Motor swap

dshedd82

New Member
Feb 21, 2021
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Amarillo, Texas
My ‘91 mustang 5.0 has seen better days. With the motor needing a new top end and the transmission having a burnt up torque converter and no overdrive gear. My buddy had a motor and tranny sitting at his shop that came out of an ‘02 F150 Harley Davidson Edition pickup with the 5.4L with supercharger and tranny still attached and the entire wiring harness along with computer and fuel pump. He gave me this to see if I could get it going in my car but I’m wondering if this has even been done before? If so, what all extra parts will I need to make swap happen? I’ve talked to lmr.com and they said no wiring harness adapters have ever been made for this swap and that I’d have to splice harnesses. I’m ok with that part but does anyone know what k-member I need or if factory will work with it? Any and all info for this would be greatly appreciated!
 
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90sickfox

Wasn't a pretty sight...and I've got big hands
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You need a modular motor k member. AJE makes the k member and motor mount plates in an affordable package. I've been using them for 15yrs. I've got no complaints. Other, more expensive, ones are more robust and better suited for road race or auto X type situations. I drove with one on the beat up streets of Maryland for 3 years daily driven and another 5 years occasionally.

The bulk of the harness in the fox is not needed. The issue with the 5.4 factory harness is that it has a PATS system that wants signal from the chip key in order to start the car. I'd get around this by using a Megasquirt to control the engine. That's just me though. Takes a bunch of guesswork out. There are threads in the megasquirt forum about lightening 5.4 installs.
 

dshedd82

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Feb 21, 2021
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Thanks! I knew I’d need a different k member but wasn’t sure which one to get. And I hadn’t even thought about that system needing that chipped key so I’ll check out that mega squirt site like you said. I appreciate your knowledge about this swap!
 

General karthief

wonder how much it would cost to ship you a pair
Mod Dude
Aug 25, 2016
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There is a lot of fab work to it, @a91what did a m90 then sold the stuff to someone else, he may jump in here an post a link to that member's build unless I find it first.
 
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a91what

SendMeUrDataLog
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I think the op is asking if he can swap in the entire 5.4.
K member for a mod motor and start dropping it in. Gonna be tight.
 

90sickfox

Wasn't a pretty sight...and I've got big hands
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I had a 5.4 blower that I was going to put on a 5.0. All you really need to do is make a box type upper intake that the supercharger would bolt to. The explorer lower would be the easiest and cheapest. You'd have to buy an extended snout and use a bearing support system. There was a guy that used to make a kit for that Eaton 112 but he took a few people's money and disappeared. Would be easier to put the whole 5.4 in a fox.

That 5.4 will be tight. It's wider than a new 5.0. You'll have to go manual or hydroboost for the brakes. A brake vacuum booster will not fit.
 

dshedd82

New Member
Feb 21, 2021
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Yes I’ve already pulled old motor and tranny and have been doing it all slow going back in as I’m finding out just how much bigger this 5.4 really is. I’ve pulled break booster already and knew it wouldn’t be able to go back. And I’m going to have to weld new supports for tranny support. And I wasn’t sure about the motor sitting on factory k member till I tried dropping motor in and immediately had to do some research. Lol it’s my first stang and bought it for pissing contest with step-dad cuz I want to build something faster than his ‘70 gto judge that has a 455 and pushing close to 600 hp. Not sure if this will do it or not but I’m hopeful. There’s just no replacement for displacement!!!
 

dshedd82

New Member
Feb 21, 2021
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Amarillo, Texas
I had a 5.4 blower that I was going to put on a 5.0. All you really need to do is make a box type upper intake that the supercharger would bolt to. The explorer lower would be the easiest and cheapest. You'd have to buy an extended snout and use a bearing support system. There was a guy that used to make a kit for that Eaton 112 but he took a few people's money and disappeared. Would be easier to put the whole 5.4 in a fox.

That 5.4 will be tight. It's wider than a new 5.0. You'll have to go manual or hydroboost for the brakes. A brake vacuum booster will not fit.
 

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90sickfox

Wasn't a pretty sight...and I've got big hands
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When you said you had accessories you meant it. It's way bigger than a 5.0. It's more like the size of a 460. It will be tight. The oil pan may have to be changed also. I'm not 100% on that.
 

MustangIIMatt

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When you said you had accessories you meant it. It's way bigger than a 5.0. It's more like the size of a 460. It will be tight. The oil pan may have to be changed also. I'm not 100% on that.
It's bigger than a 460.

5848d1123680885-ford-lincoln-4-6-dohc-engine-specs.jpg


The 5.4 is bigger than the 4.6 externally.

Kinda puts into perspective how bat:poo: crazy I am to want to swap that 4.6 DOHC into that dressed up Pinto of mine, doesn't it? :confused:


But if a 5.4SOHC supercharged can be shoved into a Mustang II:
4d1299055573-modular-engine-swap-mustang-ii-stang2.jpg

Then this guy should have no problem getting one into his fox, and maybe I'm not as crazy as I think I am.
 
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ChillPhatCat

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I read up a while on putting a 4.6 DOHC from a MK VIII in there... just ridiculously wide is the number 1 concern. I saw that there are aftermarket alternatives to hydroboost, and they do make those small diameter brake boosters, 7" diameter... not sure if that would fit. I love the modular platform however. I waffle between an engine swap (Mod or LS), or just get an entirely separate Fox coupe for go fast and do only a couple simple things with the 4 cyl.
 

dshedd82

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Feb 21, 2021
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Amarillo, Texas
The motor will fit after I get my k member for modular motor. I don’t think any brake booster will fit once motor is in so will have to go with something like hydroboost to make it fit. Then my next issue will be the wiring harness and hooking it all up to the car since everything will have different ends. Lmr.com says they don’t make any adapters for this type of swap and that I’ll have to splice wires. So this should get interesting. And I’m assuming my speedometer won’t work since the ‘91 used a cable and the ‘02 was digital. Anyone know of a cheap digital cluster for this car?
 

a91what

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The motor will fit after I get my k member for modular motor. I don’t think any brake booster will fit once motor is in so will have to go with something like hydroboost to make it fit. Then my next issue will be the wiring harness and hooking it all up to the car since everything will have different ends. Lmr.com says they don’t make any adapters for this type of swap and that I’ll have to splice wires. So this should get interesting. And I’m assuming my speedometer won’t work since the ‘91 used a cable and the ‘02 was digital. Anyone know of a cheap digital cluster for this car?
First I need to know what you are doing for engine management