Hello group. We are taking a 5.3L LY5 engine with all accessories, manifolds, harness, ecu, and transmission controller removed from a 2008 Chevy Tahoe and installing them in a 2007 3.7L Hummer H3. Here are both..



The transmission being used for this is a 4L60E built by RPM transmissions and has a loose converter. The 5.3L we rebuilt with a DOD delete and a BTR stage 2 truck cam. We are building our own harness for this and plan on using both the ECU from the H3 and the ECU/TCM from the Tahoe. We are pretty far along now, check out this short..


We have released a lot of content on this conversion and plan on releasing more at each step until it is complete. If you have an interest in converting your I5 H3 to a v8, come follow us on Youtube: Second Shift Performance - YouTube

 

Would have been cheaper and quicker to sell the 07 and buy a 2008-9 Alpha, cam & tune that and call it done.

Good luck.

 

Ya so as a part of the rebuild on the 5.3L we also changed the camshaft bearings before we put the stage 2 camshaft in. Here are the bearings that came out of the 5.3L with under 100k miles on the odometer..



These motors are hard on the camshaft bearings and also the valve guides are common to wear by 100k. But also the 4l60E GM transmission is absolute junk. A fresh build is always a nice way to go. And speaking of fresh build here are the big 3 pieces used for this effort. The built RPM Transmission 4l60E with Corvette servo and 2500 stall converter next to the rebuilt engine next to the cooling system upgrade..

 

We are almost done lacing the 2 engine harnesses together. We are hoping to bring life to this thing this week. Here is where we are at with it today..

 

All that work and a HOT AIR intake.
Might want to source an 08-10 Hummer H3 Alpha air box.
Draws air from outside the engine compartment.
It gets HOT AF under the hood of a v8 H3.

 

It can't possibly be any worse than the supercharged 6.2L powered H2 was. OMG @ 150f IAT the second you open the throttle.

I have a build thread on the Procharged LSX376-B8 powered 08 H2 here:
Lsx376-b8 + Procharger In A 2008 Hummer H2 | Supercharger Builds (superchargerforums.com)

 

We are at the end of the build. Just tuning work left. So here is the before picture with the 3.7L engine still in place..



And here is the after picture with the 5.3L v8 engine and dual engine controllers..

 

So here is a 4k timelapse of the wiring and completion of the conversion..

 

How much is this conversion costing the customer? I can’t imagine this is an affordable swap option, even with using a used engine like you guys did. Like previously mentioned, it would probably have been more cost effective to find a H3 with the V8 and do a rebuild or freshen it up if needed?

Or if they really like their H3, leave it with the 3.7 and go just buy a Tahoe if you need a SUV with a V8.

But it is interesting to see how you have chosen to go about this, and plan to run two different ECU’s in the same vehicle. Definitely different than the other ways I’ve seen & read about others doing this swap.

 

Nikal you should see my 3d printers.

As for the rest of everybody, I made this in case anyone out there finds themselves trying to get a crank signal out of the factory ignition switch without a crank/start output.