Should You Rev the Engine When Jumping a Car?

The Answer: Yes and No

The answer to the question of whether or not you should rev the engine when jumping a car is both yes and no. It depends on the situation.

When to Rev the Engine

There are a few situations in which it is helpful to rev the engine when jumping a car. These include:

When the battery is completely dead. If the battery is completely dead, it will not have enough power to start the car, even with a jump start. Revving the engine will help to increase the voltage of the alternator, which will provide more power to the battery and help it to start.
When the car has a large engine. Large engines require more power to start than small engines. Revving the engine will help to provide this extra power and make it more likely that the car will start.
When the weather is cold. Cold weather can make it difficult for a car to start. Revving the engine will help to warm up the engine and make it easier to start.

When Not to Rev the Engine

There are also a few situations in which it is not helpful to rev the engine when jumping a car. These include:

When the battery is not completely dead. If the battery is not completely dead, it will have enough power to start the car without revving the engine. Revving the engine in this situation can actually damage the battery.
When the car has a small engine. Small engines do not require as much power to start as large engines. Revving the engine in this situation will not provide any benefit and could actually damage the engine.
When the weather is warm. Warm weather makes it easier for a car to start. Revving the engine in this situation will not provide any benefit and could actually waste gas.

Conclusion

So, should you rev the engine when jumping a car? The answer is yes if the battery is completely dead, the car has a large engine, or the weather is cold. The answer is no if the battery is not completely dead, the car has a small engine, or the weather is warm.

If you are not sure whether or not you should rev the engine when jumping a car, it is always best to consult with a mechanic.