2005 4.0 to 4.6/5.0 Swap

justinc87

Member
Jul 21, 2020
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4
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Colorado
Hello everyone,

Yes, I am aware there are plenty of other posts regarding this. Just want some specific info without looking 20 places if anyone can help.
I have a 4.0 that's getting close to 200k on it, and shortly after purchasing it, it developed transmission issues. So I am just going to do a swap on them both.

I've heard the 4.6 is more "plug and play" compatible being that it was a factory option. Is that the case or would the 5.0 be just as much work? I'd prefer that, but for cost/install reasons I'd gladly do the 4.6. Is there any specific issues or tips that anyone knows of that have done a upgrade swap like this? I'll be paying someone to do it, so I'm mostly thinking as to what the best route would be.

I do also know that I'll have to change out the gearing in the back axle to account for the difference in torque. Is there anything else that would need to be changed that's not engine/transmission related?
 
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EmmJay

Member
Jun 16, 2019
57
15
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USA
If cost is a concern then go with the 4.6L swap as it was a factory option for your model year. Just to buy a 5.0L in decent condition will be expensive as will what you will need to get it running properly. Also, you might want to consider just sell your current Mustang and buying a V8 version. You might actually spend less money going this route.
 

justinc87

Member
Jul 21, 2020
8
4
13
33
Colorado
If cost is a concern then go with the 4.6L swap as it was a factory option for your model year. Just to buy a 5.0L in decent condition will be expensive as will what you will need to get it running properly. Also, you might want to consider just sell your current Mustang and buying a V8 version. You might actually spend less money going this route.

I was of a similar mindset. I've had 2 other similar year model GT's and was always happy with them. I just hear a lot of good about the coyotes. I would sell but being that I just bought it for $4,200 and now that I know of it's transmission issues, I doubt I could get what I just got it for, not without making someone else a sucker which I'd prefer not to do. I appreciate your view and perspective on it!
 
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EmmJay

Member
Jun 16, 2019
57
15
18
119
USA
As long as what you lose on the sale doesn't exceed the cost of converting to the 4.6L then the best choice is just to buy a GT, IMO. Even if buying the GT is somewhat more I would still go that route. Plus, if you are swapping the auto transmission for another auto then you might be seeing the same problem a few miles down the road. If you are swapping to a manual then you will have a much more reliable drive train. My experience with projects like this is they always cost more than expected and are twice as frustrating as you expect. If I were you I would put a cheap automatic from a salvage yard in it and sell it. Then buy a GT. Also, buying a good 5.0L engine/transmission will cost you about what you paid for your current 4.0L.