69 Barracuda Hemi swap

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McMoparJr

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Hey guys, I’ve got a 1969 Barracuda with a 318 with the automatic right now but I’m getting ready to do a hemi swap. Eventually I wanna put a 392 based stroker motor with the 8HP90 8 speed automatic in it, however first I’m putting a 5.7 Hemi with the 545RFE 5 speed auto in it, I was wondering how extensive the modifications would be to the floor pan to make them fit and if the required modifications for the 545 and 8HP’s would be similar. Also where I could get motor & transmission mounts for each if they are available and anything else I’d need the 5.7 and 545 is out of a ram 1500 so I have motor transmission, wiring harness, computer, etc. provided they are all usable for the swap. the 392 would come from a scat pack car since I’d use the shifter from the car. Any other parts I’d need for either please let me know too. Any other info I need to know would be appreciated too.
Thanks in advance everyone
 
The 545 and 8HP transmissions are very girthy. For sure tunnel and torsion bar cross member mods. Holley has a modular trans crossmember. It allows use of many different transmissions with one crossmember and different bolt on brackets for each trans. Sound German Engineering makes a stand alone for the 8HP. TTI and Holley have swap brackets.
 
The 545 and 8HP transmissions are very girthy. For sure tunnel and torsion bar cross member mods. Holley has a modular trans crossmember. It allows use of many different transmissions with one crossmember and different bolt on brackets for each trans. Sound German Engineering makes a stand alone for the 8HP. TTI and Holley have swap brackets.
Ok, awesome thanks, I’ll take a look
 
If you have a welder you can make it work. Just focus on a good trans brace
 
You might as well do the 392 now. If you do the 5.7 you will have to get a different wiring harness and computer. Also depending on your suspension k frame etc your headers may be different. And if you change transmission harness and ECM will be different. Also if you get a truck 5.7 and switch to a 392 you will have to get a different radiator as the inlet and outlet are different.
 
You might as well do the 392 now. If you do the 5.7 you will have to get a different wiring harness and computer. Also depending on your suspension k frame etc your headers may be different. And if you change transmission harness and ECM will be different. Also if you get a truck 5.7 and switch to a 392 you will have to get a different radiator as the inlet and outlet are different.

I think you are correct if the 5.7 he is running is a pre-Eagle 5.7. But if the 5.7 is '09 or later, seems like he should be able to swap to a 392 with the addition of a wire for the SRV control. I'm kind of planning something similar with my 2017 5.7 swap using a NGC controller and wiring it for the SRV solenoid even though I probably won't have a 6.4 intake to begin with.

At the same time, no idea what kind of mods would need to be done to get the harness to interface with the 8HP90 later on. Might be worth reaching out to Hotwire Auto and ask them if they could build the harness for both at once or something. BTW, the controller Hotwire sells is an aftermarket setup, don't believe anyone had made an A8 swap work using the OEM systems.

Not certain, but I think the only differences between the '08 and down harness and the '09+ is a wire for VCT and probably the crank and cam sensors. Worse case, someone should be able to swap the connectors on the cam and crank plugs (they are all 3 wire I think) and add the 1 VCT wire. And if the harness had the MDS controls and they were deleted, you could just swap one of those at the PCM to the VCT pin and then move a couple of pins at the connector at the back of the cylinder head.
 
When I talked to Hotwire about swapping my 5.7 to a 392 they told me I would need a new harness. I have an 05. Thats why I was saying depending on what year the 5.7 is. But he could still build a very healthy 5.7. I was under the impression the op wanted to do a 5.7 then later do a 392.
 
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When I talked to Hotwire about swapping my 5.7 to a 392 they told me I would need a new harness. I have an 05. Thats why I was saying depending on what year the 5.7 is. But he could still build a very healthy 5.7. I was under the impression the op wanted to do a 5.7 then later do a 392.
Yeah you have a pre eagle… non vvt completely different 5.7 hemi. Op could just do the vvt 5.7 and 6.4 8hp90 now. The vvt 5.7 is plenty fun and plenty of mods to make or stroke to 392 later for same if not cheaper than getting a brand new 6.4. Allows to grow and the engine is a lot cheaper to start with. Boom, best of both worlds and room to grow in any direction
 
When I talked to Hotwire about swapping my 5.7 to a 392 they told me I would need a new harness. I have an 05. Thats why I was saying depending on what year the 5.7 is.

It would make sense that if you buy a harness from someone that they would expect you to need a new one to make a swap like that. I was looking at it from the idea of building my own so the addition of a wire, or moving one to a different pin makes it easy for me to think it would be ok.

I am pretty sure that the PCM would need to be swapped if you are running an '08 and down Hemi as it won't have the code for VCT let alone the SRV. Plus the code will be for the wrong tone ring on the crank. And swapping to a later NGC controller to get around those might mean that the pins in the existing harness are not in the right places. So it could be more than the single wire I was thinking of.

At some point I will know more since I am starting with a '08 6.1 harness and will be re-pinning it to match the '09 NGC controller I will be using.

I was under the impression the op wanted to do a 5.7 then later do a 392.

I agree, that's how I read it too.

I think if he swaps in an Eagle 5.7 to begin with, a 6.4/392 swap later probably isn't much work. If he uses an '08 and down 5.7, it will probably be more work.

In theory, one could lock out the VCT and SRV on the 392 and swap the crank tone ring for a 6.1 tone ring, and then maybe it would only need a tune to make it work. But in my mind, the VCT is part of why a 6.4 feels so much stronger than a 6.1. It has way more bottom end torque which is at least in part due to the VCT.
 
Yeah you have a pre eagle… non vvt completely different 5.7 hemi. Op could just do the vvt 5.7 and 6.4 8hp90 now. The vvt 5.7 is plenty fun and plenty of mods to make or stroke to 392 later for same if not cheaper than getting a brand new 6.4. Allows to grow and the engine is a lot cheaper to start with. Boom, best of both worlds and room to grow in any direction

You make a good point, seems like the 8HP90 swap would make sense in the beginning. Side steps the issues of having to rewire it later.
 
You make a good point, seems like the 8HP90 swap would make sense in the beginning. Side steps the issues of having to rewire it later.
Plus those transmission are commonly available now and then only have to modify the transmission tunnel once!
 
Plus those transmission are commonly available now and then only have to modify the transmission tunnel once!

I've been debating about an A8 swap instead of the TR6060/T56 Magnum swap I have been planning. At least the 8HP70 are cheap enough that even with the aftermarket controller they are cheaper than a TR6060. And I am cutting the tunnel out either way.

Biggest hang up is the car is an original 4 speed car and it feels wrong to swap an auto into it. :lol:
 
I've been debating about an A8 swap instead of the TR6060/T56 Magnum swap I have been planning. At least the 8HP70 are cheap enough that even with the aftermarket controller they are cheaper than a TR6060. And I am cutting the tunnel out either way.

Biggest hang up is the car is an original 4 speed car and it feels wrong to swap an auto into it. :lol:
I didn’t feel bad about my original 3 speed on the tree. :rofl::rofl::thumbsup:
 
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