Originally Posted by JMC

Notes for 4.6 to 5.4 swap Part 1 Revised 04 April 2015
Application: These notes cover the F-150 from 1997 to 2004 Heritage model years. They do not cover swaps to a supercharged 5.4 engine.



Before you start: All you are doing is putting a bigger displacement motor in place of your 4.6. I recommend you use your 4.6 ignition and PCM along with its engine harness.

Cylinder Heads: The following info applies to the F-150 and not any other vehicle engine.
4.6 Engine: The 4.6 engine had Non Pi Heads from 1997 to 2000. The Pi heads were introduced to this engine for the 2001 model year.
5.4 Engine: The 5.4 engine had Non Pi Heads from 1997 to 1998. The Pi heads were introduced to this engine for the 1999 model year.

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.

Originally Posted by white elephant

I personally think the torque converter argument is incorrect. The 70 in 4r70w is not 700ftlb of torque, but rather 700 nm of torque which = 516 ftlbs. I think the 4.6 converter helps the 4.6 move the truck better with lesser engine torque. Considering Ford sold f150 ' s with a 4r70w and the 5.4, there is now way in hell they were able to engineer a trans to live or die by a 0.4 variation in torque. I honestly think the only reason why they put the 4r100 in F-150s is so that they could have the economies of scale they needed to put them into the diesel trucks bringing the cost of the 4r100 down.

Originally Posted by builtinbetter

The way the specs read the 98 5.4 doesn't have much more power than the 02 4.6 anyway. I just figured i would put my issue out here anyway to see if someone had a work around.

Originally Posted by white elephant

Are you sure the difference in length matters? It didn't even cross my mind to check when I did mine. It could be a different length for all I know.

Originally Posted by white elephant

Are you sure the difference in length matters? It didn't even cross my mind to check when I did mine. It could be a different length for all I know.

Originally Posted by builtinbetter

Yeah becausei installed it and it would bind up the torque converter. It wouldn't let the motor turn over enough to let it start. I ended up installing a new tranny pump because i probably destroyed mine when i mated the motor and tranny.

Originally Posted by JMC

I want to put the complete 99 4.6 npi motor,tranny,ecm,and full engine wiring harness onto the 99 5.4, AM I ON THE RIGHT TRACK???????
Please contact at chrismsavage@outlook.com or someone can text me ar 573-454-1606

Simply put if you go from a 5.4 to a 4.6 you will be disappointed with the performance. You are going from 260 HP to 231 and 350 lbs/ft to 293. But it is your truck so....

If you use the 4.6 wiring harness you will need to look at the pinouts for the PCM, you called it an ecm, engine, transmission and bodyharnesses and compare it to the 5.4 harnesses to be sure that Ford did not change some of the wire locations on the connectors. The PCM will not properly communicate with the PATS in your instrument cluster so you will need the Dealer to fix that.

Originally Posted by savageautosales

I also have the complete instrument cluster and ALL wiring. I am led to
believe that the wiring behind the dash and cluster would be the same on
all of them, The steering column and that wiring harness has to be changed
anyway due to busted ignition (repo with no keys), now being as I am using
the 4.6 steering column , PCM, and engine wiring harness that has PATS,
wouldnt that be fine? Oh, and I am using the 5.4 tranny and converter (both
are 4R70W) , and the 4.6 exhaust.

By the way, thanks for your time.