LS swap everything - halp plz!!

except for rotary cars :P I got you all excited there huh?

Actually, this is in regards to my frankenburban 85 K20. Everyone is swapping LS's into everything else and with that is good and bad, good being that there is a lot of information out there, bad being there is too much information out there. The driveability of a carb towing sucks and all of the various weather I do I am constantly dicking with the timing or tweaking the idle jets. I get about 9-11 mpg towing and 13mpg unloaded on a good day. I should expect about 14 unloaded and 12 towing with an efi swap so not a huge difference but major driveability increase. I am also tired of the SBC because it was designed before computers and even a crate engine has bullE36 M3 gasket leaks that makes it quite frustrating.

Right now I'm torn on 3 ways. easiest easier and hard as berkeley but rewarding as all hell.

1. easiest - 5.3 swap keep existing SM465 manual transmission. buy engine mounts adapters, perform simple harness modifications and exhaust done

2. easier - Lq4 6.0 swap keeping the manual transmission, do everything outlined above

3. hard as f**** - Lq4 with 4L80E - basically require a donor truck swap everything over, trans crossmember? NP208 compatibility? increased wiring complexity.

4. just drop the suburban body on a similar wheelbase LS powered chevy truck?

at this point its tempting just to go buy a newer truck or van but I like the space in the k5 burban and with historic plates/insurance it is CHEAP to keep on the road considering I have only driven it about 20k miles since I've owned it the past 4 years or so.

Benefits of my truck having being diesel, then tbi and now a carb with various engines is that I have a late model gas tank with TBI fuel pump sending unit assembly so swapping the fuel pump from a low pressure to higher pressure is easy, the lines are already run to the front of the engine. Right now with 35" tires and an estimated 260hp/350tq it struggles on uphill with a 6000lb truck towing an additional ~5000lbs luckily the 4.10s help but I have 1:1 in my tallest gear which means at 3100 RPM I am towing at 70mph however I don't really want to be towing with a 30 year old truck at 80mph...

Do I go with the electronic overdrive but I don't really want to tow much faster than 70 but a lower rpm would be a bit nicer in the cab and with a 6.0 the fuel consumption would be better. Or do I stick with SM465 for the sake of making the swap easier and that they are quite strong and mine isn't showing any signs of blowing up or failing me soon. The 4L80E is massive and stout and a truck that size manual really doesn't matter. plus with the bench seat the GF is much cozier when I don't have to grab gears through town.

Everyone says the 5.3 can make 6.0 power and I believe it to be true but I don't want a smaller engine (keep going down 6.2 > 5.7 and now 5.3??? whats next 3800 turbo?) but that engine has to rev high and when towing I just want to roll into the power and turbo charger would be cool but its a bit much for my needs/goals.

Lucky for me I live near Detroit so finding one of these trucks beat up or an engine with a warranty is not difficult at all.

whats the hive's thoughts and opinions? I am leaning towards the dirty dingo engine mounts since they are adjustable which makes it easier to install whatever engine/trans combo I choose. A lot of the resources I see are very generalized. any recommendations?

You might not like what I am about to say, but one of the easiest swaps would be a 6.5TD. 25mpg empty, bolt-in swap, and just a chip and exhaust away from 250hp/450tq or more. I had a bone-stock 98 1-ton (195hp) and there wasn't a single mountain in Montana it didn't top at 65 or better while towing 10k. Super reliable, ridiculously easy to drop in (it was designed as a direct replacement for a BBC), and very minimal EFI parts.

When I hear truck, MPG, and towing in the same sentence, diesel is the real easy button, especially when you have such an easy swap staring you in the face.

If you already have an SM465, I would keep it. None of the automatics (short of an Allison) will give you the reliability you have now, especially because none of them like to tow in OD. The gear spread you have with the SM465 is not all that different from the 4L80E, its just a lower first and 1:1 top instead of 2.48/.74 top. But my guess is with 35" tires, your highway RPMs are just fine with the 4.10s and a 1:1. Put it this way... with 35" tires and towing, you need to focus on overcoming inertia and worry less about a 200 rpm difference on the highway.

1 easiest - 5.3 swap keep existing SM465 manual transmission. buy engine mounts adapters, perform simple harness modifications and exhaust done 2 easier - Lq4 6.0 swap keeping the manual transmission, do everything outlined above 3 hard as f**** - Lq4 with 4L80E - basically require a donor truck swap everything over, trans crossmember? NP208 compatibility? increased wiring complexity. 4 just drop the suburban body on a similar wheelbase LS powered chevy truck?

option 1 is not too bad if you are up to the task of the large learning curve. I'm putting a heavily modded LQ9 into the 67 LeMans and the learning curve is pretty intense. Once you've done it a couple times it gets easy but if its your first, "easy" is not the word I would use.

