Forum Discussion
4x4ord
Dec 22, 2020Explorer III
ShinerBock wrote:
The cam in the pump is not like the cam in an engine. The cam in the CP3 is more like the crankshaft in the engine. Increase the crank stroke on an engine and what does it do to its compression ratio and cylinder pressure?
Consider this: When the engine is running at 2500 rpm the CP4 pump is capable of pumping a certain volume of fuel. I don't know what that volume is but say it is 2 litres per minute. The CP 3 might be capable of pumping 2.5 litres per minute. Under part engine loads these pumps need to be throttled back. The injectors might only be injecting .5 litres per minute. There is a mechanism in place for controlling the pressure to what the ECM is calling for and limiting the volume of fuel being pumped. I believe the pump is throttled back by only allowing the required fuel to flow into the pump. Push the accelerator down and the fuel control actuator allows more fuel into the pump to match the fuel being injected into the engine. This is controlled electronically but exactly how I don't know. The thing is, if more pressure is being asked for by the ECM the pump needs to respond by pushing more volume into the rail. I think the change in the cam is likely more to do with providing higher volume for aftermarket HP increases... but I really don't know much about this stuff.
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