----- Original Message -----
From: gary baker
Sent: Tuesday, 30 April 2002 9:49 PM
To: Rick Byrnes; Dick J; Albaugh, Neil; 'Keith Turk'; ardunbill@webtv.net;
Dave Seely; list
Subject: Re: Fuel Injection
Rick
EFI comes in several categories - OEM for production vehicles ( made
specifically for each type and make of car) and after market ( cheep,
expensive and don't ask ) for racing forget the OEM, in the aftermarket
groups you get what you pay for mostly
The following make up the EFI unit ( you also have to supply the fuel delivery
system pumps , fuel lines fuel rail -injectors and injector ports and other
hardware and all the I/O sensors ,relays and other stuff to make it work) CPU
6-32 bit, 8mhz- 32mhz max cylinders 6-16 fuel maps 16-40 load points per map
16-21 total fuel points 256- 840 total ignition points 256-840 fuel correction
factors ( coolant temp, air temp, full throttle, closed throttle, battery
volts, cold start, throttle pump, injector trim barometric pressure ) only the
top end makes have all these features , ignition correction - coolant temp,
air temp altitude, injector outputs 6-8, ign op's 6-8 aux i/p's 0-3 aux
o/p's 0-9 O2 sensors narrow band or wide band , closed loop operation ,data
logging, boost control , traction control, nitrous management, VTEC control,
anti lag, flat shift, programmable PC or hand unit the cheep units don't have
the features from data logging down.
In my humble opinion all this stuff means jack shit at WOT when the injectors
are maxed out at 80% duty cycle ( means they are open all the time just like
mechanical injection ) and please don't think that EFI is no good it is
excellent especially when your playing the piano( up and down the rev range ie
road racing)or if you don't max out the injectors .
I'm coming from the point that my liner has two modes start/idle and WOT .
FOR ANYONE INTERESTED HERE ARE SOME FORMULAS .
selecting injectors naturally aspirated engines B.S.F.C. .05 forced induction
B.S.F.C. .07and upward
B.S.F.C. = brake specific fuel consumption in lbs per hour ( how much fuel you
use per horsepower per hour)
horsepower x B.S.F.C./ # of injectors x .80 (duty cycle)
to find the HP value for injectors injector size ( lbs/hr) x 80% duty cycle /
.05 B.S.F.C.
TO CONVERT
CC/min to lbs /hr divide by 10.5
lbs/ hr to gal/ hr divide by 6
cc/ min to gal / hr multiply by .015873
to find fuelflow change from a fuel pressure change
new PSI/ old PSI X old fuel flow = new flow
to convert injector flow rates to HP potential x static flow rates by 0.8 then
use either
cc/min to HP x by .190476x number of injectors
lbs/ hr to HP X by 2x number of injectors
Gary
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