Diesel Fuel Injection

Basics

• This paper aims to go over the history/technology behind Fuel Injection in the context of Diesel Engines (ie Compression Ignition Engines although there is probably overlap with RCCI Engines )
• It will also then aim to delve into Hardware+EFI Software and other questions related to actual hardware development
  • Either from a scratch built Billet Engine or from a White Label Single Cylinder Diesel Engine modification/iteration project

Older/Lower Tech

“Dumb” Mechanical Plunger

• These injectors are basically a metal syringe fed via a low pressure fuel supply (akin to thay used to fill a Carburetor Bowl
• A Camshaft then presses down the piston inside the injector spraying the fluid out
• A spring then returns it to it’s starting position
• Due to low pressure and larger orifice size they don’t atomize the fuel as well
  • They do have less issues with clogging though making Fuel Cleanliness less of an issue, re Fuel Polishing etc
• Akin to the issues facing pre-Pneumatic Valve Springs racing engines, this may limit the upper rev range of the engine before other factors do
  • Although high rev diesels aren’t needed that much, but still a factor to consider

Hybrid Plungers

• These are oil actuated or electrically tweaked/monitored (yet still camshaft actuated)
• May be more reliable than some modern systems, but odd “middle” in a situation where high tech or ultra low tech may be preferable

Common Rail Injection

• This used a high pressure pump and reservoir (the “common rail” + tubing) and all that the injectors do is simply open and close a valve
• Often driven by a Piezoelectric Actuator
• Atomizes Fuel Better + More Independent of Camshaft/Rev Range Limitations
  • Especially models using VERY High pressure (grab spec sheet)
• Tend to have tighter tolerances and more requirements for Fuel Cleanliness etc though so this can cause issues
• Also some options run into issues with Right to Repair / Design for Repair issues/part availability

Internal Links

• Diesel Engines
• Fuel Injection / EFI / Fuel Injector