Verify Answer- Porsche Power Question

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In summary, a Porsche 944 Turbo has a rated engine power of 217 hp (161882 W), with 30% power lost in the drive train and 70% reaching the wheels. The total mass of the car & driver is 1480 kg, with two thirds of the weight over the drive wheels. The maximum acceleration can be calculated using the coefficient of static friction, which is 1, resulting in an acceleration of 6.53 m/s^2. However, this assumes that the car is geared for maximum acceleration at 1 g. The second question is not clearly defined, but assuming the same gearing, the Porsche would reach a speed of 11.72 m/s (26.2 mph) at maximum
  • #1
bcjochim07
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A Porsche 944 Turbo has a rated engine power of 217 hp (161882 W). 70% of the power is lost in the drive train, and 30% reaches the wheels. The total mass of the car & driver is 1480 kg, and two thirds of the weight is over the drive wheels.

What is the max acceleration if the coefficient of static friction is 1?

(2/3)(1480 kg)(9.80)*1= 9669.33 N Force of static friction

Set this = to mtotal* a 9669.33N=(1480)a a= 6.53 m/s^2

What is the speed of the Porsche at max power output?

P=Fv

F= 9669.33 N P= (161882 W) * (.70) = 113317.4 W

113317.4= (9669.33 N)v
v=11.72 m/s which is about 26.2 mph Does this seem fast enough?
 
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  • #2
The calculation of acceleration is correct, but the second question is not well defined.
The speed you calculated is the maximum speed when the acceleration is still limited by friction and not by engine power, but even this is true only if one gear is set to maximize power at that speed (the engine's power depends on rpm).
 
  • #3
You original statement needs to be revised to read 30% loss in drive train, 70% reaches the wheels. Your calculations seem correct, assuming the car is geared so that max power occurs at an acceleration rate of 1 g. However, the second question isn't worded to state that the same gearing used for max acceleration of 1g would be used for determining the car's speed at max power. It would have been better stated to ask for the maximum speed that the maximum acceleration of 1g occurs at.

30% seems a little high for drive train losses, generally it's usually around 15%, although an all wheel drive car could have higher drive train losses.
 
  • #4
Jeff Reid said:
Your calculations seem correct, assuming the car is geared so that max power occurs at an acceleration rate of 1 g. QUOTE]
This assumption has nothing in common with our problem.
 
  • #5
so much so wrong
thats a problem with numbers out side the real world
a 26.2 mph sports car ??

a porsche 944 is far closer to the idea 50/50 weight front rear
power loss is about 15%
and they top 140 mph
 

1. What is the Porsche Power Question?

The Porsche Power Question is a scientific question that has been debated for many years. It asks whether or not the amount of power generated by the engine of a Porsche automobile is accurate.

2. What are some theories about the Porsche Power Question?

There are several theories about the Porsche Power Question. Some believe that the power generated by the engine is overstated, while others argue that it is actually underestimated. There are also theories that suggest the power output may vary depending on the specific model and modifications of the car.

3. How is the Porsche Power Question being studied?

The Porsche Power Question is being studied through various methods, including dyno testing, computer simulations, and real-world track tests. Engineers and scientists are constantly analyzing data and making adjustments to try and accurately measure the power output of Porsche engines.

4. What is the significance of the Porsche Power Question?

The Porsche Power Question is significant because it not only affects the performance and reputation of the brand, but it also has implications for the entire automotive industry. The accuracy of power output measurements can impact consumer trust, as well as regulatory standards for emissions and fuel efficiency.

5. Is there a definitive answer to the Porsche Power Question?

Currently, there is no definitive answer to the Porsche Power Question. The debate continues among scientists, engineers, and car enthusiasts. However, advancements in technology and testing methods are helping to bring us closer to a more accurate understanding of the power output of Porsche engines.

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