Newbie... 5.9 mag to 5.7 hemi in 03 with a 12 donar truck

[Rob R]

Hello...im new to truck forums and have checked a few out to see if i can find an answer or help me deciding if its worth or even doable.
I have a 2003 ram 1500 with a 5.9 thats not working the best...idles great but is gutless...plus im thinking the tranny might be starting to slip. So i have a great deal from a family member on a 2012 dodge ram with a 5.7 hemi. Everyhing under hood and drivetrain is top shelf... So i guess my question is.... Can it be done and if so what are my challenges and am i gonna need alot of dough for other parts.... Or any major custom work.
If this post or a similiar one with info i need can you please refer me the post...tye1 for your time and input.

 

[fastf]

Build the 5.9 unless you just gotta have a hemi .Its gonna take a lot to make that 5.7 work in that old a truck.That old engine is tough and you still get parts to make it go just check Summit racing.

 

[Rob R]

Tyvm... And good to know.. Prob take that comment and run with it. Irs mainly a sled hauler. .bought ir late fall....never had much power from beginning and struggles to pull 2 sleds on a trailer and never had a vehicle so hard on gas in my life. So havent drove it much but had to last weekend and when i got home the engine bay was covered mainly on drivers side... Guess ill look deeper into it wirh warmer weather coming.... Tx for the great input

 

[chrisp2493]

Quite a few issues between the motors, you’ll have to lock out the VVT and the crank tone wheel needs changed out because it has a 56 tooth reluctor and the older hemis have a 32 tooth reluctor wheel so it won’t run on the computer. It’s a lot of work, there’s a reason nobody actually goes through with it.

 

[fastf]

To tell you the truth if you bought a Dodge aka Ram for gas milege you got the wrong thing .I have owned a lot of Dodge aka Ram trucks it just aint in the cards.But you want a tough truck you came to the place everyone is a beast for hauling and such .The 5.9 360 isn't good on gas but the one I had was a lot of lowend touque.

 

[Justin_Hart]

My 02 1500 5.9 is terrible on gas to. but its simple i can still work on it without a team of engineers in my corner. I have 3.92 gears and 285 70 17 tires is why ive always figured its kinda gutless. never have put smaller tires on it and cant afford taller gears so i deal with it.

I used to pull the farms 20ft goose neck stock trailer around. It would pull it all kinds of low end torque. You just wasnt going to win any races lol.

Sent from my SM-G930R4 using Tapatalk

 

[fastf]

The 5.9 360 isn't a racing engine but a very dependable engine and like you said its simple to work on.

 

[ric3xrt]

from the economics point rebuild the 5.9, need a little extra grunt, stroke it to 4.08...cranks are cheap for the magnum engines
Plenty of smallblock mopar guys who will disagree about the 5.9 racing capabilities,

 

[HemiLonestar]

You can't even just drop that '12 hemi into an 03-08 hemi truck. That's gonna be more can of worms and money than you wanna get into.

 

[bulrid8]

Have you put a tuner on your engine? The 5.9 is one engine that really wakes up with a tuner. It is very detuned from the factory.

Mine keeps up with most trucks and still average 12.7 mpg. I will not ***** about that mileage from a 4x4 V8 with 285/70/17 tires.

Sent from my SM-G955U using Tapatalk

 

[Rob R]

Thank you everyone for your input...all very useful. I have decided to keep the 360. I heard theres some type of censor that can cause the 360 to lose power on the drivers side...its sprayed oil on the inside of engine bay when the engine is under strain. I bought this truck late in the fall with many problems i didnt expect...heater (blend doors) oil pan (fixed now) and some other smaller jobs. Its never had any power since i bought it and struggles to pull itself up a hill at 60mph/100kmh. So im sure theres some issue there for power loss and will work on it rather than replace the motor with a 5.7. Again thank you for all your opinions and keeping me on the right track.

 

[Paul Morton]

Hi sorry to butt in can anyone recommend a good tuner for the 5.9? I just got a 2002 over here running on lpg just wondered if there are any that would take that in to the equation?

Paul