Dealing with knock

As shown in this example when the knock detection system had to take action, can it be dealt with by adding fuel instead of retarding timing? how would the engine respond to it?

You can try adding fuel and this may be effective. Anything that cools the combustion charge temperature will help reduce the likelihood of knock. Retarding timing is the quickest and most effective way of reducing knock which is why this is the method knock detection systems use. When we're tuning though we can attempt a richer mixture in an engine that's very knock sensitive and sometimes that will allow us to use more ignition advance and achieve more power without knock.

G'day Agustin.

Running a richer mixture can absolutely help with knock, as the extra fuel helps to cool the combustion charge. However, depending on the circumstance, knock can very quickly be damaging, and the sure fire way to deal with it is to pull some ignition advance, so it's the common strategy.

Pulling ignition timing is also marginally quicker than adding extra fuel, as the ignition timing can be pulled on the very next combustion event, but depending on the setup of the fuel injectors, the fuel may already have been injected.

Our practical dyno tuning course has a really great section on this though, where we let you advance the timing till knock is detected, recording the advance at while this occurred. You then adjust the fuel table to richen it up and repeat the test, seeing the difference in the advance angle where you first encounter knock.