There are two different 273 HiPo motors. One was a regular production option from 1965 to 1967. These were known as the Commando 273 in Plymouths and the Charger 273 in the Dart. They were available with either automatic or 4-speed transmissions.
The other HiPo was the D/Dart model of 1966. While the D/Dart was a separate model, Mopar offered the parts to retrofit a Commando or Charger 273 to D/Dart specs. The D/Dart model came only with a 4-speed and had a 4.86:1 8.75" rear
......................Charger/Commando................D/Dart
Horsepower...... 235 @ 5200 ......................275 @ N/A
Torque............ 280 @ 4000 ...........................N/A
Camshaft I .......... .425" .............................. .495"
E ....................... .425"............................... .505"
Duration ................248º............................... 284º
Overlap ..................46º .................................N/A
Carburetor..... 625 cfm AFB....................... 750 cfm Holley
Exhaust........ cast iron manifolds............... headers by Doug
Warranty........5 yr/50,000 miles...................... NONE
Dick Maxwell was the staff engineer on the D/Dart program.
