Quote:
Originally Posted by toohighpsi
You kinda have to forget traditional thinking relating to fuel system and the LT1s. The fuel pump is now a positive displacement and fixed to engine speed (forget the in tank pump, it is simply a transfer pump and as long as it supplies some pressure to the main pump it is adequate).
Since our fuel system is now a positive displacement pump, and our engine is a positive displacement pump, they should be able to match each other very well - except for changes in VE (volumetric efficiency) - and that is where the problem lies. The fuel pump is moving a virtually incompressible fluid which provides a fairly linear delivery, the engine does not. The point of peak torque is also the point which requires the most fuel (highest pulswidth) for a given rpm so with a DI engine this becomes the limiting point of the fuel system. In reality at high RPM you normally have adequate fuel due to the lower VE of the engine, it's the peak torque points that test the limits of the fuel system.
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Exactly.I have concrete data of this actual problem.