5.7 to 6.4 swap PCM?

598 Views 13 Replies 8 Participants Last post by stevewhite, 7 d ago

Bigred61

Discussion Starter · 12 d ago

I currently have a 2014 Challenger R/T manual. I love the older look of the grill and that is why I have kept this car instead of trading up.
Has about 100k miles on it now and has treated me well.

I may have a line on a 6.4 engine and it has sparked my interest in maybe doing a swap. There are actually 2 available. One engine is non-mds and one has mds, either would work with replacing lifters. Both are below 60k miles. Neither have the pcm or wiring harness.

The engines are complete intake and headers. I know Modern Muscle sales a switch to activate the runners in the 6.4 intake.

What is holding me back is that I have not been able to find a clear answer on the harness and pcm question. Will the 6.4 drop right in, or will I need to replace the engine wire harness and get a new pcm?

I wouldn’t mind the nice HP jump with the 6.4
and I could keep the 5.7 and maybe build it out or sale it, it is a good running motor at this point

Anyway, looking for a clear answer on this one.

Here is a picture of my car as it sits today.

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Xylander

· #2 · 12 d ago

I can't comment on the particulars of a swap like this, other than to say I haven't done a 5.7 to a 6.4. But, given the ballpark engine cost and labor required to do the job... I'll just point out that the power gain would be less than if you just put a blower on the 5.7. That would be "cooler," cheaper, easier, and take less time than doing an engine swap.

I have been involved with a few Hellcat swaps, and I'd be amazed if that PCM didn't have to be part matched to the engine like the HC's does. When engine swapping these, the actual engine swap is the easy part. It's the electrical component swaps that's the real hairy PITA.

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Bigred61

Discussion Starter · #3 · 12 d ago

Xylander said:
I can't comment on the particulars of a swap like this, other than to say I haven't done a 5.7 to a 6.4. But, given the ballpark engine cost and labor required to do the job... I'll just point out that the power gain would be less than if you just put a blower on the 5.7. That would be "cooler," cheaper, easier, and take less time than doing an engine swap.

There won’t be labor costs involved. I will be doing the engine swap in my own garage on my lift.

When I put I Magnuson on my MSRT8 I think final bill ended up being around 15k between parts, labor, exhaust and tune.

The other advantage with one of these motors is less miles. Wouldn’t mind putting the blower on my 5.7, but not sure with the mileage.

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Tempting, and I have thought of the same thing. I can't see why you would need a PCM swap. A tune for sure, which would be no different if you were to put a stroker 5.7 in. If you run the 6.4 intake, that would need a window switch to kick the short runners in around 4800 RPM. You could keep it simple and run your 5.7 intake, maybe have it ported. You will give up a little low end, but not much.

Conversely, building a stroker 5.7 will give you more torque than a 392 because of the longer stroke, and slightly under square bore & stroke. Plus it will have forged internals and be more boost friendly should you ever want to go FI. I think a stroker 5.7 long block with ported eagle heads and a cam of your choosing would be not only stronger and more powerful than a stock 6.4, but potentially a better value and foundation for any future mods.

OR...buy the 6.4 and send it out for a 426 stroker build. I think that would be my choice.

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Bigred61

Discussion Starter · #7 · 11 d ago

lieu910 said:
Tempting, and I have thought of the same thing. I can't see why you would need a PCM swap. A tune for sure, which would be no different if you were to put a stroker 5.7 in. If you run the 6.4 intake, that would need a window switch to kick the short runners in around 4800 RPM. You could keep it simple and run your 5.7 intake, maybe have it ported. You will give up a little low end, but not much.

Conversely, building a stroker 5.7 will give you more torque than a 392 because of the longer stroke, and slightly under square bore & stroke. Plus it will have forged internals and be more boost friendly should you ever want to go FI. I think a stroker 5.7 long block with ported eagle heads and a cam of your choosing would be not only stronger and more powerful than a stock 6.4, but potentially a better value and foundation for any future mods.

OR...buy the 6.4 and send it out for a 426 stroker build. I think that would be my choice.

