Yet the injectors must be fairly robust in terms of flow and pressure because the injector can only spray when the exhaust valve is closed. Compared to port injection, there is roughly 25 percent of the time per crankshaft rotation to get the same mass of fuel into the chamber.
Additionally, the injectors must compete with , psi of cylinder pressure, rather than just Direct-injection engines use between , psi of fuel pressure to squeeze out as much volume as needed in such a short window and keep pace with cylinder pressure.
The design of the piston crown is crucial for proper combustion in a GDI engine. In high-boost applications, even a well-designed piston has issues keeping the fuel from the cylinder wall more on this later. In addition to improved fuel mileage, the efficiency of direct injection allows for higher static compression ratios. The LT1 is GDI taps into the unused cooling potential of fuel, the latent heat of vaporization, in dropping combustion chamber temperatures.
A cooler chamber means greater resistance to knock, and the ability to run more compression. Moving away from the combustion chamber, it is important to note several other key differences between port and direct injection. At the back of the engine, behind the intake manifold, is a beefy little stainless steel contraption that is the high-pressure, mechanical fuel pump. The pump is actuated by a unique looking lifter that rides on a triangle lobe on the rear of the camshaft.
This trio of lobes equates to three pumps per cam revolution. Because of this design, the volume of fuel is fixed based upon rpm. Thankfully, manufacturers such as COMP Cams are able to use different lobe profiles to increase the fuel flow for those looking to make substantially more power than stock.
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Uh oh! Page not found! The pump runs when the engine runs. This setup keeps the fuel pump closely aligned with the engine. This ensures that the engine always gets the kind of fuel pressure it needs to run well. Its purpose is to pressurize the fuel that comes in from the fuel tank before sending it to the fuel rail.
The sensor helps the powertrain control module PCM change the volume of the fuel entering the pump inlet. Typically, a high-pressure GDI pump creates about 2, psi. The sensor and the PCM help regulate the pressure to keep the fuel pressure at an ideal level for the engine in real time. The camshaft pushes the plunger up and down at a rapid pace.
This process occurs repeatedly and consistently. With the help of the fuel pressure sensor, the PCM controls the amount of fuel that enters the high-pressure GDI fuel pump. Specifically, they are for late model:.
We do this to match the performance and durability of OEM fuel pumps.
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