He is also doing a "high MPG Tune" combined with a high performance tune, sounds like the best of both worlds. I'll update after a couple days of driving it, I know there are many gearheads on here like me that love power/performance mods on our engines.

 

What happened to: "This will be a do it myself build, pretty easy" ???????????

Good choices, should be fun, except for writing the check.

I did my H3 Alpha couple years ago with a TSP Stage 2 Low Lift Truck Camshaft 212/218 .550"/.550" 112 LSA and GM LS6 Single Beehive Valve Springs. Had the TB port and polished, swapped to an electric SuperModulation Sfan4500. The stock LH8 heads in the 2008 & 09 H3 Alphas use 799 heads, same everything as 243s (CC and valve sizes etc..).

 

Got the H2 back a week ago. Not overly impressed with it. Doesn't seem like after all that work I picked up much power. Avg. MPG dropped 1 MPG. It's going back in for a Procharger. Just working out the details now. If that doesn't wake the beast up, I give up.

 

That has to be frustrating for sure. What did the shop say? Dyno numbers before and after?

Procharger should wake it up.

 

IMHO there is no such thing as a high mpg tune and hi performance tune. They live at differnt ends of the spectrum.
What intake did you choose, what throttle body and what injectors?
Did you put in even a mild stall converter?
My build was similar and I could smoke all 4 tires at will.

 

I'm no expert when it comes to tuning. I was told the High MPG tune was credible and doable along with a nice street tune. Kept my stock 6.0 truck intake, factory throttle body and injectors and no upgraded stall converter. This build was from information gathered by myself from a lot of the corvette forums, LS build forums and Richard Holdeners videos. Like any project, I can look back at what I should have done differently, but I'm fortunate enough that I have a healthy budget for this project. So, I started with the top end engine build which in the end would support a supercharger, which is where I'm going. Put down my deposit yesterday for the Procharger D1SC, 60lb injectors and modified tune.

For those scratching their heads wondering why would someone put in $20K on this project in an 07 H2, I've been wanting a cadillac V series sedan or SUV for a long time.......but, I love my Hummer as a daily driver and decided it would be "cooler" to go this route. Each to our own. The shop doing (and did) the work is a Procharger dealer, has a couple early 2000 vettes in his garage with the procharger setups not to mention some kick *** wild builds their working on.

I did take the Hummer for a 4 hour drive yesterday up into the mountains, and my avg mileage actually improved overall + 1mpg. Power range is between 4K and past 6K, she really pulls and comes alive at those higher rpm's, shifting is amazing as those shifting points were addressed during the tune as well. Over all I'm pretty satisfied with the build and hopefully will love the low end/mid range torque the supercharger will give me.

 

You've got a solid build going and the next step logically is either the supercharger or/and gears. These trucks are heavy and square so it takes a good bit of torque and HP to get them moving.
Keep us posted on the pro-charger, that or a magna-charger will be the next step for my H2.
For me the convertor and gears where needed for the engine mods to really work

Neal

 

Ok sounds like you have it under control. If you run into issues with the injectors, look up the TBSS swap, its really easy and if you get lucky and find one with Flex fuel injectors it will save you a few bucks too.
Don't be afraid to throw some timing at it either, they can take more than most tuners think. A TBSS stall converter will do you wonders too but thats another job!
Good luck!
TH

 

Great points, thank you. Stall converter and Transmission will be the next project. Been looking at a different intake, think I'll pick up a TBSS intake, seems there are quite a few for sale near me.

 

Researching at the Vette Forums and LS build forums when your motor is going in a HEAVY OFF ROAD BRICK is not much help IMHO. Light street performance vehicles (2wd at that) have almost nothing in common with an H2 or what is going to power it. I still like your choices made.

I kind of agree with tharber, when I first read this I thought you are getting BS blown at you when somebody says Performance High MPG tune in the same sentence. I did my own tuning after some help from PCMofNC to start the process, spent miles logging to see where I could add low end/mid range TQ and response. I learned that your cam needs a tune looking to use what it brings and for your specific uses. The cam itself made an nice improvement before my tune, it just idled too low and stalled in reverse. Add a finished tune, and the then the cam really shines. I tuned for 87 gas, not mid/premium. Perhaps they have too mild a tune for your end target? Even without the cam and heads, a good tune should have woke up your 6.0 L.

Good luck and keep after it.