E85 Flexible-Fuel Capability (LE9)
GM has led the industry in introducing flex-fuel capability to its cars and trucks, and the new flex-fuel 2.2L I-4 VVT ( LE8 ) extends availability to an even broader range of customers. E85 is a clean-burning alternative fuel made in the United States from corn and other crops, composed of 85 percent ethanol alcohol and 15 percent gasoline. The 2.2L's flex-fuel technology is both sophisticated and durable.
Flex fuel engines require special valves and valve seats to withstand the wear and corrosive effects of ethanol. The nitrided Silcrome 1 intake valves and 21-43 exhaust valves used in the 2.2L I-4 are up to the challenge. Compared to conventional iron-alloy valve material, nitrided Silcrome 1 includes tungsten, vanadium, manganese, silicone and higher chromium content. It is harder, and it improves durability, even under the rigors of ethanol operation. The 21-43 exhaust valves work equally well. Valve seat inserts have been upgraded to premium materials with a high percent of tool steel and solid lubricants resulting in excellent durability whether E85 or gasoline is run in the engine.
Hardware changes for flex-fuel operation are limited to the injectors. Because ethanol has fewer BTUs (less energy) than the same volume of gasoline, more fuel is required to produce the same horsepower at wide-open throttle. Flex fuel engines use unique stainless injectors with a greater cone angle and higher maximum fuel-flow rate. The fuel rail matches the injectors, but it's manufactured of the same stainless steel used for all 2.2L I-4 fuel rails.
The flex-fuel 2.2L doesn't require a special fuel sensor. The first flex-fuel engines used a light-reactive sensor to measure fuel composition from 100 percent gasoline to 85 percent ethanol. The 2.2L has a virtual sensor-software programmed in the E37 ECM with no separate physical sensor whatsoever. Based on readings from the oxygen (O2) sensors, fuel level sensor and vehicle speed sensors, the ECM adjusts the length of time the fuel injectors open for the type of fuel used. Within a few miles after filling up, the E37 controller determines what fuel is powering the 2.2L I-4 and manages the engine accordingly.
E85 fuel provides an environmentally friendly companion or alternative to gasoline. It is biodegradable and doesn't contaminate the water supply. Ethanol can be produced from various feed stocks, including corn and wheat stalks, forestry and agricultural waste, and even municipal waste.