Ford’s venerable Modular engines have been a Ford mainstay for three decades. The 4.6L “Mod’ Motor” SOHC V8 first appeared in the 1991 Lincoln Town Car and quickly made its way across most Ford car and truck lines in the years to follow. Ford upped the performance agenda with a screaming 32 valve DOHC Modular in the Lincoln Mark VIII in 1993 and in the SVT Mustang Cobra in 1996.
It even installed this beast sideways in the front-drive Lincoln Continental sedan!
The term “Modular” has never been about the engine itself, but instead Ford’s approach to making quick production line changeovers from one type of Modular engine to another without losing precious time.
Although there has always been a lot of confusion regarding the Ford Modular engines, one basic fact remains consistent—they are darned confusing.
Understanding Ford Romeo & Windsor Modular Engines
We’re going to ease the confusion for you. Ford built the Modular engines in two plants—Romeo, Michigan (originally a Ford Tractor plant) and Windsor (Essex), Ontario, Canada. What’s more, because each Modular engine plant had its own approach to this engine’s architecture, it is challenging to determine which parts fit which engine.
Engineering differences and changes are commonplace at Ford, which makes us envious of the Chevy guys where ease of interchangeability has been a given across the decades. Very little has changed in the small block Chevy since its introduction in 1955. What’s more, Chevrolet is still making these timeless mills seven decades later.
Romeo and Windsor had different approaches to the Modular engines—making interchangeability challenging and frustrating. Some components interchange while others do not. For example, Romeo and Windsor 16-valve SOHC engines employ different cylinder heads, valve covers, timing covers, and valvetrains. There’s a wide variety of timing covers for different applications because these engines were factory installed in several vehicle types. Romeo engines use different timing components than Windsor engines. They are not interchangeable.
In fact, there are more differences in these engines than we have room to address here.
There are very significant differences in these engines you must be aware of or face unnecessary loss of time and a lot of expense. Best advice is to stick with Romeo heads on a Romeo block—and Windsor heads on a Windsor block to minimize wasted time and frustration. Do not be tempted to mix them up.
From 1991-96, there was one Modular engine plant—Romeo. With the introduction of the all-new Ford F-150 and F-250 trucks for 1997 came “truck-based” Modular engines from the Windsor engine plant displacing 4.6L, 5.4L (both V8s) and the 6.8L (V10). The 6.8L V10 replaced the time-proven 460ci big block V8.
Suffice it to say Windsor Modulars are truck engines by design although you will see Windsor engines at times in passenger cars—especially the Mustang GT in 1999 and 2000. Early 1997 F-150 trucks built in early in 1996 were fitted with 4.6L Romeo Modular engines.
Romeo Modulars have six-bolt cranks while Windsor engines have eight-bolt. This fact alone confirms the Windsor Modular’s status as a heavy-duty truck engine.
Building a High Performance Ford Modular V8
JGM Performance Engineering in Valencia, California decided to build this 5.3L SOHC Modular V8 from scratch using all new parts, including the Ford Performance M-6010-BOSS50 Windsor 5.0L block topped with Trick Flow Twisted Wedge Race 195 heads. They wanted a high-revving street/strip beast that would be civilized for the daily commute, yet ready for race action on a Saturday night.
Trick Flow Twisted Wedge Race 195 Series cylinder heads are the most optimum cylinder heads for the Ford Modulars thanks to such an innovative design that reinvents the “PI” (Performance Improved) Modular head. What makes them innovative is their combustion chambers and intake valves are relocated to the opposite side of the camshaft.
Other nice features include factory PI-shaped intake ports (making them compatible with all induction systems), runners that deliver CNC caliber porting along with CNC-profiled combustion chambers, 3/4 inch thick decks, patented replaceable cam bearing journals, and 3/4 inch reach spark plugs.
The Twisted Wedge Race 195 heads are engineered for Modular engines with nice power adders and/or high revving applications because these engines like to rev. These heads fit all SOHC Romeo and Windsor engines and will accept all OE-style camshafts, followers, lash adjusters, valve covers, and most factory Ford timing covers.
Because JGM wanted 500 horsepower, they looked to Trick Flow Specialties for answers.
What makes this Modular engine build exciting is the Trick Flow Twisted Wedge cylinder heads, camshaft, and valvetrain along with Edelbrock Victor Jr. single plane induction topped with Holley 750 cfm HP carburetion
Trick Flow Specialties (TFS) went back to the drawing board with the Modular head—reinventing its rather conservative 16-valve cylinder heads. It is remarkable just how different these poly-angle valve TFS heads are. The original Modular “Non-PI” heads flowed 175/150 cfm intake/exhaust at 0.600 inch lift. The 1999-up Performance Improved (PI) head flows 203/185 cfm intake/exhaust at 0.600 inch lift. JGM flow-benched the TFS Twisted Wedge heads and found 276/199 cfm at 0.600 inch right out of the box without port and bowl work—incredible flow numbers prior to any port work (which would push these flow numbers even higher).
JGM originally intended to build a 5.3L Modular first with carburetion and a series of dyno tests—then, switch to the engine’s factory-engineered EFI induction system with port fuel injection and a variety of intake manifolds and throttle bodies.
Disappointment abounds when we tell you this engine has yet to make it to the dyno. JGM has been extraordinarily busy with dyno appointments, which has prohibited this engine from getting to their dyno room. As a result, we’re going to give you the recipe for a terrific 5.3L SOHC Modular and see how this formula works for you. When JGM gets this engine on the dyno, we will report the numbers to you. We’re always interested in your feedback and what your experiences have been with Ford’s time-proven Modular mill. How did you make power and what went into your build?
Jim Smart is a veteran automotive journalist, technical editor, and historian with hundreds of how-to and feature articles to his credit. Jim's also an enthusiast, and has owned and restored many classic vehicles, including an impressive mix of vintage Ford Mustangs.