by ChrisGD4 » Wed Apr 02, 2014 10:34 pm
I have just become aware of the discussion you are having about the power band. I have enjoyed reading the banter. First, let me say I would never make such a statement about 90% without some evidence to support it. Granted, that evidence goes back to around 1988 and I fully accept things have changed. It all started when I was part of the Home Office Working Party tasked with updating Roadcraft and in particular, investigating different cornering techniques. I was at Ford’s test track at Boreham in Essex along with six other police instructors, being taught a cornering method, known as ‘the trailing throttle’. The Ford Rally Team Instructor whose name escapes me was advocating changing up at peak torque, which for the car we were using was around 4,000 revs. There are of course, three values – peak torque, peak performance and peak revs (limiter). I later made contact with the technical depts of Rover and Vauxhall Motors. Both disagreed with the Ford Rally Trainer and said 90% of where the red line starts would be around peak performance. A few weeks later the Met.Police rented exclusive use of Bruntingthorpe for the day to evaluate a number of driving techniques. Whilst there I took the opportunity to test the 90% theory. With a pair of identical cars (Rover 827) I lined up alongside one of my colleagues, Barry Craven, at the start of the long straight. We moved off together and accelerated flat out, I changed up at 90% and Barry waited to the red line before changing. However, we agreed to both use only 50% in first gear. We were neck and neck until I changed up into 3rd gear and began accelerating hard whilst Barry was finishing off 2nd gear and I began to move ahead. By the time I changed up into 5th gear, around 115 MPH I was well ahead of Barry. We changed roles with Barry changing up at 90% and again we found 90% was faster. We changed to a pair of Vauxhall Senators and got the same result. Another interesting fact we discovered was regarding automatics in Sport mode. Driven flat out they all changed automatically at the 90% mark – peak performance. So, up until I retired from Hendon in 2002 we used the 90% rule and also, never drove a car at more than 9/10ths capacity. Out of interest - There is Case Law, a Stated Case, Mansell v Regina with regards to driving 10/10ths. I would be very interested in the results if a similar test were conducted on both manual and automatic cars. If today's exerience is different - I will be quite happy and not upset in the slightest. At the moment I'm training regularly in a McLaren 12c - 0 to 62 in 3.2 seconds and we don't get the chance to use the 90%. Roundabout approaches? I will leave that for another day! All the best - Chris Gilbert
Chris Gilbert