Common Gen III V-8 Engine RPO Packages, Power Outputs, And Compression Ratios

RPO Description
L, (ci)
Power Output
LS1 5.7 (346) car
305/335 to 325/350
GTO 350/365  
LS6 5.7 (346) car    
Corvette 385/385 '01 10.46
405/400 '02 and newer  
LQ9 6.0 (364) trck/suv    
Escalade & 345/380 10.08
Silverado SS    
LQ4 6.0 (364) trck/suv    
GMC/Chevrolet/ 300/360 to 330/370 9.41  
Hummer fullsize    
LM4 5.3 (325) trck/suv    
'01-and-newer 290/325 to 300/335 9.49  
fullsize, '04 SSR  
'04 Trailblazer/Envoy/  
LM7 5.3 (325) trck/suv    
  '99-and-newer 285/325 to 295/330 9.49  
LR4 4.8 (293) trck/suv  
'99-and-newer 270/285 to 280/290 9.47  

Do I Have To Pull The Engine To Work On It?
Of all the vehicles the Gen III V-8 has powered, the trucks and SUVs are the easiest to make changes to the engine while it is still bolted in the vehicle. But that's not saying much. Changing the heads or cam on a Gen III V-8 in a Corvette or Camaro is simply not advised due to the lack of space in the engine bay, but on a truck it is doable.

On the trucks/SUVs, you'll probably find the time it takes to do it either in the vehicle or out of the vehicle is similar, but the frustration level of doing the work in the vehicle is much higher. We'd recommend pulling the vehicle if you are doing anything more than adding an intake or swapping the heads. The camshaft change or bottom-end work really requires some space to accomplish and you'll be able to really get around the engine to do the work correctly (such as angle-torquing the head fasteners).

More than anything, you'll probably find the engine removal will go much more quickly the second and third times because you'll know the little tricks to making everything happen - and soon it will be a no-brainer whether you work on the engine in the vehicle or on an engine stand.