Option 2 is the same as option 1

Option 3 is not as hard as you think, its just 13 more wires

Option 4 is the really hard one. GMT800 trucks are different enough on the frame side of things that it will be a pretty in-depth customization to get it to sit on the later frame. Plus you still have the nightmare of wiring it all, adapting things like steering, chassis electrical, ABS, plumbing... all the problems of an LS swap but in reverse.

The 5.3 can make the same peak power as the bigger engines, but it definitely gives up on torque by comparison. I've had a "400 hp" (claimed, but I never got it past 350 on our dyno) 5.3 and a mostly-stock 5.7, and the latter was noticeably quicker.

But in your case, I'd either go with Curtis' diesel or the 5.3. It'll be such an improvement from your current lump that bench racing anything else will be forgotten.

The 6.0 is not known for it's efficiency. The EPA only rated it for 13 highway, in a 2WD 3/4 ton with overdrive. One of those "gets (abysmal MPG figure here) uphill or downhill, loaded or unloaded" engines. I'd go with the 5.3 or the diesel suggestion.

BrokenYugo speaks the truth. The 6.0L sucks a disproportionate amount of fuel. Not sure why, but it is not a frugal drinker.

It's a sad state of affairs when the 6.5TD is the logical choice. lol

Stock up on PDM's.

If mpg matters and you stick with your current transmission then a 4.8 might be worth considering. While my current 2500HD with the 6L and magic transmission is awesome, the 4.8L 1500 it replaced was no slouch and got a solid 6-8 mpg better fuel economy across the board.

The 6.5 was a good engine for a lot of reasons, but it got outshined by the big power numbers from the other trucks. I would get from a 93 or earlier for the mechanical injection, plus I think they had a bit more power.

In reply to oldopelguy:

IDK if I'd go with the 4.8 in a tow pig with a granny low 4 speed, as I recall from the one time I drove one (1/2 ton, auto, unloaded) it had plenty of power but it felt like it really needed to be kept wound up to get the power out of it. They are about $100 cheaper than a comparable 5.3 though.

I had this exact issue a 18months ago.

I had a 89 tbi 350, sm465, k2500, single cab, long bed.

I swapped in a lq4. Took 4 weekends with the help of the wife, drive in garage to drive out, so simple.

I had it tuned on 87 octane to keep fuel cheap and can get as good as 16.5 mpg doing 70mph with the last 17k miles averaging 14.2mpg, towing mixed in there. 11mpg being the worse ive ever gotten.

In the garage, this is the most reliable vechile I own. Would do it again in a heartbeat. You should too.

You expressed hesitation in towing at 80mph in a 30-year-old vehicle but only your last option would change that.

Unless you were only referring to the motor and not old suspension etc.

The 6.0 won't be harder to install than the 5.3, so I'd vote for that engine. The transmission is a matter of personal preference; a 4L80E won't be much harder to swap over to than it would be to retain the existing transmission since you'll probably want to pull the transmission out for the swap anyway, and the crossmember is usually just a matter of drilling a few extra holes.

MattW wrote: It's a sad state of affairs when the 6.5TD is the logical choice. lol Stock up on PDM's.

Nah. Just move them away from the heat and they'll outlast you.

And in the world of diesels, they hang in there with the best ever in my opinion. Cummins 6BT, 7.3L stroke, Dmax, 6.5L, all great oil burners.

The 6.5L was a joint design between GM and Detroit. They are simple, bulletproof, and make more than enough power. Most people seem to want insane power levels for towing, but for me having enough power is the key. If I put a 10k trailer behind it and I can merge with traffic or top a mountain without slowing down traffic, I'm happy. For that, I don't need more than 400 ft-lbs or so.

Anything more is excess wear and tear (and excess money to attain, excess fuel, excess money for clutches or transmissions...)

curtis73 wrote: You might not like what I am about to say, but one of the easiest swaps would be a 6.5TD. 25mpg empty, bolt-in swap, and just a chip and exhaust away from 250hp/450tq or more. I had a bone-stock 98 1-ton (195hp) and there wasn't a single mountain in Montana it didn't top at 65 or better while towing 10k. Super reliable, ridiculously easy to drop in (it was designed as a direct replacement for a BBC), and very minimal EFI parts. When I hear truck, MPG, and towing in the same sentence, diesel is the real easy button, especially when you have such an easy swap staring you in the face. If you already have an SM465, I would keep it. None of the automatics (short of an Allison) will give you the reliability you have now, especially because none of them like to tow in OD. The gear spread you have with the SM465 is not all that different from the 4L80E, its just a lower first and 1:1 top instead of 2.48/.74 top. But my guess is with 35" tires, your highway RPMs are just fine with the 4.10s and a 1:1. Put it this way... with 35" tires and towing, you need to focus on overcoming inertia and worry less about a 200 rpm difference on the highway.

