How To Read a Cummins Engine Model Code

The Leading Digits Are The Cylinder Count

In the mechanical families the first character is the number of cylinders: 4BT3.9 is a four-cylinder engine, 6BT5.9 and 6CT8.3 are six-cylinder engines. The number that follows the letters is the displacement in litres, so 6BT5.9 is a 5.9 litre six-cylinder engine and 6LTAA8.9 is an 8.9 litre unit.

The electronic families replace that pattern with a family name and a displacement: QSB6.7, QSL9, QSM11, QSK19, QSK38, QSK50, QSK60 and QST30 all carry their displacement in the name.

The Letters Describe Aspiration and Cooling

T means turbocharged and A means aftercooled or charge air cooled. A 6BT5.9 is turbocharged; a 6BTA5.9 is turbocharged and aftercooled; a 6BTAA5.9 uses air to air charge cooling. The specification table on every product page in this catalogue states the aspiration in full, so the code only has to get you to the right shortlist.

The Suffix Tells You The Duty

A suffix of G or GM indicates generator drive, M indicates marine duty, P indicates a pump or industrial power unit and C indicates construction. 6BTA5.9-GM100 is a marine generator engine rated at 100 kW; NTA855-P360 is an industrial power unit of 360 HP. The number in the suffix is usually the rating in kW or HP.

Always Confirm Against The Serial Number

Model codes repeat across build variants with different flywheel housings, fuel systems and emission levels. Send the engine serial number or a photograph of the nameplate with your enquiry; MEP Power checks the configuration before quoting so the unit that arrives fits the machine it is going into.