Brake horsepower and relationship advice

Relationship between CC and BHP - Team-BHP

brake horsepower and relationship advice

That's why the power is torque times engine speed. Since torque is bhp divided by engine speed, for a given bhp a lower engine speed. kW, horsepower, bhp no doubt you've seen one or the other written in a car Car Advice. Horsepower, kilowatts, BHP, and PS explained. Watt’s horsepower formula is confusing, but there’s no need to understand it in order to understand why horsepower ratings affect cars. Torque is another engine spec the affects a car’s performance. The engines in high-performance cars are tuned so that the horsepower and.

The older American standard SAE gross horsepowerreferred to as bhp used an engine without alternator, water pump, and other auxiliary components such as power steering pump, muffled exhaust system, etc.

The newer American standard referred to as SAE net horsepower tests an engine with all the auxiliary components see "Engine power test standards" below.

Brake refers to the device which was used to load an engine and hold it at a desired rotational speed. During testing, the output torque and rotational speed were measured to determine the brake horsepower. Horsepower was originally measured and calculated by use of the "indicator diagram" a James Watt invention of the late 18th centuryand later by means of a Prony brake connected to the engine's output shaft.

Horsepower, kilowatts, BHP, and PS explained

More recently, an electrical brake dynamometer is used instead of a Prony brake. Although the output delivered to the drive wheels is less than that obtainable at the engine's crankshaft, use of a chassis dynamometer gives an indication of an engine's "real world" horsepower after power losses in the drive train and gearbox. Shaft horsepower[ edit ] Shaft horsepower shp is the power delivered to a propeller shaft, a turbine shaft — or to an output shaft of an automotive transmission.

brake horsepower and relationship advice

Shaft horsepower is a common rating for jet engines, industrial turbines, and some marine applications. Reciprocating internal-combustion automobile engines are rated instead in the US by SAE certified net power, which is measured at the engine's crankshaft, and so does not account for losses in the transmission. Equivalent shaft horsepower eshp is sometimes used to rate turboprop engines.

It includes the equivalent power derived from jet thrust.

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The vehicle is generally attached to the dynamometer and accelerates a large roller and Power Absorbing Unit which is driven by the vehicle's drive wheel s. The actual power is then computer calculated based on the rotational inertia of the roller, its resultant acceleration rates and power applied by the Power Absorbing Unit.

Some motor vehicle and motorbike dynamometers can also be purely inertia-based where the power output is calculated from measuring the acceleration of a roller drum with a known rotational inertia and known parasitic frictional losses of the roller drum's bearings. Engine power test standards[ edit ] There exist a number of different standard determining how the power and torque of an automobile engine is measured and corrected.

Correction factors are used to adjust power and torque measurements to standard atmospheric conditions, to provide a more accurate comparison between engines as they are affected by the pressure, humidity, and temperature of ambient air.

brake horsepower and relationship advice

This contrasts with both SAE net power and DIN standards, which account for engine accessories but not transmission losses. The atmospheric correction standards for barometric pressure, humidity and temperature for SAE gross power testing were relatively idealistic. Like SAE gross and other brake horsepower protocols, SAE net hp is measured at the engine's crankshaft, and so does not account for transmission losses.

power - What is the relationship and difference between BHP and Torque? - Physics Stack Exchange

However, similar to the DIN standard, SAE net power testing protocol calls for standard production-type belt-driven accessories, air cleaner, emission controls, exhaust system, and other power-consuming accessories. At some point though the ability to get gas flows into and out of the cylinders start to dominate Almost all the tricks of "tuning" and "pumping" a naturally-aspirated engine are about increasing the flow through the intakes at high RPM.

Where the thread-starter's confusion lies and many people on this thread I think is that they and many of the automotive racer types use "power" sloppily and say nonsense like "torque is more important that power" or even "torque is power" Stuff like this is just wrong on the face of it because it doesn't even have correct units.

What they really mean, and has a real practical truth to it From a driver's perspective it is critical to be able to deliver the early acceleration the limit the adhesion can handle right from the exit of a corner.

This pays BIG dividends in speed around the course. This is a somewhat tricky optimization because there are generally a mix of corners with different exit speeds, and there are the question s of how many gear-shifts with associated loss of output they cause etc.

Cars with flatter torque vs RPM curves optimize toward shifting less too. Turbochargers make this whole thing a lot worse because of turbo lag on throttle-up.

brake horsepower and relationship advice

Drivers like torque at low RPM Electrons and light flow throughout the universe. Apr 9, Posted: Wed Mar 31, 5: High RPM engines are generally considered more "sophisticated", requiring more advanced transmissions and better drivers to maximize them. High torque engines are considered more "brute force", allowing for less sophisticated transmissions and for the pure pull of the engine to make up for the driver. Every driver benefits from a wide and deep power band; even moreso with fewer gears and longer gearchange intervals.

As for Turbo vs. Given the mechanical limitations of bore and stroke in Otto, Miller, and Atkinson cycle, adding compression via heat-recovery is a net win. Today's most powerful and most efficient piston engines are all forced induction.

Given the mechanical limitations of rotary engine compression, turbos are an even bigger win for rotaries except that additional compression complicates existing rotor tip seal challenges.