| but... The idea of using a mechanical fuel pump on a Z32 may seem totally out of the box but there are many other platforms that have been taking advantage of them. The mechanical fuel pump is primarily for high-HP E85 or methanol applications where the volumetric fuel flow needed to make peak power can quickly out-pace an electric fuel pump or even multiple pumps. The problem is compounded when the rail fuel pressure is boost referenced so you have 43.5 PSI at low-load but at full boost (40+PSI) the fuel pressure can easily be 83.5+PSI - because electric fuel pumps basically run their motor at a constant load/RPM, the volumetric flow decreases when the pressure is increased, which is exactly what you don't want to happen at full boost. You can add multiple e-pumps to the tank to multiply the flow, but the drawbacks are increased amperage draw, noise, excess heat input to the fuel, or overly-complex control systems to turn the pumps on and off when needed. No doubt though, running a mechanical fuel pump will be complex as well. A low pressure feed is needed to push the fuel to the mechanical pump because they're not exactly good at pulling fuel all the way from the tank. But remember an e-pump flows less at higher pressure?...That also means they can potentially flow much more at lower pressure, so a stock TT fuel pump set to around 5 PSI may just be able to provide the volumetric flow needed to feed a high-power E85 beast (yet to be determined), while the mechanical pump does all of the heavy work to pressurize the rails and keep the AFR and tune happy. Also, since the mechanical pump is engine-driven, it's flow rate can keep pace with the engine's fuel flow demand as RPM increases. One caveat of the mechanical pump is there needs to be a prime system to pressurize the rails for quick startup, another is the OE radiator fan and shroud will need to be replaced with an E-fan for clearance. I have yet to work out all of this, but I figured while I was making the cam sync hub, it was easy enough to incorporate the ability to run a mechanical pump and let people take advantage of it as they need.
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