> -----Original Message-----
> From: piclist-bounces@mit.edu [mailto:piclist-bounces@mit.edu] On
Behalf
> Of Andre Abelian
> Sent: 07 March 2011 18:33
> To: Microcontroller discussion list - Public.
> Subject: Re: [EE]: VW engine RPM question
>=20
> Jack,
>=20
> sorry yes I mean beetle.
> this means 8000rpm/60 =3D133hz/2 =3D 66.6 this is what I should see per
> cylinder
> right?
> and by looking at main sensor side (or coil side) I should see
> 66.6*4=3D266.4hz
> now I am totally lost... are you sure it divided by 2?
>=20
> thanks
>=20

If the rotor you are looking it is part of the distributor then it
*absolutely, definitely* will be turning at 1/2 crankshaft speed.  A 4
cylinder, 4-stroke engine requires a spark every 180 degrees of the
crankshaft (hence every 90 degrees of the camshaft and distributor).
The total spark frequency is therefore (8000/60) * 2 =3D 266.7Hz.  Each
cylinder has an ignition event every two turns of the crank, so spark
frequency at a given spark plug will be (8000/60)/2 =3D 66.7Hz.

This assumes your Beetle engine will hang together for more than one
spark period at 8000RPM...

Mike

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