Piston Force Graphs: Manipulating Parameters in Combustion Pistons

In summary, the conversation revolves around viewing graphs of piston force versus piston displacement or time in a combustion piston and how the graph varies by manipulating parameters such as fuel amount, air amount, piston geometry, and rpm. It is mentioned that the highest force on the piston is at top dead center (TDC) in the overlap position and that lighter pistons allow for higher rpm. The argument between using lighter weight pistons for faster revs or longer rods/higher ratios for more power is also discussed. The conversation also suggests reading further discussions on piston force in the Mechanical Engineering forum and provides a link to a forum thread on formulas for engine cylinder pressure.
  • #1
physea
211
3
Hello guys!
Can I view graphs of Piston Force versus Piston Displacement or time, in a combustion piston?
I would be interested to see how the graph varies by manipulating parameters such as fuel amount, air amount, piston geometry, rpm, etc
Thanks!
 
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  • #4
hmm I can tell you that the highest force on the piston is at tdc in the overlap position. The less the piston weighs the higher rpm you can run. The less the piston weighs the less the connecting rod has to weigh. You would think rod angle is the limiting factor in rod ratio/ stroke. The 900 cubic inch pro mod engines have a rod ratio/ angle that you think would not work. (1.3 lol) They use a 11.1 inch deck height A 5.5 inch stroke. A 7.250 long connecting rod. and a 5.1 inch bore. red line is about 8000 lol rpm If you look at the rod angle you would think the piston would go through the side of the block- it does when you make a mistake.The biggest drag/ load are the valve springs. They are maybe 500 lbs on the seat- 1200 lbs on the nose x 16 x 8000 rpm. I think net lift is now 1.2 inches. NASCAR engines like to run close to the theoretical rod ratio 1.83? There is an argument over whether the lighter weight let's the engine rev faster or whether the longer rod/ higher ratio make more power. The drag racers go with lighter. NASCAR goes with rod ratios closer to ideal. If you do the load versus weight cals. you will see why light weight pistons are most important.
 

Related to Piston Force Graphs: Manipulating Parameters in Combustion Pistons

1. What is a piston force graph?

A piston force graph is a visual representation of the forces acting on a piston during the combustion process inside an engine. It shows how the force changes over time as the piston moves up and down in the cylinder.

2. How is a piston force graph created?

A piston force graph is created by measuring the pressure inside the cylinder at different points in the combustion process and plotting it against the position of the piston. This data can be collected using sensors and specialized equipment.

3. What parameters can be manipulated in a piston force graph?

The parameters that can be manipulated in a piston force graph include the air-fuel ratio, ignition timing, and valve timing. These parameters affect the combustion process and thus, the forces acting on the piston.

4. How do changes in parameters affect the piston force graph?

Changes in parameters can affect the piston force graph in various ways. For example, a higher air-fuel ratio can result in a higher peak force, while a delayed ignition timing can result in a delayed peak force. It is important to carefully manipulate these parameters to achieve optimal engine performance.

5. Why is understanding piston force graphs important?

Understanding piston force graphs is crucial in optimizing engine performance and efficiency. By analyzing the graph, scientists and engineers can identify areas where the engine can be improved and make necessary adjustments to achieve better performance, fuel efficiency, and emissions control.

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