Just starting down this road...can I use the same harness? What internals shud I look to change? I was thinking blueprinting and new pistons, cams, lifters...beefeier motor to handle more boost! Are the stock 6.0 alum blocks? R/

 

Everything from the 5.3 will work on the 6.0. I believe the only aluminum 6.0 block is the LS2. All the 6.0 out of the trucks are going to be iron.

 

Are you planning to buy a complete 6L and swap it in or a 6L block and build it? All the accessories and wiring harness will swap right over. The 6L block is identical to your 5.3L as far as mounting points and wiring are concerned, just more cubes I did the swap a couple months ago, the performance difference was night and day in my heavy a$$ Tahoe.

 

Was hoping to find a used 6.0l complete and just have it rebuilt to my specs. Look for a rolled truck or something like that. I'm assuming I shud be able to pick one up pretty cheap and just do the upgrades (bore, cams, pistons, etc...) but I dunno, might not actually save allthat much if I can swaps all the externals. Maybe cheaper to buy the block and rolling stock new? R/

 

I'd like to do the cheapest mod possible. Plan was to buy a used complete 6.0l and upgrade the rolling stock. What did u do? Which do u think will be cheaper? R/

 

I found an 18K mile 6L complete for $1800. I swapped it for the 5.3 and put the Radix back in top. I kept the same 3.2" pulley that was making 9psi on 5.3, it makes about 6-7 psi on the 6L. I also added a mild cam. I have not been back to the dyno but the seat of the pant meter is pegged. Buying a running 6L is going to be the cheapest I think. If you are planning to up the boost to 12psi (which is about all the radix is gonna put out on a 6L) then you would want to get the forged rotating assy. That is gonna increase your budget quite a bit. Here was my cost sheet just to give you an idea:
Short Block+Shipping 1,800.00
Injectors 210.00
Volt Booster/ Pump 130.00
Rotors 750.88
Pads 154.85
Tune 90.00
Injector Adapters 76.00
Plugs TR-6 16.00
Inline pump 228.00
Rod bolts 163.60
Oil pump 165.00
Cam/Springs/Tool 878.06
Converter 500.00
Gaskets/Push Rods 141.99
Crank pin kit107.00
Oil/Coolant 50.00
There are several thing on my list you wont need such as rotors, pads, converter, or the cam if you don't want. Just subtract the things you wont need and get a better idea of what you're about to get into. Adding a forged rotating assy is gonna be another $2k from what I've seen. To do a forged 408ci engine you can get into the $10K range pretty quick

 

thnx! thats great help...sounds like pretty much what I was thinking. Was gonna drop the Radix on top with @ 2.9 pulley (10-12lbs), and do the forged piston, cam, rods...etc. No need to do it all at once but over a period of months, as its gonna take that long to get the block machined. I figure if I'm gonna go to all the trouble of swapping motors, I'll make sure the used one has been prepped at hopped. I already priced a 390 short block as was told $12k installed new and tuned...I just don't wanna be a guinea pig.
Did u change tranny? Thats another $2500 for a stage 5 kit! R/

 

You will need an upgraded trans if you want it to last long under all the power and the weight of your truck. You can get a decent 6L throwin some forged piston bore it and have a 370 throw some arp rodbolts in there, mild cam, might as well throw a high stall in there since you have the motor pulled anyway, springs, pushrods etc. It will cost you 5K by my guesstimate to do a nice 6L and stall which isnt bad for the 150hp you can gian by going with more cubes, cam, smaller pulley and all.

 

A trans upgrade is gonna almost be required. At the minimum do a shift kit (Transgo HD). But, a 6L with 12 pounds is gonna eat up your 4L60E/65E tranny even with a shift kit. The kit will just prolong the tranny life. A built 65E (or 80E if you want to spend even more) would be a better move. Do a search on the 65E vs. 80E, many threads about it.
The thing to keep in mind is, if you decide to buy a built tranny you don't want to wait until the stock ones craps out. All the metal garbage that will get into the system from the stocker crapping out will cause you to have to get the lines and cooler blown out and the converter opened and serviced if you don't replace it. Then there is no guarantee it was all be removed and the crap could damage the new expensive tranny. It's best to pull the stock while its still in good shape and try to get a few bucks for it. Or take the stock one to a tranny builder if you have time. Chevy engines love to make HP/TQ and Chevy transmissions like to take a .

 

You can run intercooled 12psi on the stock 6.0L components. Especially if it is an LQ4. That is right at the limit of what is considered safe on an LQ9.

Note that you MUST have a good tune to do this, however. No mail order without logging software to help, but you're best off with a dyno tune or an in-person tune.