Marc wrote:bikesandcars wrote:I think I need more basic ignition research...
I could be wrong but I think a rev limiter on a traditional setup (non MSD type box) works by grounding the negative terminal on the coil to the chassis ground thus collapsing the magnetic field in the coil and preventing firing.
What it sounds like here is the opposite, actually interrupting the power.
It may be better to put an always off relay between the ground and the negative wire terminal on the coil that would ground the coil when fired no?
that's a good point. cutting the power may allow a stray spark to escape. shunting the ground will prevent that one spark event from escaping by just leaving the coil charged.
good call!
Either way would likely work well enough for a rev limiter, since you only need a resolution of a couple of hundred rpm anyway, that extra spark or 3 won't cause the engine to overrev too much.
Either solution, however, would have the added bonus of throwing flames out of the exhaust on shifts, assuming your exhaust doesn't route all the way to the back of the car.
Keep in mind that a spark-only rev limiter might not be enough to keep the revs down on a white-hot turbo car running a fair amount of boost (not likely to last anyway for Lemons), nor will it help in a misshift (amazing how many people think it does). Don't ask me how I know...