Among the many characteristics that differentiate diesel and gasoline engines, a diesel's lack of engine braking is probably the least pronounced-yet one of the most significant. While diesels are widely known for their ability to haul freight up steep grades, they're also notorious for freewheeling down the other side, requiring frequent braking to keep speed under control. If you drive solo, this is probably not a big deal, but if you tow, you've no doubt noticed that a trailer can push your rig to scary downhill speeds.
An exhaust brake is an effective cure for this problem. Mounted on the discharge side of the turbo or in the exhaust pipe, an exhaust brake incorporates a butterfly valve that creates exhaust backpressure when closed. This backpressure flows all the way into the engine's cylinders, where it creates resistance on the pistons' upstrokes. The effect is similar to decelerating with a gasoline engine, except it's magnified several fold. A typical gasoline engine produces 3-11 psi of backpressure under ideal conditions, while an exhaust-brake-equipped diesel can generate up to 60 psi.
BD Diesel Performance has been building exhaust-brake systems for more than 30 years and has numerous applications for Dodge Cummins, Chevy/GMC Duramax, and 7.3L Ford Power Stroke applications-and now the company has introduced an exhaust-brake system for the Ford 6.0L Power Stroke (the only company to do so, as of press time). That's certainly not because the 6.0L is rare; the engine's emissions systems and electronics are more to blame than anything else.
The 6.0L Challenge
"The 6.0L was the first Ford diesel with an EGR [exhaust gas recirculation] valve, which was combined with a variable-geometry turbo [VGT]," explains BD's vehicle service manager, Blair Parker. "That presented some challenges because if you don't modify the signals the computer sees when the exhaust brake is closed, you've got problems."
Specifically, Parker explains, if you show the computer too much backpressure, it will command the VGT's vanes to a full open position, creating sluggish response when throttle is reapplied. But if you don't show it enough backpressure, the EGR valve opens and dumps the backpressure in the system.
The BD brake incorporates the company's variable-orifice technology to regulate exhaust backpressure. The offset butterfly valve is mounted to a stainless steel, piston-ring-sealed shaft. | 
Available for '03-'07 Ford 6.0L Power Stroke applications, the BD exhaust-brake kit comes complete with the brake, compressor, all necessary mounting flanges, hardware, air lines, and wiring. The BD kit for automatic-transmission applications also includes the AutoLoc/PressureLoc module, which is not shown. | 
The first step is to measure the section of pipe that is to be cut out, taking into consideration the width of the exhaust-brake housing and flange adapters. |
 |  |  |
With the flanges and clamps on the exhaust pipe, the BD brake is installed and clamped into place to determine exact fit, then welded.