Re: Roe\'s SC - who\'s running one?
This is some information I have been able to gather from Sean Roe and other sources about the unit.
The Roe Racing supercharger is an Opcon Autorotor. It is a Positive Displacement Twin Screw Supercharger. I have been told by the experts that it is one of the best on the market. Sean has really done his work on this unit. The fit and finish is fantastic. My Viper tech rarely comments on the quality of the mods I drop into my car, but he raved about this unit. I live in Califoirnia and run 91 octane on the street so I am currently using the VEC1 and a MSD boost retard unit supplied by Sean to make the necessary changes to air, fuel and timing. Sean is working with Autorotor on a cost effective engine management system. When he has perfected the unit, the VEC1 and MSD goes away for the much more efficient solution.
The Viper V10 is well suited for forced induction because the very large crankshaft and main bearings, the heavy valve train assembly which has two piece valves and light valve pressure and due to the engine having no camshaft bearings. The engine is built to handle a tremendous amount of power without having to reach high rpm. The SC has immediate power all the way through the power curve. This type of system pumps a constant amount of air per revolution which begins boost at a very low RPM. It also heats the air less which eliminates the need for an intercooler at lower boost. Sean's unit current runs five founds of boost.
The twin screw compressor is 75% to 85% adiabatic and volumetric efficient. A roots is commonly 40% to 55%. Common centrifugal superchargers have a peak of 65% to 80% but do just that, peak. Over an entire rpm range, a screw compressor has an average efficiency far greater than the roots or centrifugal.
Positive Displacement Twin Screw Autorotor Supercharger Operating Principles
Inlet Phase – The male and female rotors rotate counter to each other. As the lobes of each rotor travel past each inlet port, air is trapped between consecutive lobes and the cylindrical casing. The air moves axially (forward) throughout the case and fill the interlobe space between adjacent lobes.
Compression Phase – As the rotors mesh, the air is trapped between the rotors and the casing. Continued rotation progressively reduces the space occupied by the air causing compression.
Discharge Phase – Compression continues until the interlobe space becomes exposed to the outlet port, through which the air is discharged into the manifold.
The compression sequence continues on all rotor segments simultaneously. Timing gears synchronize the rotors. The rotors do not touch the casing or each other thus assuring long life, consistent performance and low power drain.
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Some of the experts may correct me on some of this, but I believe all of it to be fairly accurate.
