Hemi 5.7L Engine Swap In a Hmmwv

[Agelai]

Yup, you read the title, what’s everyone’s thought?

Hemi 5.7L Engine Swap In a Hmmwv

- 5.7L Engine
- Transmission

 

[Mogman]

This should be moved to the mod/hotrod forum.
Anything is possible , knock yourself out!

 

[Agelai]

I'm wonder how the drivetrain would work with this build

 

[MarkM]

Good luck with the fuel milage.

Mark

 

[Mogman]

I'm wonder how the drivetrain would work with this build

Not sure what you mean, you will need to custom build everything, mounts/ rear crossmember, convert the truck to 12V, find and or adapt a transfer case with a driver side drop, most likely unless you can adapt the original transfer case all new drive shafts will be needed, adapt the cooling system, custom stand alone wire harness for the engine and transmission and possibly the transfer case.
Custom tuning for your stand alone installation, custom exhaust, custom intake system, adapt the Mopar power steering pump to GM fittings, even more custom work if the donor vehicle did not have hydra boost brakes, match fit fan and fan clutch to the HMMWV fan shroud.
Other than that it will be a snap! Just about any "light or med duty" drive train can be adapted, they have even stuffed the long and tall 6BT into these things.
Yes it will likely get poor mileage and you will be dealing with an engine that produces more heat including exhaust heat trying to push that shoe box down the road but heck YOLO!!!
You want to use a transmission with a .6/.7:1 top gear

 

[Mogman]

I am not sure why you think it would be cheaper than doing a Duramax, I still had to do all of the above work on the DuraVee so the only real difference would be the donor vehicle cost and I would be surprised if you could pick up a Hemi for less than a Dmax, can't turn around down here without tripping over one.

 

[jrtoffroad]

I run a 6.1 Hemi in my 4wd offroad race car. The engines are great, but the dodge electronics/control system is a nightmare. After lots of time and money and a number of races lost because of issues, I finally gave up on running the computer controlled trans and went with a Holley Terminator Standalone control system and a 46re trans with a manual valve body. Couldn't be happier. Might be a good option if you really want to go the hemi route.

I have heard the newer PCM is a little better to work with than the older stuff that I was running. To get everything to work in my conversion I had to have the PCM, TCM, FCM, and ABS Module all from the same donor application. But it still seldom did what it was told and wanted to go into limp mode if I looked at it wrong.

I do a lot of tuning and conversions and, in my experience, the GM stuff is MUCH easier to work with and far cheaper.

 

[Mogman]

I was looking around, man those 8 speeds look pretty dang long, long is your enemy in a HMMWV swap, you may have body and fuel tank clearance issues.

 

[Agelai]

I run a 6.1 Hemi in my 4wd offroad race car. The engines are great, but the dodge electronics/control system is a nightmare. After lots of time and money and a number of races lost because of issues, I finally gave up on running the computer controlled trans and went with a Holley Terminator Standalone control system and a 46re trans with a manual valve body. Couldn't be happier. Might be a good option if you really want to go the hemi route.

I have heard the newer PCM is a little better to work with than the older stuff that I was running. To get everything to work in my conversion I had to have the PCM, TCM, FCM, and ABS Module all from the same donor application. But it still seldom did what it was told and wanted to go into limp mode if I looked at it wrong.

I do a lot of tuning and conversions and, in my experience, the GM stuff is MUCH easier to work with and far cheaper.

yeah I’ve been looking into swapping an LS1 engine into it instead.

 

[GTUnit]

The Hemi 5.7 has problems. They like to drop valve seats in around year 2005 gen cars.
Newer 5.7's roller lifter bearings seize wiping out cam lobes. I would rethink that choice.

 

[AFGVET]

Do you just "want" to do this or is there a need to replace the engine?
My suggestion is: 1st Consider the torque that is required.
-OR-
In other terms: Do your targeting.
In targeting we consider the effects required, the environment, time line and then we assign a system against it.
You might consider doing the same.