Most of the diesel swap info I find is cummins, 4BT is just not worth it for the price the the need to support the extra mass for a 6Bt requires a 2nd look at front axle and front suspension or its going to bounce like crazy down the road with stiff leafs. I haven't looked too much into the duramax diesel, I'm not against it but I know less about them and the maintenance seems more expensive and gasser tend to better sitting over long durations of time compared to diesel, and with my gearing a diesel roaring at 3krpm towing at 70 mph isn't ideal.

I don't mind my SM465 (it does have a certain cool factor) but the gear spacing is terrible between 2nd and 3rd - way to far apart - but with more power maybe this isn't a problem. The gearing is quite different from 4l80E and SM465, granted they are both 4 speeds the 4L80 has overdrive:

Keith Tanner wrote: The 5.3 can make the same peak power as the bigger engines, but it definitely gives up on torque by comparison. I've had a "400 hp" (claimed, but I never got it past 350 on our dyno) 5.3 and a mostly-stock 5.7, and the latter was noticeably quicker. But in your case, I'd either go with Curtis' diesel or the 5.3. It'll be such an improvement from your current lump that bench racing anything else will be forgotten.

In regards to peak power 6.0 vs 5.3 I know they can make the same peak power but I want more power down low.

BrokenYugo wrote: The 6.0 is not known for it's efficiency. The EPA only rated it for 13 highway, in a 2WD 3/4 ton with overdrive.

I'm okay with those figures :)

oldopelguy wrote: If mpg matters and you stick with your current transmission then a 4.8 might be worth considering. While my current 2500HD with the 6L and magic transmission is awesome, the 4.8L 1500 it replaced was no slouch and got a solid 6-8 mpg better fuel economy across the board.

I'm not going down that far in displacement without a turbo and that's out of the picture at the moment. Plus there are no factory 3/4 ton trucks equipped with a 4.8 for a reason.

fidelity101 wrote: I'm not going down that far in displacement without a turbo and that's out of the picture at the moment. Plus there are no factory 3/4 ton trucks equipped with a 4.8 for a reason.

As crazy as it sounds, this was a pretty common combo for rental vans. Why either U-Haul or GM thought that a smallblock that is happiest above 5000 RPM belonged in a moving van is beyond me.

MadScientistMatt wrote:

fidelity101 wrote: I'm not going down that far in displacement without a turbo and that's out of the picture at the moment. Plus there are no factory 3/4 ton trucks equipped with a 4.8 for a reason.

As crazy as it sounds, this was a pretty common combo for rental vans. Why either U-Haul or GM thought that a smallblock that is happiest above 5000 RPM belonged in a moving van is beyond me.

Perfect example is the toyota camper trucks that just a 4 cyl relating to that my friends family had a 3/4 or 1 ton chevy camper van and that thing would just scream down the road to drive 80, 3500-4000rpm or so but it did it. all the time

fidelity101 wrote:

Keith Tanner wrote: The 5.3 can make the same peak power as the bigger engines, but it definitely gives up on torque by comparison. I've had a "400 hp" (claimed, but I never got it past 350 on our dyno) 5.3 and a mostly-stock 5.7, and the latter was noticeably quicker. But in your case, I'd either go with Curtis' diesel or the 5.3. It'll be such an improvement from your current lump that bench racing anything else will be forgotten.

In regards to peak power 6.0 vs 5.3 I know they can make the same peak power but I want more power down low.

Understood, which is why that last sentence is in there. The 5.3 is the easy option, as you said, and it's still going to be a step up from what you have. You'll always want more - my tow rig is somewhere around 650 tq, and there are times when I want more - but I think you'll be able to do what you want to do quite happily with a 5.3. In terms of time and effort, it would be my choice.

THis was my 6.5TD:

Towed a lot, but never got over 14 mpg even empty, and I had as much optimized as I could, from free flow 4" exhaust to balanced injectors and relocated PMD. THere'sa reason I swapped up to a 8.1 liter gasser Suburban. Lower maintenance costs, more power, quieter running, and similar fuel mileage.

Keith Tanner wrote:

fidelity101 wrote:

Keith Tanner wrote: The 5.3 can make the same peak power as the bigger engines, but it definitely gives up on torque by comparison. I've had a "400 hp" (claimed, but I never got it past 350 on our dyno) 5.3 and a mostly-stock 5.7, and the latter was noticeably quicker. But in your case, I'd either go with Curtis' diesel or the 5.3. It'll be such an improvement from your current lump that bench racing anything else will be forgotten.

In regards to peak power 6.0 vs 5.3 I know they can make the same peak power but I want more power down low.

