Need help in calculating Engine Air Flow and Specs Explanation

  • #1

Main Question or Discussion Point

hello everyone,
i hope you're doing well, i am new to this forum so i am not sure if this is the right place for my question
what i am doing is trying to calculate the air flow needed for intake of an RC engine Zenoah G320RC
in the attachment files, it's a pdf for the info about the Standard Zenoah G320RC engine, but the one i am using is a tuned version of that one with a 30% to 40% more power, but will use the standard specs for the moment to learn, so i have been searching for calculating the air flow, the formula needs VE % but it doesn't seems to be mentioned in the specs file so i need your help to figure out how to calculate the Air Flow needed please ?

and i would like to know if a bigger air intake surface would have negative effect or it would be just more structural material which should be eliminated for weight purpose ?

thanks in advance to everyone
 

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Answers and Replies

  • #2
jack action
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VE is calculated by dividing the actual measured airflow by the theoretical airflow that can go in the engine (displacement X rpm). So you either need to actually measure the airflow of the engine or used a complex engine cycle simulator to do the calculations. There are no easier way.

The intake design (cross-area and length) can affect airflow by taking advantage of the pressure waves created by the engine's cycle. Although, on the intake side of a 2-stroke engine, it is not of a big effect because the crankcase is part of the intake system; So it shouldn't make a big difference to alter your intake design (as long as you don't restrict the flow).
 
  • #3
VE is calculated by dividing the actual measured airflow by the theoretical airflow that can go in the engine (displacement X rpm). So you either need to actually measure the airflow of the engine or used a complex engine cycle simulator to do the calculations. There are no easier way.

The intake design (cross-area and length) can affect airflow by taking advantage of the pressure waves created by the engine's cycle. Although, on the intake side of a 2-stroke engine, it is not of a big effect because the crankcase is part of the intake system; So it shouldn't make a big difference to alter your intake design (as long as you don't restrict the flow).
hello Jack and thank you for your reply, there is no way to measure that or in a software, so you saying that if my air intake surface is bigger it will do harm if it was a 4 stroke ? my engine is 2 stroke
 
  • #4
jack action
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I don't know if it will do harm, but it can affect the airflow. A given cross-section area and length of the intake system perform better at a given rpm. If that rpm doesn't coincide with the rpm range you expect from your engine, then it can do harm.
 
  • #5
I don't know if it will do harm, but it can affect the airflow. A given cross-section area and length of the intake system perform better at a given rpm. If that rpm doesn't coincide with the rpm range you expect from your engine, then it can do harm.
ow ! ok thank you Jack for the info :)
 

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