We recently had the opportunity to convert to the Rtech centrifugal supercharging system from an 8-71 Roots blower, on an engine built specifically for the Roots blower. Some of the things you may see on such an engine are:

- low compression
- big cam
- locked ignition timing
- dual carbs

None of these things are necessary or desirable with a centrifugal blower, and to make the conversion even more of a challenge the candidate was a single engine deckboat which can be heavily loaded. The owner's expectations were high, and to begin with he felt that the 8-71 did not have enough punch. The boat's manners around the dock were also less than civilized.

In this thread we will describe how this conversion was done and how the tuning of the engine changes. The final result was a gain of 7 mph and very docile behaviour around the dock. Acceleration with a full tank of fuel put a grin on four big guys' faces.

I can't upload pictures right now without getting timed out; I'll post some later.

Some after pictures.