Turbocharged Six Cylinder Ford Mustang - Inline Is Real Fine

Dyno-Testing Facts
McLearran Racing dyno-tested the new Classic Inlines aluminum head on Kelly's 10-second Falcon sedan drag car with a turbocharged, intercooled 273ci six and a C4 transmission. Here's what happened at IA Performance in Tucson.

Kelly's first pass on the dyno using a North American iron Ford head with log manifold yielded the following results:

Will says air/fuel ratio was stable at 11:1 running on E85 Ethanol fuel with a 450-cfm Holley two-barrel carburetor. The improvement in torque on the second run came from a timing retard and increase in boost. Note that horsepower fell, yet torque increased. Torque is what matters most.

Here's what happened when the McLearrans installed the new aluminum head from Classic Inlines:

The common denominator is tuning and torque. Everything else remained the same except for a cylinder-head swap. The Classic Inlines aluminum head has given this 273ci stroker a broader torque curve on top of more horsepower and torque. This swap has yielded 40 hp and 64 additional lb-ft of torque. The McLearrans want to lean the mixture just a pinch to improve horsepower, in addition to 17 pounds of boost. A cam swap is also in the works. We'll keep you posted.

Other Ford-six buffs have noted even greater improvement in performance using a 500-cfm Holley, richer jetting, and ignition-timing tweaks. Much depends on camshaft profile, elevation, temperature, relative humidity, and good old-fashioned tuning know-how.

Because Winterboer has fitted his SportsRoof with a fuel-injected 273ci six-stroker, we don't know what to expect. When he puts this beast on a dyno, we'll bring you the results.