People who are considering a European getaway have plenty to consider, from whether to take to the Eurotunnel or ferry to what to pack. I also often see people asking on forums, “Will 130bhp be enough to comfortably power a 4000kg ’van around Europe?” The answer to the question, of course, is “Maybe”. Would more power be better?
Well, probably yes, but it all depends on how it’s delivered. Looking at Fiat’s torque and power output curves for the 2.3 engine, max power occurs at around 3500rpm, while max torque occurs from around 1400rpm all the way up to 2500 or even 3000rpm for the 180bhp motor, and that flat torque ‘curve’ is what makes for a driveable motor.
Power and performance
A lot of importance is put on the power output of engines, usually expressed as bhp (although PS and kW are also used), but what exactly is power when we think of engine output?
Well, bhp (brake horsepower) is actually a mathematical figure, obtained by multiplying the maximum torque of an engine by the engine speed (in rpm) that it is generated at, and divided by a constant.
In other words, bhp figures are less important; what really counts is the torque figure and how it’s delivered.
Torque is simply turning force, expressed as a load figure at a set radius from the centreline of rotation.
For example, 1lb ft is a load of 1lb at a radius of 1ft, while 1Nm is a load of 1N (Newton) at 1m radius. One of the oldest sayings in the motor industry is “torque turns wheels” – something which will be rather useful when driving a motorhome!
It’s also worth bearing in mind that an engine running with no load on it makes very little torque (and therefore bhp). Only running against a load does it generate significant torque. That load is the ‘brake’ part of ‘brake horsepower’, a physical load applied to the engine on an engine dynamometer or via the wheels and transmission on a chassis dynamometer or rolling road.
Consider this example. The Suzuki Hayabusa 1300cc motorbike produces 180bhp at 9500rpm, but only manages a maximum 145Nm of torque – and it needs 7500rpm to do so.
That bike engine can churn out 180bhp (the same as the highest factory output Ducato), but would be useless in the engine bay of a motorhome, as it doesn’t provide anywhere near enough torque and is revving like crazy to make what it does.
Towards the other end of the scale would be something like the US Duramax V8 engine, all 6.6 litres of it, which can produce 1234Nm of torque at just 1600rpm and 445bhp at 2800rpm – but weighs in at a hefty 280kg and would more than fill a Ducato engine bay.
See what I had to say about replacing a Fiat Ducato door mirror after a smashed mirror housing occurred.
Image: Getty Images/iStockphoto
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