Common engine swaps

[cs641]

Just bought a Humvee thru GP. Was sold untested and it could be anything from a dead motor to a broken wire or dead battery. I’m just pondering the worst case scenario of a dead motor. What else have folks swapped in? Since the trans is a 4L80E is an LS swap doable on these?

 

[Mogman]

Yes the LS has been swapped in along with some gen I, small and big blocks, also the Cummins 4 and 6BT and of course the Duramax, the last two require extensive modifications and mucho expense.
Having the 4L80 is no different as far as options than the TH-400

 

[cs641]

Yes the LS has been swapped in along with some gen I, small and big blocks, also the Cummins 4 and 6BT and of course the Duramax, the last two require extensive modifications and mucho expense.
Having the 4L80 is no different as far as options than the TH-400

OK, so bellhousing is the same? Also, I see conversion mounts listed online for the civilian H1,would these also work for the military version?

Really hoping my unit runs with fresh batteries and I can keep it original but we’ll see.

 

[Mogman]

No the bell housing and LS engine are not compatible, you will have to do some kind of adaption, I am doing the reverse right now, installing a 6L transmission on a 6.2L and it required a bell housing spacer plate and spacers for the TC, a gen 1 would bolt right up but not an LS.

You will also have to deal with different flex plate/torque converter hole spacing.

Most of the bell housing and block holes are the same as are the locating dowels so spacing becomes the major issue
This is a comparison between the gen 1 and LS crank to show the difference in flange depth.


Here is somewhat of a "guide"

The Great Chevy Auto Trans Interchange Guide

Bolt any bowtie automatic to any Chevy engine – if you know the tricksBolt any bowtie automatic to any Chevy engine – if you know the tricks!

www.streetmusclemag.com

 

[Mogman]

Looks like it will not be too hard, only a spacer/bolts and correct flex plate should get you going, the applicable sentence below.

" To accommodate an older transmission where the crankshaft flange is extended, Chevrolet created a 0.400-inch steel spacer to be used with the most common LS engines using a flush crankshaft. This spacer is located between the crank flange and the flexplate and is used in conjunction with a flat LS flexplate. This adapter also requires longer bolts. We’ve listed both the GM and ARP bolts in our parts list. "

You will also need some motor mount adapters, the LS does not share the same mounting configuration as the Gen I engine.

 

[cs641]

Looks like it will not be too hard, only a spacer/bolts and correct flex plate should get you going, the applicable sentence below.

" To accommodate an older transmission where the crankshaft flange is extended, Chevrolet created a 0.400-inch steel spacer to be used with the most common LS engines using a flush crankshaft. This spacer is located between the crank flange and the flexplate and is used in conjunction with a flat LS flexplate. This adapter also requires longer bolts. We’ve listed both the GM and ARP bolts in our parts list. "

You will also need some motor mount adapters, the LS does not share the same mounting configuration as the Gen I engine.

Cooy that.

I see LS conversion mounts listed for the hummer H1. Would they work for theHMMWV?

 

[Mogman]

Cooy that.

I see LS conversion mounts listed for the hummer H1. Would they work for theHMMWV?

Should, look around though as there are ALLOT of LS/Gen I conversion mounts, I would suspect the HUMMER ones would be priced as such, look at the pictures real close then go look at others, many times in the HMMWV world folks just re-label stuff to make money.

 

[jrtoffroad]

Maybe I misread early comments, but just to clarify:
You do not need a bellhousing adapter to mount an 'early' 4l80e to an LS engine. It will bolt up just fine, although you will give up 1 mounting bolt; with the LS engines GM moved the 1 o'clock mount to 12 o'clock. I have never seen this be an issue, even with some very high HP racing applications (I ran a th400 behind a built LS1 for many years in a ultra4 car). As mentioned, you do have to match you flexplate to your torque converter, but that's easy and cheap.

 

[Mogman]

If you have

Maybe I misread early comments, but just to clarify:
You do not need a bellhousing adapter to mount an 'early' 4l80e to an LS engine. It will bolt up just fine, although you will give up 1 mounting bolt; with the LS engines GM moved the 1 o'clock mount to 12 o'clock. I have never seen this be an issue, even with some very high HP racing applications (I ran a th400 behind a built LS1 for many years in a ultra4 car). As mentioned, you do have to match you flexplate to your torque converter, but that's easy and cheap.

If you have an LS with a flush crankshaft flange you will need the 0.4" crankshaft spacer or the torque converter nose will not be located in the crankshaft pilot, no you do not need a bell housing adapter for that application.