Here is an interesting article from www.autospeed.com


Thankyou for your article on power v torque. I now understand the basic concepts of how torque, power and rpm are related - though I still have some questions when comparing a high power, low torque engine to a high torque, lower power engine. For example... The 1989 Bentley Eight has a huge 6.8-litre V8 that, I read, has 420Nm of torque and surprisingly low 154KW of power. I found this odd so I went on the web found your great site, did the math and concluded it must rev to only about 3200 rpm!

Now let's take Honda's 2.0-litre engine from the S2000 that develops 176kW at 8300 rpm and therefore has 203Nm (they claim 208Nm) and stick it into a big heavy Bentley. Drag it against the standard Bentley and which would win? On paper the one with more power should win, but in real life I don't see how a revy little 2.0-litre could pull a 2-tonne car faster than a big V8 with a truckload of torque.

Andrew McCluskey
Australia

Wow - here's an interesting one!

Gearing would play a major part in determining the standing start performance of the S2000 engine'd Bentley; if the gearing were too tall, it might take several seconds just to get the 'revy little motor' up to the zone where it has a power advantage. We imagine the necessary gearing would be so short and closely stacked you'd need to make a multitude of gearchanges on sprints to, say, 100 km/h; the gearshifts themselves would cause their own time loss. The Bentley, therefore, would probably win.

In rolling times, though, the VTEC motor could easily be zapped up to around 8000 rpm (with the right gearing) and, yes, it would pull away from the less powerful but torquier Bentley motor