on the motronic, are injectors able to keep open 100% duty cycle?
06-04-2004, 12:31 AM
#1
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on the motronic, are injectors able to keep open 100% duty cycle?
I was thinking.
7500rpm/min -> 125rpm/s -> 8ms/rpm
and you have 2revs availeble for injecting fuel,
so basicly 16ms
If "requested injection time" is more,
will injectors just stay open all the time?
If so, 550cc injectors (running at specified fuelpressure) delivers 9,167cc/sec, so with fuel density 0.75grams/cc, that would be 6.88grams/sec.
with 4 injectors that is 27,5grams/sec.
with an AFR 12:1, that amount of fuel can handle 330grams air per second, so about 410chp.
That is IF injectors can stay fully open.
Just thinking out loud, maybe trying to get some input
7500rpm/min -> 125rpm/s -> 8ms/rpm
and you have 2revs availeble for injecting fuel,
so basicly 16ms
If "requested injection time" is more,
will injectors just stay open all the time?
If so, 550cc injectors (running at specified fuelpressure) delivers 9,167cc/sec, so with fuel density 0.75grams/cc, that would be 6.88grams/sec.
with 4 injectors that is 27,5grams/sec.
with an AFR 12:1, that amount of fuel can handle 330grams air per second, so about 410chp.
That is IF injectors can stay fully open.
Just thinking out loud, maybe trying to get some input
06-04-2004, 04:21 AM
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75% DC and 450chp would require 800cc injectors...
that seems heavy...
How big injectors is ok without giving a very rough idle ?
I'm thinking about some 60lbs Siemen Deka's high impedance...
that is about 700cc at 4bar.
Think idle will be ok ?
How big injectors is ok without giving a very rough idle ?
I'm thinking about some 60lbs Siemen Deka's high impedance...
that is about 700cc at 4bar.
Think idle will be ok ?
06-04-2004, 04:30 AM
#4
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Idle on a 700cc shouldn't be that bad...
But then again, you can alway$ do $taged injector$, but it might get expen$ive.
:-)
I $ay give it a $hot and $ee how it goe$.
I don't think you'll have a problem unless you go much past 850cc or so. Only one way to find out, right?
:-)
I $ay give it a $hot and $ee how it goe$.
I don't think you'll have a problem unless you go much past 850cc or so. Only one way to find out, right?
06-04-2004, 06:24 AM
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I've found some that give 552cc@2.5bar, 852cc@6bar... These would be perfect for what Im up to...
I guess that would equal about 700cc@4bar...
They're high impedance (12ohms) and are a straight fit on fuelrail/manifold...
They're high impedance (12ohms) and are a straight fit on fuelrail/manifold...
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06-04-2004, 11:23 AM
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Sadly, pretty much all K03 chips on the S4s max out the injectors.
And from what I've seen, K04 kits using RS4 injectors tend to come pretty close to maxing those out as well at high RPMs.
-Dave Pramanik
-Dave Pramanik