Hi, the info from B&S for the EFI system is a bit sketchy at the moment. It is an open-loop system from Kokusan and completely different to the Delphi EFI on the 810 and the big block engines:
Vanguard has also developed a horizontal shaft small-block (627 cc) engine, with an initial application in fire and rescue equipment. Offered in a 23 gross hp rating, the engine incorporates an open-loop EFI system developed by Japan’s Kokusan Denki Co. Ltd. and has the ability to be operated with either an electric starting system using a battery or a recoil starting system. “This one is a bit unique,” Leech said. “It’s completely different than the Delphi system we use on the other engines in that it can work with a battery or without. Kokusan developed a technology that Delphi did not have.” Batteryless EFI itself is not new, as it has been a staple on small two- and four-stroke engines used on such things as off-road motorcycles and snowmobiles. The Kokusan system uses energy generated by the pull of the recoil starter to power the engine control unit (ECU), fuel pump and injectors — in that order — to start the engine. The Vanguard small-block engine with recoil start has been specified by a global manufacturer of fire equipment for a portable generator set used in fire and rescue applications
I bet that will create quite some interest in the flying apparatus circles. If the EFI is using a MAP sensor or mass flow meter, the EFI would be fully altitude-compensating to 3,000+ meters (10,000'). Unfortunately, I haven't been able to source a parts manual yet to check what components are used in the EFI system.
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These are V-twins. Might be interesting to see if there's a way to alter the 90* timing to the rotary's 180 & deliver enough fuel for a rotary using this system & larger injectors...