i have a 02 gmc sierra with the 4.8 (cold air intake, 85mm throttle body, open cut-outs). none of these seemed to produce much of a H.P. or torque gain and I can't really think of anything that will provide significant gains short of forced induction. I wouldn't mind doing a s/c or turbo but I would prefer not to do it on the stock motor. I've read a lot about the 6.0 and 8.1 being able to produce and handle large amounts of power on basically stock block and internals. I would really like suggestions on whether to build the 4.8 or swap to the 6.0 or 8.1. If the swap would be better, then what needs to be done to get it right(such as motor mounts, etc.). Also, once I had the bigger motor in, I would like a tranny that can hold high horsepower but don't know what would be good. I read that the 2500 or 3500HD transmission is good. I appreciate your suggestions.

'02 GMC Sierra 1500 4.8L stock 3.42's
best r.t = .001 (very proud of that)
best e.t = 16.0 in the 1/4

 

Pretty sure the 8.1 is gonna require some frame boogerin'. Go for the 6.0.

 

I'll make ya a sweet deal on a STS turbo kit, lol. A 6.0 is a direct swap, all that is needed is a new tune. Trans would hold up to a bolt on 6.0 motor if you did a servo and shift kit. 8.1 would be a LOT of work to make it fit and work.

 

How about building the 4.8? Throw in a nice cam, long tubes, a higher stall TC and a lower gear rearend; and your truck cold potentially be a monster.

 

Go for the 6.0. Much easier and all your old parts are a bolt on.

 

STS sounds like a TON of fun, but the 6.0L swap would be a simple, reliable answer.

 

Go with the 6.0, by the time it is said and done you will be kicking your self in the *** if ya try to do the 8.1, plus the after market isn't big on 8.1 upgrades.. Just my .02

John

 

6.0. 8.1 too heavy and not near potential of 6.0.

 

dont waste your time with a 8.1

 

I'm doing the same thing to 2 trucks pretty soon. One from a 4.8L to a 6.0L LQ9.and a 5.3L to a 6.0L LQ9.
Bolt on.
Same opinion 6.0L would be a good choice.