What Muffler?

[KeltonDSMer]

Get a actuated valve and weld in a Y split right after headers. Can keep stock exhaust and flip a switch and have straight pipe.

 

I really like cutouts! A cool thought on this setup would be to use a cheap standard plunger-type external waste gate in place of the electric solenoid-actuated butterfly. This way you can have the exhaust open automatically at a given boost pressure, and the user can adjust that pressure with WG springs or a cheapo ball/spring boost controller.

 

Spool will suffer until the bypass opens, but a fun thought non the less .

[mr moose]

For turbo engines, absolutely. Not always the case with N/A motors, however. Depending on the cylinder head design, exhaust systems are developed that take advantage of "scavenging". Here is the (not so great) wiki for what I am referring to if you are interested in a quick read: https://en.wikipedia.org/wiki/Scavenging_%28automotive%29

 

In this particular situation though, you are 100% correct that the "ideal" system is as open as possible.

 

I kinda disagree,  for any engine the less resistance in the exhaust the better.   there is a slight argument in header (extractor) design that would cause the exhaust flow from one cylinder to vacuum the exhaust from another. but after the headers a short open pipe is the best.

 

Although you are not talking about back pressure, see myth 5 in the below link as it explains why less restriction is always better providing the rest of the engine is tuned for the change in exhaust:

 

http://www.autospeed.com/cms/article.html?&title=Automotive-Myths&A=113096

[DildorTheDecent]

Ok, get muffler that'll pass. Then just gut the insides of it. Slam it back together

That's the same theory i've had for ages. 

[Vendetta]

I really like cutouts! A cool thought on this setup would be to use a cheap standard plunger-type external waste gate in place of the electric solenoid-actuated butterfly. This way you can have the exhaust open automatically at a given boost pressure, and the user can adjust that pressure with WG springs or a cheapo ball/spring boost controller.

 

Spool will suffer until the bypass opens, but a fun thought non the less .

Yea I've heard of people thinking about doing it that way but I personally would just stick with actuated valve. That way when I want to cruise and listen to amazing soundtrack I can just flip it and not worry about it.

[Gala]

@ You can take a 68mm external wastegate or a wastegate from a turbo, run a vacuum line and weld in a Y pipe. That way you have a boost actuated Y pipe. 

Here is an example:

[KeltonDSMer]

I kinda disagree,  for any engine the less resistance in the exhaust the better.   there is a slight argument in header (extractor) design that would cause the exhaust flow from one cylinder to vacuum the exhaust from another. but after the headers a short open pipe is the best.

 

Although you are not talking about back pressure, see myth 5 in the below link as it explains why less restriction is always better providing the rest of the engine is tuned for the change in exhaust:

 

http://www.autospeed.com/cms/article.html?&title=Automotive-Myths&A=113096

 

Yeah, the ex. manifold/header design really is what matters as far as scavenging properties are concerned. Once all cylinder's exhaust has merged I agree that open pipe is ideal. Thanks for not assuming I was claiming "hur dur you need backpressure", I can't stand hearing that argument . Thanks for the link too, that was fun quick read.

 

It does get get a bit weird with true dual systems on V motors (to cross-pipe somewhere in the middle or keep two isolated systems). That cross pipe can definitely affect where in the RPM range those vacuum pulses occur.

[mr moose]

 Thanks for not assuming I was claiming "hur dur you need backpressure", I can't stand hearing that argument . Thanks for the link too, that was fun quick read.

 

 

 

Your welcome.