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random knowledge rpm while cranking

Printed From: the12volt.com
Forum Name: Car Security and Convenience
Forum Discription: Car Alarms, Keyless Entries, Remote Starters, Immobilizer Bypasses, Sensors, Door Locks, Window Modules, Heated Mirrors, Heated Seats, etc.
URL: https://www.the12volt.com/installbay/forum_posts.asp?tid=104469
Printed Date: July 06, 2025 at 11:50 PM


Topic: random knowledge rpm while cranking

Posted By: KPierson
Subject: random knowledge rpm while cranking
Date Posted: May 04, 2008 at 10:49 AM

Ever wanted to know approximately what RPM a motor cranks at?  I needed to find this piece of information and had no luck searching on the 'net.

So, I measured it myself by monitoring the frequency of the distributor with my coil pack unplugged (test car was a 1995 Eagle Talon).  The coil pack was unplugged so I could crank the car for an extended period without the motor turning over.

The car idles at around 32.9 hz which equals ~1,000 RPM at 2 pulses per revolution.  While cranking the the reading was right at 7 hz which equals ~210 RPM.

I would guess this number would vary a bit from car to car (based on motor compression, cca, starter torque, etc) but I would expect it to be in that general area.

Random knowledge is great.



-------------
Kevin Pierson



Replies:

Posted By: tedmond
Date Posted: May 05, 2008 at 2:55 PM
actaully i was always curious to know because it requires alot of spark to start a car. Well thanks for the info kpierson, I learned something new today. cheers !


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