Switchable exhaust valves, any experiences?

[Butter Face]

Just looking for some advice on fitting a variable exhaust system.

I need to get a 3 inch exhaust system fitted to release a bit more power from my car, but I don't want an unsociable sounding exhaust on my rattly old Japanese hatchback.

I have seen these exhaust valves that fit on as part of a custom exhaust system that diverts gas flow depending on if the valve is open/closed like this.



My understanding is that you have a large box on the side with the valve so that when it opens the gas goes through the box and keeps the noise down, but flick the switch and it closes and diverts down a straight pipe for more noiizzeee.

If anyone has fitted one or seen one I would appreciated any input!

Cheers

[Magic919]

You'll find a few guys on the Monaro/VXR8 section that run cutouts.

[HappyMidget]

Magic919 said:

You'll find a few guys on the Monaro/VXR8 section that run cutouts.

Plenty do, been a thread recently posted/updated in that has the info you need on which to order Will try and dig it out

[HappyMidget]

Found it: http://www.pistonheads.com/gassing/topic.asp?h=0&a...

[Butter Face]

Cheers for the link, had a read and that gives a great cheap link but no info on how they fit/work on a custom system?

I assume they don't just block the exhaust? You need to divert the gas somewhere?

[Ive]

I had a similar issue going to 2.5". Noise was fine at WOT and high rpm, but too much low frequency noise for my taste at low rpm, e.g. driving in town. But I needed that 2.5" throughput.
As most road driving happens at low load I have inserted pneumatically and ECU controlled valve into the 2.5" flow path that gets permanently bypassed by a 1" pipe. The entire assembly site before the muffler.
The pneumatic valve is controlled by a BMW exhaust flap control valve that is connected my programmable ECU. I employed the unused VTEC feature of my Emerald K3 ECU for this.
Below 3000 rpm and 30% throttle the valve is closed and gases have to pass the 1" pipe. This leads to a huge reduction in low frequency noise without actually changing the sound that much.
You also cannot feel the transition and only hear it when you carefully listen. I have set the switch point in such a way that there is no power loss around that area of the map.
This is mounted onto a Lotus Elise S1 with a supercharged Rover K.



Just food for thought.

[Butter Face]

Cheers mate, that's incredibly helpful, I'm running a Supercharged K20 with KPro so the output can be used from that.

[Ive]

besides the BMW control valve you need a check valve to keep the valve closed independent of plenum pressure.
Part number of the control valve:
Pierburg 7.22341.00
costs about 15 quid new.

The exhaust valve should be of the normally open type. The plenum's vacuum pulls it to the closed position. Th check valve keeps it closed and the BMW valve vents it if it sees 12V.
connection:
Plenum-----check-valve-----BMW valve------exhaust flap.

[Butter Face]

Cheers again.

That setup looks very similar to a lot of the valves you can buy on eBay that are electrically controlled rather than a vacumn so I may look at one of those. That bypass pipe is a great idea though.

[Ive]

unless you get a OEM grade electronically actuated valve, e.g. from Pierburg (expensive), forget these as shown in your original post. They are toys made in china with insulation that will melt the first time you boot it.
Even the OEM electric ones have lower max. temperature specifications that the pneumatic ones. This is the reason ALL OEMs fit pneumatic valves on their sportscars, not electric ones. Porsche, BMW, Aston, Nissan, Ferrari, Lamborghini.....
Connecting it to your VTEC output of the ECU makes for a seamless fit and forget solution. It is simple, easy to install and cheap.
two wires and a few meters of rubber pipe. That is all. Pneumatic valves are also much more compact, so easier to integrate into your exhaust system.

The check valves I uses are infusion non-return valve for medical purposes. you can buy them online for next to nothing. or ask your doctor for one the next time you are there. Silicone vacuum pipe fits snug over the female Luer connectors.


Pneumatic valves can be bought for about 120 quids and they last.

Here is a proper OEM quality electric valve. But it only comes in 57mm.

Edited by Ive on Thursday 18th August 21:41

[Butter Face]

Thanks for the info mate, have you a part number or fitment info for the exhaust valve?

[Ive]

here is a rather expensive example in 75mm:
http://www.rs-power-shop.com/en/powersprint-pipe-u...

This chap in Germany sells some for €130, even in 76mm:
https://www.ebay-kleinanzeigen.de/s-anzeige/abgask...

The electronic control valve number is already in my post above. if you enter it in google, you'll find it. it is used in almost every BMW these days starting from the E36.