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Rebuild Magnum 5.9 or Swap Hemi 5.7 (Gen III)

  • Rebuild Magnum 5.9

    Votes: 0 0.0%
  • Swap Hemi 5.7 (Gen III)

    Votes: 1 100.0%
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· Registered
1999 Dodge Durango 5.9 4x4
21 Posts
Discussion Starter · #1 ·

I would prefer the 6.4 or even 6.1 Hemi but, they're more than I would like to spend on this project.


Rebuild current Magnum 5.9
I would have to build it up to keep-up with the modern Hemi's out there plus, I'll be towing long distances. I not only want the power but, I need it as well. (I suffer from a lead foot.)


Swap with a Hemi 5.7 (Gen III)
I would have to bore it out because I simply cannot go down in displacement, it goes against my religion.


$5,000. I'm okay with refurbished parts. At the end of the day, I still need money left to pay for the stuff to tow. I'd hate to spend all my money on the engine & have nothing to tow.

My specific applications for my 99' Durango 4x4:

35% around a semi-urban city with some suburbs on the outskirts of the city
20% towing my 2,800 lb car to the track
10% out to the desert to shoot the dunes
10% up to snowy mountains for snowboarding
10% bad weather
(10% maybe tow a speed boat someday too)
5% other road trips

Long-Term Consideration:

150k miles @ $5/gal:
Magnum 5.9 avg. 11.5 mpg = $65k
Hemi 5.7 avg. 18.5 mpg = $40k
(City mpg ➕ Hwy mpg ➗ 2 = Avg. mpg)
That makes the Hemi $25k cheaper than the Magnum, in gas, after 150k miles! (…. if it lasts)

Aluminum is not as durable as iron.

Hemi would be more complex & expensive to repair.

Hemi parts may be easier to find, maybe even more-so as the years pass.

· Registered
231 Posts
I was going to say rebuild the 5.9. I have a 5.9 and I am partial to them. BUT, you bring up a number of good points, gas mileage, parts, ease of finding said parts. I thisk your really only big hurdle is going to be the swap, with the harness, ECU drivetran, but once you are over that and you build it right, it should last for a good long time. Now about the part "may be complex and easier to repair" Look, if you can swap out a Hemi you sure as hell can repair them, complexity should not even be in your vocabulary. LOL!!
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