LS3 Conversion and Transmission Upgrades.

[Chase Wright]

Hey all, I've been seriously thinking about doing an LS3 conversion in my 06 H3 and one big question that I have, is what needs to be done to the tranny to prevent it from blowing up the with the high power output with the V8. I'm open to all opinions on what parts to use and such, along with the PCM and ECM retune for the V8.

 

[cgalpha08]

You could get a rebuild kit such as "monster in a box", may help with the increased power. IMO the extra power on the front diff worries me more than the transmission.

 

[Chase Wright]

Any recommendations on what to use to strengthen the front diff?

 

[cgalpha08]

Any recommendations on what to use to strengthen the front diff?

SAS lol....but seriously that's really the only option.

 

[5gn-h3t]

Might as well go all out. Just use an LS3 with a trans and transfer case from a full size truck and convert the front end to a solid axle. Just match the axle's drop to the transfer case you end up with.

A 6.2, 6L90E, divorced NP205 sounds good.

 

[amrg]

The torque of the LS3 + the first gear reduction of the 6 speed will put a huge strain on the differentials!
But I believe its the right thing to do esp if some torque management is added in the tuning to prevent full torque being delivered when accelerating from a dead stop.

 

[4speedfunk]

Forget any sort of divorced t-case. Forget keeping the stock tranny (wont bolt up to a V8).
If you use any late model GM motor/transi/t-case for your swap, you'll want to use a Ford front solid axle. This will move the front drive to the drivers-side (opposite of stock). Frankly....because it's already pre-engineered for you, I would take a hard look at swapping the front IFS in from the same GM donor truck the motor came from. Buy a wrecked 2015 HD2500, and get to choppin!

 

[amrg]

The I5 trans will bolt to a V8 but alot of trans parts will need to be swapped. "Humvee" did this in his thread.
If someone was to "upgrade" his 4L60e, then swappig those parts will not cost more labour wise. If not, a V8 4L60e is a better option.

 

[4speedfunk]

At some point it makes far more sense to drop an H3 body down on some other chassis. When you consider all the little projects it takes to swap in a different drivetrain...the big project of swapping the body starts to be a real possibility. Chopping a frame down to reduce the wheelbase is peanuts compared to shoe-horning a drivetrain and upgrading the axles and such.
I personally don't think the stock frame is up to the task of handling big hp and torque numbers. The body swap is essentially a cosmetic thing. All the drivetrain and chassis could remain stock.
I vote for a late model Dodge 2500. Solid front axle, monster rear axle, Cummins 24v, stick shift, bulletproof t-case....all completely installed and figured out for you. All you gotta do is figure out how to make the H3 body fit it.

 

[Chase Wright]

Since the LS3 puts out so much power would you guys recommend a smaller LSX like the LS1 or LS2? I would like to stay with an LS because of the amount of performance parts available for them. I know that Mash Motors does a Vortec 6000 6.0L conversion but I really don't want to pay 18k for that. Any suggestions on where to go from there, the plan is to make this truck last for a long time after the 5 cylinder is replaced.

 

[SuperBuickGuy]

At some point it makes far more sense to drop an H3 body down on some other chassis. When you consider all the little projects it takes to swap in a different drivetrain...the big project of swapping the body starts to be a real possibility. Chopping a frame down to reduce the wheelbase is peanuts compared to shoe-horning a drivetrain and upgrading the axles and such.
I personally don't think the stock frame is up to the task of handling big hp and torque numbers. The body swap is essentially a cosmetic thing. All the drivetrain and chassis could remain stock.
I vote for a late model Dodge 2500. Solid front axle, monster rear axle, Cummins 24v, stick shift, bulletproof t-case....all completely installed and figured out for you. All you gotta do is figure out how to make the H3 body fit it.

I totally get why you say this - but I still think you're utterly nuts. It's far easier to weld new brackets onto a H3 frame then it is to try to adapt a frame to another vehicle... not to mention the wiring, plumbing, and accessory issues that doing such a swap entails.

my first body-on-new-frame

1954 Studebaker truck onto a shorted 3/4 ton chevy frame (20" shorter). I put a 500 ci cadillac motor in it. That was an "easy" swap but countless hours of work to pull off



I did finish it, then pulled it apart and put it on an S10 frame. Last I know it was still running that combo 1/4 mile at a time.

 

[JPaul]

If I ever had a Studebaker, I'd have to have a stuffed Fozzie Bear in it.

 

[4speedfunk]

I think both ideas are nuts. Sell it and buy something with more power.

 

[5gn-h3t]

I think both ideas are nuts. Sell it and buy something with more power.

It's bad when the guy that cut the front end off his truck tells you that you're nuts. Haha.

 

[5gn-h3t]

I really love the Hummer styling. You would lose that if you bought something else. I would love to do drivetrain swap too. Someday. At the rate I move, should only take me about 5 years.

 

[4speedfunk]

5gn...you know first hand how much work the SAS is. My point is...you gotta really really love your H3 to do a motor swap, (or a body swap). After doing several SAS's myself...I'm not sure I love my H3 enough to ever put myself thru that kind of torment and frustration.
It's so much easier and cheaper to go get a 71 Blazer and stuff a big block in it.

 

[GreatDaneHummer]

Since the LS3 puts out so much power would you guys recommend a smaller LSX like the LS1 or LS2? I would like to stay with an LS because of the amount of performance parts available for them. I know that Mash Motors does a Vortec 6000 6.0L conversion but I really don't want to pay 18k for that. Any suggestions on where to go from there, the plan is to make this truck last for a long time after the 5 cylinder is replaced.

They actually do not do the 6.0L anymore. They now put in a 6.2L with trans for $23k... reusing the stock transfer case.

 

[GreatDaneHummer]

I will throw another crazy idea out there. What about using the new GM Canyon / Colorado diesel power train? Engine, trans etc.

 

[Chase Wright]

I've thought about doing a diesel conversion but I keep leaning more towards the LSX motors because of the ability to get parts for them and how popular they are for engine swaps.

 

[5gn-h3t]

4speedfunk - you are absolutely right. I've done 5 engine swaps and the SAS is my third major suspension re-vamp. They were all expensive and painful but for some reason I still keep doing it. Lol

Chase - You better really love your H3! It won't be cheap, easy, or relaxing to upgrade the engine in any way. You could probably trade your H3 in on most newer vehicles and come out ahead.

 

[4speedfunk]

H3's are just now getting to the price point where you can "play" with them. Pick up a nice used one for $8k-$9k, or a non-running one for $3k...and start choppin!

When I did mine, I cut apart a 38,000 mile 2008 model in 2011 because I kept smoking stock front axles. Hell, it still smelled new! The dealer and I had words and ultimately, GM lost a life-long customer. If it hadn't been for GM going total retard, and refusing to honor a 100k mile warranty, I'm not sure I would have tackled the SAS. I was sort of forced into fixing it, and unlike GM...I gave enough of a damn to actually upgrade it rather than keep throwing horrendously under-sized parts at it over and over again. So...THANK YOU GM! It was the best thing I could have done and it was worth the hassle. The best part is...Hummer is gone. And I'm still here. So Mary Barra...if you're out there listening...take a flyin suck on that one!

Guys. Whether you realize it or not...we're on our own from here on out. Don't be scared. Start choppin.