'04 5.3 to 6.0 upgrade

kraicekjb · December 22, 2011

I have a 04 suburban with a 5.3. It just hit 104K miles. I am thinking about swapping the 5.3 with 6.0. I have done some research and everyone is saying that its a easy swap. The only thing needed is a tune for the 6.0. Is this true? Does everything bolt up the same? Also, some are saying the tranny will be fine and others say to upgrade. Would it be cheaper and more beneficial to keep the 5.3 and mod it? If so what are your thoughts. Id also like to be able to keep a decent MPG. Thanks guys.

txab · December 22, 2011

With 104k on the trans, I'd beef it up since you're doing the swap. The stock 4l60E has several known weak points.

Have you tried a tune on your 5.3 to see if it might make you happier with it's performance?

kraicekjb · December 22, 2011

What are some of the weak points and what would be good to "beef" it up? I have thought about getting a tune, since it does have a CAI and TB spacer. But I wanna do the electric fan upgrade so I've waited on that. And Im not really sure which tune to go with. Ive heard alot of great things about the Blackbear tune but not not sure how to go about getting it. Is it really as good as they say it is?Thanks alot.

Wires · December 23, 2011

I believe the 5.3 and 6.0 are basically the same motor with a larger bore I believe.

You are going to take a HUGE MPG hit going from the 5.3 to the 6.0 though. The 6.0 is a nasty gas pig (not sure why). The 6.2 address that with about the same MPG as the 5.3 and a lot more power.

I'd rebuild the 5.3, and then toss on a Magnacharger. It'll allow that engine to push 385HP, and still net you 18MPG on the highway. Otherwise, do the blackbear or Westers tune, and you'll be really happy with it.

BlackZ71Silverado · December 23, 2011

I believe the 5.3 and 6.0 are basically the same motor with a larger bore I believe.

You are going to take a HUGE MPG hit going from the 5.3 to the 6.0 though. The 6.0 is a nasty gas pig (not sure why). The 6.2 address that with about the same MPG as the 5.3 and a lot more power.

I'd rebuild the 5.3, and then toss on a Magnacharger. It'll allow that engine to push 385HP, and still net you 18MPG on the highway. Otherwise, do the blackbear or Westers tune, and you'll be really happy with it.

What MPG did you get with your 6.0? My dad has a 2008 6.0 V-Max and the mpg is not all that bad. What gears were in your truck that you were getting the terrible mpg with?

The 6.2L has the 6 speed tranny and higher gears that the 6.0 doesn't have on the 1500 model trucks, that makes a difference. The 2500 6.0 is a much heavier vehicle, that would contribute to worse MPG.

kraicekjb · December 23, 2011

I believe the 5.3 and 6.0 are basically the same motor with a larger bore I believe.

You are going to take a HUGE MPG hit going from the 5.3 to the 6.0 though. The 6.0 is a nasty gas pig (not sure why). The 6.2 address that with about the same MPG as the 5.3 and a lot more power.

I'd rebuild the 5.3, and then toss on a Magnacharger. It'll allow that engine to push 385HP, and still net you 18MPG on the highway. Otherwise, do the blackbear or Westers tune, and you'll be really happy with it.

Thanks. Would it even be possible to do a swap with a 6.2?

The magna charger would be nice, but Im pretty sure thewife wont buy off on that one. When rebuilding what would be some good mods, since it'll be broken down anyway.

Thanks for the info.

Grebbler · December 23, 2011

104k? That motor just got broken in

What's the gear ratio and tire size? Is it a 4x4?

These motors are crippled by the computer and a tune will fix that. When I got my truck it would hesitate at take off and feel weak where I was scared to pull into traffic. I got a Blackbear tune and now my mileage is worse since I can't resist stomping on the pedal to put the sightseers and cell phone dweebs behind me

Best single upgrade I have done. I sent a deposit and they sent an OBD cable that I plugged into a laptop. I drove around a bit to log driving and performance data and sent the logs in. They spotted a leaking intake gasket from the logs and I fixed that. They sent out a reprogrammed computer, I swapped it with my old one and drove some more to test the truck and log the "after" data.

When I was finally able calm down and wipe the cheese eating grin off my face from how much nicer it was to drive - I sent in the final logs in and they pronounced the operation a success and the peasants rejoiced.

If you have gears lower than 3.73's I would swap gears. 3.73 should be the lowest anyone would have in a truck that size - higher if you have oversize tires. The 5.3 has a high power band and needs the revs to really shine.

As for the tranny, the shortcomings of the 4l60e is so well known that any good trans shop will most likely have an "upgrade" package deal that will include a sun shell (The Beast), better clutches and servos, etc.

NOTE: Do any hardware fixes or mods before a computer tune. Note any speedometer errors so the tuner can take care of that, too.

nickvrebel · December 23, 2011

I've done this swap on 3 trucks personally and know of more than I can count that I've seen in person...

I can confirm that if you get a 2001-2006 6.0L (either LQ4 or LQ9) it will bolt right up. If the motor is used and was previously bolted to a 4L80e (HD truck) you will need to take off the flex plate and a spacer on the back of the crank shaft snout and reuse the flex plate from the 5.3L. At that point all accessories and components will bolt right back up.

The truck will start and drive just fine with the stock 5.3L tune, but I would recommend getting the tune done properly before towing or anything beyond putting around town.

You will take a fuel economy hit. How hard you drive it will determine how much, if you drive aggressive it will be dramatic.

Your transmission most likely at that age could use a "freshening up" at the same time. It won't instantly break because of the 6.0L, but at it's mileage it's time is likely limited regardless, a freshen up with new clutches and a few beefed up hard parts and it will be fine. The transmission is easy to pull while the motor is out, so that's an ideal time to do this.

The power and torque from the 6.0L in comparison is sick. If that is something that gets your heart pumping then do it. A good used low mileage motor should be available from a salvage yard for $1,000-1,500. The LQ9 is more desirable, it comes from the Silverado SS, Denali (truck and SUV) and Escalade. The LQ9 has higher compression and it is recommended that you run premium gas in this motor.

You do not need anything except the "long block", which is the motor itself complete from heads to oil pan. You can reuse your intake manifold, accessories (alternator, power steering, a/c), all brackets/ mounts and wiring harness.

The 99-00 6.0 will have cast iron heads - you DO NOT want this motor, it will be priced CHEAP and there is a reason. The heads perform poorly and the crankshaft snout does not use a spacer, it's just made longer so it is unusable with the 4L60e transmission (what you have).

We performed swaps in a carport, just need an engine hoist available. The a/c system does not need to be opened and neither does the power steering setup, it can all be unbolted and shoved to the side with lines attached. The swap takes about a day and a half for two people when a basic understanding of mechanics and a decent tool set. I did one swap with the owner and his buddy in 2 days - they were scared to remove a water pump when we started.

kraicekjb · December 23, 2011

Thanks alot guys.

@ Nick, phenomenal write up. Lots of good info. My questions is, honestly would it be worth it to put the time and money in the swap or would I be better off going with the 5.3 with upgrades?

@ Grebbler, Its RWD and I'm not sure what gears are in it. A few people have asked me. How do I find out for sure? I recently upgraded to 305/40 R22 from the stock 265/70 R16's. Immediately I noticed a difference. It's not really "sluggish", if you will, but I just want to make sure it turns the 22's with ease. Before It would spin the tires off the line, now it wont.lol. I want it to be able to burn out if i want it to. Also, Im going to call around and see what I can find out about an upgrade to the tranny.