[Vulcan50]

I can Explain the wiring to the car. But not really at the controller portion, since I wasn't going that route I didn't care to investigate it. The wiring for the car, you're basically just rerouting the current carried in the purple wire through the controller. In my case it's being rerouted through the switch. Ignoring the obvious difference between the controller and my switch they function similar except the fact that My switch style offers a third function option.

So basically you will cut the purple wire and extend both ends of the purple wire to the controller. The controller may need some sort of a power supply, which could be anything that is on the car is on.

[Aus335iguy]

Im looking to implement a second valve and a third function option might be what i need ... can you elaborate ?

[Vulcan50]

What do you mean by a second valve? My switch setup allows 3 functions...

1. Stock (opens and closes the way it did from the factory).
2. Always open
3. Always closed (all exhaust is routed through the quiet muffler on the right)

This is all via the stock exhaust/valve components.

[Aus335iguy]

Originally Posted by Vulcan50

What do you mean by a second valve? My switch setup allows 3 functions...

1. Stock (opens and closes the way it did from the factory).
2. Always open
3. Always closed (all exhaust is routed through the quiet muffler on the right)

This is all via the stock exhaust/valve components.

I'm planning on putting a second valve between the two mufflers.
Centre open, left closed quiet(stock)
Centre open left open loud(PE)
Centre closed left open extra loud (essentially a muffler delete)

[Vulcan50]

I don't understand what the center valve being closed would do. If anything it would be quieter than no valve in the middle and the stock one open. Fluids want to take the path of least resistance, so really any exhaust on the driver side pipe will exit the driver side whether the center valve is blocking another path or not. As I said prior a center valve would restrict any exhaust coming down the passenger side from exiting the louder side (driver side). My guess is that it would be quieter. Though really any difference would be negligible. Plus there is still an x-pipe that seems like it would negate the center valve.

[Aus335iguy]

Originally Posted by Vulcan50

I don't understand what the center valve being closed would do. If anything it would be quieter than no valve in the middle and the stock one open. Fluids want to take the path of least resistance, so really any exhaust on the driver side pipe will exit the driver side whether the center valve is blocking another path or not. As I said prior a center valve would restrict any exhaust coming down the passenger side from exiting the louder side (driver side). My guess is that it would be quieter. Though really any difference would be negligible. Plus there is still an x-pipe that seems like it would negate the center valve.

So the crossover pipe is the one that gets rid of drone. That's why the PE exhaust keeps that part and doesn't have any drone. Otherwise PE is just straight pipe .

If we apply the logic that blocking it off makes it quieter, opening it makes it louder. Why would bmw add weight and cost to make something louder?

Oh and exhausts aren't just about flow, there's wave action happening. That's why the PE cross piece quietens the drone.

Also, the side on flow in a t piece which is inside the stock cans creates a Venturi effect and sucks exhaust in from the other side.

[Vulcan50]

I still feel like closing the center valve would not make it any louder than with it open. Because all you would be doing is decreasing the amount of flow through the loud exhaust side.

As for why BMW would do this, it is as a brand new luxury car. Granted a high-performing one, which is why they have the option for it to open (increased performance in some regard). Though they want it quiet when you're just cruising. That is my take on the system. If I'm wrong please tell me what you think.

This may be a situation of marking it up, and seeing how it works.

[Aus335iguy]

Originally Posted by Vulcan50

I still feel like closing the center valve would not make it any louder than with it open. Because all you would be doing is decreasing the amount of flow through the loud exhaust side.

As for why BMW would do this, it is as a brand new luxury car. Granted a high-performing one, which is why they have the option for it to open (increased performance in some regard). Though they want it quiet when you're just cruising. That is my take on the system. If I'm wrong please tell me what you think.

This may be a situation of marking it up, and seeing how it works.

On a PE exhaust there is no valve, but the centre section remains the same. It's there to stop drone.
The gasses go through both straight pipe sections and the only "muffler" on a PE exhaust is the centre section. With it gone (blocked by the valve) effectively you'll have a muffler delete.

[Vulcan50]

The performance exhaust is basically equivalent to a slightly louder version of the driver side muffler. So if you leave the standard exhaust intact except for adding a center valve, closing the valve wouldn't result in a noticeable difference.

What I plan to do is a muffler delete on the driver side/loud side while maintaining the cross over. Giving me the options that I have now but the loud mode will be louder.

[Aus335iguy]

Originally Posted by Vulcan50

The performance exhaust is basically equivalent to a slightly louder version of the driver side muffler. So if you leave the standard exhaust intact except for adding a center valve, closing the valve wouldn't result in a noticeable difference.

What I plan to do is a muffler delete on the driver side/loud side while maintaining the cross over. Giving me the options that I have now but the loud mode will be louder.

I'm saying for a PE exhaust though. It's straight pipe on both sides of those

Originally Posted by Vulcan50

The performance exhaust is basically equivalent to a slightly louder version of the driver side muffler. So if you leave the standard exhaust intact except for adding a center valve, closing the valve wouldn't result in a noticeable difference.

