8.1 Vortec VS 383 Stroker VS 6.0 Iron LS

PICS!!!!!!! ^^^^^^^^^^^^^

After seeing this again. Sometimes that AC pump is down in the frame rail. You may need to relocate or some have boxed the frame out.

forcruzen said:

After seeing this again. Sometimes that AC pump is down in the frame rail. You may need to relocate or some have boxed the frame out.

Click to expand...

This seriously makes me lean more and more twards the 8.1

Shorty81 said:

I had a 76 date coded 454 of "unknown origin". It needed some major cylinder clean up. I order a Skip White 496 complete rotating assembly. 750 holley, Wiend dual plane, 781 iron heads. Happy motor, runs great torque monster. Gets 11 mpg in K20, 3:73, SM465, 208.This is my old school 8.1!!

Click to expand...

I have been looking at that same set up, drooling really. Want Airflow Research 335 heads on it though, cause I likem.

My advice on a ls swap is buy a whole 1999-2002 silverado/suburban 2500 6.0 that runs. Drive by cable (99-02) is simpler IMO. Don't sell anything off the donor until the job is finished. You would be amazed at how frustrating and expensive it will be if you have to buy everything separate. It all transfers. Radiator, cooling system, hoses, engine, driveshaft(find a long bed donor) engine, transmission, harness(lt1swap.com). So many little things that you can just pull yourself in your yard. Utx on youtube has excellent videos to watch.

Love the idea of an 8.1. I currently have a '06 2500hd cc with 8.1 and 6 speed Allison (only year that got 6 speed auto for 8.1). I tow camper and sleds with it and love it. It's just such a strong running motor. Does drink a little oil after extended periods of foot to the floor pulling NH hills at speed. I found that using mineral oil or semi-synthetic slows oil loss a little.

I've owned a few 6.0 and none of them got better mpg than my 8.1. Not saying 8.1 is a fuel miser, just not as bad as 6.0 from my experience.

In a year or two I'll be contemplating swapping 350 in my 77 c15 for a 5.3 ls I have sitting in shop corner. So I'll be watching this thread. As time goes on and there seem to be more and more ls swaps I'm leaning towards staying old school sbc.

Mogulmasher said:

Love the idea of an 8.1. I currently have a '06 2500hd cc with 8.1 and 6 speed Allison (only year that got 6 speed auto for 8.1). I tow camper and sleds with it and love it. It's just such a strong running motor. Does drink a little oil after extended periods of foot to the floor pulling NH hills at speed. I found that using mineral oil or semi-synthetic slows oil loss a little.

I've owned a few 6.0 and none of them got better mpg than my 8.1. Not saying 8.1 is a fuel miser, just not as bad as 6.0 from my experience.

In a year or two I'll be contemplating swapping 350 in my 77 c15 for a 5.3 ls I have sitting in shop corner. So I'll be watching this thread. As time goes on and there seem to be more and more ls swaps I'm leaning towards staying old school sbc.

Click to expand...

yeah, that's kinda how I've been feeling, That why I want the 8.1 since it and the 7.4 Vortec are technically not LS engines. or sticking with the 350 and stroking it out to 383 and throwing a Holley sniper on it for MPG when I want MPG and power when I want Power. but then again I can also do that with Holleys efi for the 8.1. Im gonna have to probably pro con it all on a page

Mogulmasher said:

Love the idea of an 8.1. I currently have a '06 2500hd cc with 8.1 and 6 speed Allison (only year that got 6 speed auto for 8.1). I tow camper and sleds with it and love it. It's just such a strong running motor. Does drink a little oil after extended periods of foot to the floor pulling NH hills at speed. I found that using mineral oil or semi-synthetic slows oil loss a little.

I've owned a few 6.0 and none of them got better mpg than my 8.1. Not saying 8.1 is a fuel miser, just not as bad as 6.0 from my experience.

In a year or two I'll be contemplating swapping 350 in my 77 c15 for a 5.3 ls I have sitting in shop corner. So I'll be watching this thread. As time goes on and there seem to be more and more ls swaps I'm leaning towards staying old school sbc.

Click to expand...

I'm keeping mine sbc for that reason. When it goes I'll build it back better

Curious from people that have run these newer efi systems like Holley Sniper on a sbc, how much better does mpg get? My guess is not much. I bet a carbed 5.3 still gets better mpg than a Sniper equipped sbc. I mean ls is so much more efficient and is a full roller motor....

I think rear-end gear and od trans are only way to gain any significant mpg from an old sbc or bbc.

Mogulmasher said:

Curious from people that have run these newer efi systems like Holley Sniper on a sbc, how much better does mpg get? My guess is not much. I bet a carbed 5.3 still gets better mpg than a Sniper equipped sbc. I mean ls is so much more efficient and is a full roller motor....

I think rear-end gear and od trans are only way to gain any significant mpg from an old sbc or bbc.

Click to expand...

I'd take the other side of that bet. The 5.3s get good milage from the modern engine management. Compare a factory 5.3 pickup and a factory 5.7 vortec pickup not a big difference mpg wise because they both have way better engine management than a carbureator and mechanical distributor.

Sniper probably won’t do much better than an optimally tuned q jet. That is, unless you go up and down in elevation by a considerable amount.

I’d get a MPFI system such as the Edelbrock pro-flo 4 if you are going to add the complexity of an aftermarket EFI an are primarily concerned with mpg.

Who drives a truck a for gas milage???

1lejohn said:

Who drives a truck a for gas milage???

Click to expand...

Guys/gals that need one for pulling their heavy toys?
The body is rotting off my '08 Duramax, but I'll never let it go due to it's power and mpg with 9000 lbs behind it on our hills.
The square is just for off road adventuring.

1lejohn said:

Who drives a truck a for gas milage???

Click to expand...

The trucks worthless if I can't afford to drive it. I drive my trucks only when I have too, to do something I can't do with my DD. I'm just lucky enough to be able to afford more than1 vehicle,some guys have to choose 1 car or 1 truck. Everything is an hour drive from here. If I can spend 40 dollars on fuel or I can spend 16 dollars on fuel roundvtrip I prefer 16,and these dollar figures can get actually a little more spread than that,depending on your choice of drivetrain in the same truck body. Who drives a truck just to look good?

If you want MPG and reliability with EFI, I still think the factory stuff is going to be better than any aftermarket, so long as you have a decent tune done (which is needed either way).
There has been testing done before, I think the final conclusion is that a carb, when properly tuned for a specific point, gets better power and efficiency. But the really big caveat to that is that the tuning would need to change every time the air pressure changes from elevation, or the temperature changes, or the engine is warming up, or the fuel quality changes from tank to tank, or any other parameter changes by a small amount. At that point, you would need something like a computer that could handle all of those variations, probably some type of sensor in the exhaust to make sure the changes are right, and a way for the computer to adjust how much fuel is being added/injected, and I think you see where I'm going...
Good EFI on an older engine is better than a carb on a newer engine for 99% of the stuff out there, but there's a bit more to be had with a newer engine that has inherently better efficiency (like modern heads and bearings).

All that said, I'm liking the 8.1...