Compression - How much is too much?

[oldeskewltoy]

I'm by no means the end all expert... but higher compression does NOT allow MORE air and fuel(intake charge). Cam lift and duration control the intake charge.

Higher compression allows for higher cylinder pressures which can, in of itself, produce more power from the same intake charge.

The problem becomes at one point does the added compression overheat the intake charge igniting it BEFORE the ignition ignites it.

Now... we need to add dynamic compression ratio to the equation. DCR takes into account cam duration. The longer the duration on the intake lobe, the higher the compression the engine can run. This is because the intake valve closes later in the compression cycle. This later closing compresses the intake charge to a similar pressure before iginition, as the lower compression engine did with shorter duration camshafts.

Ideally we want to maximize the intake charge and keep it cool enough to maximize the compression allowing a VERY high cylinder pressure. We can accomplish this a few ways...
1) remove the heat....
1a) lower the temp of the intake charge (intercooler?)
1b) remove hotspots inside the combustion area to remove points of pre-ignition
2) raise the temp the gas can ignite without a spark - higher octane


Books can, and already have been written on this subject. In reality it just takes someone with experience to know what to do... and more importantly what not to do.