MMX sales a switch that allows the 6.4 intake to be functional, that is probably the route I will go.

For the price the guys is asking for one of these motors it is hard to pass up. All my “performance” mods and money goes into my boosted MSRT8, I just wouldn’t mind having a little more pep in my Challenger, my biggest concern was the PCM.

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Gg2684

· #8 · 11 d ago (Edited)

Bigred61 said:
There won’t be labor costs involved. I will be doing the engine swap in my own garage on my lift.

When I put I Magnuson on my MSRT8 I think final bill ended up being around 15k between parts, labor, exhaust and tune.

The other advantage with one of these motors is less miles. Wouldn’t mind putting the blower on my 5.7, but not sure with the mileage.

Perhaps, but the blower route would require all board members to advise the OP to buy a used hellcat which would then require everyone to advise against every used hellcat currently listed because they all been flogged 1/4 at a time leading to directing the OP to a buy a new Redeye which finally, would result in the entire fourm advising them to contact Steve White as they are the only reputable "Stealership" in the country. You are all welcome for saving all the time and typing, and yes, I will see my self out.

Also would agree that the mechanics of the swap are likely the "easiest" part - syncing up the electronics and tuning could be an issue - this forum is not exactly the most ambitious for modding or swapping so it might be good to contact some of the larger/reputable speed shops to inquire about the art of the possible and at least get a rough idea of what you may be in for.

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Xylander

· #9 · 11 d ago

The problems with the electrical kinda revolve around what year model the 392 is. If it's newer than the owner's 2014, then a LOT of the electrical modules will have compatibility issues because the 2014 and prior had easily unlockable PCMs, but Dodge changed a lot on the security side for 2015 and later. It would be like trying to install an older hard drive into a newer computer that didn't have the compliant drivers, or the older drive wasn't directly compatible with the newer operating system. That's the kind of crap you have to deal with. I've said it before, if you insist on doing the job, plan on getting a full wiring harness and having to rewire the entire car. That, or just accept the fact that parts of the car will not work properly and you'll have permanent TCs.

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Bigred61

Discussion Starter · #10 · 11 d ago

Xylander said:
The problems with the electrical kinda revolve around what year model the 392 is. If it's newer than the owner's 2014, then a LOT of the electrical modules will have compatibility issues because the 2014 and prior had easily unlockable PCMs, but Dodge changed a lot on the security side for 2015 and later. It would be like trying to install an older hard drive into a newer computer that didn't have the compliant drivers, or the older drive wasn't directly compatible with the newer operating system. That's the kind of crap you have to deal with. I've said it before, if you insist on doing the job, plan on getting a full wiring harness and having to rewire the entire car. That, or just accept the fact that parts of the car will not work properly and you'll have permanent TCs.

That was one of the other concerns I had. I have to check the VIN’s he sent me again, but I am pretty sure the 6.4 that has the MDS is out of a 2013. It is a 5speed, the other one, which is a manual, is like a 2015 or 2016.

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stevewhite

· #11 · 7 d ago

as long as the engines are of similar years, easy simply program the pcm, 2015 and newer are compatible up to 20 or 22
14 is a little shaky, sometime in 13 or early 14 they change the tone ring, not compatible, however we have made it work, but its better to be 15 and newer etc

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Bigred61

Discussion Starter · #12 · 7 d ago

stevewhite said:
as long as the engines are of similar years, easy simply program the pcm, 2015 and newer are compatible up to 20 or 22
14 is a little shaky, sometime in 13 or early 14 they change the tone ring, not compatible, however we have made it work, but its better to be 15 and newer etc

Thank you very much! That certainly helps me narrow things down!

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Stay Thirsty My Friends

· #13 · 7 d ago

Fine looking machine.

Also consider there might also be a suspension change needed for the extra weight of the engine in the front.

Generally I would not agree with a blower, but I think rebuilding the 5.7 and adding a blower is better thinking than getting 6.4 with 60k miles on it. Would you rebuild the 6.4's?

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stevewhite

· #14 · 7 d ago

weight is a non issue

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