Understood, which is why that last sentence is in there. The 5.3 is the easy option, as you said, and it's still going to be a step up from what you have. You'll always want more - my tow rig is somewhere around 650 tq, and there are times when I want more - but I think you'll be able to do what you want to do quite happily with a 5.3. In terms of time and effort, it would be my choice.

More is never enough, soon I'll be asking advice on turbo v supercharge the LQ4 because I need more ooomph.

fidelity101 wrote:

curtis73 wrote: You might not like what I am about to say, but one of the easiest swaps would be a 6.5TD. 25mpg empty, bolt-in swap, and just a chip and exhaust away from 250hp/450tq or more. I had a bone-stock 98 1-ton (195hp) and there wasn't a single mountain in Montana it didn't top at 65 or better while towing 10k. Super reliable, ridiculously easy to drop in (it was designed as a direct replacement for a BBC), and very minimal EFI parts. When I hear truck, MPG, and towing in the same sentence, diesel is the real easy button, especially when you have such an easy swap staring you in the face. If you already have an SM465, I would keep it. None of the automatics (short of an Allison) will give you the reliability you have now, especially because none of them like to tow in OD. The gear spread you have with the SM465 is not all that different from the 4L80E, its just a lower first and 1:1 top instead of 2.48/.74 top. But my guess is with 35" tires, your highway RPMs are just fine with the 4.10s and a 1:1. Put it this way... with 35" tires and towing, you need to focus on overcoming inertia and worry less about a 200 rpm difference on the highway.

Most of the diesel swap info I find is cummins, 4BT is just not worth it for the price the the need to support the extra mass for a 6Bt requires a 2nd look at front axle and front suspension or its going to bounce like crazy down the road with stiff leafs. I haven't looked too much into the duramax diesel, I'm not against it but I know less about them and the maintenance seems more expensive and gasser tend to better sitting over long durations of time compared to diesel, and with my gearing a diesel roaring at 3krpm towing at 70 mph isn't ideal. I don't mind my SM465 (it does have a certain cool factor) but the gear spacing is terrible between 2nd and 3rd - way to far apart - but with more power maybe this isn't a problem. The gearing is quite different from 4l80E and SM465, granted they are both 4 speeds the 4L80 has overdrive:

Won't deny, the 465 is a wide ratio box. With a flat diesel torque curve its not a big issue but you could do better in the ratio department.

I also agree that (while its a great engine) the 6BT is very heavy and bloody expensive to buy due to demand.

I wouldn't let the maintenance of a diesel concern you. In almost every situation, people who don't like diesel are the ones who just haven't really tried one. Its like saying you don't like Sushi but you've never tried it. They hear all about the maintenance and they look at how diesel fuel is more expensive... and then they actually use one and they're hooked. I've had two 6.5L, several Dmax, several 7.3L strokes, and one Cummins 6BT. I don't care how many times I had to do a 14 quart oil change, nothing could pry the smile from my face when I towed with one. If you're coming from an SBC to any of the above diesels, there just isn't a way to adequately describe the difference you'll notice.

And, seriously... your only added maintenance is greater oil quantity and a fuel filter every once in a while. Its very much not a big deal. In return you get 50% more torque, 50% better MPG, a vastly broader torque curve, and a complete lack of a potentially troublesome ignition system.

Dmax is a wonderful engine, and it actually wouldn't be that much harder to drop one in than an LS gas unit, but take a look at what a used Dmax brings on the market these days.

The ONLY reason I am not driving a diesel truck right now is because I couldn't afford a decent one on my budget, and it ticks me off every day I have to drive this gas slug. I keep thinking about how wimpy it is while it sucks down gas at 12 mpg when I could be getting 22 mpg while being smooshed into the seat every time I hit the pedal if I had a nicely tuned Dmax.

BrokenYugo wrote: The 6.0 is not known for it's efficiency. The EPA only rated it for 13 highway, in a 2WD 3/4 ton with overdrive. One of those "gets (abysmal MPG figure here) uphill or downhill, loaded or unloaded" engines. I'd go with the 5.3 or the diesel suggestion.

All of this^ Also, Chris_V beat me to it; if you are looking at 6.0 the 8.1 gets a #little worse fuel economy for a lot of torque. It's an easy trade.

After reading this i really dont understand the love for the 5.3, mine gets better gas mileage then my f150 did but my f150 pulled alot better. Maybe its the lack of tow package gearing on my chevy but my 5k lb truck with 5k behind it really seemed too struggle in stop and go.... id look into an 8.1 if i wanted to spend the money to upgrade my truck.

I checked local craigslist and a Dmax silverado is about the same price as an LQ4 truck.

Here is another option...

Sell frankenburban (maybe get 4-5K) and use that for a down payment on a 03-07 3/4 suburban. Get the 4L80E and LQ4 I want without any of the work and gain added creature comforts like cruise control but loose all of the cool factor.