RE: I converted a glow engine to run on E85
Today I converted my Saito 120 to spark ignition and E85. The Saito carb is fine on top end and idle, but midrange is very rich. I think these Saito engines were set up to use high-nitro fuels, up to 30%, so they flow lots of fuel in the midrange. This leads me to think that an engine set up for FAI or moderate nitro would work better with the E85. I need to change the spraybar profile a little in the midrange. I know it's the mixture because I can pinch the fuel line and smooth it out. I soldered the hole in the spraybar closed, and then opened it back up again with a little smaller slit. The Saito spraybar is very difficult to work on, I couldn't get it out of the carb body to save my life. I resorted to scraping at it with a sharpened screwdriver and hobby blade. We'll see tomorrow if that is better. I know it's a lot leaner in the midrange now, maybe too lean?
One thing I recently learned is that nitromethane has a fuel/air ratio of 1: 1.6 which is very different from methanol at 1:6 or ethanol which is around 1:9, or gasoline which is 1:15. I'll bet E85 is somewhere around 1:10 since it's a mixture. So anything designed to run a lot of nitro glow fuel is going to be very rich on low-nitro glow fuel or ethanol or gasoline. I never was really impressed with the way the engine transitioned on even 15% nitro glow fuel, so I know why the midrange is even richer on this carb. The ASP 1.08 I converted was designed to run on low nitro fuel. I was able to dial that carb in to perfection, utter perfection. That motor never ran so good. Oh I also converted my 18cc Poulan leaf blower to E85 today, that was no more complicated than just opening the main needle valve a half turn. I started it up with gasoline in the fuel lines, and gradually it burned that out and transitioned to E85 with 4% castor. That made finding the new needle position real easy, I just kept adjusting it as it ran until it smoothed out and stopped changing. It is so much nicer to work with the E85, it has a slight gasoline odor but it's not a stinkbomb on your hands like gasoline. My experience with this fuel change has shown me why in the past I've had to change glow fuels to really dial in an engine. I cannot imagine flying with 30% nitro like many Saito owners do, but now I know why those engines really like it. -Tom