tach

[partybarge341]

can a automotive tach be wired to work with a 2 stroke outboard

[Lyle29464]

Only if the car has a very strange engine.

[NYBo]

Sure it can. It just won't work right.

A proper marine tach isn't that expensive (especially if you snag one off eBay), and it will not only work properly, it will also stand up to the marine environment.

[Silvertip]

It will also turn to rust in a heartbeat. An auto tach counts pulses from the ignition system so it is number-of-cylinders dependant. Since a car has a four stroke engine, each cylinder produces one pulse for every two crankshaft rotations. A two stroke fires each cylinder ever crankshaft revolution and the tach signal is derived from the charging system so it doesn't matter if the engine has one cylinder or 100. Most outboards use a 12 pole alternator which produces 6 pulses per revolution. So -- you can do the math to determine if there is a numerical correlation, but then the auto tach may not recognize the pulse "shape" coming from the outboard so there are two issues. Do a search on this forum -- I've run those numbers for folks several times and I won't keep doing it. It is simple math.