Muffler or No Muffler?

At my local track it seems alot of the karts in open run mufflers? I would think running no muffler would be faster because you can flow air better. Is this true or is it better to run a muffler? I wouldnt think it would be better to run a muffler but for some reason a bunch of people do.
 

XXX#40

2A supporter
At my local track it seems alot of the karts in open run mufflers? I would think running no muffler would be faster because you can flow air better. Is this true or is it better to run a muffler? I wouldnt think it would be better to run a muffler but for some reason a bunch of people do.
It's about back pressure and a few other things.
Some engines benefit from a muffler like plate engines
 

K12

Member
No muffler. On a 4stroke backpressure is bad. If a muffler helps, there are other fixes needed. Look at race cars, dragsters etc. Once you understand pipe diameter and length and why, it will be clear to you. I know many arguments are onthe way. Go for it.
 

mike97760

Site Supporter
My open Predators use 390 alky carbs with adapters which don't run right without a muffler. The both ran great until they didn't. Turns out that my son had taken the mufflers off and installed open exhaust tips. The motors wouldn't idle down and they just didnt run quite right. While Im looking for problems in other areas an engine builder friend stopped by, saw what I had, and told me to use the RLV modified muffler (I had one laying around) and it went back to running good, just like that. Something about required pulses to make the carb respond correctly.
 

XXX#40

2A supporter
No muffler. On a 4stroke backpressure is bad. If a muffler helps, there are other fixes needed. Look at race cars, dragsters etc. Once you understand pipe diameter and length and why, it will be clear to you. I know many arguments are onthe way. Go for it.
Rules regarding diameter and length, single cylinder engine......
 

95 shaw

Site Supporter
There are sound waves, but also pressure waves. Both are affected by pipe length, pipe diameter, and whether there is a muffler or not.

The whole exhaust as a system has an effect on engine performance.

Most chosen exhausts are driven by the rules the engine was built to run under.

2 stroke engines with expansion chambers tune both pressure wave and sound wave by varying different lengths within the systems.
The expansion chamber is not a muffler, as it can make the exhaust noise even louder.

Four stroke engines with limited exhaust length are primarily influenced and tuned via pressure wave adjustments.

Edit

For better clarity, pressure wave should actually read inertia wave.

Sorry for any confusion.
 
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There are sound waves, but also pressure waves. Both are affected by pipe length, pipe diameter, and whether there is a muffler or not.

The whole exhaust as a system has an effect on engine performance.

Most chosen exhausts are driven by the rules the engine was built to run under.

2 stroke engines with expansion chambers tune both pressure wave and sound wave by varying different lengths within the systems.
The expansion chamber is not a muffler, as it can make the exhaust noise even louder.

Four stroke engines with limited exhaust length are primarily influenced and tuned via pressure wave adjustments.
To my understanding the pressure wave is the sound wave. But I guess I never claimed to be reading genius lol
 
I have earbuds in when I am racing so I can barely hear my predator motor with a header pipe and rlv muffler. But i am sure my stock appearing motor without the muffler would probably be easy to hear.
 

95 shaw

Site Supporter
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95 shaw

Site Supporter
Our headers are best described as zoomies.

A check of the math will tell you that it is, in fact, the second returning wave that is most important for tuning high end rpm.

The sound wave travels much faster, an important factor in tuning this wave, as each wave loses some energy.

Something to think about.
 
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