V6 (1994-2004) Mustangs Technical discussions on the 3.8L and 3.9L V6 torque monsters

3.8L to 5.4L swap

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Old 07-25-2011, 04:54 PM
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82T-Top
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Default 3.8L to 5.4L swap

Ok for starters after reading other v6 to v8 swaps I have found that majority of ppl suggest not to do it for cost, waste of time reasons, and so on..... I understand it will cost more and the time is not an issue because thats the fun to me in a car hobby.

The help i am after is to get an idea of the major things i will need for this swap..... and i would like to start this thread for any others looking to do this.

This will not be a build in a couple of months it will be a winter project but i am doing the homework now and going to start collecting parts so i should have nearly everything by the time i am ready to swap.

I have google'd swaps but could only find a 130 or more page swap from 3.8 and 5.4 and it went on and off topic so much that i didnt have the patience to read allllll of the pages. From observation it seemed as if the computer from a 4.6 could be flashed to work for the 5.4 but im sure ill have to replace the 3.8 harness for 5.4.... Are there any other clearance issues besides the intake and oil pan?? being a DOHC the width seems that it could be an issue?

As for the motor i have read a thread somewhere that a DOHC took more work and upon the OP asking why? the thread ended..... i personally would rather put in the DOHC and call it done the first time but if there is something mysterious about it please inform me.

Parts im going to go with for this build:

5.4L DOHC

8.8 rearend (IRS could POSSIBLY be in future but for now id rather get the car on the road!)

5spd or 6spd

I believe i had read the 4.6 oil pan will bolt on and help for clearance.

Tubular k-member, i know its not needed but after seeing somebody recommend it and having one on my 85 it is something i want.

Aluminum driveshaft will be in the works but for now a gt DS will do fine if i go with the 5spd (ill need to find out which DS will measure up since the 6spd was for the irs only?)

A shorter intake is something i will do some research on later tonight unless the 19995 cobra r style hood will clear the intake i will just leave it and learn how to make the truck intake run better for a car setup!
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Old 07-25-2011, 05:33 PM
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ESG-642T
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you may want to read that 130page thread, as any hardcore engine swap thread will go way off topic anyway.

You also have to figure out DOHC or SOHC, it would be simpler to swap a 351w / stroker.
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Old 07-25-2011, 07:56 PM
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LilRoush
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If you go to the DOHC 5.4L you'll make the swap worth while. As for the intake, I'd do the BOSS 290 intake (Aussie version of the 2000 R).You can find them floating around the US if you look. You just need to flip the top so the inlet tube goes to the passanger side. Also, I've seen the Mach harness used, so I'm sure you can make that or the Cobra harness work.

I'd go T56 just because I have a 5 speed and a 6 speed, and I LOVE the 6 so much more.

Here's a 5.4L with the Boss intake to give you an idea on hood needed. A small cowl would clear for sure.







Out of the car, with black valve covers, but shows the intake better:



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Old 07-25-2011, 08:06 PM
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For the record, the red car in my other post made 404/387 @ wheels NA. It was tuned at Steeda (in Ft Lauderdale).
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Old 07-25-2011, 09:29 PM
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wow those intakes look really nice!! is $1k pretty much the cost of them when finding them? i searched and came across other classified threads in svt forums from like 2008 and thats the price tag on 2 of them ( didnt have a lot of time to look anywhere else yet) if that is the price, i read that the wiring harness from the 4.6 is just a plug and go but ill have to get a tune the connectors from a 4.6 itself.

Now for power i know i want to go with the DOHC now like roush said but i would like the hp numbers to be around 375-400 to the wheels. would this be possible with cams and a good tune? (not knowing if there was anything else done to the red one bc i like those numbers a lot!!)
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Old 07-25-2011, 09:45 PM
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price..... haha how much am I loonking to spend? seems relatively simple for the 4.6s but i still need complete driveline...... not looking to be the most over the top car.... i dont mind used but not abused parts... i would like to get a savings goal in my head for the swap and i was thinking $3500-4000... would this be reasonable? probably going to settle with a 5spd unless i can find a 6spd for less than 2500..... lol
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Old 07-26-2011, 08:22 AM
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Yeah, $1000 - $1500 seems to be about average. The only difference between it and the R is the R uses 13" long runners, and the BOSS 290 uses 10" long runners in the lower intake.

To give you an idea, there's a complete (ready to drop in) 4 cam 5.4L with the Boss manifold locally for sale for $6000. Here's the cut/paste description from the listing:

Iron block (std bore)
Stock hyper pistons (9.65:1)
Stock rods
New forged 8 bolt crank
Ported 01 Cobra heads
04 Mach cams
Aussie Boss lower intake
Modded Boss upper intake
Includes 32# injectors (Aussie)
Includes Mach 1 engine wiring harness (for connectors)
Includes ignition coils
Includes oil pan
Includes Cam covers (black) and coil covers (silver)
Includes fuel rail
Includes throttle and cruise cables
Includes IAC valve
Includes Mach 1 air inlet hose (TB to air cleaner)
Includes modded (drop) engine mounts
Includes crossmember spacers and bolts
Includes Mach 1 exhaust manifolds
Includes Genuine Aussie Ford coolant crossover w/stat
(that saves the expense and hassle of the Cobra radiator hose setup)
Includes timing cover and tensioner
NEW water pump and pulley included
NEW 8 rib harmonic balancer included

Includes small parts to keep AC system intact
Illustated install guide included
Note: Alternator NOT included

This motor is a fresh 5.4 Navi based motor,
ready to be installed into a 96-04 Mustang
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Old 07-26-2011, 09:56 AM
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When ever you do this swap, please take a lot pics and make a thread/writeup on this, I wanna sticky one.
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Old 07-26-2011, 12:37 PM
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03shadow
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would be an awesome swap, costly for sure. but if you have the cash and time im sure youll love it. good luck!
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Old 07-26-2011, 12:52 PM
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seems like eventually im going to have to bite the bullet and get the boss intake.... lol seems to be money well spent after reading the articles on it and cause it looks so cool probably because its different and ive never seen on on any cars.

I went to mustang week last week and looked all over and could not find any 5.4 swaps so i didnt get to look much there... i did look at some in fox bodies though and one guy even had a twin turbo setup in a 93.

As for when i do the swap i will take many many pictures!!

Thanks shadow it'll be fun thats for sure!!

Only thing im not to familiar with is the electrical aspect of it (what all i'll be needing wiring harness, ecm, ect...) but that could be because i haven't had the most experience with the computer systems on these.... ill start doin some homework on it and jump in when comfortable.
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