I'm hoping that is where this will lead. These kind of opensource projects often fork off into related projects. Adapting OpenAero EFI (Anyone have other name proposals?) to 1/2 VW should be almost as simple as changing the timing in the software and mounting the sensors. From there to the O-100 it's not much more than a higher flow injectors.
And Ross reports that, while he has sold some SDS systems to full VW owners, the folks flying VWs have generally been reluctant to spend the money for this fully engineered and supported solution. So, maybe some people using VWs would be interested, too, if the architecture can be stretched to deliver 7 GPH. The VW heads could really benefit from port injection--many induction systems are far from balanced, and being able to richen-up the mix on one or two problematic cylinders as a temporary measure to get CHTs down in a climb would be very welcome. There are quite a few full VWs flying out there--many more than 1/2VWs and industrial engines combined.
Power hog is relative. The Kohler EFI engine comes with either a 20 or 25 amp alternator. That means that 20 amps is enough to run a small EFI and have enough left over to run some other electrical load.
And the B&S EFI systems come on engines with alternators as small as 7 amps (no starter or engine battery), so there's that.
The B&S 810cc EFI engines have a list price about $250 more than the same engines with a carburetor. While list price reflects market forces (not costs), it does at least indicate that the EFI parts & installation probably isn't costing them much more than about $250 above the price of a carb.
But a lot of these kind of specifics, while needing to be determined, probably should be left for later in the process?
Yes. Still, a feasibility assessment might be needed at an early stage. If the parts (fuel pump, injectors, CPU/controller, sensors, new throttle body, mounts for injectors, cockpit controls and display, etc) are going to cost $1000, then . . . .
If we can take a step back and see what we actually require from a system, we will likely find we don't a complex one.
Mixture accuracy of car EFIs is very accurate to meet emission requirements. For an engine with no cat, we can slacken these requirements a lot and still have trouble measuring a power or economy change. I'm away from my books right now, but I think something like +/- 5% would be fine for us. That will allow simpler and cruder fuelling implementations. We can use methods that are inadequate for meeting EPA requirements, but will still provide some advantage over carbs. I suspect that altitude compensation being the main one.
A significant source of inflight engine failure is carb ice. Yes, it is avoidable, but even some very competent pilots have been stung. So, while carbs seldom fail, it's worth including carb ice when we weigh reliabiliity of EFI vs a carb.
Maybe the small/simple EFI quest will branch into two efforts:
1)
Bare bones, simple and cheap: Minimal sensors, no attempt to provide info to external systems, reliance on pilot actions to fine-tune mixture to each cylinder based on EGT. Maybe a small dedicated display in the cockpit for fuel flow, RPM, etc.
2)
Highly automated, fuel efficient, fully integrated with other aircraft systems: Full sensor suite, full exchange with other systems (CANBus, etc).
