Steve Baur
Former Editor, Modified Mustangs & Fords
June 1, 2009

The mantra "there's no replacement for displacement" has been around for some 40 years, and while the power-adder crowd might beg to differ on this subject, there is no doubt that big cubic inches means big power when it comes to the internal combustion engine. The Big 3 automakers knew this, too, and that's why engine displacement increased throughout the musclecar era.

Despite its miniscule size (compared to the older big-blocks), the 5.0L powerplant in '79-'95 late-model Mustangs is a formidable piece of street hardware. The late-model Mustang aftermarket knew it was a great foundation for a street machine and has supplied us with a plethora of performance parts for it over the years. The best part is that the majority of these components can be used on the 351 Windsor engine block.

Jonathan and Tiffany Insley competed in the True Street class at the NMRA Columbus event in Ohio. On the 315mm Nitto Drag radials, the GT galloped to a best e.t. of 11.95 at 120 mph and averaged 12.05 seconds over its three runs in the event.

While 351 ci offers a healthy 49ci increase over the 302, boring and stroking a Windsor can offer up many more cubes. Marietta, Ohio's Jonathan Insley eventually found that the 289 rwhp coming from his modified 5.0L engine wasn't getting the job done, so like many others before him, he chose to bore and stroke his engine--but not the stock 302.

No, for this new powerplant, Jonathan called up Delk Performance in Lebanon, Tennessee, and had them assemble a 427ci short-block using a late-model roller-cam 351 Windsor block. The 9.5-inch deck-height block was filled with an Eagle forged steel crankshaft and forged I-beam connecting rods, as well as Mahle forged aluminum pistons. Thanks to a set of AFR 225 cylinder heads and the dished Mahle pistons, the engine maintains a pump-gas-friendly 10:1 compression ratio. Actuating the 2.08-inch intake and 1.64-inch exhaust valves is a Trickflow TrackMax camshaft that offers a 236/248-degree split duration at 0.050, and it lifts the valves up 0.574-inch on the intake and 0.595 on the exhaust.

While there are numerous intake manifold choices for the 351-based EFI engine, Jonathan chose an Edelbrock Super Victor single-plane manifold modified for fuel injection, and fed it using an Accufab 90mm throttle body and a Pro-M 90mm mass airflow meter. A JLT cold-air kit feeds all 427 cubes with fresh air, while 42-lb/hr fuel injectors and a 255-lph in-tank pump supply the high test. MAC long-tube headers with 1 3/4-inch primaries funnel the exhaust to a Dr. Gas 3-inch cross-pipe.

"The car had a Dynomax after-cat on it when I bought it, but as far as I'm concerned, all 5.0L Mustangs should have come stock with Flowmasters," says Jonathan. That said, a Flowmaster 2.5-inch exhaust with two-chamber American Thunder mufflers makes this Mustang loud and proud.

Lebanon, Tennessee's Delk Performance screwed together 427 ci of Windsor power for the Insley Mustang. On Delk's chassis dyno, the Pony pounded out 465.3 rwhp and 453.7 lb-ft of torque.

After purchasing this '95 Mustang GT, Jonathan found that the stock AOD-E automatic couldn't handle even the stock engine, so he swapped in a T5 manual transmission. It worked well behind the hopped-up 302, but for the 427-cube upgrade, Jonathan chose to bolt up a Tremec 3550 five-speed gearbox using a Ram steel flywheel and McLeod 800 clutch and pressure-plate setup. Ford Racing Performance Parts' aluminum driveshaft twists the 3.73 cogs in the stock 8.8 housing, which rotates an Eaton limited-slip differential and Moser 31-spline axle shafts.

Shortly after the new engine and transmission combo was up and running, Jonathan dropped the GT off to Ashley Carr of Carr Auto Body in Newport, Ohio. Carr was put to work shaving the door handles, radio antenna, and the fender and trunk emblems. He also bolted up the Cobra front bumper cover, Saleen rear spoiler, and Cervini's Auto Designs Stalker hood. Once bodywork was complete, the sheetmetal (and fiberglass) was covered in Ford's factory-issue Rio Red tri-coat finish.