# Converting engine bmep to engine torque

• nb89
In summary, the mean effective pressure (BMEP) is calculated by dividing the torque exerted by an engine over a revolution (two for a four-stroke and one for a two-stroke) by its displacement. The displacement refers to the cylinder volume displaced per cycle. However, this calculation only provides an average torque and may not be useful for designing shafting as the torque from an IC engine can fluctuate significantly. The maximum torque can be several times higher than the average torque.
nb89
I looked it up on wikipedia and found this:

http://en.wikipedia.org/wiki/Mean_effective_pressure

which states that 'BMEP is calculated by taking the torque exerted by the engine over a revolution for a two-stroke engine and two revolutions for a four-stroke, and dividing it by its displacement.' I am confused about what the displacement is. What is it the displacement of?

Displacement of the engine. It's the cylinder volume displaced per cycle.

Be aware, however, that this is the torque integrated over the thermodynamic cycle (one crank revolutions or two), so that the torque you calculate when you multiply BMEP by displacement is only average torque. This is important because torque from an IC engine fluctuates significantly. For a single cylinder engine, the torque can completely reverse during a part of the cycle, and the maximum torque will be several times the average torque. Thus if you need a value for designing shafting, the BMEP*displacement is not of much help.

## 1. What is engine bmep and how is it related to engine torque?

Engine bmep (brake mean effective pressure) is a measure of the average pressure exerted on the piston during the power stroke of an engine. It is related to engine torque through the equation torque = bmep x displacement x number of cylinders. This means that an engine with a higher bmep will produce more torque.

## 2. Why is it necessary to convert engine bmep to torque?

Converting engine bmep to torque is necessary because it provides a more accurate measure of an engine's performance. Bmep only takes into account the pressure exerted on the piston, while torque takes into account the distance that force is being applied over. This is important for determining an engine's efficiency and power output.

## 3. How is engine bmep measured?

Engine bmep is typically measured using a dynamometer, which is a device that applies a load to the engine while it is running. The resulting force and engine speed are recorded, and bmep is calculated using the equation bmep = (force x 2π x engine speed) / (displacement x number of cylinders).

## 4. Can engine torque be calculated directly from bmep?

No, engine torque cannot be calculated directly from bmep. As mentioned earlier, engine torque also takes into account the displacement of the engine and the number of cylinders. These factors are necessary for accurately calculating torque.

## 5. How can converting engine bmep to torque be useful in engine design and optimization?

Converting engine bmep to torque can be useful in engine design and optimization because it allows engineers to see how changes in bmep can affect torque output. This information can be used to make design decisions that will improve an engine's efficiency and performance.

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