Do pipes have an effect on Compression?

[richybanshee]

I will like to know(wondering) if pipes have an effect, if any, on compression.

For example:

T5 pipes and CPI pipes: the width of the pipes is very different, also the parts that together form the exhaust. This pipes go after different power bands. The pressures the pipes produces will be different ... so anyone ... what do you know?

 

 

Another example, does not have to do with pipes: porting

 

Thanks for your help!!!

Edited November 2, 2007 by richybanshee

[black sunshine]

Pipes=no (unless they are plugged)

 

Porting can, depends what type. If the intake and exhaust ports are raised, there is less stroke that is compressing. Probably not a properly worded theory, but you know what I mean

[blowit]

I will like to know(wondering) if pipes have an effect, if any, on compression.

For example:

T5 pipes and CPI pipes: the width of the pipes is very different, also the parts that together form the exhaust. This pipes go after different power bands. The pressures the pipes produces will be different ... so anyone ... what do you know?

Another example, does not have to do with pipes: porting

 

Thanks for your help!!!

 

 

Technically, pipes would change the running compression but not static. Because 2-stroke pipes use return wave technology, you will have a difference in air density in the combustion chamber after the return wave hits. This return wave effect is exactly why you might be looking at the CPI pipe. Return wave tuned at a higher rpm with a stronger pulse. This is why jetting, detonation, and HP, are all affected by the pipes. Anyway, unless you are on the ragged edge with timing or compression, you will likely have nothing to worry about and static pumping numbers will not change because you are not firing the engine to get a return wave from the pipe.

 

 

Brandon

[FasterThanU90]

wow Blowit i`ve never thought if it in that way, but is'nt the return wave spent gases aka hydrocarbons ?

[FasterThanU90]

>> u want more scavenging to get a fresh gas mixture in the combustion chamber, why big bores have bigger pipes more combustion exhuast to expelllllll

[blowit]

>> u want more scavenging to get a fresh gas mixture in the combustion chamber, why big bores have bigger pipes more combustion exhuast to expelllllll

 

 

The bigger pipe is not really to "expel" more gases, but increase the negative wave amplitude at the exhaust port and allow more room for expansion. What happens at the neg wave it it pulls the spent gases out put also pulls some of the fresh air fuel with it. The last phase of the pipe process is the pos wave hitting the cylinder with that extra bit of fuel. Think if the pipe as a "smart" supercharger. And since the reeds are closed, the pipe will boost density at the last second.

 

The large bell on the pipe has nothing to do with getting rid of gases, just tuning of sonic air. Like an echo chamber. The diverging cone angle decides the neg wave amplitude but sometimes what we want and what will fit are two different things.

 

 

 

Brandon

[FasterThanU90]

yea bigger scavenging effect with the bigger pipe actually loop-scavenging on a 2stroke