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I have recently purchased an 800cc dune buggy but unfortunately it doesn't come with a RPM sensor so I have been looking at my options in terms of installing one. In the process I have found that the way that engines typically measure RPM is through a crankshaft position sensor (please correct me if I'm wrong).

So could someone advise how I would go about determining if my engine supports the installation of such a device and how I would go about purchasing one that would be compatible with my engine?

Any guidance would be highly appreciated.

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Do you just want a tachometer (RPM gauge), or are you planning something more involved? If you just want a gauge, have you looked into gauges that work inductively off a spark plug wire? I've seen digital gauges like these on power equipment, and I imagine you could fit them to any engine with a traditional high voltage spark plug wire (i.e. anything but coil-on-plug configurations). –  mac Oct 10 '12 at 16:21

2 Answers 2

up vote 2 down vote accepted

You don't mention the type of engine you've got or the age.

Older engines that are fitted with distributors and mechanical ignition systems typically drive their tachometers off the coil trigger wire, as this pulses each time a spark plug is fired. If that is the case, you simply need to connect a suitable tacho to the -ve terminal of the coil (i.e. the same one as the lead from the distributor).

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Sorry I would have mentioned it but it was back at the shop for some final adjustments so I didn't have it available. But really you've provided the information I need. Thank you. –  Maxim Gershkovich Oct 12 '12 at 0:56

Very much engine specific. One of my cars has a replacement engine block that came from a car that only had a cam angle sensor (and mine requires cam AND crank angle sensors). Even though it's technically the same block other than the one sensor hole missing it was still a bit of an ordeal. A hole had to be drilled and tapped (very carefully), seals fitted, etc. In my case it's been pretty good, but others (it's a fairly common swap, lots of people have done this) have reported having leaks around it that they just can't ever seem to fix.

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