Can you stick the L92 square port heads in a Trailblazer ss? If so anyone on here heave this setup?

 

Yeah, there's been several who've done it. Need to pick up a L92 or L76 intake as well though.

 

I have been running the L92 heads on my setup for well over a year. Like stated above if you are staying N/A just get the L92 intake and everything will bolt back up including the engine cover.

 

What kind of gains can be had w/ the swap?

 

will the l92 and intake fit a 4.8 also? Ive heard these are the best factory heads you can buy from GM, true?

 

No, the valves on the L92/LS3 head are too big for any of the LS engines with bores smaller than 4.00", such as the 5.7 LS1, the 4.8 and the 5.3. They probably would flow too much for these smaller engines anyhow. The Intake flows like 330 CFM @.600" lift, so even on the 6.0 and 6.2 these heads only start to work good with large duration/lift cams. These are the best flowing heads you can get for that price range (less than a $1,000.00 a set, even w/ good aftermarket springs) IMO.