Car Tech.2010

DRIVING and alcohol don't usually mix, but giving a petrol engine an occasional slug of the hard stuff could make it as fuel-efficient as a petrol-electric hybrid. So says the Ford Motor Company, which on 19 May revealed test results on a novel ethanol-assisted engine. Called a direct-injection ethanol engine, the unit runs primarily on petrol. When it needs to deliver maximum power - to climb a hill or overtake, for example - the engine management computer adds a little ethanol to the fuel injected into the combustion chambers.This arrangement allows the engine to operate at a much higher compression ratio - a measure of the amount by which the fuel-air mixture is compressed before being ignited - than normal. As a result, an average car engine can be "downsized" to one that should have around 23 per cent better fuel efficiency, Ford says.
Normally, the downside of a high compression ratio is that it encourages premature ignition or "knocking", which drastically cuts down the power output. Adding ethanol to the fuel suppresses knocking.

"We're trying to get the best of both worlds," says Paul Whitaker of AVL Powertrain Engineering of Plymouth, Michigan, which is developing the technology with Ford. "It's like knock suppression on demand." Test results on a pickup truck fitted with the new engine were presented at the US Department of Energy's annual vehicle technology review meeting in Arlington, Virginia. They showed a 23 per cent improvement in fuel efficiency for the same performance levels. The ethanol from a 40-litre auxiliary tank would last about 30,000 kilometres, Ford says.Whitaker says the next step is to road test the engine in a variety of vehicles and to ensure that the engine does not become unusable if the ethanol tank runs dry. Ford's announcement of the test results came as President Barack Obama announced regulations that will require the fuel economy of new cars and light trucks to be raised by an average of 30 per cent by 2016. Obama predicts that consumers might have to pay an extra $1300 per vehicle to get that extra efficiency. Ford says its ethanol-assisted engine will cost $1100 to $1500 more than a conventional engine.
This is just one-third of the extra cost of a hybrid petrol-electric engine over a normal petrol engine. Hybrids typically deliver 25 to 35 per cent better fuel economy than a conventional engine.