Poking around i've noticed that the lq4 in stock form produces anywhere from 300 to 335 hp. Well which is it? Were the early iron head models the ones that produce 300 and the aluminum head models produce 335? Would there be any difference between a GMC hd and a Chevy hd, both with vin letter U?
Just curious here. 35 HP isn't a crap load but its enough to make a difference.

 

in reality a stock lq4 is gonna make about 260-280 to the wheels depending on drivetrain. I made 301 at the tires with a 4l60 and it had z06 cam and ls6 springs and a tune with 3" exhaust.

 

hmm never thought about drive train, i'd imagine the 5speed manuals got the higher rating.

 

I think lq9's made 335 IIRC?

 

lq9s made upwards of 370 hp, as far as the lq4 goes, 300 hp was probably first model year which was 1999-2000, and the 335 hp one was more recent years

 

Thought the lq9 was rated at 345?

 

The various LQ4’s were rated at different power levels depending on which vehicle they were installed in. As installed in 2500 & 3500 series trucks, they were rated at 300hp 360lb•ft. In the Sierra C3 and later the Sierra Denali, they were rated at 325hp 370lb•ft. Yukon Denali’s were originally rated at 320hp, but after 2003 were also upgraded to the 325hp rating. In 2005 the 6.0L was advertised at 335hp 375lb•ft as installed in the Yukon Denali & 2500 XL and coincided with the year the Sierra Denali started receiving the LQ9. I have shown the information as applies to the line-up from GMC and which basically caries over to Chevrolet. Irregardless, all the 6.0L LQ4’s were basically the same outside of the original ’99 & ’00 models that were equipped with iron heads and a smaller camshaft. The differences in output were due exhaust configurations and tuning.


All LQ9’s were rated at 345hp and 380ft•lb.