1. Limited time only! Sign up for a free 30min personal tutor trial with Chegg Tutors
    Dismiss Notice
Dismiss Notice
Join Physics Forums Today!
The friendliest, high quality science and math community on the planet! Everyone who loves science is here!

Piston forces

  1. Mar 2, 2017 #1
    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
  2. jcsd
  3. Mar 2, 2017 #2


    User Avatar
    Science Advisor
    Gold Member

  4. Mar 3, 2017 #3
  5. Oct 13, 2017 #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 lets 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.
  6. Oct 15, 2017 #5

    Ranger Mike

    User Avatar
    Science Advisor
    Gold Member

Share this great discussion with others via Reddit, Google+, Twitter, or Facebook

Have something to add?
Draft saved Draft deleted