Since all S54 motors use the same injectors in stock form, I'm assuming they use the same pumps as well (as would seem appropriate for the same injectors); with the FPR being the exception to similarities between the systems on the M3 and Z4M.
Here we go (in bold):
Originally Posted by nik@vf-engineering (on M3Forum)
After reading some carefully constructed and twisted wording in a current thread about "truth and fairness" [in the open market of E46M superchargers], I thought that a simple explanation on the fuel pressure of the E46 M3 would an interesting topic.
On a similar thread I read that the someone believed that the fuel system on the E46 M3 is simply in-adequate for power greater than 430-450 rwhp with a supercharger [based on 20-25 seconds top of 6th gear pulls on a race track].
Keeping in mind at this rpm in 6th one would be hitting high 170's mph, it is not suggested to try this on the street which is where most of these applications are used. The few that may be hitting 170+mph for 20-25seconds straight, better have a roll cage, race gas and supporting custom mods.
With regards to VF-Engineering supercharger systems delivering well in excess of 450whp - the fuel systems ARE capable of handling upto 500whp on 91 octane. We have tested this in the arena in which these products are used. With correctly scaled fuel pressure to injector size ratio, the stock fuel pump can support the flow rate required to deliver the whp.
However when using superchargers in a low efficiency setup, the power gain to fuel supply ratio drops. The larger the supercharger (within reason) the less, the energy draw from the crank. The greater the volume of induction charge with least amount of crank draw with produce a more fuel efficient power gain. This is what VF achieves with the Vortech V1 / V2 and V3 units. Size does matter in this case.
Dropping fuel pressure coupled with the correctle specd fuel injectors (kept under 80% duty cycle) will reduce the need to enlarge the diameter of fuel lines or fuel line fittings unnessesarily and continue to provide the volume of fuel needed for a healthy AFRs with more to go.
Increasing fuel line diamters will allow an increased amount of through flow but will make the fuel pump work harder to keep the pressure up. However our testing and testing by several of our performance partners here and in Germany has shown that the stock fuel lines can more than adequately support 600+whp when used with a Bosch 044 intank pump upgrade.
By the time we need to upgrade the fuel system we're going to need a head gasket and studs anyway; then you might as well build the rest...