Are you saying the cylinder compression pressure only varies ~2:1 between idle and full throttle?
I'm pretty sure the idle control system sets the idle rpm.
Are you saying the cylinder compression pressure only varies ~2:1 between idle and full throttle?
I'm pretty sure the idle control system sets the idle rpm.
At idle very little petrol/air mix is let into the cylinder, so when compressed it's only a fraction of the pressure of a compressed pedal-to-the-floor fill. It's engine basics stuff.
NT
It's probably a good bit more than that. Point is the physics, which I gather you now understand.
Cheers
Phil Hobbs
-- Dr Philip C D Hobbs Principal Consultant
The ratio of power produced at full pelt versus idle is what... I don't recall, but certainly more than 20:1. Fuel consumption ditto. So I wouldn't expect unignited compressed fill at idle to even reach atmospheric pressure.
NT
manifold pressure, air entering the cylinder is manifold pressure times volumetric efficiency, and that varies with rpm
that is just a technicality, in the simplest case that is just an end stop that prevents the throttle from closing all the way
I looked up some numbers, 2liter engine, ~450gr/h gasoline at idle
0.450gr*14.7 = 6.6kg/h air 6.6kg/1.15kg/m^3 = 5.74m^3/h air 5740/60 = 95 liter/minute 95liter/750rpm = 0.12 liter/revolution0.12 times a compression ratio of 9:1 is roughly 1 bar ignoring all the details
And more recently Egypt:
-- Mike Perkins Video Solutions Ltd
Untested by JET. It has the odor of an LTspice model, so behavior and convergence are automatically suspect >:-)
.SUBCKT SPARK_GAP2 1 2 PARAMS: V_GLOW=1500 V_ARC=150 I_SUS=.002 V_BREAKDN=12000 I_ARC=.2
hummmmm. Haven't thought about spark plugs before. Another idea....
If they behave like CCFL, i.e. strike voltage than v fall, then my CCFL.sss SuperSpice download example might be of use.
.SUBCKT CCFL_XN !0_1 !1_10
I got the basics of this one from my bible "The Spice Book"
-- Kevin Aylward
Though the 110 is a different car
NT
The idle control system on my 1961 Alfa Rojunko Spider was the usual stop screw, but it was adjustable by rotating the choke knob, which pulled out for choke. Regular adjustment was necessary. The car's best feature was however the convenient lifting lug at the balance point of the engine/ transmission combo for easy removal. I could get that engine out in under 30 minutes by the third or fourth time :-).
The issue with the syntax is the line that starts ")}". This is a continuation line, and should be preceded by "+". Alternatively if you remove the line break and terminate the previous line "> {I_ARC}, 12,0,)}" the spice model will run. Good luck.
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