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rpm confusion

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Old Mar 1, 2007 | 01:46 PM
  #1  
driftxsequence's Avatar
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rpm confusion

ima lil confused about the rpms and all
i remember someone saying before that if your reving at 9k RPMS, that your rotors are only doing like 3k RPMS correct?

so does that mean if your idling at 900 RPMS, that your rotors are really only rotating at 300 RPMS?

i dont yet have an rx7 yet since im too young but i plan on getting one in the near future, probly start out with a 2nd gen for reliability reasons etc, but i was in my neighborhood and i was walking with friends and i heard a 3rd gen with an apexi n1 exhaust go down the road and i pointed it out and my friends thought i was a freak..hahaa
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Old Mar 1, 2007 | 02:34 PM
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if the tach says its doing 9k rpms then you would think the engine is revolving 9k times per min
just the same for piston engines. they have 4 strokes does that mean they are only doing 1/4 of the actual rpm posted on the tach.
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Old Mar 1, 2007 | 02:47 PM
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From: Kennewick, Washington
Originally Posted by NCMontegott
if the tach says its doing 9k rpms then you would think the engine is revolving 9k times per min
just the same for piston engines. they have 4 strokes does that mean they are only doing 1/4 of the actual rpm posted on the tach.

RPM is in respect to the eccentric shaft (or crankshaft) in a rotary, 9k rpm of the eccentric shaft is 3k rpm of the rotors. in a piston engine 9k rpm is 9k ups and downs per minute for each piston and 9k rpm for the crankshaft.

Last edited by Monkman33; Mar 1, 2007 at 02:53 PM.
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Old Mar 1, 2007 | 02:56 PM
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From: Bath, OH
Remember that each of the three faces of the rotor has a combustion event each time around, so the power and exhaust pulses (for 2 rotors) are at the same frequency as those of a 12-cylinder piston engine (they have power pulses every other revolution) at the same RPM.

Dave
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