I picked up a 2005 after not having an H2 for 15 years. I forgot how the 6.0 and 4l65 combo is just a dog. Are there any good sites, posts members that can help with options to upgrade to a 6.2 with a 6 speed? Doesn’t anyone still make a supercharger kit for these?

 

Both Mash Motors and Predator Motorsports do H2 upgrades. I believe Magnuson still manufactures superchargers for the H2.

Keep in mind unless your light footed you can count on the 4l65 going south in no time after the upgrade.

 

thanks. Don’t companies offer HD rebuilds for the 4l65?

 

Yes they do and that will help, but if your pushing big power in an H2 the real solution is a 4L80 conversion and for the 4l60/65 series. You could do a 6l80 conversion using a separate trans controller but its still wont be as bullet proof or as strong as a 4l80 or Allison 1000.

 

Thanks for the info. I’ve read where the 4l80e can be sluggish in first and second. If I build the motor, I’d aim for the 450hp range.

 

That is sometimes noted in the trucks that came with 342 or 373 gears. The pre 08 H2's are equipped with 411 ratios so they work great with the 4l80e in its stock form plus if you use the TCI EZ-TCU Automatic Transmission Controller you can set a number of parameters to tune it to your specific needs.

At the 450hp range the 4l65 will need to be built to level 4 or greater to be able to pass the test of time with a supercharger, a thing to remember is the H2 is 6600lb brick and one of the reasons your lucky to get 120k out of a stock H2 trans.

 

sell it and get an’08-‘09.

 

I think I can answer this with some authority considering I have owned an 05, and 06 and now an 08.

While it is true the 08/09 Hummer H2 is about 1.5 seconds quicker in the quarter mile that's not an overwhelming difference. A supercharged H2 LQ4 will easily dust a stock 08/09. Plus the cost of the 08/09 will easily pay for your 05's upgrades.

 

Another thing is the 6.2 is electrically from a totally different generation electrical system and PCM so the entire wiring harness and whatnot from the 6.2 will be useless. 24x versus 58x reluctor wheel - Lingenfelter makes an adapter to convert that. Then extend and put different plugs on the knock sensors, different plugs for the injectors (or adapter pigtails), extend wires for some other misc sensors, also will be going from a return fuel rail to a returnless one so will need a Vette fuel filter/regulator to put on the end of the rail for the fuel lines, figure out how you want to deal with the VVT on the 6.2 (remove or adapt), will need a throttle body electrical adapter for the larger throttle body. Custom dyno tune will be needed as well. There is a bit more as well....

Everything is out there for gen III to gen IV swaps but its far from just dropping it in an plugging everything in.

Far easier and cheaper to just add power to the LQ4.

 

The 6.0 is a solid LS engine and can easily handle 800 HP but do you really want that in a 6000 plus pound truck.
The key is to decide what you want out of the truck then decide how to get there.
I agree with H2-SUT, the 08/09's are much improved but not to the point that I would ditch the 05 over performance or lack of.

Neal