Optimizing Car Performance: Power, torque, rpm

In summary, to avoid overheating, the best gear to choose is one that has a low enough rpm and provides enough torque for the application.
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FrvrUndd
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You want to select a gear such that the rpm is low enough to avoid overheating and you want to choose a gear that gives you enough torque for the application.
A car is going up a 20% grade at a speed of 60 km/h.

Gear ratios:
1st - 3.143:1
2nd - 1.870:1
3rd - 1.235:1
4th - .949:1
5th - .727:1
Reverse - 3.308:1
Differential Ratio (final drive ratio between axle and transmission gear) - 4.2941:1
Wheel diameter = 16in
Mass=1218 kg
Tachometer redline = 6800 rpm


Questions:

If the coefficient of static friction btween the tires and the ground is .9, what is the minimum power required to keep the car moving at the same speed?

What is the minimum torque required on the wheel?

If the driver chooses to go up the grade in fifth gear, what is the rpm of the engine? What is it for first gear?

The torque output by the engine is related to the force produced by the piston upon ignition of the gas and varies with the angular velocity of the engine. Assume that the engine torque is giving by
t(engine)=Aw^2(engine)+Bw(engine)+C, where A=-.0004 Nms^2/rad, B=.731 Nms/rad, and C=16.789. Given this information, what is the torque on the wheels in fifth gear? What is it in first gear?

Given the torque requirements and the fact that you do not want to overheat the engine, what is the gear you should use?
 
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  • #2
Answer:The minimum power required to keep the car moving at the same speed is 24.3 kW. The minimum torque required on the wheel is 893.5 Nm. If the driver chooses to go up the grade in fifth gear, the engine rpm is 2265 rpm. For first gear, it is 6778 rpm.The torque on the wheels in fifth gear is 705.8 Nm and in first gear is 2099.7 Nm. Given the torque requirements and the fact that you do not want to overheat the engine, the best gear to use would be fourth gear as it has a lower rpm than fifth gear and gives enough torque for the application.
 

1. What is the difference between power and torque in a car?

Power and torque are two important measures of a car's performance. Power is the rate at which work is done, while torque is the rotational force produced by the engine. In simpler terms, power is how quickly you can go, while torque is how much force is available to move you. Both power and torque are important for a car's overall performance, but they have different effects on driving experience.

2. How do power and torque affect a car's acceleration?

Power and torque both play a role in a car's acceleration. Power has a more direct effect on acceleration, as it is a measure of how quickly energy can be transferred to the wheels. On the other hand, torque determines how much force is available to overcome the car's inertia and accelerate. In general, a car with higher power and torque will have better acceleration.

3. What is the ideal rpm range for maximum car performance?

The ideal rpm range for maximum car performance varies depending on the car's engine and transmission. In general, most cars perform best at higher rpms, as this allows the engine to produce more power and torque. However, constantly revving the engine at high rpms can also lead to excessive wear and tear, so it's important to follow the manufacturer's recommended rpm range for optimal performance.

4. How can I increase my car's power and torque?

There are several ways to increase a car's power and torque. One option is to install aftermarket performance parts, such as a cold air intake or a performance exhaust system. These can improve the flow of air and exhaust, allowing the engine to produce more power and torque. Another option is to tune the engine's computer to optimize its performance. Additionally, regular maintenance and using high-quality fuel can also help improve a car's power and torque.

5. Can I optimize my car's performance without sacrificing fuel efficiency?

Yes, it is possible to optimize a car's performance without sacrificing fuel efficiency. One way to do this is by using a performance tuner or chip that allows you to adjust the engine's performance settings. This can help you find a balance between power and fuel efficiency. Additionally, regular maintenance and driving habits, such as avoiding excessive idling and accelerating slowly, can also help improve fuel efficiency while still optimizing performance.

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