Automotive Engine Conversions

The Ellison Throttle Body injectors have been used in a number of auto engines converted for aircraft use including:  Subaru, Corvair, GM, Ford, VW, V6, V8, In-line, rotary and others.  In some applications the Ellison TBI can be bolted on and the engine will run as desired with very little adjustment, however many installations require a broad "Engine Systems" approach to ensure not only accurate fuel metering, but appropriate ignition timing, valve time, induction an exhaust system design, propeller loading, and integration with the airframe.  It can be a daunting challenge to get all the system details surrounding an auto conversion working in a safe and reliable manner.  Customers with auto engine conversions often call us with a problem they think may be due to fuel metering, but after investigating in detail there are usually other contributing factors.  While the Ellison Throttle Body Injector can be made to work in most automotive engine conversions, the aircraft builder needs to approach the use of these engines as a development exercise, and recognize that the time required to get the engine operating may rival that spent building the entire airframe!

The Ellison Body Injectors (TBI) are unsuitable for automotive use.  The TBI uses a tube with many holes to meter fuel in the venturi.  This tube is covered by a slide valve used for the throttle.  At low power settings, which are common in auto applications but not in aircraft, the fuel metering steps from slightly lean to slightly rich as the throttle is opened.  This variation in mixture results in poor fuel economy as well as illegal levels of exhaust emissions.  Aircraft, on the other hand are always above 50% power and the digital nature of the fuel metering irrelevant.