a power boost
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• Four-valve cylinder heads, electronically controlled fuel injection systems and higher power outputs are among the developments Scania expects to see on heavy diesel engines in the next 10 years.
Hakan Samuelsson, head of powertrain development, said at Scania's new factory at Angers in France that four valve heads improve gas flow and allow for central location of the fuel injectors, which aids combustion. Electronically controlled fuel injection, such as the Cummins CELECT system, with either in-line or unit injection systems will be needed for Euro-2 and Euro-3 emissions limits set for the late 1990s.
Samuelsson also predicts redesigned pistons and new materials used in their construction: "Higher placed piston rings are also beneficial in reducing the volume between the top ring and piston crown — an inefficient area for combustion".
Turbo lag will be reduced by using variable geometry turbochargers which can also help to reduce diesel smoke.
Using results from Scania's STRASS road simulation programme Samuelsson calculated that by 2000 I believe it is likely that we will see engines with a power output of 400-425hp for those operating on normal roads, and engines up to 525550hp for operations in hilly country or at higher GVW." The figures quoted are for operation at 44 tonnes GVW.
Among other changes, Samuelsson sees a need for the increasing use of retarders and better exhaust brakes "to increase downhill speed safely." On transmissions, he believes that synchromesh gearboxes will become more commonplace, but that synchronisation might be by electronic rather than mechanical means.
Samuelsson also indicated that Scania's electronic braking system, is now undergoing field trials but thought that it would be "some time yet" before the system is marketed.