Why not do an instructional video and sell those instead? You do the video once and your done. Then sell support via phone at a fee?
That way when it doesn't work because the owner screwed it up you get paid!
And of course there is always version two and three and four of your video.
1. Video one: Wiring and Sensors
2. Video two: Turbos and intercoolers
3. Video three: Specific applications to the 240,260, 280, 510
Reason I mention this is I'm into Surfing. I wanted to build a surfboard myself. There were specific videos that I bought showing you materials and how to's. After I was done watching them, I decided not to do it.
But the creater of the video still got paid!
I'm not one for spelling either, sorry if I came across snotty.