[JMC]

Notes for 4.6 to 5.4 swap Part 1 Revised 4 May 2009

Exhaust: The collectors on the exhaust manifolds are set at different angles and locations. The 4.6 exhaust might not bolt up to 5.4 manifold. You may need to have a muffler shop modify your 4.6 exhaust to match up.

Ignition: All 5.4 engines use Cop ignition. . 2000 and later 4.6 use COP ignition. 1997-99 4.6 engines use coil packs. It is easier to wire your 5.4 using the harness from the 4.6 and use the 4.6 ignition coil packs if applicable. If you use the 4.6 Coil pack ignition you will have to fab a bracket for the driver side coil pack.

Engine harness: To use a 4.6 PCM to run a 5.4 engine: The IAC harness must be relocated to the rear of the throttle body elbow. The oil sender wire on the 4.6 may be too short so measure or test fit the harness to see if it must be extended. All 97-00 and some 2001 4.6 engines use some sort of intake manifold runner control valve. Remove it from the 4.6 and plug it into the 4.6 harness and bolt it to the engine some where out of the way. Note; you can get a tune to remove its function and eliminate it all together.
All 97-98 4.6 engines use an Engine Coolant Temp sensor (ECT) and an Engine Coolant Temp sender. By the 99 Model year the ECT was dropped in both the 4.6 and 5.4 harness as the Cylinder Head Temperature sensor (CHT) was used for the PCM to monitor coolant temps. None of the 00+ 5.4s use ECT sensor or sender. Some of the 99 5.4s still use the sender to feed info to the instrument cluster. You will have to tap the intake manifold crossover pipe to fit the sensor(s) if your 4.6 has them and the 5.4 doesn’t.

Transmissions: the 4.6 and 5.4 have the same bellhousing bolt pattern. That means that all the transmissions will bolt up. All the 5.4 engines have 8 bolt crankshafts. Some 4.6 engines (ROMEO ENGINE) have 6 bolt cranks. You will need the flex plate from the 5.4.
Manual transmissions: If you don’t have an 8 bolt flywheel a flywheel from a 1997-8 4.6 Windsor engine will work. As it has 8 bolts it will bolt right up to the 5.4 crank. Remove the flex plate spacer and install a pilot bearing from a 4.6.
Special note about the different automatic transmissions and their respective harnesses. You cannot run a 4R100 transmission with a PCM that had a 4R70W transmission and vice versa. The transmission harnesses are different and will not plug into the different engine bay harness. The control functions in the PCM are not compatible so the transmission will not function properly.


Torque Converters:
4R70W
ENGINE Stall Speed Multiplication
4.2 1978-2330 2.3:1
4.6 2105-2505 2.3:1
5.4 1830-2190 1.9:1

4R100
All Engines ?????? 2.2:1
If you swap a 5.4 into a 4.6 engine bay and use the 4.6 converter you will multiply the 5.4's torque at a higher rate and at a higher stall speed which will put the torque at the transmission input shaft close to the limit if not over the limit of the 4R70W. The 99+ 5.4 produces 350 ft/lbs of torque. 90% of that is available at 2000 rpm. The stall speed of the 4.6 is above the 2000 rpm range so more than 90% is available. 350 ft/lbs x 2.3(4.6 multiplier) x 90% is 724.5 ft/lbs.