9 replies to this topic

[slipstream]

I know that HP and Drag are the most imporatant factors to determine top speed, but what are the most important factors to determine Acceleration on the Race Track ? I know for road cars its the Torque curve but F-1 cars do not have a very good Torque to weight ratio so how are they so quick ?

[Art]

Slipstream.

I am not sure but I would guess. Light weight grip from the tires and torque.

Art

[IndyIan]

Slipstream,
The acceleration of an F1 car is caused by HP! They have low torque because they rev to 18000rpm
The torque at the wheels is what accelerates the car and with high gear ratios they turn low torque at 18000rpm to alot of torque at the wheels. The light weight helps too.

An interesting note is that over 125 mph F1 cars don't accelerate that fast in medium or high downforce trim. I've read that the Maclaren F1 road car actually accelerates faster from that speed.
Hope this helps

[PDA]

From low speed, all F1 cars have much more power available than their tyres can handle, they cannot begin to apply full power without tyre spin until they are doing between 75 and 100 mph (approx.). Above 100-120, while power to weight is still important, drag becomes increasingly important. SO at low speeds, the tyres are the most important factor (and probably the traction control system) at high speed, power to drag ratio becomes predominant.

[Nathan]

Torque, gear ratios and weight along with proper tires. By that I mean not too grippy.
Engine torque is multiplied by the final overall gear ratio. This is divided by the cars weight, and that gives you the acceleration G forces. One G force equals roughly 38m/s. So...

say a car has 100ft./lbs of torque and a final overall drive ratio in 1st gear of say 10:1. That means at peak, the car puts down 1000ft./lbs of torque to the tires. If the car weighs say 2000-lbs, that means the acceleration rate is 0.5g's. That calculates to roghly 19m/s, or around 63 feet per second. If you wanted to know, at that rate, after a second the car would be going around 40mph. But my example is based on a constant, flat torque curve, perfect wheel grip, zero clutch slip etc.

But atleast this may help you out

[Nathan]

PDA

To prevent tire spin in low gears, a team can limit the rev limiter to prevent over torquing the tires, rather than use a illegal traction control unit. Basically that means the engine will only rev to say 10,000rpm, where power output is low, and gradually increase the rev limiter as speeds rise and tire spin is not a problem.

[IndyIan]

Nathan,
You are a bit confused with your acceleration calculations. 1 G is 9.81 metres per second squared. This means if you drop something in a vacuum it's velocity increases 9.81 m/s every second it falls. So after 2 seconds of free fall the object would be going 19.62m/s.
Hope this helps.

[slipstream]

Thanks for the replies to my topic.The information so far has been helpful. I know that from racing Motorcyles that it is important to Have Good Throttle Response and a quick Revving engine for good acceleration in the lower the gears, how important is it for Auto Racing ? I would think that F-1 Cars would have very good Throttle Response and be very quick revving.

[PDA]

Nathan
Rule 5.10 states that rev limiters may only limit revs at "significantly above the peak of the power cirve". So your idea is illegal.

I suggest you download the tech regs from www.FIA.COM as they provide answers to many of your questions and comments. For anybody really interested in the technical aspects of motor racing, they are mandatory reading.

[Nathan]

2 words.

Lightweight Flywheel

= quicker rsponse and revving, and more wheel horsepower as well