E85 conversions

The series II VE Commodore fitted with 3.0 litre and 6 litre engines released in late 2010 were the first Australian made vehicles to offer flex-fuel capability, though some earlier imported Saab and Chrysler models sold in Australia are also flex-fuel capable.

Flex-fuel vehicles can run on straight unleaded, or petrol / ethanol blends up to 85 percent (E85).

While E85 is relatively new to Australian motorists, high percentage ethanol fuels aren’t new in global terms and the technology to run them is well understood by vehicle makers.

There are many changes to the fuel and engine management systems of these vehicles to ensure proper performance and durability. For the flex-fuel Commodore, Holden introduced stainless steel fuel tanks and lines and different engine valves and valve seats.  E85 compatible fuel pumps, hoses and fuel sender units are fitted. The engine management system can identify the amount of ethanol in the tank and adjust the engine management system mapping accordingly. 

A number of after-market ‘conversion kits’ claim to enable engines not so designed, to run on fuel blends containing up to 85 percent ethanol.

Basically, they interface with the engine’s management system and increase the injector opening time to enrichen the fuel / air mixture, compensating for the significant mixture leaning produced by high concentrations of ethanol. For E85, about 30 percent more fuel needs to be delivered to the engine to compensate for this leaning effect.

Many provide a manual enrichment-factor adjustment, but guesswork is required to determine the actual percentage of ethanol in the tank at any time and therefore the level of enrichment needed.  In production flex-fuel vehicles, this is achieved automatically by the engine management system via a flex-fuel sensor in the fuel line, with the necessary enrichment varying depending on the actual fuel blend being delivered to the engine at any given time. 

We remain sceptical about such unsophisticated conversions as, while they may provide a hit or miss method of addressing the fuel mixture issue and therefore the drivability problems that will arise, the resulting fuel mixture, and consequently the vehicle’s exhaust emissions, will be based entirely on guesswork.   

Nor do these conversions address all the other compatibility issues the car makers attend to for proper performance and durability.

Vehicle owners should not overlook the fact that they have a legal obligation to comply with and maintain their vehicle’s emission compliance. If considering such conversion products always obtain a written guarantee that the product has been tested and is legal for use in Australia.

Like any modification, such conversions may put your new car warranty at risk if it can be shown that the device has caused or contributed to a fault.