Originally Posted by kelley1
Thanks for the reply, but I am thinking of swapping engines. I have 2 6.0's not sure if they are 4 or 9's
The LQ4 is the lower compression engine and has dished pistons for a SCR of 9.5:1. The LQ9 is the higher compression engine with flat top pistons, and a SCR of 10.0:1.
They typically used different auto transmissions too so the flex plates might have been different but I'm not sure about that.
Near as I can tell, they were the same engines with the exception of the compression ratio so peek in a plug hole and see if you can see whether it's a flat top piston or a dish piston.
If the piston is dished it's an LQ4, if it's flat then it's an LQ9.