Michael, I know one thing for sure that the rotor has 4 magnets and 1 turn of rotor = will=20 fire 4 cylinder. I just do not understand what does "Four stroke is 1 spark every two revolu= tion"=20 means? can you give and example? thanks AA ________________________________ From: Michael Watterson To: Microcontroller discussion list - Public. Sent: Mon, March 7, 2011 11:25:56 AM Subject: Re: [EE]: VW engine RPM question On 07/03/2011 18:58, Michael Rigby-Jones wrote: > This assumes your Beetle engine will hang together for more than one > spark period at 8000RPM... > red line at 5,000 rpm? my VW van did 55mph it was revised flatter flat air cooled twin done after Beetle ceased=20 production. Eventually the covers over the push rods started to leak :( It had electronic Ignition. When I was very small my Grandfather had a=20 Beetle with 6V electrics. Most 1960s to 1980s cars I worked on 12V and ignition coil + "points"=20 and distributor cap with 4 sparks in turn per revolution, 4 cam bumps =20 on shaft opening the "points" to interrupt current to ground through=20 ignition coil. Four stroke is 1 spark every two revolution. So distributor shaft is at=20 engine RPM x2 since it does 1/4 revolution for distributor each piston=20 stroke? --=20 http://www.piclist.com PIC/SX FAQ & list archive View/change your membership options at http://mailman.mit.edu/mailman/listinfo/piclist =20 --=20 http://www.piclist.com PIC/SX FAQ & list archive View/change your membership options at http://mailman.mit.edu/mailman/listinfo/piclist .