internal close up of an engine with the pistons in motion
Under the right pressure.

350 bar GDi: A great solution to rising regulations.

Gasoline direct injection (GDi) engines have certainly earned their rightful place on advancing propulsion roadmaps. The technologies behind these systems deliver a path to increased performance, improved fuel economy and reduced carbon dioxide (CO2) emissions through more precise, leaner and complete combustion.

Granted, the benefits do have a few strings attached. Direct injection engine systems are generally more complex to engineer, manufacture and maintain. Durability also comes into play given the high pressures and extreme heat fuel lines and injectors, for instance, need to withstand. Unnecessary service visits and owner complaints can erupt when normal-operation noise from the fuel pump is interpreted as a problem. And then there’s the increase in particulate emissions – both in mass (PM) and number (PN) – due to the reduced evaporation and mixing time the fuel has when injected directly into the combustion chamber before it is ignited.

With gasoline direct injection, the question becomes: How do you maximize the positives and minimize the negatives? One way is through pressure. 

The premise: The higher the pressure, the smaller the fuel droplet size. The smaller the droplet size, the more efficient the evaporation. The more efficient the evaporation, the lower PM/PN.

However, with increased pressures come challenges in the form of durability, fuel economy and engine noise due to the higher loads. As a result, you’re often forced to manage the trade-offs and accept the compromises with many higher-pressure gasoline direct injection systems.

That is unless you partner with Delphi Technologies.

Delphi Technologies 350 bar GDi system.


Gas engine low particulate fuel injection system graphic


With our leading-edge 350-bar GDi system, Delphi Technologies was the first in the industry to push the pressures and forego the flaws. This gasoline engine innovation delivers:

  • Substantially reduced particulate emissions. The system produces up to 70 percent fewer and smaller particles than current 200-bar systems.
  • Advanced componentry built for precision and endurance. The system features several redesigned elements – such as our latest fuel injector – that are more precise and durable than the competition at these higher pressures.
  • Improved performance. The higher pressures boost coking resistance, trimming the build-up of cooked fuel deposits that can foul injectors – and reduce customer satisfaction scores.
  • Lower fuel-pump noise thresholds and greatly improved efficiency. Our latest fuel pump design operates at lower dBA (decibels), achieving industry-leading noise levels. It also features our newest advance – the patent-pending plunger ring seal. The PRS virtually eliminates internal leak paths, allowing the pump to quickly come up to pressure, as well as achieve higher pressures at lower RPMs. Both are critical for fuel economy and emissions gains.

The system also boasts upgrades in materials, as well as new component fabrication and system manufacturing techniques that reduce complexity and stabilize costs. 

Finally, our 350-bar GDi system has been developed and tested for all international fuel blends, allowing you to easily – and quickly – deploy in all global gasoline powertrain platforms. 

Fast Take: 350-bar GDi – A better pressure of choice.



How we made it work.

In developing our 350-bar gasoline direct injection system, Delphi Technologies engineers encountered – and resolved – several crucial challenges.

The first was particulates. They had to engineer a system that would reduce fuel droplet size, plus increase spray timing and speed to remove the conditions that allow particulates to form.

The second was wear and tear. They knew higher pressures put increased stress on fuel injection components. As a result, fuel rail, injector and pump stability and longevity, to name a few, had to be improved.

The third was fuel economy. The energy needed to create higher pressures is derived from the engine. The system had to be designed to produce more power with minimal increases in torque to avoid hits to fuel economy. The same was true for durability. Making the system stronger could not equate into making it bigger or heavier. The design had to be small, compact and flexible; otherwise they’d see offsets in fuel consumption.

Finally, they had to watch that noise. With higher pressures you get higher loads – particularly in the fuel pump. Delphi Technology’s Gen I fuel pump was already best-in-case on exterior noise. The engineers were determined to sustain this level of performance.



Over the course of about 18 months, our engineers overcame these challenges, reinventing the 200-bar system largely through the development of new software and closed-loop controls, changes in prototype development and testing approaches, as well as fuel injector and pump advances.

With our latest injector, the team designed it with an optimized pressure vessel, improved rail interface and a 30 percent increase in magnetic performance that delivers enhanced fuel-delivery precision. These enhancements were married to carry-over features that include reduced welds for enhanced durability, changes to the mounting methods to better withstand the higher pressures and minimize injector-to-cylinder head misalignments, and redesigned armature assembly to boost fuel flow.

With our fuel pump, it was about delivering better durability and steady performance, under higher pressures without increasing the noise levels. Achieving this included improvements to the fuel inlet, internal damper assembly, mounting flange and outlet fitting to reduce noise levels. We also implemented performance enhancements such as redesigning – and in some cases eliminating – internal elements such as O-rings on the damper cup assembly, which can be prone to leaks and contribute to evaporative emissions.

And then there’s the PRS. This special polymer seal is integrated with the plunger, virtually eliminating the leak path between the plunger and the sleeve in which it rides. It allows the pump to come up to pressure right at the start and achieve high pressure at low RPMs for fuel economy and emissions gains.

Looking ahead.

Delphi Technologies doesn’t intend to stop at 350-bar GDi. In fact, we just unveiled our industry-leading 500+ bar GDi system, which further reduces PM/PN emissions and provides gains in fuel economy. Best yet: It dispels the long-held industry belief that deploying higher than 350-bar always leads to high-priced engine modifications. 

We’ve also expanded our GDi service program with tools, training and more to ensure dealers and independent repair shops have what’s needed to service advancing GDi systems.

Want to know more? Contact Us today to discover how we can put our advancing GDi engine solutions to work for you.