This is my second post to this forum and I am looking for help from those who have done this before or know what has to be done. I am preparing to do a new LS3 crate engine swap in my 2010 H3T which has a 5 CYL engine now. From reading available information on this site and other sources it appears it would not be that difficult. If anyone here has successfully completed an LS2 or LS3 conversion to a H3T I would greatly appreciate hearing about the details. What I have learned so far is the 4L60E transmission can be used and needs the 8 cylinder input shaft, torque converter, bell housing and I will need 8 cyl engine mounts to handle the mechanical part of the conversion. I haven't sorted out the exhaust and cat's yet so I am all ears on this one. "Current Performance Inc.'' has told me that can program and modify my current ECM and harness to correctly work with the LS3. I plan to re use the current accessories and brackets where possible, some things will require new brackets. I plan to buy new A/C and radiator hoses as needed and possibly replace the oil pan and pick up assembly with the H3T 8 cyl oil pan. I also live in a state where emissions testing will have to pass, according to my local GM dealer they indicated they would have to get the emissions re-certified to match my VIN# which they have done before on another vehicle with a similar swap, am I leaving anything out that needs to be addressed in completing this conversion ? Thanks

 

I have only seen one H3 that has had the LS3 swap it was a 2006 Yellow h3. He never posted up about what parts he used though. I have been seriously considering the swap for a while but could not figure out what to use for motor mounts and also what to do about the tranny as I have a manual 5 speed and wanted to swap to a NV4500.

Also the H3 alpha that came with the 5.3 had a modified firewall to clear the bigger motor so I think you might need custom motor mounts to move the motor forwards more. I did the 1" daystar bodylift so maybe that will give enough clearance.

 

Oil pan will def. need to be replaced with the LH8 pan. You wil also need to source all of the accessory mounts from an LH8, they are more compact than a standard LS motor.

Check out the colorado/canyon forums for more info on the computer stuff.

 

Thanks for the information, I assume you refer to the oil pan from a 5.3 H3 with the LH8 designation ?
At this point since my H3T is a 2010 I am going to assume that GM used the same firewall clearance on the 09 and 10 H3's unless someone has information that there are 2 different firewalls for those years. Gm lists 2 different engine mounts for the 8 cylinder and 5 cylinder engines, so I am probably going to start with those to see if everything fits. Current Performance told me they have mounts for the Colorado or Canyon that should work if it becomes an issue.

 

The firewall on the 09 and 10s are the same Alpha or I5. At least they were on our 09 I5 and 10 Alpha H3Ts.

 

That is very good news, I was hoping that would be the case. On the oil pan, you indicate the LH8 for the swap out I see 2 pans listed one with a bypass and one with out, any thoughts on which one should be used ? Thanks

 

Nope, not a clue. I just know that there is 1 oil pan that fits the 5.3L LH8 in an H3/H3T. If it wasn't so fricking cold out I would crawl under there and find the part #.

Maybe someone in a warmer climate can help ya out with that?

 

I think it would be quicker, cheaper, easier, and less emissions hassle to trade your H3T in on an Alpha. But hey, that's just me.

 

That's OK, I,m about to get 2' of snow here. I will figure it out once everything is all apart. Thanks for the help

 

I wanted an Alpha but could not find a real nice 2010, your right it would be a lot easier and would be my preference to start with an Alpha. If I could find one in Blue or Black, not smoked in, no accident history, automatic, original condition, that is mint, not off roaded, not driven in the snow and is low miles at a reasonable price I would sell the one I have rather than go through all the extra work.