I think we need a FAQ on 4.6 SOHC engine compatibility as it seems almost every day someone asks "will it fit" question.

VIN codes:

Panther platform SOHC 4.6 is a Romeo engine though different VIN codes were used.

1991 - 2009 - VIN code W gasoline engine
1996 - 2005 - VIN code 9 CNG
2006 - 2011 - VIN code V flex fuel.

According to my notes there was also a VIN code 6 available for 1996 model year only. This was a Windsor block with 6 or 8 bolt flywheel. I can't confirm if this is accurate though as I've yet to see one.

Year to year changes

Panther platform got 4.6 in 1991 on the Town Car and 1992 on CV/GMQ.

All 1991 and 1992 models built prior to 2/18/92 were equipped with a 2 bolt starter and AOD transmission. These cars have unique engine blocks that will only work with AOD transmission. AODE and 4R70W will not bolt up to these.

Cars built 2/19/92 and later were equipped with a 3 bolt starter and AODE transmission.

1993 motor is identical to the later 1992 version. 7 rib drivebelt and pulleys were replaced with 6 rib.

1994 motor is identical to 1993. New exhaust manifolds were used that relocated front O2 sensors to the catalytic converters.

1995 motor is similar to the 1994 model year. OBD-I was replaced with EEC-V/OBD-II.

1996-1997 motor saw first major redesign. The aluminum intake was replaced with a plastic version. The accessories that mount on top were also rearranged. Heads were slightly changed.

1998-2000 were identical to the 1996-1997 models. Mechanical cooling fan was ditched in favor of electric. Ignition coils and wires were replaced with Coil On Plugs system. Fuel rail was changed to hook up from pass side. One of the intake manifold temperature sensors unit was moved to driver side cylinder head. 1999 got 11.25" torque converter for police which uses different fly wheel.

2000 New drive belt routing was utilized. 11.25" torque converter standard on HPP as well as police.

2001-2002 saw yet another major redesign. Heads, intake and cams were upgraded to bump the power ratings. Mid 2001 got a new water pump design. Alternator was changed. 2001 came with gray fuel injectors.

2003 got engine knock sensors. Oil pan, oil pick up tube and exhaust manifolds were redesigned to accommodate new suspension setup. Fuel system was redesigned to returnless setup. Intake manifold got aluminum crossover pipe. EGR system was changed. New valve covers with pass side oil fill were installed. Early production 2003 motors had poor quality timing chain guides and should be avoided unless guides were replaced.

2004 got a bigger alternator.

2005 throttle by wire replaced conventional cable setup. IAC was eliminated.
There were minor changes over the years but overall engine remained unchanged until 2011.

2006 flex fuel option was added. New fuel injectors are used.

2007-2011 valve covers were slightly redesigned.

Basic Breakdown

Basic interchange by year goes as follows:

1991-1992 with AOD (bastard block)
1992-1995 NPI with aluminum intake
1996-2000 NPI
2001-2002 PI
2003-2011 PI

You may have to swap over some parts to get the engines to work in your car. Sensors, exhaust manifolds, accessories, oil pans, etc.

Will it fit?

I won't cover all the possibilities as there are too many to cover so ask if not sure.

Like mentioned above any Romeo or Windsor 4.6 will interchange with exception of the bastard block 1992.

Vehicles equipped with SOHC 4.6

1991 – 2000 Lincoln Town Car - Romeo NPI
2001 - 2011 Lincoln Town Car - Romeo PI
1992 – 2000 Ford Crown Victoria/Mercury Grand Marquis - Romeo NPI
2001 – 2011 Ford Crown Victoria/Mercury Grand Marquis - Romeo PI
1994 – 1997 Ford Thunderbird - Romeo NPI
1994 – 1997 Mercury Cougar - Romeo NPI
1997 – 2000 Ford F-Series - Romeo or Windsor NPI
2001 – 2003 Ford F-Series - Romeo or Windsor PI
2004 - 2010 Ford F-Series - Romeo PI
1997 – 1998 Ford E-Series - Windsor NPI
1999 - 2000 Ford E-Series - Romeo NPI
2001 - 2011 Ford E-Series - Romeo PI
2002 – 2005 Ford Explorer/Mercury Mountaineer - Windsor Aluminum Block PI (80 lb lighter)
1997 - 2000 Ford Expedition Romeo or Windsor NPI
2001 - 2004 Ford Expedition Romeo PI
1996 – 1998 Ford Mustang - Windsor NPI
1999 – 2004 Ford Mustang - Windsor PI
2003–2005 Rover 75 - Windsor PI
2003–2005 MG ZT - Windsor PI
2011–present MV-1 - Romeo PI

Edited by BigNSlow (08/24/19 08:44 PM)