Is it possible to go from a 5.7 Hemi to 5.9 Magnum in a 2003?

[JGROOK81]

I have a 2003 Ram 4x4 quad cab. It has the 5.7 hemi engine in it. My truck needs an engine. I got to looking at replacement engines new and used. I'm thinking of going used because of my money situation. I noticed that the 5.9 was an option for that year and is considerably cheaper than the Hemi engine is used. My question is would it be possible to go from a 5.7 to a 5.9 without much trouble? What would be needed in order to do this? Obviously I would need a computer from a 5.9 donor truck. Also would the transmission bolt up to the 5.9 engine. What about the transmission, I'm a bigger fan of center cam engines than OHV engines. From what I've seen they last longer, are more durable and way cheaper to replace.

 

[JohnnyMac]

I'm not sure what the difference in price is, but I had a 5.9 in my 2000 Ram and it was pretty much a dog, and got around 10 mpg (best ever was 12.9 on a road trip). I towed a 6k (ish) boat up the AlCan and spent quite a bit of time chugging along in 2nd gear making 5-6 mpg. If you do go the way of the 5.9, make sure the plenum gasket has been upgraded. What would it cost to rebuild what you have?

 

[turkeybird56]

Well, if U want an XMAS present/motor, FCA/Chrysler offering crate Hemi Motors to include the 392. Now whether or not and how it bolt up to both frame, trans, and all other items, hmmmm: Not sure a lot of 2003 parts fit on a 392... May be one heck of a project. Just throwing the thoughts out there for U...

 

[chrisp2493]

Not really sure why you want to do that, you'll be going backwards in power and a ton of headache in the process. The Hemi is pretty reliable. What exactly is wrong with it that you need a completely different engine? But the transmission bolt pattern in the same, I don't know if you need some kind of adapter to go to the torque convertor. The hemi uses a fly wheel, the 46re trans behind a 5.9 has the starter teeth on the convertor. I had to use an adapter plate on my 46re swap on my hemi. I would recommend against trying to do this swap

 

[JGROOK81]

I'm not sure what the difference in price is, but I had a 5.9 in my 2000 Ram and it was pretty much a dog, and got around 10 mpg (best ever was 12.9 on a road trip). I towed a 6k (ish) boat up the AlCan and spent quite a bit of time chugging along in 2nd gear making 5-6 mpg. If you do go the way of the 5.9, make sure the plenum gasket has been upgraded. What would it cost to rebuild what you have?

I haven't priced to rebuild the 5.7. used they run between $1300 on up to $2400 depending on where you look. Now the 5.9 however you can get all day long from between $400 on up to $1200. I realize the 5.7 is considered better for fuel mileage and power. I'm thinking in terms of keeping cost down for repair.

 

[JGROOK81]

Not really sure why you want to do that, you'll be going backwards in power and a ton of headache in the process. The Hemi is pretty reliable. What exactly is wrong with it that you need a completely different engine? But the transmission bolt pattern in the same, I don't know if you need some kind of adapter to go to the torque convertor. The hemi uses a fly wheel, the 46re trans behind a 5.9 has the starter teeth on the convertor. I had to use an adapter plate on my 46re swap on my hemi. I would recommend against trying to do this swap

The reason being is cost factor. I didn't know if you could swap out a 5.9 in place of the Hemi mainly because of a cost standpoint. Used hemi average of about $1500 used 5.9 average cost $500. Just trying to save some money. Obviously if it won't work it won't work. That's why I was asking. I do know that in 2003 Dodge offered the 5.9 as an option. So my gears got to turning and I was wondering what the headache would be? The current engine is toast and needs replaced. It wasn't taken care of properly by the previous owner.

 

[318willrun]

Can it be done? Certainly.
The bolt in I'd think would be the easy part. Everything else (electronics) may be the challenge.

 

[Hootbro]

I do not think the math would work out. To many variables.

 

[chrisp2493]

You’d be dealing with a complete engine. New alternator, water pump, power steering, ac compressor, more then likely new ac lines, computer and wire harness, motor mounts, the list goes on. It’s not going to be worth the little bit you’ll save on a cheaper used motor


I Bleed Ram Trucks

 

[HemiLonestar]

By the time you paid for all the items and work (engine, trans, computer module flashing, wiring harness alterations, etc) that considerably cheaper 360 wouldn't be so cheaper anymore compared to just getting the correct engine and dropping it in.

 

[Silver Goose]

I don't know what your time is worth and or you going to hire the work done? If hired out you will be taking a bath. Every item will have to be reviewed, checked for fit and function. The transmission adaptor could set you back quite a few dollars if it is not on the market and must be fabricated. I would hope that you will be going through the 5.9 before installing and fixing anything wrong.

All in all looks like a bottomless pit and you will still be out of a truck.

Larry

 

[ST-8]

By the time you paid for all the items and work (engine, trans, computer module flashing, wiring harness alterations, etc) that considerably cheaper 360 wouldn't be so cheaper anymore compared to just getting the correct engine and dropping it in.

This!!!