TBI injector flow vs pressure and demand

[olbap <olbap@mail.mia.bellsouth.net>]

A fellow thirdgener over at thirdgen.org brought up some interesting points
about the fuel demands of a given motor and TBI's ability to meet those needs
there are some neat calculations here:
http://www.isuzuperformance.com/isupage/tech/injsize.html

I worked out using this formula: (expected hp x BSFC) / (# of injectors x
duty cycle) = fuel flow in pounds / hour
that a 300 hp motor (what im aiming for here) would need approx. 75lb
injectors at 100%  duty cycle to adequately feed it at its peak. with a .5
BSFC (average efficiency)

using the pressure vs flow formula: (original pressure x Desired Flow x
Desired flow) / (Original Flow x Original Flow)
I worked out that Id need about 25 psi of fuel pressure to equal 80 lbs
through my stock injectors.   I am issuming my injectors are rated 50 lbs at
10 psi which could be wrong. Reason I chose 80lbs is because i hear 100%
duty cycle can hurt an injector.
Anyways, this was pretty shocking to me since im running only 14 psi and in
WOT it seems to be drowning the motor up till about 5000 rpm at which point
it could possibly be going lean since a DMM isnt the most accurate o2
monitoring device (its not too fast) and the car seems to drop off in power
or atleast not gain any more power.
My question is, how accurate are these formulas?
If they are, that would call for some drastic leaning out of the lower rpm
fuel tables so I could run 25 psi.
What % duty cycle does GM program in max?  Ive heard 80%, true/false?

Sorry for the relatively dumb questions but you guys are probably the only
people on the net that know.

Pablo

----------------------------------------------------------------------------
To unsubscribe from gmecm, send "unsubscribe gmecm" (without the quotes)
in the body of a message (not the subject) to majordomo@lists.diy-efi.org