Piston Force Graphs: Manipulating Parameters in Combustion Pistons

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SUMMARY

This discussion focuses on the manipulation of parameters affecting piston force in combustion engines, specifically examining the relationship between piston force, displacement, and time. Key factors include fuel amount, air amount, piston geometry, and RPM, with insights drawn from high-performance engines such as 900 cubic inch Pro Mod engines. The conversation highlights the importance of piston weight and rod ratio in optimizing engine performance, with lighter pistons allowing for higher RPMs and reduced load on connecting rods. Additionally, the discussion references the significance of valve spring load in overall engine dynamics.

PREREQUISITES
  • Understanding of combustion engine mechanics
  • Familiarity with piston dynamics and geometry
  • Knowledge of performance tuning parameters
  • Basic principles of mechanical engineering
NEXT STEPS
  • Research "Piston Force vs. Piston Displacement" graphs in combustion engines
  • Explore "Effects of Piston Weight on RPM" in high-performance applications
  • Study "Rod Ratio Optimization" in NASCAR and drag racing engines
  • Investigate "Valve Spring Load Calculations" for performance tuning
USEFUL FOR

Engineers, automotive performance tuners, and enthusiasts interested in optimizing combustion engine efficiency and power output through parameter manipulation.

physea
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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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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.
 

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