By:  Ed Olin
  Some history:
In the 1980's Ford made a decision to design a new family of engines starting from a clean sheet of paper rather than base them on the engines currently being produced at the time. Some goals for these new engines included improved fuel economy, better NVH (Noise Vibration Harshness in engineering terms - or just plain smoother and quieter to most people), better sealing, and improved specific output (power/displacement - or hp/L or hp/cubic inch to most people). Primarily these new engines were to replace the 5.0L car engines that were in widespread use in Mustang, Crown Victoria, Grand Marquis, Mark VII, Town Car, and then possible variations of the engine could be used in other vehicles. There was lots of debate during the initial design phases as would be expected for any project as major as this and many alternatives were looked at, but eventually a V-8 with a 4.6L displacement and overhead cams (OHC) was decided upon.

Romeo Michigan was chosen as the location for the plant to build the engines for the cars. The modular term came about due to the many interchangeable components between the SOHC and DOHC engines and also the ability for much of the machining and assembly of the engines to take place on the same equipment lines. That way if the market demanded more DOHC engines, then they could rather easily be manufactured while SOHC production was decreased.

The 4.6L SOHC engine first came out in the 1991 Lincoln Town Car and was later installed in the Crown Victoria, Grand Marquis, Thunderbird and Cougar. The 4.6L DOHC engine debuted in the 1993 Lincoln Mark VIII and was later installed in the front wheel drive Continental. Readers of the Corral website are familiar mostly with the 1996 and later usage of the 4.6L SOHC in the Mustang GT and the 4.6L DOHC in the Mustang Cobra.

The decision to switch over to modular engines for the trucks added another twist to the modular term and a new name (Triton) for the truck engine family. The plant in Windsor Ontario producing the truck engines can make the 4.6L version, but also the 5.4L (taller deck height version of the 4.6L) and the 6.8L V-10 (just a 5.4L with 2 more cylinders). This makes for many interchangeable components such as pistons, rings, connecting rods, bearings, oil pumps, valvetrain parts, water pumps, etc. However, not all components are interchangeable with the 4.6L car family of engines due to the desire to increase robustness in certain areas of the engines for the more severe usage they would expect to see in the trucks.

The 4.6L, 5.4L, 6.8L truck engines replace the 5.0L, 5.8L, 7.5L engines respectively in the full size vans and F-series pickups. The 4.6L truck modular engine made its debut in early 1996 in the newly designed 1997 F-150 and F-250 trucks and the full size vans. The 5.4L was available later that same year and then joined by the 6.8L in the full size van. The all new 1999 F-250HD and F-350 (and the rest of the Super Duty truck line) debuted in early 1998 with the 5.4L and 6.8L truck engines.

Major points of interest on the modular engines:

  • All cylinder blocks have deep skirts with cross-bolted main caps for rigidity
  • DOHC engines have aluminum cylinder blocks
  • SOHC engines have cast iron cylinder blocks
  • All cylinder heads are aluminum
  • All valvetrains are of the hydraulic roller-finger-follower type for reduced friction and zero maintenance
  • All accessories are rigidly mounted directly to the block with no brackets for improved NVH and cost
  • Very long head bolts are used to reduce distortion of the cylinder bores and provide improved sealing
  • What the modular engine means to the Mustang
    POTENTIAL!!! As much as some people seem to dislike the word it must be stated here, since that has always been what the true hot rodder looks for when choosing an engine to work with.

    At first it would appear that Ford didn't really take advantage of the OHC technology and push for a big power increase for the GT engine over the previous 5.0L engine. But it must be remembered that Mustang use accounts for a small percentage of the number of 4.6L SOHC engines built each year, so the engine has to be acceptable to the rest of the vehicles too, with very few differences to be cost effective. The potential is there, especially for the aftermarket, even if Ford doesn't take complete advantage of it.

    The SOHC engine came onto the Mustang GT scene with some awfully big shoes to fill, since the fuel injected, 5.0L powered Mustang seemed to dominate the dragstrips and aftermarket. That didn't exactly happen overnight, as many people were tossing the fuel injection aside when it first appeared in 1986, thinking it was a waste for racing. It took several years for the aftermarket to step up and start producing a significant quantity of speed parts for the fuel injected 5.0L engine. The 4.6L SOHC has been out in the Mustang since the 1996 model year and there are already a number of aftermarket parts to make the car fast. In fact there are enough bolt-ons available now to produce over 500 hp in a very mild, easy to drive, state of tune. The parts are not as cheap as buying for the 5.0L, due to the engine's complexity and still limited competition between aftermarket companies, but at least the electronics support is greater than it has ever been. Even higher power numbers can certainly be expected in the future as more people work with the engine.

    The DOHC engine made its debut in the 1996 model year also, as a Mustang Cobra, but with a new level of refinement and a huge power increase over the previous 5.0L Cobra, and more powerful than the Z-28 and Trans Am vehicles from GM. This appeared to be a turning point for Ford's view of the Mustang, as the GT was no longer positioned against its long standing rivals, but the Cobra was there to fight that battle now.

    The DOHC Cobra engine starts to show some use of this "OHC potential" since it produces more Hp/L than its pushrod rivals. And anyone who has ever been in a Cobra with a Vortech supercharger installed knows that these engines really respond well to the aftermarket parts being developed for them.

    Ed Olin (EDO)

    Look for possible future articles to cover the following topics:

  • Modular engine dimensions and general info
  • Glossary of terms
  • Working on the engines
  • Aftermarket parts - where to get what and how it works
  • Images and text (c) Copyright 1998 The Corral Modular.
    All Rights Reserved, Duplication Strictly Prohibited.
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