plugs & hp increases

[Andrew Rabbitt]

> if the platinums run hotter then, if the system were at it's
> limit, it'd start to detonate or pre-ignite (can't get that
> straight  8^)  ....  
> 
If you get pre-ignition, it doesn't matter what spark-plug you have,
'cos it's not doing much for you! :)

> and combustion chamber design affects
> things like that, so different types of engines could
> conceivably not like platinum plugs ..... just a thought
> 
I suspect what's happening is you're changing the burn rate, which
effectively changes the ignition angle (sort of).  Since most cars run
retarded at idle (to maintain catalyst temps and reduce combustion
noise), if you slow the burn rate down further (by changing plugs), you
could fall off the ragged edge, hence the unstable idle control.

This is just a theory, of course.

Andrew Rabbitt