Why 5252 rpm

Share This Article:. Follow Us Today:. Viknesh Vijayenthiran - Editor. Stephen Edelstein - Contributing Writer. More than one third of Cadillac dealerships bail on brand's electric future.

Buzz: Car News Headlines. Acura Integra prototype debut set for Nov. Motor Authority Newsletter Sign up to get the latest performance and luxury automotive news, delivered to your inbox daily! Sign Up Today! Follow Us on Instagram motorauthority. Car Tech Features View All. The answer to my question, and indeed much more, came from an intelligent young man with some grays himself named Jason Fenske who operates a YouTube channel titled Engineering Explained.

A mechanical engineer with a passion for cars, Fenske explains the mathematics behind engines, transmissions and driving characteristics, in a matter-of-fact manner that most of us can understand well, after watching more than once anyhow.

The explanation offered by Fenske focuses solely on the manipulation of known equations to eventually relate power, horsepower and torque. For example, we have heard engine builders , camshaft consultants , and other " technical experts" ask customers:. And the question is usually asked in a tone which strongly suggests that these "experts" believe power and torque are somehow mutually exclusive.

At the bottom of this page, the derivation of that equation is shown, for anyone interested. Referring to Figure 1 , assume that the handle is attached to the crank-arm so that it is parallel to the supported shaft and is located at a radius of 12" from the center of the shaft. In this example, consider the shaft to be fixed to the wall.

Let the arrow represent a lb. Because the shaft is fixed to the wall, the shaft does not turn, but there is a torque of pound-feet pounds times 1 foot applied to the shaft. In the same way that one ton is a large amount of weight by definition, pounds , one horsepower is a large amount of power. The definition of one horsepower is 33, foot-pounds per minute. Consider the following change to the handle-and-crank-arm sketch above. The handle is still 12" from the center of the shaft, but now, instead of being fixed to the wall, the shaft now goes through the wall, supported by frictionless bearings, and is attached to a generator behind the wall.

Suppose, as illustrated in Figure 2 , that a constant force of lbs. In other words, the "arrow" rotates with the handle and remains in the same position relative to the crank and handle, as shown in the sequence below.

That is called a "tangential force". If that constant lb. The point to be taken from those numbers is that a given amount of horsepower can be made from an infinite number of combinations of torque and RPM. In fact, in cars of equal weight, the smaller engine will probably race BETTER because it's much lighter, therefore puts less weight on the front end. AND, in reality, the car with the lighter 2-liter engine will likely weigh less than the big V8-powered car, so will be a better race car for several reasons.

A dynamometer determines the POWER an engine produces by applying a load to the engine output shaft by means of a water brake, a generator, an eddy-current absorber, or any other controllable device capable of absorbing power. But why? Jason Fenske at Engineering Explained details why hp and torque always seem to cross at rpm in his latest video, but just be warned, there's lots of math involved.

I could try writing out all of the equations and formulas he uses right here, but honestly you'll be better off watching the video below. The visual aid of a whiteboard is necessary. You're probably wondering if this horsepower and torque crossover means anything.