If nothing else, the thinking behind the 99kW/135hp Valtra-Valmet 8350 HiTech should stir debate. The theory is that by reducing engine rated speed to 1,800rpm from the more conventional 2,000rpm plus, the tractor should be quieter and more economical, too. There is no denying the logic, but what of the other less obvious effects of reducing engine revs on tractor performance? Our test seeks to provide the answers

The Finns have something of a reputation for engine innovation, for taking an imaginative approach to squeezing more grunt out of a litre of diesel.

Sigma Power, as featured on the flagship 118kW/160hp model 8750 (profi 6/97), is a case in point; it uses electronics and boost controllers to pump out an additional 30hp when on heavy pto work. Now, on the smaller 8350, Valtra has adopted a different approach, this time limiting the engine speed on the 620 DSRIE Sisu engine to 1,800rpm and tailoring the other engine characteristics to suit. In effect, the designers have taken the more powerful 8450’s 103kW/140hp, achieved at 2,200rpm, and tweaked it. The result, says Valtra, is a reduction in fuel consumption of 5-10% and, importantly for the operator, a commensurate reduction for in-cab noise levels of 3-4dB(A). So that’s the verdict according to Valtra. But does the DLG test station agree? The answer: Yes, in part. Our test tractor performed much as Valtra indicated it would, burning 246g of fuel per kWh at rated speed and full load, consumption that is down nearly 10% on other previously tested Valmets. Performance at other work levels were also down 5-10%, which suggests that farmers should indeed save around 10% on diesel costs when compared with other Valmet tractors. The caveat, however, is that the 8350’s fuel economy still only rates a ‘good average’ when compared with rival models from other manufacturers – no more, no less.

Pto output at rated speed (1,800rpm) was 92kW, rising to 96.9kW at only 1,600rpm and only dropping below the 92kW mark at a lowly 1,400rpm. That means that output is maintained constant through more than 22% of the speed range, with the tractor providing an extra power of as much as 5kW – very good results.

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