What I plan to do is a muffler delete on the driver side/loud side while maintaining the cross over. Giving me the options that I have now but the loud mode will be louder.

Yeah exactly, which is why adding a "center" valve is likely to be pretty pointless.

That muffler delete valve option sounds like the best of both worlds though

Originally Posted by Aus335iguy

I'm saying for a PE exhaust though. It's straight pipe on both sides of those

Have you seen what the "PE mod" does? The actual PE exhaust is unlikely to be any different...hence why everyone is telling you not to waste your time with a center valve.

[Aus335iguy]

Originally Posted by FCobra94

Yeah exactly, which is why adding a "center" valve is likely to be pretty pointless.

That muffler delete valve option sounds like the best of both worlds though

Have you seen what the "PE mod" does? The actual PE exhaust is unlikely to be any different...hence why everyone is telling you not to waste your time with a center valve.

Agree to disagree then

EB89 when you get your j pipes changed out with a resonator, try and make the pipe between the two halves the same length as what would be inside the standard cans. I'm pretty sure it's about 1meter long for a reason. I think it's tuned for about 300 hz
*edit, more likely 100-150 hz I got my wavelengths wrong.

[EB89]

Originally Posted by Aus335iguy

Agree to disagree then

EB89 when you get your j pipes changed out with a resonator, try and make the pipe between the two halves the same length as what would be inside the standard cans. I'm pretty sure it's about 1meter long for a reason. I think it's tuned for about 300 hz

You are correct, that pipe that joins the two mufflers in both the stock and PE muffler is for drone elimination.

I have found some calculations for the length it should be. It would be good to have it measured to see what BMW uses as they pretty much nailed it

https://www.reddit.com/r/FocusST/com...or_tube_aka_j/

For our cars, I have been told we are 3 pulses per rev

So the calculation for 2000rpm drone is

((343)/(2000 * 4 * (1/60))) / 4 = 85.75cm

or 1800rpm

((343)/(1800 * 4 * (1/60))) / 4 = 95.27cm

Im not going to put a resonator between the muffler delete pipes, im going for a right angle straight pipe at one of these lengths, leaning towards 1800rpm drone length.

Im interested to know why BMWs pipes arent straight in the mufflers and they bend. Perhaps to get the exact length they needed...

[Aus335iguy]

Originally Posted by EB89

You are correct, that pipe that joins the two mufflers in both the stock and PE muffler is for drone elimination.

I have found some calculations for the length it should be. It would be good to have it measured to see what BMW uses as they pretty much nailed it

https://www.reddit.com/r/FocusST/com...or_tube_aka_j/

For our cars, I have been told we are 3 pulses per rev

So the calculation for 2000rpm drone is

((343)/(2000 * 4 * (1/60))) / 4 = 85.75cm

or 1800rpm

((343)/(1800 * 4 * (1/60))) / 4 = 95.27cm

Im not going to put a resonator between the muffler delete pipes, im going for a right angle straight pipe at one of these lengths, leaning towards 1800rpm drone length.

Im interested to know why BMWs pipes arent straight in the mufflers and they bend. Perhaps to get the exact length they needed...

That's exactly why it's bent yes. The length of the pipe determines the frequency of the sound you want to attenuate and the the amount of perforated area determines how much of that sound you want to eliminate.... if you change either of those two factors you change the sound or tuning of the exhaust.

Yeah, but a properly sized helmholtz will accomplish the same thing while being less complex and requiring fewer parts.

Your idea of adding two valves, including a center valve, *might* add the perception of "loudness" given the introduction of a minute amount of drone, but that's about it.

For that reason, Vulcan50's idea makes the most sense here...I look forward to you proving me wrong otherwise though.

[EB89]

@Aus335iguy I think I might get my stock muffler modded, but at the same time get the pipes measured while its open.

People seem to have great results straight piping only the outer pipes when doing the PE mod and leaving the inner pipes and baffling alone.

Ill get the inner pipe measurement and see if and exact length pipe can fit between a muffler delete, if anyone got it right it was BMW, thats the length we need to know

Would be very cool to make a droneless MD

[Aus335iguy]

Originally Posted by FCobra94

Yeah, but a properly sized helmholtz will accomplish the same thing while being less complex and requiring fewer parts.

Your idea of adding two valves, including a center valve, *might* add the perception of "loudness" given the introduction of a minute amount of drone, but that's about it.

For that reason, Vulcan50's idea makes the most sense here...I look forward to you proving me wrong otherwise though.

Yeah I think I understand what youre getting at but I think I'm not explaining it properly. It'll all come out in the wash as they say

[Aus335iguy]

Originally Posted by EB89

@Aus335iguy I think I might get my stock muffler modded, but at the same time get the pipes measured while its open.

People seem to have great results straight piping only the outer pipes when doing the PE mod and leaving the inner pipes and baffling alone.

Ill get the inner pipe measurement and see if and exact length pipe can fit between a muffler delete, if anyone got it right it was BMW, thats the length we need to know

Would be very cool to make a droneless MD

That's my understanding of the PE mod. Straight pipes on the outer section only.

[Vulcan50]

Any word on the outcome of the center valve?