Exhaust Brake FAQ

How does an exhaust brake work?

Most exhaust brakes have a toggle switch mounted on the dash to turn on the exhaust brake controls. The exhaust brake also has a throttle position switch. When the toggle switch is on and the throttle is released, the brake is activated (butterfly closed) to provide exhaust retardation. When the butterfly is closed, it turns the engine into an “air compressor” by forcing air out of the engine under pressure (on the exhaust stroke). This causes the engine to provide retarding power through its connection to the drive wheels. The brake releases as soon as either the throttle is applied or the switch is flipped off.

How do exhaust brakes on automatic transmissions work?

The torque converter clutch must be locked up during deceleration to fully utilize the hold back of an exhaust brake. If the torque converter is not locked up, then the drive wheels will “drive” the torque converter, not the engine. The exhaust brake has more “hold back” at higher RPM because of higher back pressure. The B/D AutoLoc device controls the torque convertor clutch for lockup on deceleration.

How does and exhaust brake work with a VGT Turbo

The variable vane turbocharger can be used to slow you down. By electronically closing off the turbine vanes which can create up to 130 retarding horsepower. This braking force will help to maintain your speeds on descents and curves, giving you better control of your truck and load. Works with your cruise control to automatically accelerate and decelerate to maintain vehicle speed.


Do exhaust brakes work on gasoline engines?

We don’t recommend using an exhaust brake on a gasoline engine because they create too much heat. Unlike a diesel engine, which delivers zero fuel on deceleration, when the engine is above idle rpm, a gasoline engine continues to deliver fuel on deceleration.