dual 3" exhaust no muffler vs. dual 4" with mufflers
Moderator: Team
Re: dual 3" exhaust no muffler vs. dual 4" with mufflers
Err... I think the OP may have left the room. The last post before yours was more than ten years ago...
Felix, qui potuit rerum cognscere causas.
Happy is he who can discover the cause of things.
Happy is he who can discover the cause of things.
Re: dual 3" exhaust no muffler vs. dual 4" with mufflers
Paradigms often shift without the clutch -- https://www.youtube.com/watch?v=cxn-LxwsrnU
https://www.instagram.com/ptuomov/
Put Search Keywords Here
https://www.instagram.com/ptuomov/
Put Search Keywords Here
-
David Redszus
- Guru
- Posts: 9633
- Joined: Tue Nov 27, 2007 9:27 am
- Location: Chicago
- Contact:
Re: dual 3" exhaust no muffler vs. dual 4" with mufflers
Just an interesting observation regarding designing exhaust systems.
Air particle velocity is not affected by pipe diameter, as long as the pressure ratio remains unchanged.
However, at the same pressure ratio, a 50% increase in pipe diameter will double the air mass flow.
Sooo...while gas particle velocity is not affected by pipe diameter, the mass flow will change with rpm.
Many flow calculation are incorrect due to the fact that an incorrect value is used for the ratio of specific heats of the gas mixture. The ratio is affected by fuel vapor, humidity, and temperature. While a value of 1.4 is often use for air, an exhaust gas value should be closer to 1.21.
Since pressure ratio is so very critical for analysis, a data logger with exhaust gas pressure sensors should be
a basic requirement.
Air particle velocity is not affected by pipe diameter, as long as the pressure ratio remains unchanged.
However, at the same pressure ratio, a 50% increase in pipe diameter will double the air mass flow.
Sooo...while gas particle velocity is not affected by pipe diameter, the mass flow will change with rpm.
Many flow calculation are incorrect due to the fact that an incorrect value is used for the ratio of specific heats of the gas mixture. The ratio is affected by fuel vapor, humidity, and temperature. While a value of 1.4 is often use for air, an exhaust gas value should be closer to 1.21.
Since pressure ratio is so very critical for analysis, a data logger with exhaust gas pressure sensors should be
a basic requirement.