This brings up a very good point. If you're trying to tune the car & you assume the ECU is a black box, then you need to correct around it. In this case varying the fuel pressure is a key tool for doing this. Whereas if you have direct control over the ECU (as I do with the Motec), your whole goal is to keep the fuel pressure constant & change the fuel delivery by adjusting the injectors directly. Both approaches produce similar results as long as you can closely monitor the cumulative system behavior & correct as necessary. Very interesting discussion... BTW, that's one of my favorite Engineering forums...(no I wasn't the one who mentioned them before). Ok, now I need to add a fuel temp sensor too....
Works, Yea, you have a real vacuum lag it the regulator I think. With what you are running I think your pressure is a bit low most of the time. Being you are using a Motec (god help you) then I would absolutely go with an aftermarket system. But you might be good if you just blocked off the regulator vacuum line and just run max pressure all the time and use the Motec to talk to the injectors.
Jim it is the volume of gas in the tank and the properties of gas that cools it down not so much the container it is held in. A static test of the fuel psi is not a good way to determine the output under a load. You need to have the vehicle on a Chassis Dyno for more accurate fuel pump supply reading under a simulated load. The fuel pump for the R53 according to the VDO Siemans the supplier to BMW/MINI is spec'd for stock fuel injectors and a slight on the shy side for even JCW upgrade and is not recommended by them as optimum choice for any increased levels. Whether a failure has been directed to a low fuel pump psi or volume has never yet been established. Many claim to run very high HP levels on the stock pump with out problem? I think this may indicate no one has actually run tests fuel pump specific yet? There are formulas engine related universally used to determine fuel pump requirements as well as injector sizes for specific applications. I was interested about the fuel pump supply needs when a few years ago tried to get the most out of my M7 Venom NOS kit. The NOS shut down if I tried to use the largest supplied NOS nozzle. This I later determined was because a lean condition of fuel supply shortage. I ran a gauge and saw that at idle I was at 45psi. Cruise 60psi and at 6k it went to 66psi. When the NOS was activated the WOT and NOS the psi went down to 55. My first thought was a less than efficient pump. So I installed a new stock pump which netted the same results. Frustrated I than did a fast in line install of a Bosch HP fuel pump I used on a track 280Z. The stock fuel rail indicated 45psi at idle but at WOT I was getting a healthy 70psi. Looking at the plugs it also showed a bit of rich condition. So it was easy to see that a need to go to a manual return fuel system was in order. I welded an AN #6 fitting and manual adjustment regulator set at 45psi and a simple line Teeing into my fill neck at the tank. 45psi at idle and no matter what condition NOS or WOT psi max 65psi. Plugs looked great and the M7 Venom system never shut down even going to a .80 nozzle which is 4 times larger than they recommend. At this point I cleaned up all the components and replaced my in line pump with its own fuel line direct from tank. The first set up was feeding off the stock fuel pump which acted as a primer to the in line pump. I ran 2 primary fuel pumps than. Stock for normal driving and the second activated by 14.5 psi boost or automatic if I engage the power supply to the NOS system. The current fuel system is even more sophisticated and refined than this. It include 2 automatically adjustable fuel regulators 2 high pressure/volume fuel pumps dedicated line feed and a #8 return line directly to the fuel tank, an inverter control for the fuel pumps based on psi and rpm, 3 fuel pressure gauges and several redundant safety switches. Does everyone or any one need all this. I doubt it!? Now if I had a stand alone ECU like works4me I would use the ECU to increase or decrease the delivery pressure by altering the injection pulse width by engine load demand and not worry so much about my fuel system. But it would still have a better fuel pump and Return Fuel System.