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:
| Run | Peak HP | Peak TQ |
| 1 | 283 at 4,800 rpm | 416 at 2,700 rpm |
| 2 | 270 at 4,800 rpm | 437 at 2,575 rpm |
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.
 Whenever you're boosting cylinder...  Whenever you're boosting cylinder pressure via a turbocharger or supercharger, the block deck should be O-ringed for superior cylinder sealing. Head gaskets alone won't get it. The block deck must first be cut for O-rings. This happens after decking. Always put the O-ring gaps away from one another. |  This husband and wife team...  This husband and wife team work closely together. Here, the couple installs the piston and rod assemblies, each being devil's advocate, watching out for each other. |  McLearran checked deck height...  McLearran checked deck height during the mock-up phase. He'll check it again during final assembly. Because we're turbocharging, every aspect of chamber volume must be checked to confirm compression. Deck height is only a part of it-again, a dished piston is used for reduced compression. |
Here's what happened when the McLearrans installed the new aluminum head from Classic Inlines:
| Run | Peak HP | Peak TQ |
| 1 | 323 at 4,800 rpm | 480 at 2,700 rpm |
| 2 | 318 at 4,700 rpm | 502 at 2,650 rpm |
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.
 Rod bearings get the same...  Rod bearings get the same treatment as the mains-with dry surfaces between bearing and rod. With Winterboer's 273ci six, McLearran has to keep piston/rod temperatures in mind. It's a narrow window where clearances border on loose, yet are tight. |  A Good Support System Because...  A Good Support System
Because Winterboer wanted an adequate electrical system to support this project, he looked to Mustangs Plus for answers. The company provided him with a trunk-mount battery kit, along with a Tuff Stuff Performance Products single-wire alternator and starter. This high-quality, high-torque starter doesn't knuckle under when header heat becomes overwhelming. Winterboer opted for the trunk-mount battery for both improved weight distribution and to make room for the turbocharger. |  McLearran is pretty grassroots...  McLearran is pretty grassroots in his methods-fuel-line hoses make terrific journal protectors. They protect journals and cylinder walls against scoring should Will become careless. |
 McLearran studs the block...  McLearran studs the block deck for much the same reason he studs the main caps-strength and rigidity. Studs act differently than bolts in that they provide extraordinary strength. Main caps won't move, and neither will the cylinder head. This is especially important with artificial aspiration. |  In the Clutch Winterboer...  In the Clutch
Winterboer opted for a Centerforce Dual-Friction clutch and zero-balance flywheel (Ford sixes are internally balanced). Because he's going with a World Class T5 five-speed, he looked to California Pony Cars for the transmission crossmember and yoke. Mustangs Plus provided the aluminum driveshaft (not pictured here). We'll have more on the driveline in our final installment. |  McLearran Racing does a quick...  McLearran Racing does a quick engine fit check just to see how our 273ci turbo screamer measures up to its new home. The engine fits nicely with only minor issues. |