Kevin Tetz
May 3, 2010

Engine Upgrade
Modular Engine Swap

The shroud has long been lifted when it comes to the stigma of modifying a classic Mustang beyond the point of reversing it back to stock. Now don't get us wrong, we love the fact that there are so many bolt-in and bolt-on options for improving the performance of a classic Mustang, or any other '60s era machine, and the car be easily returned to its original state if ever so desired. A small-block upgrade of a tired inline-six car ups the fun factor of an otherwise basic "secretary's" vehicle, giving it a second chance at becoming what is inherent in its DNA. The same goes for brake upgrades, wheels and tires, suspension, and more.

For those who enjoy a challenge when building a car, swapping one of Ford's modular engines into a '65-'66 Mustang is becoming more and more popular, but why do the more difficult mod swap when there are hundreds of versions of the traditional small-block that bolt in with little or no trouble? The shift in the hobby over the past decade from restoration to restomods, with a focus on driveability, is the first clue that this may be a very good idea and a solid upgrade. At some point all of us have appreciated being able to jump into a late-model vehicle regardless of the season, twist the key (every time) and put pedal to metal, driving to any destination with confidence. To have this type of comfort, reliability, modern efficiency, and power wrapped up in a classic design, well that's just plain gearhead heaven. It also makes for plenty of double takes when people peer under the hood of a classic Mustang at a show or cruise night.

With millions of Ford Modular V-8 vehicles produced over the past decade, a little research will tell you that the deals are out there and that the aftermarket performance community has indeed embraced the modular engine design, making these engines ideal candidates for transplants into classic vehicles.

Although the 4.6L SOHC modular engine debuted in 1991 in the Lincoln Town Car, the 4.6L Four-Valve engines showed up in the Lincoln Mark VIII in 1993 and in Cobra Mustangs in 1996, quietly creating another performance legend with their increased efficiency coupled with a smooth and wide power band.

The 5.4L Triton Series (V-8 and V-10) debuting in 1997 with its taller deck height and increased bore is no stranger to high performance, and the supercharged Harley Davidson F-150 we drive can prove it! V-8 applications such as Lightning, Ford GT, and later Shelby Mustangs provide a proven heritage of performance and reliability, but due to its increased physical size, the 5.4L takes a second chair for swap outs in our smaller first-gen Mustangs most of the time.

Modular Four-Valve engines are more desirable for the potential of the deep breathing head design, and are available in a surprising array of donor vehicles, including, '93-'98 Lincoln Mark VIII, '00-'01 Qvalle Mangusta, '03-'05 MG X Power SV, '01-'08 Panoz Esperante, '03-'04 Mustang Mach 1, '03-'04 Mercury Marauder, '03-'05 Lincoln Aviator, and '96-'04 Mustang Cobras (with the '03 and '04 SVT "Terminator" application sporting an Eaton M112 supercharger with it's external air to water heat exchanger and "in valley" intercooler).

The dangling carrot that this article deals with specifically, is the Holy Grail of modular engines, the hand-built Romeo '03-'04 4.6 "Terminator" Cobra engines. With power potential safely into the 800 hp range on a stock bottom end, the Four-Valve Terminator engine has become deservedly legendary in a very short time; and who among us would not lust after some seat time behind a 2,800-pound 500-800hp classic Mustang?

The performance potential is staggering, putting a car like this into the realm of six-figure supercars, and just as capable with some well chosen stopping and steering upgrades; all of that with the convenience of EFI and fuel economy of a six-speed manual trans. That's called having your cake and eating it too!

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