Ideas on stoppin some pingin?

[Nilsson, Zak]

>> Only happens on wider open throttle positions such as going up a hill

Basic detonation explanation:

You get detonation when the in-cylinder temperature gets too
high. What happens is that some of the unburned combustion end gases
self ignite due to the high temps after the spark has already burned
the fuel charge. This end gas burns extremely quickly due to the high
temperature and it forms a shock front because of the sudden change in
pressure. That shock front hitting your cylinder wall, or piston ring,
or head is the "pinging" you can hear when you're detonating. I mean,
think about how hard that shock front has to be hitting your piston in
order for you to hear the impact inside the cabin.Hard enough to take
small chunks out of your cylinder wall, head and piston (crown, rings,
etc). Obviously if you ever hear detonation, back off immediately.

A whole lot of things can cause that and/or contribute to it. The more
you compress something, the hotter it gets which is why lowering your
compression ratio works for helping to prevent detonation. The temp
of your intake charge is usually a large factor also, which is why
both intercooling and water injection (and intercooler spraying) work
to help prevent detonation. The cooler and denser the intake charge,
the cooler the in-cylinder temperature. The reason you'll sometimes
hear detonation at low RPM in a high gear when the car is lugging, but
not at higher RPM is the speed of the combustion cycle. As mentioned
before, detonation is the self ignition of unburned end gases at the
end of the combustion cycle. If your combustion cycle increases speed,
there isn't enough time for the unburned end gases to ignite before
another cycle starts. So if you're detonating and letting off the
throttle isn't helping, try increasing RPM for a quick fix until you
can pull over.

Some more things you can try would be reducing boost... less heat,
less chance for detonation. Retard your timing. It serves the same
purpose as increasing RPM, i.e. increasing the speed of the combustion
cycle, preventing detonation from occurring. That would be another
good roadside fix. It's possible you've got too much backpressure
going on, how restrictive is your exhaust? The more backpressure
you have, the less heat is able to escape the cylinder during the
exhaust stroke and the hotter it gets, contributing to the onset of
detonation. Also, you can try a faster burning fuel like benzene,
or a more breakdown-resistant fuel like toluene or isooctane. The
more resistant it is to breaking down, the longer it will take for
those end gases to self ignite.

So obviously there's a lot of possible reasons that you're
detonating. I like that story about the buildup on the pistons
effectively increasing compression, that was pretty cool.  :)  But if
you're going to troubleshoot, start at the root cause for detonation:
heat. Look at the possible causes and see if there's anything you
can do about it.Hope that helps.

-Zak