As a relatively new and younger Hummer owner, what is the best way to increase the speed on a 2003 H2 model? I have to take it into the shop either way to fix some issues regarding steering and whatnot but was considering supercharging it along with adding a magnaflow exhaust, thoughts?

 

lol, it ain’t build for speed.
you talking 6614lbs that is from the factory.
If you added accessories to it like wheels, oversized tires, shocks, etc etc you talking maybe 7000lbs.
IMO, from my own experience the only engine that give you more power is the duramax with a performance kit.
I see ppl supercharging the H2 but let some of the diehard (ain’t that a Christmas movie) Hummer gurus experts chime in on that.
Btw, the 08 and 09 with the 6.2 and 6 speed engine is a bit feistier than the 03 to 07 models that has the 6.0 with 4 speed in them.

 

Yeah goal isn’t to go crazy fast just would like half decent acceleration, love the car and I understand it’s certainly not built for extreme racing. Thanks for your advice.

 

Get to know a Transmission Service owner real well, take them to dinner, maybe a sports game.... so when you tear the chit outta your Auto Trans trying to make speed, you have a trusted guy to fix it over and over.

I have a friend that put a MagnaCharger on his H2, six transmissions later and counting.

Better off removing the H2 badges, sell the H2, buy a V8 car with some performance mods (your choice) and put the H2 badges on that.

 

My opinion,
The H2 is no different then any other vehicle when it comes to adding power and the LS platform is a good engine to do it. The 6.0 in the H2 is a great engine and can be made to put out tons of power.
A supercharger is a good choice if grunt is what your looking for, I think its a great choice for the H2 seeing how heavy the truck is, a little more gear can also help if acceleration is a concern, a supercharger and some gears will wake it up nicely.
Long tuber headers and full 3" exhaust will also help
DOC also has a good point about the trans but with some tuning you can help the trans live or find a good builder and have one built for your needs, the 4L60 can be built to hold just about anything you throw at it.

Neal

 

Great point.
But majority of H2 owners are looking for a simple solution and do go the route you mention as that’s a fairly drastic upgrade to get a few miles faster on the clock.
For my daily ride I got a Chevy 2500HD Diesel, deleted and tuned at a Pro shop for $12k.
Tons of more power and speed but I replaced the head gasket twice already with only 270k miles on the counter.
But it’s al worth it for me.

 

Simple solution would be to find a bolt on whipple kit. They’re fairly simple. Then you’ll have to build the trans.

i have a magnacharger on my 08 and am very pleased. It’ll do an 8 sec real world 0-60 loaded down with 37s about 1000ft above sea level.

 

I have a 2003, I know they are about 100 hp underpowered , I just got used to it drive it like an old man's Cadillac

 

I'm surprised I haven't seen a thread where someone converted to a manual transmission. Not sure what tuning would be required, as far as the engine not having a tranny to talk to. But definitely would be more durable and high horsepower applications. And there should be something right off the shelf at GM that would bolt right in, including to the transfer case. Pedal assembly as well.

 

This is one of those subjects that have been really talked about a great deal.

It all comes down to weight and aerodynamics. If you have pre-08 you can add a better cam, change the heads and intake or just bolt on a supercharger and you will notice a major improvement (and also sacrifice the trans as the 4L60/5 won't like it)
As far as a manual trans is concerned yes I am sure that could be accomplished but you will be facing some major re-programming issues and my guess is that many of the functions of the 4wd system will be lost.

With that said if you don't really care about all that put a front independent suspension (non-4wd) from a 2500HD, dump the trans, transfer case and associated 4wd stuff, add a manual trans and a drive shaft right to the rear, you will dump a whole bunch of weight and there you have it.
A much lighter and quicker H2 that is not really an H2 anymore. My suggestion, do what Blk Wlf did or if you want a go fast truck, find yourself an old Chevy 454 SS and go nuts,

Decisions like this are tough and all boil down to what kind of future your expecting for your H2, and some of these mods talked about could be a detriment to its future value. If money or future value means nothing and its all about personal satisfaction a Duramax conversion trumps all other options. Plus gives you something that will literally dust anything else you could do to the H2 short of a Jet engine, lol