Date: 18 Dec 2001 05:30:41 -0800 From: johsnopsamanytime.co.uk (Johannes H Andersen) Subject: Re: Torque and Power
"pmg" <pmgnopsamytogroup.com.au> wrote in message news:<3c1e6ac0$0$25276$afc38c87nopsam.optusnet.com.au>... > Thanks H > That was a great explanation.........all understood > > Pete the satisfied At a particular engine RPM, the relationship between torque and power is: Power = constant * RPM * torque This means that we can deduct everything we want to know from the torque curve as function of RPM. I wish I could show an example of the torque curve. The maximum power can be found by: d(Power)/d(RPM) = 0 Hence at maximum power: 0 = torque + RPM * d(torque)/D(RPM) Or d(torque)/d(RPM) = - torque/RPM at maximum power i.e. the torque curve always slopes downwards at maximum power. From this we can conclude that the maximum torque happens at an RPM before maximum power. The torque curve can have many different shapes, it may be flat before it drops off, or it raises to a peak just before it drops off. In the latter case, the engine works almost like an on/off switch. This may be OK for a racing car where the driver doesn't mind constantly revving up the engine, but it would not be very pleasant for general use. I remember a popular forms of tuning involving "sports" camshaft. This was quite bad because although power was increased, the torque curve shifted in the wrong direction. In contrast, turbocharging is a very benign form of tuning. Johannes
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