I suppose I might as well wade into this one as well.

 

I'm sure this will ruffle a feather or two out there, but I would be a little leary of installing a engine that wasn't at least related to a certified design. There are no shoulders to pull over to on the highway in the sky. 

 

I know modern auto engines are extremely reliable, but they aren't really intended to operate at high power for more than a fraction of their operating life and they still lack redundant ignition systems. Sure, you could add a second one yourself, but where are you going to put the second spark plug? Not the sort of thing you are going to coble up in your garage. Then there is the issue of the PSRU. Without one, you won't find much benefit from an auto engine. Many aircraft designs over the years have used them and some are still in production today, so they can be reliable. However, designing these components to survive the driveline vibration between the engine and propellor and to be reasonably light at the same time is challenging. If you are going to design / produce it yourself, you would want to be a sharp engineer. Simply adapting one from another application is a crap shoot, since the system impulses and harmonics are likely to be very different.

 

If you want an LS1 derivative engine, check out Silver Wings Aviation and the old Engine Air power plant. If they are still solvent, they have a product that has gone through its trials and tribulations, but is actually flying in a handfull of airplanes. They have had some well publicized failures that you might want to look up. Last I knew, they claimed to be seeking certicification for the design.

 

Rob