[Adam C.]

So with the cam finished, we turn our attention to the cylinder block. There aren't a whole lot of things that we can fiddle with here.

First we will look at compression ratio. I often hear that in order to run a high flowing cylinder head you need to have high compression (I even had a twisted wedge rep tell me this once). Where does this stuff come from?

Here we move the compression ratio up and down a whole 2 points. On the low end we have what a supercharged or turbo engine would run, on the high end we're talking 110+ octane.

Remember, we are looking at the effect of compression ratio on TUNING, not power. We are seeing if by changing the compression ratio, we are changing the amount of air the engine is able to take in.

There is little difference in VE by changing the CR, in fact, the low CR case is better over most of the range. Again, this is with our huge flowing heads (300 CFM).

Note that the difference in horsepower due to compression ratio is due primarily to Thermodynamic Efficiency, and not to airflow. Here we are only looking at airflow.