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The SVC project began in 1990, and at one stage Saab even had a 1.4-litre, six-cylinder unit on the go. If Saab decides to go ahead with SVC, it could have an engine in production within four years which would cost about the same as the current asymmetric turbo V6.
But the possibilities go further. Saab is already talking about using alternative fuels that the engine could detect and adapt to, from methanol (very high-octane and able to exploit a high compression ratio) to diesel, perhaps with spark-assisted ignition. However, what's next from Saab is Combustion Control.
Saab Combustion Control, or SCC, is a tricky concept to get your head around. It's driven by the need to comply with both US emissions rules, which demand the near-total cleaning-up of exhaust gases that only a three-way catalyst can give, and European rules which are less stringent about nitrogen oxides (as long as most are dealt with) but are going to get tighter on greenhouse gases (carbon dioxide, emissions of which are in exact proportion to fuel consumption).
Sounds boring, but it has to be done unless car makers have two different engine ranges for the different markets. Future lean-burn Euro engines will produce too much NOx, but absorption catalysts will absorb 85 per cent of it, which is enough for us. That's no good for the US, though, especially Los Angeles with its photochemical smogs.
Saab's SCC uses exhaust gases to fill the cylinder mainly with an inert mixture under gentle driving, so that the small amount of fuel-air mix that's left is in the chemically-correct, or stoichiometric, ratio that a three-way cat needs to work properly. What's in the cylinder is not 'lean' in the usual sense, therefore, although the economy benefits are the same.
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