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I have a 5.7 6sp challenger and I’m in the process of getting a new motor. MMX has the 6.4 crate for $7,900 and they have the forged long block for 7,800 not much in a price difference. I’m set on getting the 6.4 i know most of the 5.7 stuff would work my only problem is the difference in the motors I know one is forged and the other isn’t. also know that I need a way to activate the active runners on the 6.4 and last question if I get either one can I use the crate engine harness kit would I have any issues with it installed
 

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2010 R/T Classic 6M
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I have a 5.7 6sp challenger and I’m in the process of getting a new motor. MMX has the 6.4 crate for $7,900 and they have the forged long block for 7,800 not much in a price difference. I’m set on getting the 6.4 i know most of the 5.7 stuff would work my only problem is the difference in the motors I know one is forged and the other isn’t. also know that I need a way to activate the active runners on the 6.4 and last question if I get either one can I use the crate engine harness kit would I have any issues with it installed
Do you plan on modding it? If so then get the forged block
 
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2014 Shaker Boosted 392 Stroker M6
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You can get a forged 5.7 short block for around $4K.
 
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Yes I plan on modding it. If I get that would the crate engine harness kit work?
Well you shouldn't need the engine harness, and like Gila said, you can get the shortblock for even cheaper and use your current heads. Unless you windowed the stock block or something?
 

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2011 R/T 6M Bright White, 590whp 490wtq, Whipple 10psi, 274 cam, 1 7/8 LT headers, 429 gears
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I have a 5.7 6sp challenger and I’m in the process of getting a new motor. MMX has the 6.4 crate for $7,900 and they have the forged long block for 7,800 not much in a price difference. I’m set on getting the 6.4 i know most of the 5.7 stuff would work my only problem is the difference in the motors I know one is forged and the other isn’t. also know that I need a way to activate the active runners on the 6.4 and last question if I get either one can I use the crate engine harness kit would I have any issues with it installed
If you go with the 6.4 harness you will have what yo need for the active runners, no pcm change required (You can validate this with mmx ).

6.4 advantages over the 5.7 are..

Better flowing heads
Sodium filled exhaust valves
Forged crank
Piston squiters
Better cooling
More displacement
Variable runner intake
Lighter pistons if going NA (not good for boost)
More HP and TQ
Avilable drop-in forged rods and pistons (cheaper to complete a forged bottom end)

My personal opinion is go for the 6.4. Dollar for dollar chasing HP/TQ the 6.4 has the advantage, no replacement for displacement and better flowing heads.

Sent from my SM-T350 using Tapatalk
 
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