.net/for...-8-van-539084/