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Stack inj. alky fuel pump size.

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alkyal:
Basic info: 305 cu in chevy[actually 312 cu in] 100% methanol fuel. Rear mounted tank. Most are using a K/W 400 pump. Using your calculator, It shows approx 46% of the fuel going to the Engine. 8 nozzles with .025 or .024 dia. The main is shown to be approx .085. When I enter a KW300 pump, the numbers show a .062 main. and a fuel pressure drop of approx 20 psi. The amount of fuel to the engine also increases to well over 50%. These engines due to restrictions produce approx 520 hp max. Also how much do you think a Fuel filter between the tank and pump affects the ability of the pump/system to function as calculated? Thanks Al

Spud Miller:

 Hi Al,

 Unless one of the other components (or conditions) change, the system pressure should not have changed with a pump substitution. The pill going down to a .062 from an .085 is normal, and the fuel to the motor going from 46% to 50% of the pumps output sounds about right. But there is only one answer for pressure with a given set of nozzles. In other words, to get  the 1.58 GPM desired to fall out of the nozzles at 8000 engine RPM, that pressure should be 96 PSI with either pump. The change in pills is what makes up that diff for the change in output.
 
 Regardless of the details, if I had both pumps laying there, I'd definitely put the 400 pump on it to get that main pill size up higher.

 Have fun!
 Spud

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