6.7 Cummins ISB engine performance mods can improve power delivery, throttle response, towing performance, and overall engine efficiency. The ISB6.7 is used in medium-duty trucks, buses, RVs, emergency vehicles, and other applications, with factory ratings varying considerably by application. For example, Cummins lists EPA 2010 medium-duty versions from 200–325 hp and up to 750 lb-ft of torque.

Turbocharger Upgrades

The turbocharger is one of the main areas to consider when improving ISB6.7 performance. Later versions use a Cummins VGT turbocharger designed to provide strong low-speed response while supporting airflow at higher engine speeds. Cummins also notes that its VGT system can improve fuel economy and engine braking performance.

A properly matched replacement or upgraded turbo can provide additional airflow for an engine operating under heavier loads. The turbo should be selected according to the engine's original rating, application, and desired performance rather than simply choosing the largest available option.

Airflow Improvements

Improving and maintaining the air-handling system is another important part of a performance build. A clean air filter, properly sealed intake system, healthy charge-air cooler, and leak-free boost hoses can help the engine maintain efficient airflow.

The ISB6.7 combines turbocharging with high-pressure common-rail fuel injection, so airflow and fuel delivery need to remain balanced.

Fuel System Upgrades

The ISB6.7 uses a high-pressure common-rail fuel system with electronically controlled injectors. Cummins states that the system provides precise fuel control for performance, emissions, and fuel economy.