Re: Rotrex Guy
Well, as you know a lot depends on how much the internals and tranny will take. That said, if we take ultimate power production out of the equation (as well as its impact) and the knock characteristics of this motor are similar to others in my experience. I have been able to run 15'ish psi on 10.5:1 with my other Rotrex setups and 13 psi on 11.5:1 on pump gas (IAT's of 17 degrees Fahrenheit above ambient). Of course you reach a point of diminishing returns as boost goes up and spark comes down.
The real fun with any supercharger is finding the sweet spot between Boost, Spark, Fuel, and Parasitic loss.
Going turbo is another matter as they tend to run hotter but net more HP per psi due to no parasitic loss.
However, back to the diminishing returns statement. Max boost can be somewhat of a misnomer in that you can run a whole lot more boost than you would think as long you can pull spark and add fuel. I guess the real answer is that it depends on your particular setup; the characteristics of your power adder, fuel delivery system, and at what point adding boost fails to net a gain at the wheels on the dyno!