Fuel System Layout


The Westport engine fuel system, featuring Westport multipoint injection (MPI), is designed to provide a complete, fully integrated solution that will meet the strictest emission standards.



Westport Industrial Engine MPI System Advantages


 mixer systemWestport solution
Fuel Induction Mixer Sequential multipoint injection
Layout Large mixer and reducer

Compact system design

(simple injectors/nozzles)

Starting Variable Within 2 crank revolutions


(airflow pressure losses through
mixer system at mid/higher engine speeds)

Optimal torque curve

(better volumetric efficiency)


Inherently slow response to transient load requests

Improved transient response

(fuel injection close to the intake valve)


Slower air/fuel toggling

(longer transport path between mixer and O2 sensor)

Precise and quick lambda toggling control

Expensive catalyst required to reduce emissions

Better emissions control allows for smaller catalyst volume

(lower precious metal loading)

Back-Fire Risk
(through intake system)


(large combustible volume in intake manifold)

Not possible

(minimal combustible volume with port injection)

Variable NG
BTU Capability
Manual adjustment required

Automatic BTU compensation

(closed loop air/fuel ratio control)

Dual-fuel Capable
(with auto-switching)

Certified emissions achievable with primary fuel only


The advanced sequential multipoint system injects gaseous LPG/natural gas into the intake port. The fuel injectors are microprocessor controlled and the injector pulse-width is based on a speed/density algorithm.

Closed loop fuel control uses a standard switching type oxygen sensor to maintain a stoichiometric fuel mixture and adjust adaptive learning parameters as the system ages. Regulatory exhaust emissions are obtained by use of a three-way catalyst.

The engine ECU includes basic diagnostic features as required by the EPA such as fault diagnostics and a malfunction indication light (MIL) system which can be incorporated in the dashboard. Communication with the ECU is through a laptop service tool. Service software runs on a laptop computer and will connect to the ECU through a USB port.

The Westport MPI system has many advantages over the traditional mixer system, including fast start in all temperature conditions, and excellent transient response.


Last modified on Tuesday, 13 May 2014 01:58