Engine Talk

[ebbfolls]

To the threadstarter who wanted to know kung pano malalaman ang lakas ng engine-- sa POWER rating po yun. Power is the ability to produce work(or results) per a given amount of time.

Horsepower(HP) = Torque X RPM/5252



Mr. Speedyfix,

You are right about your argument about the variables being virtually impossible to control, as to make a valid test between 2 different engines. But in theory, 2 engines making the same amount of power, regardless of what rpm they make their max power, are equally POWERFUL one to the other. Now, say a Toyota 2.0 liter is making 160 HP at 5000 rpm and a Honda 2.0 liter is making 160 HP at 7000 rpm. Both engines are of the same power, thus both are capable of doing the SAME AMOUNT OF WORK, at the SAME AMOUNT OF TIME. (But because their max power figures occur at different engine speeds, both have different TORQUE figures at the rpm where they both make their maximum power. But torque only tells about how strong an engine is without regard for time, while HP tells about how fast an engine can produce results.)

So, if both engines are made to power cars of the same weight, both cars will have the same acceleration times and top speeds, because they are being propelled forward by engines that have the same amount of capacity to do work.

However, since you mentioned flywheel weight, then that would also have to be put nto consideration if we are to talk about acceleration. The engine with the less rotational mass(moment of inertia), will of course be able to accelerate quicker (By the way, a lighter flywheel only means the engine will be able to accelerate quicker to a certain rpm, but max rpm is still a function of the torque band, regardless of flywheel weight). However, top speed still be the same because both engines will only be able to accelerate to the point at which they can no longer produce more power to push the car against the resistance of the air and other frictional forces.