The transmission

Abstract

Unlike the steam engine, the petrol engine is characterized by a lack of flexibility in its torque range. At tick-over speeds of 500–700 r.p.m., or thereabouts, on the modern car engine all the power produced in the combustion chamber is absorbed in overcoming the internal resistance of the engine. With the throttle almost closed, at tick-over, however, satisfactory carburation is achieved. If the clutch is engaged and the throttle opened wider the experienced driver knows that the engine speed must rise to 1000–1500 r.p.m. before the clutch is fully engaged or the torque transmitted will be insufficient and the engine will stall. The lack of torque at low engine speeds and large throttle openings is entirely a question of carburettor limitations. Large throttle openings at low speeds cause a breakdown in carburation since the air velocity in the induction tract becomes too low to carry the fuel droplets in suspension. With the relatively large choke sizes used on sports cars this effect is aggravated.

‘Consider that men will do the same things nevertheless, even though thou shouldst burst.’

Marcus Aurelius