Quote:
Originally Posted by redpoint5
Wouldn't the direct injection eliminate pre-detonation? What is the limiting factor on CR if the fuel is directly injected? Can't we just go 20/1 and run the gas engine like a heat engine with no spark plugs?
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...Google "HCCI engine" and see what Ford (and others) are already doing in this area, ie: gasoline-fueled diesel-like engine. From WIKI:
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As of August 2007 there were no HCCI engines being produced in commercial scale. However several car manufacturers have fully functioning HCCI prototypes:
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General Motors has demonstrated Opel Vectra and Saturn Aura with modified HCCI engines.
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Mercedes-Benz has developed a prototype engine called DiesOtto, with controlled auto ignition. It was displayed in its F 700 concept car at the 2007 Frankfurt Auto Show.
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Volkswagen are developing two types of engine for HCCI operation. The first, called Combined Combustion System or CCS, is based on the VW Group 2.0-litre diesel engine but uses homogenous intake charge rather than traditional diesel injection. It requires the use of synthetic fuel to achieve maximum benefit. The second is called Gasoline Compression Ignition or GCI; it uses HCCI when cruising and spark ignition when accelerating. Both engines have been demonstrated in Touran prototypes, and the company expects them to be ready for production in about 2015.
• In May 2008, General Motors gave Auto Express access to a Vauxhall Insignia prototype fitted with a 2.2-litre HCCI engine, which will be offered alongside their ecoFLEX range of small-capacity, turbocharged petrol and diesel engines when the car goes into production. Official figures are not yet available, but fuel economy is expected to be in the region of 43mpg with carbon dioxide emissions of about 150 grams per kilometre, improving on the 37mpg and 180g/km produced by the current 2.2-litre petrol engine. The new engine operates in HCCI mode at low speeds or when cruising, switching to conventional spark-ignition when the throttle is opened.
• In October 2005, the Wall Street Journal reported that
Honda was developing an HCCI engine as part of an effort to produce a next generation hybrid car.
• Oxy-Gen Combustion a UK based Clean Technology company has produced a full load HCCI concept engine with the aid of Michelin and Shell.
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...gasoline, by itself, tends to be too
inconsistent about ignition, unlike diesel fuel, but they're all working on it because the Diesel cycle is much
more efficient than the normal gasoline Otto cycle.