IDLE fuel/HP requirements

[garfield at pilgrimhouse.com]

On Sun, 22 Feb 98 10:43:39 PST, "bruce plecan" <nacelp at bright.net>
wrote:

>  Several weeks ago, I posted some tables, that included idle
>fuel, and idle timing.  If your playing with a GM ecm they reflect
>what a "large" cammed engine set of tables might look like.

Yeah, actually I wasn't looking for tables, so much as "ruleOthumb",
since my task isn't to calibrate an ecm (more on that below), but to
just "ballpark" the pulse width as a starting point. I was just looking
for rough fuel figures, nothing exact or precise. I've got some actual
pulse width measurements now, so not to worry. Sometimes is you wait
long enough, the question answers itself!

>If your using a aftermarket ecm then the correlation isn't as close
>if your using pulse width.   If noone responds, to a posting then 
>maybe it was too vague and needed reposted in a more specific
>manner, like, what ecm are you using?, are you using pulse
>widths for your calibrations, or VE?

Brace yersef for a shock (get a grip on that hat). NO ecm. The
controller is for a small aviation engine, there's a "man in the loop"
watching EGT to manually set mixture at cruise (remember, we've still
got leaded fuel, so O2 feedback isn't used), and at full power, a
dirty-rich enrichment level is typical/expected, since we are most
concerned about power and not emissions or economy during takeoff &
climbout. So the problems/issues are quite a bit different than
automotive. This system is alot like an electric version of the older
fuel injection systems used in racing. Or another way of thinking about
it is a modern, dual-redundant, minimum parts count equivalent to the
analog ProJection system, except it CAN use MAP as a load variable
input, and it IS semi-sequential. I've had one channel running on the
bench for awhile, and am building a 4-channel setup for on-engine
testing now. Hence, I'm trying to get a RANGE to expect for idle fuel
flow.

Since asking about the load at IDLE is alot like asking how many
calories an animal burns when sitting still (lots of variations), I
understand that it varies alot with the accessories/losses in the engine
itself. (The variations from IAT I've got covered already). THOSE rough
estimates were what I was looking for. But hey, since this is an
eXperimental science, I just made a wee Bosch connector adapter to
expose the injector terminals whilst running, and now I'm asking
everyone I know if I can "measure" their FI with my scope. That should
do me. I just wanna get a feel for what kinda RANGE I'm dealing with at
IDLE, sans the heavy idle loads like A/C.

I'll interject another "theory/ballpark" question on y'all. Anyone know
roughly what percentage of intake air is supplied by the IAC system? Is
it capable of a 5% tweak, 10%, 25%, more?

Garfield