project 1999 Mustang 3.8 to 2002 4.6 engine - Ford Mustang Forum

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post #1 of 5 (permalink) Old 02-09-2011 Thread Starter
tobe1424's Avatar
Joined: Sep 2010
Location: Miami
Posts: 54
project 1999 Mustang 3.8 to 2002 4.6 engine

So I bought a 99 v6 mustang and now I am eager to swap everything from my 02 GT to the 99. I am real short on time so it was decided that the swap should be broken down in the several projects.

Phase I

I wanted to start out with the fuel pump and fuel tank.

Is it possible to swap the GT pump/tank into the v6 and continue driving the v6 without any incompatibility/rigs issues?

original link when I crashed my car:

I copied and pasted this from another forum:

K member- It is believed that the K members are interchangable, this is true between 4cyl., 3.8L V6, and the 5.0L V8, but they are conciderably different on the 4.6L. I originally attempted to modify the K Member to work, but it is completely shaped wrong and DOES require hanging. Your old steering rack WILL bolt right up.

Engine, intake, fuel injector system A/C compressor, coil packs and wires, waterpunp, etc.- Well duh!

Computer- This might not be a requirement, you might get away with a chip, dunno. I had a GT comp, so in she went,

Engine harness- This will have to be changed out for obvious reasons.

Headers- I had to change headers beuase the ones that were on the motor (rown Vic police car) were too small in diameter and the flange hit the firewall.

Transmission- I had to change out transmissions bauase her AOD-E will NOT bolt onto a 4.6L. Thankfully, I had three 4R70Ws lying around. Standard (manual) transmissions should interchange though.

Transmission harness- The harness is the same between AOD-E and 4R70W, but the O2 sensor harnesses are different. You probably can modify your old harness to work though.

Which brings us to O2 sensors. I am not sure what the differences are, but the part numbers for the 3.8L and the 4.6L sensors are different, so I changed them out to be safe. Her old O2 sensors did screw right into the GT pipes though. Again, if using the old trans harness, you can reuse the O2s.

Brake booster- The Modular motors (even the 16 valve GT) will not clear the vacuum booster, so you will need to get a 1996+ GT hydroboost.

Brake booster to steering lines- The booster runs off the power steering pump, therefore you will need to get a set of 1996+ hydroboost and power steering rack lines.

Slight modification of the brake lines will be necessary, as the V6 lines go in from the side, the GT goes into the booster from the bottom.

Transmission tail piece- The ONLY reason why I had to swap these tailpieces out is because the Crown Vic has a larger diameter yoke, therefore the rear seal is too large, and for some reason I cannot get a rear trans seal for a 1996+ GT 4R70W transmission.

Exhaust- Includes intermediate pipe and mufflers.

Radiator- The hoses are in diferent places and are not the same size.

Overflow tank. To match the radiator.

Modification of the drive shaft- The old drive shaft will work, but you will need to either 1. have the shaft shortened approx. 1", or 2, cut off 1" off the yoke. The splines are the same from the V6 and the autos, but the motor pushes the trans. back slightly.

Motor mounts- They are not the same as the V6. I piked up a set of solid motor mounts for a GT for $49.00.

The dash wiring harness does NOT need to be removed for a 4.6L swap, but WILL need to be changed to swap out to a 5.0, as the pins are larger for the computer.

Starters- The starter is the same from a 3.8L to a 5.0, but are different for a 4.6L.

Alternator- Not the same as a 4.6, though 3.8 and 5.0 are the same.

A/C lines- As I stated above, the A/C ompressor is different, and the lines are too.

I have been asked this several times, and yes, fuel lines WILL bolt up the the GT rails. These do not need to be changed out.

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post #2 of 5 (permalink) Old 02-09-2011
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Location: Houston
Posts: 6,294
The V6 and GT have the same tank. The fuel pump is different. I think it would work OK to use a GT fuel pump in a V6. The Fuel pressure sensor will work with the FPDM to maintain correct fuel pressure. The load tables will be slightly off, but I think it will work well enough to get by on.

Regarding the PCM. The V6 and GT do NOT have the same computer. You will need a PCM from a GT. The donor should match the transmission as well (auto/manual). Don't forget about PATS. Do yourself a favor and transplant the cluster (PATS) from the donor as well.

2003 GT Convertible (sold & missed)
2000 GT coupe (Craigslist project. Fixed. Now my DD). Windsor to Romeo swap.
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post #3 of 5 (permalink) Old 02-10-2011 Thread Starter
tobe1424's Avatar
Joined: Sep 2010
Location: Miami
Posts: 54
Thanks for the reply. I have a complete GT. I crashed :/
You can check it out in the link in the first post.

The reason why I wanted to switch the entire tank with contents was because I have an issue with the v6 where I can only fill my gas tank for about a second before the pump stops/clicks.

My GT has 70K miles while my v6 has 170k. I was told it can be an issue with the evaporator or a seal. To eliminate any more troubleshooting, I wanted to just transfer everything from the GT.

However, I though there might be some compatibility issue with a wire or PCM or something else...

I will swap out the fuel pump for starters but I thought it might be a better idea to just swap everything...

What do you guys think?

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post #4 of 5 (permalink) Old 02-10-2011
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Joined: Mar 2009
Location: Tampa
Posts: 12,440
yes you needed to use the GT computer...why not just put a new 255lph pump in the tank? They are cheap enough and you will be ready for any future mods that might require more pump. Don't forget a new o ring for the nozzle, they are always worn out...good luck have fun
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post #5 of 5 (permalink) Old 02-10-2011 Thread Starter
tobe1424's Avatar
Joined: Sep 2010
Location: Miami
Posts: 54
So I need the PCM to run the fuel pump?

I am trying to keep this a low budget swap. Right now I can only afford to spend money on the few things that I will need to replace on the GT. For example, the disc rotor, axle(wish i replaced today), etc.

I am on the lowest budget you can imagine. Yet, I have all the components and should only be worried about swapping the 4.6; I just miss been without the sound of the 4.6...Even on a bad day just turning on the car makes my day!

Hence, I am just worried about the actual project and what tools and wonders I will be needing.

I literally want to swap everything from interior harness to sway bars..

At the moment I can only start off with Phases of the project...I don't have the resources to work on a car and do what the guys at FOOSE DESIGN do on that show OVERHAULIN'

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