Engine replacement options

[Squirrelsmith]

I want to upgrade and was wondering what the engine of choice was. I hear guys talk about the ht383 and ls swaps quite a bit. Just looking for opinions... see if something is a overwhelming favorite.
I would probably want to spend around 5k not counting labor wich i would do myself with the help of some very knowledgable friends.
A straight swap would be great but i would be willing to do a more elaborate replacement if it was worth it.

 

[Squirrelsmith]

I should add that as far as performance it would be great if the truck just didnt feel so "heavy" my dad has a 2015 gmc sierra and that feel like it has plenty of power. I think anything over 350hp would probably satify me. I would love to be able to do a burn out!!!!!

 

[bigfootchiro]

$5K without labor? LS swap for sure, IMO! LQ9 6.0 engines put out slightly more power than the LQ4 6.0, but I wouldn’t worry about that. You would still have room to tear down, check internals, cam swap, upgrade heads, springs, etc. If you want to retain AC, you’ll need a special bracket (I can tell you where to get one), Dirty Dingo motor mounts, different upper/lower radiator hoses, flexplate adapter if you’re running your 4L60E (just remember, you’ll need to severely beef it up, or 4L80E swap), PCMPOWERTUNES does the 0411 PCM with pin-out diagrams so you can swap it over. Just make sure you get a complete engine with harness. It will save you headaches! I got my LS 6.0 for $900 with 120K on it complete.

 

[iamdub]

If you can handle it, LS swap for sure. More power, more efficient, more power capability, far less leak potentials, easier to work on, etc.

 

[Squirrelsmith]

I probably could handle the ls swap i just need to get a better feeling for if its worth it to me. I like the idea of the drop in crate ht383e, nice and simple. Does anyone know what kind of mpg i would be looking at?

 

[willxfs]

I think having the 383 and fuel mileage all depends on how you drive it. Just because you can get up and go quicker means you probably will more often. Meaning crappy fuel mileage. I had my 350 built into a 383 by a guy near Houston. Its supposed to be similar to the HT383. He said it probably puts out close to 350 HP. I really dont know (kinda think that may be a strech). My rig is 1998 2door sport. It feels really strong from about 2500 to 4000 rpm. On the highway at 70 mph, I'm getting the same mileage as before. About 16 mpg. Around town, I get anyhwere from 8 or 9 to maybe 12 depending on how I drive it. I have 285/75/16 size tires and just basic mods, shorty headers, magnaflow highflow cat and muffler. Everything else is pretty much stock. I've done two mail order tunes ($200 each) and a quick dyno run (another 200) which was cut short at 3000 rpm due to lean afr's. I suspect something is still not quite rite but have given up on the tunes for a while. Maybe its mechanical. If I had to do it again, I would save the cash and get the $2000 goodwrench 350 from jegs and tune from Blackbear.

 

[Squirrelsmith]

i would like to get at least 12mpg around town, 15 would really be great. it that doable with anything?

 

[bigfootchiro]

LS will always be more efficient than the Vortec 350, IMO. It’s doable. My Hoe gets about 12 combined with the 350, so I’m sure an LS could get more.

 

[swathdiver]

How many thousands do you want to spend to get good mileage? I am reminded of the fellas who repowered their boats with diesels, spending $40K+ to pay less at the pump. It's nonsensical to decide that way.

Gen IV LS swap with the 6-speed would give you the mileage with a 5.3. Why not just supercharge your L31? It's a great engine. Put a Gear Vendors overdrive in it for highway mileage.

 

[iamdub]

James is right- you can't focus so much on MPG as anything feasibly swappable won't have a return, MPG-wise for a LONG time. But, you said you wanted to upgrade and sort of mentioned a $5,000 budget. A Gen3 LS mated to your stock (refreshed/rebuilt) trans can be had for less than this and, as-is, it should show SOME kind of MPG increase over the L31. It would definitely have more power. Find a good motor cheap enough and you might can fit a trans rebuild in that budget as well, if that needs attention. I believe there are plug-and-play harnesses for your specific combo if that part of the swap concerns you.

If you want something more of a direct swap, the 383 would do it. Having it fine-tuned and all, you may see no less MPG than what you have now if you keep your foot out of it. It's higher torque output will move your truck with less throttle input, so the fuel consumption could be about the same for a given range of driving conditions.