I've been watching a fair bit of top gear on On-Demand TV recently, and I love the show. I think it's funny, informative, well put together and all around enjoyable... But Jeremy Clarkson is annoying me horrendously And for once it’s not because he’s a bike-hater. (What’s the problem Jezza? Can’t keep up? :tongue: ) No – this time it’s because, having watched a lot of Top Gear in recent times, it’s obvious the man has not the faintest clue what he’s talking about when it comes to engines, power outputs etc. yet is considered to be the voice of the nation in all matters motoring-related. Oh yes he can spout back all the figures, but he obviously doesn't know what they mean. Speaking about the current power war between Mercedes and BMW: “Nobody actually knows what a torque is…” Actually mate – lots of people do. Torque is the measurement of turning force of a rotating shaft – either measured in pound-feet – abbreviated to lb/ft or newton-metres. Generally speaking, even though it’s an imperial measurement in a metric society, pound-feet are still used in the motor industry. One lb/ft of torque is a turning force of one pound, one foot from the centre of the rotating shaft. The last episode I saw was an old one that had him fawning over a jaguar and deriding the Vauxhall Monaro for “…only getting 300bhp out of a huge 5 litre V8 when the British have got 450bhp out of a 3.5litre V6.” OK, back to school…. First things first – bhp is NOT an absolute measure of power. It’s an entirely arbitrary mathematical value calculated by the following formula: bhp = (2pi X torque X engine revs) divided by 550 We already know what torque is. Engine revs are in revs per second. Pi never changes and I’ll use 3.142 as the standard value. So for a car that makes 100lb/ft of torque at 3500rpm (58.3rps) the equation is: (6.284 X 100 X 58.3) /550 = 66.61 – Nearly 67bhp – a modest figure. However, engines can be tuned to either make their peak torque higher or lower in the rev range. Since Pi is a constant, and torque is the absolute value, bhp can be artificially raised by tuning the engine to be revvier and produce it’s peak torque higher up the rev range. So let’s imagine the manufacturer tunes the same engine to give the same torque at 5000rpm (83.3rps) (6.284 X 100 X 83.3) /550 = 95.17 – 95bhp which sounds a lot healthier though the ACTUAL FORCE hasn’t changed. The manufacturer can then – quite legally – market this new version as the souped up sports version with a higher bhp…. despite the fact that you’ve got to rev it harder to get the same peak torque out of it making it far worse to drive! Never was this clearer than with motorcycle engines. 2003 Suzuki GSX1400 – 1.4 litre inline 4 four-stroke. 104.5lb/ft of torque at 5,000rpm (6.284 X 104.5 X 83.3) /550 = 99.4 – near as makes no odds 100bhp 2006 Yamah R6 – 599cc inline 4 four-stroke. (less than half the size)50.6lb/ft of torque at 13,000rpm (less than half the peak torque) (6.284 X 50.6 X 216.7) /550 = 125.3bhp – over 25% higher bhp figure from a less powerful motor – simply by revving it to death! BHP is a meaningless value. it's Torque that's the absolute - and he's already admitted he doesn't know what torque is! And this man was given an honorary doctorate in engineering. Can I have mine now?