I ran a search and didn't find anything. I was wondering if anyone has or has researched swapping a 4.8 or a 5.3L. into a thirdgen. With current gas prices the fuel savings may be worth it, I've heard reports of 20-25MPG in a fullsized truck. I would appreciate any thoughts, ideas, and/or pictures.
Thanks,
Will

 

Those engines are referred to as "ls" or Gen III small block. Try searching for that and you'll find a ton of info. There are multiple displacements like 4.8, 5.3, 5.7, 6.0, and now the 7.0 liter. They all have the same outside dimensions. I think all the truck motors have iron blocks which are said to be some of the strongest.

 

If you use a 5.3, or a 6.0 you will want to swap the intake over to either an LS1 or LS6 intake since it would put the TB in the right place on the engine. With the right tranny, the LT1 and LS1 can make upwards of 30 on the highway

 

Best i ever gotten in my truck (2004 silverado with a 5.3) is 18mpg on the highway. Not mind shattering by any means

 

sorry, but what is "the right place" with the truck intake the TB would be in the same place as a car intake just it would sit higher 'cause the truck intake is 3-4 inches taller

 

And from what Ive seen, the "big ugly" truck intake actually makes pretty damn good power. Some say its even better than the LS1 intake. *shrugs* to each thier own.

 

That is actually true. But you may have fitment problems if you use it, its quite tall.

 

The intake sits higher, but also it's not as long, pulling the TB in closer to the engine, which if you wanted to use a standard 4th gen CAI it wouldn't fit right because it would not come out far enough from the front of the engine.

I have a buddy who's building a 6.0 for his and is going to put an LS6 intake on it for clearance problems.

Here's a pic of the 5.3 with the truck intake



Notice how far back the TB sits?

 

I am driving a 99 silverado with a 4.8 at work that is gitting 24 MPG at 65-75 miles per hour.