Why?

Spent some time thinking about this and came to the conclusion that the biggest advantage the new Hemi has over the LA is head flow, most tests I've seen show the 5.7 peaking at 260 cfm (the 6.1 is wicked (both in cost and power) so I'm not even talking about them). So, I got to thinking that since the Edelbrock LA heads flow about the same, maybe I could I get comparable performance with an LA 360 and aluminum heads for less money.

I wrote up a spreadsheet totaling the costs of a 5.7 swap verses a rebuilt 360 and I'm surprised to say that I'm not sure it would be a cost effective method of increasing my performance.

I looked a couple of options but the cheapest I could come up with was about $4000 to put a 5.7 in my Duster, using a cut up OE harness and flashed computer, truck intake and Jeep exhaust and building my own motor mounts. Top dog swap was $6200 if I swapped to a car intake and front cover with MS3 and just buying everything.

For the 360, if I just took my existing motor with the rebuilder pistons in it and 8.5:1 compression and only swapped to a better roller cam (already have one in the motor, so no need for lifters), carb, intake and Edelbrock heads, it would cost about $3000, but no EFI. Adding EFI bumped it up $5200, $1200 more than swapping to the Hemi. If I did a full rebuild so I could bump the compression up to 10:1 or so, plus the EFI, the total ran over $6800. Making the Hemi look pretty good.

Your numbers might be different, they are specific to my situation and swapping a Hemi into a 4 speed Duster. Tried to get everything included, but I'm sure I missed stuff. I was just curious to see the differences.

Also, I used the cost of a local 5.7 truck motor for my costing at $1600. Looked at car motors, but they cost a lot more. But even after tax, I wasn't much more than just the Edelbrock heads for the LA setup. Didn't call on the motor though, so I don't know if it included a wiring harness or accessories. I did include the cost of a used alternator and water pump in the costs, though.

So, unless you already have a good motor, I might be willing to argue that it would cost less to swap a Hemi into your car than build a good 360 from scratch.

BTW, costed a 6.1 out of curiousity and it totaled out at almost $10.5K, mostly because the motor was $5700 by itself.

Just some thoughts relating the original question of "Why?".