High Power Density

Jacobs’ High Power Density® (HPD®) technology provides the lightest, most cost-effective, highest power retarding technology available.

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Jacobs High Power Density HPD Engine Brake

Performance benefits of Jacobs’ High Power Density technology

High Power Density Double Braking Power

Double the braking power at cruise speeds

The engine brake power is significantly increased at lower engine speeds compared to conventional compression release brakes.

High Power Density Increased Payload

Increased payload for the retarding performance you need

Our integrated, simple design allows for reduced package and mass as compared to other vehicle retarding solutions such as hydraulic driveline retarders. This results in increased payload by providing all the vehicle retarding performance you need from the engine.

High Power Density Lower cost of ownership

Lower total cost of ownership

While providing increased foundation brake life, truck uptime, and higher resale value, Jacobs’ HPD technology comes at a fraction of the cost of comparable driveline retarder devices that offer similar power.

Jacobs HPD: The Evolution of the Engine Brake

The constant evolution of engine, powertrain, and complete vehicle technology requires an engine brake that can answer increased retarding demands. Developed to complement these technology trends and help further future developments, Jacobs’ HPD delivers the retarding power needed to:

  1. Compensates for decreased aerodynamic drag and decreased rolling resistance of the latest trucks
  2. Compensates for the trend toward lower engine speed operation and specification of smaller displacement engines
  3. Operates at the engine speeds you use, so you avoid downshifting during retarding

In addition, HPD control is fully integrated into the engine ECM and is completely compatible with the latest developments in cruise control and safety features.

High Power Density Performance Graph

How Jacobs’ HPD technology works

Jacobs' full 2-Stroke HPD technology realizes up to 1.5 times the available braking performance of a conventional compression release engine brake. This technology can apply not only to smaller displacement engines but will also maximize the performance of your current engine.

Jacobs Modular HPD System

Standard Compression Release

  • Standard dedicated cam compression release braking system
  • Hardware includes rocker brake, normal exhaust and intake bridges, BGR/CR cam, and brake rocker biasing
  • Standard performance based on the air handling and load carrying capability of the engine

1.5 Stroke HPD

  • Hardware includes the same standard rocker brake, cylinder deactivation bridge on exhaust main event, cam design with multiple CR/BGR events, and exhaust biasing
  • Performance throughout the full RPM range is significantly improved from standard braking-efficient upgrade that does not require significant changes to the overall valvetrain
  • Cost-efficient upgrade that does not require significant changes to the overall valvetrain

2 Stroke HPD

  • Hardware includes rocker brakes and cylinder deactivation bridges on intake and exhaust, cam design with optimized intake/exhaust events, and full rocker biasingIntake optimization for HPD improves airflow and increases performance, especially at low RPM

  • Slightly more complex system to achieve highest performance level possible
  • Provides capability for full cylinder deactivation
HPD comparison graph: 2 stroke vs 1.5 stroke

Natural Gas Engine + HPD Engine Brake

The smaller turbo and smaller compression ratios of natural gas engines negatively impact the brake retarding power by up to 25%.  Jacobs' High Power Density Engine Brake makes up for this loss so fleets can still safely haul standard load sizes.

Comparison graph of Jacobs Engine Brake Technologies

Tech Talk: HPD

Dive deeper into High Power Density engine braking.  Watch our HPD Tech Talk to learn more about how the HPD engine brake works, its performance, its benefits, how it compares to a driveline retarder, and how it improves engine braking for natural gas engines.  

Jacobs technology in action
Demonstrating significant braking advantages for CNG engines

OEM development programs and trials in Europe, North America and Asia prove Jacobs’ HPD is superior to traditional compression release braking and well-suited to engines with CNG as well as diesel.

Global Capabilities — Europe

Let's talk about your program

Our engineers are always available to discuss your current or future technology challenges. Contact us using this form, and a member of our team will contact you within two business days.

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Learn more

Download this information package for more details and technical information about the Jacobs High Power Density technology.