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Old 03-17-2013, 09:28 PM   #161 (permalink)
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Originally Posted by renault_megane_dci View Post
- Injection line would inject at 300 bars. How to manage this ?
Injection pressure is created by the restriction at the injector tip. Without an injector, it would inject into fuel return flow at nearly zero PSI because of lack of restriction.
- Injection pump is build to have some kind of resistance from the injector for timing build up.
Would the lack of injector compromise the reliability of the pump ?
No. "Timing build up" is created by the needle valve in the injector, requiring a certain amount of pressure to crack and start spraying, typically ~125-300 bar. Each pump element in an inline pump also has a delivery valve on the outlet (which is a basically a check valve) that opens above a certain pressure, but not nearly as high as injector cracking pressure.

As a side note, injector cracking pressure does not determine max injection pressure. As RPM and load increases, the injection pressure is determined by the resistance of flow through the tiny needle holes after the needle valve.

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