NHRA Horsepower Ratings for the 273

273/275 D Dart

The 1966 273/275 HP is still rated at that HP factor.

Though suprisingly the NHRA lists the D Dart as being available in the
both the GT and convertible (which it wasn't).

And they factor the D Dart as a Super Stock only car. Yet, in 1966
the car was specifically built for D/Stock (10.60-11.29 Wt/Hp), and as
a 4-Speed Manual-only application.

Back in 1966, Dodge labeled the D Dart Package as a +40 HP Package
over the standard 273/235 HP 'Commando'.

The Doug Headers (placed in the trunk compartment of the D Darts) were
not part of the +40 HP increase.

It was strictly the Camcraft Camshaft, Racer Brown Valve-Springs,
Free-Flowing cast-iron intake manfold, Holley carburetor and factory
modified dual-point distributor (mechanically advanced).

The Weber Clutch assembly was obviously not a factor in the Horsepower
increase.