Full Size Jeep Network

I have a 1980 Cherokee Laredo that I just pulled the old 360 out of. I was going to just get it rebuilt, but then got to thinking about the late model swaps. I know there are several on here who have done them. I would like to know how much trouble was it? was it worth it? would you go 6.0 or is the 5.3 plenty for a weekend driver? did the fuel economy improve much? Thanks for the input. JS

I've been wondering what guys are getting (for MPG) out of the 6.0 swap. My DD is a 2500HD with the 6.0, and has plenty of pep, but the fuel mileage is horrible.

6.0 burns more than a 5.3, that is for sure.

I have a friend with a fairly new GMC Denali that is powered by a 6.0L.
He reported to me that he gets about 12/13 MPG... which I think is CRAZY!
I think with a super tuned AMC 360, a person could pull down 12/13.

Where I work, one of the company vehicles is an '08 Chevy Tahoe with a 5.3L with Active Fuel Management System that shuts off a pair of cylinder as you cruise up the Interstate.
It really does work well and that huge Land Yacht SUV can pull down 20MPG on a long trip, cruising on 4 cylinders for most of the way.
When you want to pass a truck or climb a hill, you just step down into and it feels like an old school 4 barrel carb kicking in.

I dunno how you could ever swap all that mess into another vehicle, like a FSJ.

I wouldn't own an AFM engine for any amount of money.

I have over 6,000 miles on my 5.3 now and don't regret a thing. LOVE IT! The reliability and performance alone make it worth every penny and hour to me. I am getting between 15 and 17 mpg average, which beats my old 360 by a mile and vapor lock is a distant, horrible memory. The swap wasn't exactly cheap and unless you can do the work yourself, it may be a bit much to justify, but if you have the means I say go for it! It was a very challenging project, but also the most satisfying project I have ever taken on.

Jeffsj wrote:I have over 6,000 miles on my 5.3 now and don't regret a thing. LOVE IT! The reliability and performance alone make it worth every penny and hour to me. I am getting between 15 and 17 mpg average, which beats my old 360 by a mile and vapor lock is a distant, horrible memory. The swap wasn't exactly cheap and unless you can do the work yourself, it may be a bit much to justify, but if you have the means I say go for it! It was a very challenging project, but also the most satisfying project I have ever taken on.

My '03 Silverado with a 4.8L would regularly pull down 21 mpg, so I'd say that 15 to 17 is pretty good for a brick.

lindel wrote:

Jeffsj wrote:I have over 6,000 miles on my 5.3 now and don't regret a thing. LOVE IT! The reliability and performance alone make it worth every penny and hour to me. I am getting between 15 and 17 mpg average, which beats my old 360 by a mile and vapor lock is a distant, horrible memory. The swap wasn't exactly cheap and unless you can do the work yourself, it may be a bit much to justify, but if you have the means I say go for it! It was a very challenging project, but also the most satisfying project I have ever taken on.

My '03 Silverado with a 4.8L would regularly pull down 21 mpg, so I'd say that 15 to 17 is pretty good for a brick.

I don't know what you're talking about, these things are aerodynamic marvels! The big tires help too!

j20owner wrote:I wouldn't own an AFM engine for any amount of money.

I knew I was gonna take some heat for my comments...but that's okay...I stand by what I said.
When I discussed this on the 'Mothership', I had some rocks thrown at me as well.

I know some folks have had issues with AFM, just like owners of Cadillac's 4-6-8 equipped cars of yesteryear.

What I can say, with confidence, that our company Tahoe runs great.
It is a pool car that get checked out by everyone and their brother, beat on like a rental and put away dirty and the tank empty.
I am proud to drive it.
I run it through the car wash if I am at a gas station with a car wash.
It runs good, rides good and has plenty of performance for a large full sized SUV.

I will concede there is a reason that GM LS style crate engines are not equipped with Active Fuel Management.
Some might say the reason is because it sucks.

Wait till the lifters start to stick and shut down cylinders when you need all 8. They have problems that arise as mileage increases. I work on them.

j20owner wrote:Wait till the lifters start to stick and shut down cylinders when you need all 8. They have problems that arise as mileage increases. I work on them.

Sure... and when the Oldsmobile Cutlass was the number one car in America, they were always in the shop. And then when it was the Ford Taurus, well, those were always in the shop.

If you work at a dealership, you will get the stuff that goes bad. Then again, my neighbor has a Suburban with DOD (or whatever GM calls it this week) with 200,000 miles on it. The only maintenance she actually does on a regular basis is oil changes.

Keep up with the maintenance, don't let the thing overheat, and I bet the average DOD engine has zero problems.

I was talking with my mechanic about AFM a few weeks ago. Engine oil is VERY important to those systems. You MUST use the correct spec'd oil and change it religiously. I bet that is why they continue to get a bad rap. The concept is sound. I'd use an AFM motor if I could.

The PIG Smith wrote:
Where I work, one of the company vehicles is an '08 Chevy Tahoe with a 5.3L with Active Fuel Management System that shuts off a pair of cylinder as you cruise up the Interstate.
It really does work well and that huge Land Yacht SUV can pull down 20MPG on a long trip, cruising on 4 cylinders for most of the way.

good thing its a company truck, sounds like a maintenance nightmare

I have a 5.3 in mine running 65-70 it gets around 15 mpg but its on one tons and 37s pulling my offroaf trailer at 80 it got 9.8:'(

Not long after I tore apart my 360, I had a 5.3/4L60 practically fall in my lap. I thought it over quite while and finally decided against the swap. IMO, the only reason to keep the 360 is for the novelty of it.

From a driver's pov, it would be hard to beat the smooth, reliable power, EFI and overdrive in one package that the 5.3 swap would bring to the table.

If I had to do it all over again, there's no doubt I would have went with the 5.3...

You will not be disappointed with either the 5.3 or 6.0. I did a 6.0/4L60E swap and I am lovin' it! It is absolutely the best upgrade I have ever done to my Jeep. Power, gas mileage, dependability...it was an easy choice between the 6.0 and my old 360. Like Jeff said, if you can do the install yourself, you will save a lot of money. Otherwise, be prepared... My 6.0 is PLENTY of power. I'm sure the 5.3 is more than enough when going from the OG engine.