# Determine the diameter of a piston

• skrat
In summary, the conversation discusses determining the diameter of a piston based on a given working stroke and a p(V) diagram with a compression rate of 7.5:1. The height of the clearance volume is calculated using a specific equation, but calculating the diameter remains a challenge. It is later clarified that the swept volume is also given, making the problem much simpler.
skrat

## Homework Statement

Determine the diameter of a piston if the working stroke of a piston is ##h## and if a working cylinder ##(720^\circ )## describes the following ##p(V)## diagram, where on the ##x## axis is a ratio between the current volume of a piston and the total volume (swept + clearance volume). The compression rate is 7.5:1.

## The Attempt at a Solution

I was able to calculate the height of the clearance volume (assuming it has the same shape as swept volume) by the following equation $$\frac{V_{clearance}+V_{swept}}{V_{clearance}}=7.5$$ so $$a=6.5 h.$$ And I honestly tried to calculate the diameter but everything I do leads me only to a ratio of some volumes, ergo the diameter falls out of the equation. I simply don't have an idea how to calculate the diameter of a piston.

I see your difficulty. It makes no sense to me either.
Btw, I believe the given h is Vswept, so your a = 6.5h is backwards.

I apologize, I misread the problem statement. The swept volume ##V_{swept}## is also given. In that case, this is all a trivial problem.

## 1. What is the purpose of determining the diameter of a piston?

The diameter of a piston is an important measurement that is used to calculate the displacement, or volume, of the piston. This information is crucial in determining the power and efficiency of an engine.

## 2. How do you measure the diameter of a piston?

The diameter of a piston can be measured using a caliper tool or a micrometer. Place the tool across the widest point of the piston and record the measurement in either inches or millimeters.

## 3. Why is it important to know the diameter of a piston?

The diameter of a piston is important because it affects the overall performance of an engine. A larger diameter piston will result in a higher displacement, which can increase the power output and torque of the engine.

## 4. Can the diameter of a piston be changed?

Yes, the diameter of a piston can be changed by either boring the cylinder walls to increase the size, or by using a different sized piston during the engine building process. However, this should only be done by a professional to ensure proper fit and function.

## 5. What factors can affect the diameter of a piston?

The diameter of a piston can be affected by wear and tear, overheating, and engine modifications. It is important to regularly check the diameter of the piston to ensure optimal engine performance.

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