The challenge:

Renewable fuel based on alcohols, like Methanol, Ethanol and Butanol, show great advantages not only in CO₂ reduction, but also in the engine’s efficiency and its maximum performance. They are however more difficult to vaporize than gasoline, which means difficulties at start up and in general when it is cold.

Hence the temperature of the air needs to be increased to be able to mix and ignite the fuel. Compression Ratio: conventional spark ignited engines, compression is limited by knocking at full load and hot conditions. With conventional valve systems, this means that the compression ratio needs to be low enough to run full load with the most knock-prone fuel (lowest octane number allowed in the engine).

With Free valve system, the effective compression ratio can be lowered on demand by reducing the amount of air in the cylinder before compression (Miller or Atkinson cycle).

This allows the engine compression ratio to be optimized for a high-octane number (like 100% alcohol fuels) and still be able to run full load with lower octane fuels (like Regular Gasoline). The engine will deliver less torque and power with gasoline compared to a low compression ratio engine but will be more fuel efficient.

Hence, the compression ratio for a Multi fuel engine with Free valve system is likely to be set to 15:1 or higher. Increasing compression ratio from 10 to 15 will increase temperature.

This will give very high performance and fuel efficiency with alcohol fuels and excellent start ability, while still being able to run on normal gasoline and similar fuels. Surface ignition: The ceramic hot plate and glow plug-based surface ignition methods have been tested and compared.Tests were performed in a single cylinder CI engines with a compression ratio 16.9.The engine was modified to implement SURFACE IGNITION of neat methanol.Flexible fuels vehicles are based on dual fuels systems that supply two fuels in to the combustion chamber simultaneously at various calibrated proportions.The most common fuels are gasoline and ethanol.Surface ignition concept that allows alcohol fuels to be used in neat form with normal compression ratio.Surface technology nominal clature as defined when piston assembly along with the cylinder head with

1. PSZpiece embedded in the cylinder head
2. Insulated terminal,
3. Injector,
4. Cylinder head,
5. Heated wire andshield,
6. Piston assembly. 

The dual fuels mode utilizes two fuels simultaneously while in bi-fuel mode,the engines run with one fuels at once.Dual and bi-fuel modes require two separate fuels storage.The dual fuels mode is generally preferable for compression ignition engines with a low reactivity fuels like CNG, HYDROGEN OR BIOGAS i.