PF22 Fuel System Design and Manufacturing
I developed an Excel Fuel Injector Calculator to accurately size appropriate injectors. The goal was to be able to select the largest injectors possible (while staying out of the non-linear range) to provide the best atomization. A Ricardo WAVE volumetric efficiency, lambda targets from M1 Tune, and fuel injector characterization data were used to calculate pulse width, duty cycle, and flow rate of the injectors. The values from this calculator were later validated against MoTeC measured values while running the engine on the dyno.
Outputs predicted that Duty Cycle for the Injector Dynamics 1050 Injector are as close to the non-linear range as possible while also staying below 40% duty cycle. Flow Rate Graph shows that our chosen pump flow rate exceeds the max amount of fuel the engine will require. The Walbro 414 can supply 1.9 kg/min of fuel at 2.7A. It was chosen because it meets the requirements for our fuel system yet does not have a large amp draw.
(all calculations shown for 93 Octane fuel)
The fuel tank was designed to hold ~1.3 gallons of fuel. This provided a 1.1FS on the least fuel-efficient single cylinder running E85 and a 1.5FS on our powertrain configuration. This allowed our vehicle to be forwards compatible to E85 if we got the chance to test alternative fuels.
​
Internal baffling and a hydramat ensured reliable fuel pressure.
​
A circular tank was chosen because it is so much easier to weld than low tolerance sections of bent aluminum.
A study on the opportunity cost of E85. E85 showed about a 13 competiton point advantage over 93 Octane. However, storage capabilities and access to fuel were limited. We priortized testing and practicality over fuel selection. This was done by comparing torque curves in our Matlab Quasi-Steady State Lap Time Simulation.
I got really good at welding aluminum!
4am, completing the first fuel tank!