Great Plains Diesel Technologies
707 East Lincoln Way
Ames, Iowa 50010 USA
Office: 515.233.2962
Fax: 515.232.2240

Design Status

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While the official formation of Great Plains Diesel Technologies, L.C., occurred in 2008 and operations started in 2009, design work on our injector originally began in 2001.

Development Chronology


Unit-Under-Test #2 (UUT2) design is virtually complete. UUT2 features:
  • Fits within same geometry as OEM injector it replaces.
  • Retains OEM needle and nozzle.
  • Hydraulic compensation between needle and actuator.
  • Both needle lift and actuator lift are instrumented.
  • Incorporates provision for cooling.

MAY 2017

Unit-Under-Test for Indisputable Proof (UUT-IP) is a modified OEM injector. Solenoid and servo valve removed and replaced by magnetostrictive actuator directly controlling needle lift. Indisputable proof of cause and effect was provided by direct measurement of needle lift, the cause, followed by the effect of pressure dynamics in a rate tube. Fuel pressurized to 15,000 psi injected into rate tube. Test and measurement showed:
  • Needle lift is an analog scale of electric input.
  • The time rate of change of needle lift is an analog scale of the time rate of change of electric input.
  • Needle lift profiles of forward and reverse boot shapes, each at three different engine rpms.
  • Very small lifts in very short times.
  • Continuously variable opening and closing rates shown.

JULY 2016

United States patent 9,385,300. Robust design.


Engine testing results from Unit-Under-Test 1 (UUT1) were:
  • Heat release rate sensitive to needle lift rate
  • Continuous control over needle lift and rate of lift were demonstrated
  • Ignition delay sensitive to needle lift during pilot


UUT1 bench tested, validating predictions.
  • Speed and precision very good
  • Continuous control
  • Fast pilot injections


Existing OEM injector reworked as Unit-Under-Test #1 (UUT1). Original solenoid and servo valve removed and replaced by a magnetostrictive actuator and hydraulic compensator.


Control law derived and tested. Overshoot and ringing gone. Superposition: off or on at will. Design, control, power, heat, and size now optimized. Closed loop enabled. Speed and lift continuously adjustable. Near-zero contact velocity between the valve and its seat can be programmed.

APRIL 2014

United States patent 8,683,982. Compensated direct drive continuously controllable fuel injector.


Test actuator: 10 millimeter case diameter by 33 millimeter case length. Fatigue test data: The actuator was expanded from zero to 15 micrometers and back to zero. The actuator completed more than fifty million of these cycles with no detectable degradation.


Test actuator: 10 millimeter case diameter by 33 millimeter case length. Test data: Within one millisecond, the actuator performed five separate expansions from zero to 20 micrometers and back to zero, with near-zero contact velocity and no ringing.

JUNE 2013

Flatter thermal profile proven by test.

APRIL 2013

United States patent 8,418,676. Method of reducing the time delay caused by domain alignment.


Prototype endured, unscathed, superposition due to closely-spaced multiple injections and 50,000 (fifty thousand) psi fuel pressure.


Multiple injections proven by test. Thermal predictions verified. Soft landings programmed.


United States patent 8,113,179. Method to increase response linearity by reducing the effect of hysteresis.

MAY 2010

The outstanding speed and displacement results from the original speed demonstrator led to the next level of complexity -- using the speed demonstrator actuator to operate a valve element through a hydraulic compensator. A spool valve was chosen to disconnect pressure from actuator forces. An underlapped spool valve, typically found in aircraft hydraulic systems, would theoretically open and close fuel passages almost instantaneously.

Unlike a needle, an underlapped spool valve edge can pass in front of the fuel flow passages at full speed and almost completely block fuel flow before being slowed to prevent impact with its seat. The result is the ability to crisply start and stop fuel flow, reducing the generation of NOx and DPM. When used in combination with the magnetostrictive actuator, this can be accomplished in multiple injection events or in one long, continuously controllable rate shaping event.

Two prototype spool injectors were built for bench testing. Testing indicated that proportional control can be performed with the spool valve.

APRIL 2010

Proof-of-concept actuator verified speed theory. The design target was to extend by 70 micrometers in 100 microseconds. The actuator contained a magnetostrictive alloy rod of 5.5 millimeters diameter by 85 millimeters length. The rod, highly preloaded by a fuel pressure of 28,000 psi, expanded by 100 micrometers against that fuel pressure in 89 microseconds. The 89 microseconds includes a substantial delay between electrical energization and mechanical response. In fact, this same actuator overshot to approximately 200 micrometers expansion before settling at approximately 140 micrometers expansion. In other words, the speed theory was easily proven with room to spare.

Working through the IPRT Program, Dr. LeAnn Faidley of Iowa State University headed up the testing of our proof-of-concept actuator and proved its speed and proportionality. A summary of test results are available here. Dr. Faidley published SAE Paper 2011-01-0381 based upon the results of the testing work. The paper was then presented at the annual SAE World Conference in Detroit, MI in April, 2011. The video you see below was produced by Iowa State University and features the test of the transducer unit.

JULY 2009

Great Plains Diesel Technologies, LC, opened. The initial task was to build a proof-of-concept actuator specifically to prove the speed theory.


United States patent 7,255,290. Speed theory.

MAY 2001

The question of how to make the injector faster was asked, stimulating development of the theory for maximizing speed. This result called for high compressive preload and as few turns of wire as possible.

LATE 1990s

Two original magnetostrictively-operated fuel injector designs appeared in US patents 6,279,842 and 6,298,829. GPDT's chief engineer Charlie Bright designed the actuators in both injectors. A Ford Focus car with prototypes using 6,298,829 was raced across the California desert in the Challenge Bibendum and then driven across the United States to Michigan.

Transducer Displacement Data

Transducer Speed Data