DIY rev limiter

[Matt Beaubien]

William,

> It is difficult to build an ignition based rev limiter for an RX-7 because
> of the dual ignition system.

There's nothing quite like a good challenge ;-).

> There should be only one distributor on an RX-7.  Earlier Mazda cars had
> two, but the RX-7 should have one that has two sets of points in it.

Fair enough.  I was just going by what my friend had said.  So is there a
dual prong rotor that fires one set of plugs, rotates a bit, and then fires
the second pair?

> Backfires (actually afterburn - fire in the exhaust) is okay.  Especially
> in a racing series.  Scare your opponents, amaze your friends.

What about blowing exhaust systems off?

> The bad news is that either ignition is enough on its own to ignite the
> fuel and allow you to overrev the engine.  You have to cut both ignition
> systems.  Anyway, why do you need a rev limiter?  The redline on the RX-7
> is only there to give some color to the tachometer.  I have overrevved my
> 1st generation RX-7 all the way to 8500 RPM without damage.  (don't make a
> habit of that. :} )

Wouldn't it loose a fair bit of power with only one set firing?  My friend
said that people were revving the cars too much and reliability was becoming
a factor.  Buzzing your street occasionally to 8500 RPM may be ok but when
it's done lap after lap for extended periods of time, things fail.  The goal
is to keep the cost down (ie. relatively stock, used engines) and failures
just deter people.  Also, these cars will be run on frozen lakes in the near
future.  Even with studs, traction can be lost quite easily which spins the
engine to the moon.

If both points need to be cut, so be it.  It'd be nice if it was gentler
than that so maybe every other revolution could be interrupted?
Nonetheless, does anyone have any ideas/suggestions.

Thanks.


Matt Beaubien