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A German test

 

P6

The motor of the Adler MB 250 achieves its peak performance of 16.4 PS at 5600 rpm.  The fifteen minute performance was precisely determined at 16PS.  The torque lay at 2.0mkg between 4,000 and 5800 rpm

When, about ten years ago, I published the performance characteristics of the M 250 and gave 16ps at a revolution of 5600 rpm - measured as 15 minute-performance under quite moderate cooling conditions - I encountered only unbelieving faces.  But of the four motors which I tested, subsequently to the VFM-type evaluation of the series, the weakest had 15.8 horse-power, the strongest 16.4 horse-power.  And, since then the sports-version has shown at the Rheinland-tour and at other competitions what reserves are still slumbering in this motor.

No, these 16 horsepower were not achieved with the last constructional push-up, but are the definitely healthy result of the fundamentally correct interpretation of fuel flow rate and of ignition timing, and of the precise tuning of inlet and exhaust determined in long tests, and also of excellent mechanical precision.

 5600rpm means that with a stroke of 54mm the piston speed is 10 m/sec, that is to say a definitely tame value, and with the measured standing upright peak of 116.5 km/h, 6000rpm is only exceeded slightly.  Two full-throttle journeys from Stuttgart to Frankfurt, during which in fact acceleration was only removed very briefly, when one could not get past two trucks, and during which the mean speed lay around 100 km/h, confirms the unconditional mechanical full-throttle strength of the motor.  My co-worker Ansorg travelled from Hockenheim to Esslingen an Autobahn mean of 105 km/h.

Thermically the hunt down the Autobahn does not mean a lot, but the track and field competitions have left their traces in deep ribbing and notching in the finning, and the outstanding successes at the latest six-day trials have proven to satisfaction the thermal steadfastness of the motor.  A certain confirmation was also supplied to me by measurement, which surprised even me.  At the Autobahn test ride from Stuttgart to Frankfurt the temperature of the spark plug seat (measured with a liquid thermometer from Moto-Meter) stayed between 130 and 140 degrees Celsius, a surprisingly low value, as the exterior temperature after all lay between 25 and 28 degrees Celsius.

I don't quite understand the why, in the many descriptions of the Adler MB250. special emphasis is placed on the low compression.

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