Thread: L8 vs P8
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Old Aug 4, 2006 | 04:28 PM
  #7  
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foreigneRS
Testing the future
 
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From: W. Sussex
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so what if p8 does run quicker?

if you have a 4 cylinder engine running at 8000 rpm, how quickly do you need the ecu to be?

not very quickly in processor terms, as you only have an injection or ignition event every 0.00375 seconds (so about 4ms, or 250 Hz). not exactly talking pentium 5 GHz speeds necessary here are we?

8000 / 60 = 133.3 revolutions per second

it's a 4 stroke engine, so you divide that by 2 revolutions for each complete cycle = 66.6 cycles per second

each cycle has 4 ignition or injection events = 266.6 events per second (Hz)

(you have crank position sensor events more frequently, depending on how many teeth on the pulley, but that's only twice as often a 4 lug pulley, although a lot more often on a 36-1 pulley)
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