Maximum Boost condem's the use of FMU's?

[93 mx-3 gs/se]

I consider myself a F/I novice and I am trying to hopefully educated myself enough so one day in the not so distant future I can boost my ZE. I was just reading through my copy of maximum boost and on page 20, the second paragraph says,<P> <BLOCKQUOTE><font size="1" face="Verdana, Arial">quote:</font><HR>Another popular scheme is to proportion " fuel enrichment " according to boost pressure. While this sounds better and is better, it is still technical nonsense. The situation is created wherein the same ammount of fuel would be added at 3000 rpm and 5 psi boost and at 6000 rmp and 5 psi boost. Obviously, fuel requierments would double at twice the rpm. But the boost proportioned fueler would deliver the same quantity of fuel regardless of rpm. Not a workable mechanism.<HR></BLOCKQUOTE> <P>This is strange because Corky Bell seems to contradict himself on page 92......<P> <BLOCKQUOTE><font size="1" face="Verdana, Arial">quote:</font><HR>Increasing fuel pressure as a function of of boost pressure is a viable method of increasing fuel flow to accommodate boost pressures up to about 9 psi.<HR></BLOCKQUOTE><P>Thoughts?

[maldo]

He doesn't contradict himself, he states that it isn't the best option but a viable one. If you were to go with a stand alone computer, it negates the need for an adjustable fpr in most cases as you can adjust fuel based on MAP/TPS output. You also have the ability to run specific A/F ratios at specific rpm and at specific VE.

[ikedasquid]

i think that in the first part he is denouncing the extra injector setups where the injector pulse length is determined by boost pressure alone. in the second part he is talking about rising rate fuel pressure regulators or fuel management units (fmu or rrfpr). These increase the psi, and the stock (or not) computer adjusts pulse duration for rpm just as if it was NA. together you get fuel based on rpm and boost. the only shortcoming is that the extra fuel needed follows more of a curve (hyperbolic for you math nerds) related to rpm and boost, but the fmu will raise linearly (which is an approximation, but not too far off, since you can set it for the high end -a little rich- and it will lean out in the midrange rpm)<P>i belive mr. bell was refering also to added resistors in the temp sensors circuit, and since the computer just adds fuel (not proportionate to rpm especially at top end) at cooler temps to increase vaporization, you get an effect similar to added injectors controlled only by boost.<P>or you can get the stand alone<P>just my .02

[Rayman]

think of the use of a FMU as an economical alternative of adding fuel from an otherwise stock fuel system. the only TRUE way to do it is to up the injector size and either reprogram the ECU to control them or have the ECU swapped out for a standalone replacement that can handle bigger injectors

[LinuxRacr]

You also have to take into account that his FMU increased the fuel as the boost increases too I believe.

[BATTOSAI]

Check out this link:<p>http://www.sdsefi.com/techfpr.htm