Chris Gilbert: "No more than 90% of the power band"

[true blue]

Ironically, I more often use the top end of the rev range in high performance cars in which the sound stirs the soul than in the lowest performance car which I drive regularly, which sounds to me as though it is being thrashed when you go beyond 4,500 rpm.

Yes, but if I'm right your daily driver is a diesel! (Though admittedly one that feels like it puts my 'high performance' 4.0l petrol engined car to shame).

[zadocbrown]

Maybe we are taking Chris Gilbert's statement out of context. Obviously posters here are correct in terms of squeezing the last drop of performance out of a vehicle. CG must surely realise this though? I don't think he is into motorsport, so I suspect his advice is a pragmatic approach to road driving. Driving on road in a typical road car I would agree there is no practical gain in bouncing off the rev limiter all the time.

But apparently he says: 'beyond the 90% because you're actually loosing performance'.

That is wrong regardless of context.

Yes and no. I think beyond 90% most engines will be losing performance - the question is whether you lose more performance by changing up. The answer is yes, but maybe not very much.

[ppjs]

I did a day recently with CG to establish in my own mind how I might learn from him. During the course of the day, I discovered that as part of his instructional duties at Hendon he spent regular days at tracks and other proving facilities (with drivers from other disciplines, designers and others who might be thought to know a thing or two) where considerable time was spent measuring performance of engines, brakes, suspensions etc.

I don't think CG is infallible (actually, I don't think he does either), but he certainly has put in the time.

He would not be everyone's cup of tea, but I was happy to go with his instructional style and his emphasis on information-gathering for developing a road-driving plan. We certainly looked at driving techniques outside the IAM/RoSPA box. Some of my HPC friends might have been quite surprised to see how he teaches the approach to a roundabout. It was definitely lively.

The 90% suggestion is actually quite interesting. CG (I think) applies it to the performance of the car and of the driver. If you want top operating efficiency, it is a good idea to have 10% capacity for the bit you hadn't planned.... If you don't have that you will certainly lose more than the last drop of engine performance.

[martine]

Nice post.

You're teasing us with the reference to CG's recommended approach to roundabouts though...I want to know more...

[7db]

Offside, late on the brakes, heelntoe down through the gears, managing the grip through a tight turn unwinding by the apex and at full power by the exit?

[jcochrane]

Offside, late on the brakes, heelntoe down through the gears, managing the grip through a tight turn unwinding by the apex and at full power by the exit?

Think you left out trail braking with the left foot.

[martine]

Offside, late on the brakes, heelntoe down through the gears, managing the grip through a tight turn unwinding by the apex and at full power by the exit?

[sussex2]

'ang on we are British we don't do these fancy things.

[TripleS]

Maybe we are taking Chris Gilbert's statement out of context. Obviously posters here are correct in terms of squeezing the last drop of performance out of a vehicle. CG must surely realise this though? I don't think he is into motorsport, so I suspect his advice is a pragmatic approach to road driving. Driving on road in a typical road car I would agree there is no practical gain in bouncing off the rev limiter all the time.

CG was obviously generalising, so his advice can not be appropriate for all cars.

In any case I agree with you: flogging the nuts off a car on a regular basis isn't worth doing IMHO. The performance gained, at the cost of an increased rate of wear and tear, wouldn't be worth it to me; but those who are paying will presumably do what they feel best suits them.

[Astraist]

The 90% suggestion is actually quite interesting. CG (I think) applies it to the performance of the car and of the driver. If you want top operating efficiency, it is a good idea to have 10% capacity for the bit you hadn't planned.... If you don't have that you will certainly lose more than the last drop of engine performance.

Exactly my observation from earlier down the thread.

It's reasonable to always keep all the means of car control available. By keeping a few hundreds of revs between your engine and it's peak power, and by holding back an inch on the throttle, you always maintain the ability to accelerate further, usually with little loss in the progress made, but with some better fuel efficiency and less wear and tear.

[7db]

Offside, late on the brakes, heelntoe down through the gears, managing the grip through a tight turn unwinding by the apex and at full power by the exit?

Think you left out trail braking with the left foot.

I took that as read, together with single-handed steering.

[jcochrane]

Offside, late on the brakes, heelntoe down through the gears, managing the grip through a tight turn unwinding by the apex and at full power by the exit?

Think you left out trail braking with the left foot.

I took that as read, together with single-handed steering.

No doubt because the other hand is holding a mobile phone.

[GJD]

Offside, late on the brakes, heelntoe down through the gears, managing the grip through a tight turn unwinding by the apex and at full power by the exit?

Think you left out trail braking with the left foot.

I took that as read, together with single-handed steering.

Even for the dab of oppo on exit?

[jcochrane]

You let go of the wheel for that bit...

Can always rely on a well reasoned, scientific reply from you.

[ChrisGD4]

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