Prodrive P2

[Dazed Dreamer]

http://vids.myspace.com/index.cfm?fuseaction=vids.individual&videoid=1018221566&n=2

 

"Right, now bear with me on this one, I think I've got it. First of all, the anti-lag. A normal turbo works by using the exhaust fumes exiting the engine to spin a little sort of propeller thing that drives another little propeller thing in the engine air intake which then spins round very fast and forces more oxygen into the engine. But, at low revs there aren't enough exhaust fumes to drive the little propellers and give the engine its oxygen boost. So, you press the accelerator and have to wait a second or more until there are enough fumes to get the turbo propellers spinning, at which point you go from no power to lots of power. This moment of delay is called 'turbo lag', although another phrase for it is 'bloody inconvenient', especially if you're trying to overtake another car. So, the Prodrive anti-lag system works by keeping the little propellers spinning and forcing lots of lovely oxygen into the engine even when there aren't enough exhaust fumes to turn them normally. And it does this by dumping petrol into the exhaust, just before the little propeller. As soon as the petrol touches the very hot exhaust pipe it explodes and this explosion keeps the propeller turning so when you step on the accelerator there's no irritating wait for it to for it to get spinning and instead you have an instant dollop of big fat power. Or something like that.

Ah, now the active diffs. Yes, there's one of these in the middle of the car and another one on the back axle. The middle one controls what proportion of the torques from the engine go to the back wheels and what proportion go to the fronts. And the diff at the back does the same, splitting the torques between the rear wheels. They're both controlled by a very clever computer that has a speed sensor, a steering angle sensor and something called a 'yaw sensor' which sort of measures the line that the car is taking through a corner. This is very important. If the computer looks at your steering angle and then the yaw sensor tells it the car is turning through the corner less sharply than it should be for that amount of steering lock it thinks, 'uh-oh, that's understeer'. Then it telegraphs the centre differential and tells it to make sure more torques are going to the back axle so that the front stops dragging the car wide, like a front wheel drive car would. But then, as the car leaves the corner it tells the centre diff to push more torques forward to pull the car out of the turn without oversteering like a rear wheel drive car would. Hmm, yes, that sounds about right. Ah, and the active rear diff helps you out in sudden changes of direction so that if the car is looking like it might spin, the computer can step in and push torques to one wheel to push the rear of the car back on line. And all this computer thinking and moving of torques can happen in milliseconds. It's very clever. It's also made my brain hurt."