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27-05-2003 TIME 18:10
THE DITECH ENGINE
New regulations will introduce even stricter emission controls and many fear that this could finally be the end of the two stroke engine. New technology is needed for the two stroke to survive. Luckily this is already with us in the form of the decidedly future proof DITECH engine.
Those who believe that the two-stroke has no future criticise its high fume and noise emission levels. Nevertheless the two-stroke engine still delivers more performance and is economically more valid than a four stroke of the same displacement. Even the world of motorcycle racing has turned its back on the once glorious two-stroke: in motocross and GP races four strokes are allowed to have nearly twice the displacement of two strokes, giving them a tremendous advantage.
Aprilia is one of the very few motorcycle manufacturers in the world to have made recent investments in two stroke technology. The effort that Aprilia has put into the DITECH project has nevertheless been vindicated by the incredible results achieved. These conclusively demonstrate that the much maligned two stroke still has a very long life in front of it thanks to its unquestionable performance, low manufacturing and operating costs, plus a new found environmental friendliness.
Aprilia has always been attentive to environmental issues. Back in 1992 Aprilia was the first manufacturer in the world to offer a two stroke scooter model with a catalytic exhaust. In 1993 Aprilia developed another innovative product, the world’s first four stroke, four valve scooter engine with an unbeatable emission/performance ratio (the engine hat was to equip the Leonardo scooter in 1996).
Since 1999, Aprilia’s efforts to prolong the life of two stroke technology have all been concentrated into the DITECH (Direct Injection Technology) engine. This revolutionary engine combines in a way never before possible the concepts of performance, record breaking economy and exceptionally low fume emissions. In the innovative DITECH fuel system, developed and manufactured entirely by Aprilia, fuel no longer enters the crankcase mixed with lubricant (as in conventional two stroke units), but is injected directly into the combustion chamber under the control of a system of sensors connected to an electronic control unit. The results achieved by this new technology are amazing to say the least. Fuel consumption is down 40% compared to a conventional two stroke engine, and can be even 50% less under constant speed riding conditions. Record distances of 50 kilometres have been achieved with just one litre. Compare this with an average consumption of 29 km/litre for conventional catalysed two-strokes. Even lubricant consumption is down by up to 50%.
But the most incredible news has yet to come. The real surprise from Aprilia’s DITECH two stroke is that emissions are down by an astonishing 80% compared to a traditional Euro 1 rated 50 cc two stroke It is therefore no surprise to learn that Aprilia’s DITECH engine is able to satisfy the new Euro 2 standards even without a catalytic converter in the exhaust. In greater detail, pollutant emissions are down by 80% for CO (carbon monoxide) and by 60% for HC + Nox (unburned hydrocarbons and nitrogen oxides). Also, because DITECH engines do not need catalysers, exhaust efficiency remains unaltered. The problem of exhaust clogging is eliminated, and DITECH exhausts do not require the same levels of maintenance as catalytic exhausts. Another significant benefit is that exhaust smoke is almost totally eliminated, something that only a miracle could have achieved on older two strokes.
Yet all this has been achieved without penalising overall engine performance. On the contrary, DITECH engines offer even better performance in terms of smooth power delivery and stable idling thanks to constant, optimised combustion at all engine speeds. Compared to a conventional 50 cc catalytic two stroke, the Aprilia DITECH engine gives 15% better acceleration over 100 metres. Initially applied to the liquid cooled engine of the SR 50 sports scooter, DITECH technology has recently been transferred to the air cooled engine of the Scarabeo 50, now available in a new DITECH version. This should put paid once and for all to any doubts about the wisdom of purchasing a two stroke 50 cc scooter instead of one of the four stroke alternatives which simply do not offer similar levels of performance. The saving graces and ace cards of the two stroke engine therefore remain its mechanical simplicity, high specific power, low weight and compact size, reliability and low manufacturing costs. Also, so far no really competitive alternative has emerged. Four stroke 50’s have just not caught on for their high costs and poor performance. Electric motors fare even worse: the problems are the same but far more serious, and limited autonomy practically rules them out. So once again, Aprilia has had the courage to leave the pack. And the future will prove us right.
