Talk:Basic Automobiles

can anyone tell me what is the exhaust velocity of the gas coming out of the engine? and how does it vary with brake thermal power?

can send reply at ranjan_shivek@yahoo.com

Here you can see the exhaust velocity for 1 cycle. The red line shows speed at the port and the blue shows the speed at the end of the pipe. Note that the speed is greater at the end of the pipe. As torque rises, so too does temperature,pressure and volume. Therefore the speeds will rise corrispondingly. (Image removed for copyright reasons)

"Manual transmission" section is very poor
The section on how to drive a manual transmission contains many factual errors, some in direct contradiction of statements in the better article entitled Transwiki:Manual transmission driving technique.

There's no logical connection between selecting the gear in which to leave the engine (from the best two available choices, first and reverse) when parked based on whether one is parking on an uphill or downhill slope; it's always better to leave the car in the gear that has the lower gear ratio.

Also, the "aim" of driving is not always to maximize fuel efficiency. There are situations when other considerations obtain, including the case where one wants to maximize acceleration. So it is not always best to upshift quickly (i.e., at low RPMs).

The section called "Fuel Efficiency" contains the very dangerous procedure of shutting the engine off while the car is in motion. Suggest editing to remove.

Engine braking in emergencies?
There's some seriously fishy advice in this thing:


 * That is, if you have a vehicle suddenly stop before you, or you have a pedestrian jump in front, and you must absolutely stop the vehicle. Here you can switch to the lower gear rapidly (say from the 5th to the 2nd), and use the engine for braking along with the brake pads. Thus, if you have mastered rapid downshifting, you can bring the car to a stop using this method by using all the gears from 5th down to 2nd, instead of skipping gears. This will definitely cause engine damage, but is preferable to loss of life (either to you or the other people on the road).

I don't see how engine braking would help *at all* unless you have a car with totally useless brake pads. The deceleration in braking comes from the friction between the tires and the ground and the difficult part is not exceeding the point at which the wheels slip when slamming on the brakes, but this is done automatically in all modern cars which have ABS. The difficulty never stems from lack of braking force on the wheels, which is what is suggested here; it's the exact opposite. --84.59.202.169 (discuss) 11:52, 17 April 2017 (UTC)