Exhaust valves fitted!

R

Rally

Active member
 Hampshire
I bought my zed last year with a milltek cat back exhaust and one foam piece already removed from the sound generator and was happy with the noise for a while but the car was to quite for my liking.
I use the zed on motorways a lot as I live next to the M3 and M27 and I didn't think I could live with the drone of a back box delete so ordered a pair of valves from ebay,
Screenshot_20160709-194204.png
I had them fitted at a local garage and collected the car yesterday wow they work great open the valves it makes one hell of a racket with loud pops and bangs on the overrun but closed its back to quite normal driving exactly what I wanted.FB_IMG_1468056215285.jpg
This is the only photo I have during installation they sit a quarter to half an inch lower and I can still get over speed humps etc with no issues.FB_IMG_1468089540572.jpg
So this is my new favourite toy on off on off :rofl:
 
I quite like the idea! Very interesting indeed.
Are those just exposed wires under there?

I would be interested in hearing the noise out of these!
 
It's half way through the installation the wires go into a control box then we're wired into the fuse box. I have tried to video but it really doesn't do it justice I will try again and post a link.
 
ChrisN53 said:
So with the valve open, you're dumping exhaust gas, so post-cat, pre-resonator? Must be LOUD!
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Erm very loud but I can turn off and on when I want :thumbsup:
 
ChrisN53 said:
So with the valve open, you're dumping exhaust gas, so post-cat, pre-resonator? Must be LOUD!
Click to expand...

could be me.. but thats PRE cats even!! totally free exhaust once opened! lol
 
Beedub said:
ChrisN53 said:
So with the valve open, you're dumping exhaust gas, so post-cat, pre-resonator? Must be LOUD!
Click to expand...

could be me.. but thats PRE cats even!! totally free exhaust once opened! lol
Click to expand...

It does seem to pull a little better with the valves open I thought I would loose power with everything I have read regarding back box deletes
 
Be interesting to see whether MOT inspector passes that or what it might do to insurance premium.
 
Beedub said:
ChrisN53 said:
So with the valve open, you're dumping exhaust gas, so post-cat, pre-resonator? Must be LOUD!
Click to expand...

could be me.. but thats PRE cats even!! totally free exhaust once opened! lol
Click to expand...

Will be pre secondary cats, will still be going through the main cats in the downpipe either way.

Must be rather loud with the noise waves bouncing off the ground and the bottom of the car again. Interesting mod.
 
Love the idea, but they need fitting much closer to the rear or more pipes backwards.

You're almost certainly losing power due to the lack of scavenging in the system and I dare say a fair chance of wrecking your cats with the e resonance they create.

Enjoy while it lasts or until you fail the mot.
 
They couldn't have been fitted anywhere else due to the size of them but nothing is permanent and if I replaced the middle section it would be back to factory.
It doesn't feel like I'm losing any power but the noise could be masking it.
Could you explain the issues I could have with the cats please.
If I have issue with mot's it's easy to swap out the middle section of exhaust now the corroded down pipe bolts have been replaced.
It's just a bit of fun and some extra noise when I want it unlike a back box delete and nothing is permanent and can be put back to stock easily when I have had enough or for an mot.
 
Rally said:
They couldn't have been fitted anywhere else due to the size of them but nothing is permanent and if I replaced the middle section it would be back to factory.
It doesn't feel like I'm losing any power but the noise could be masking it.
Could you explain the issues I could have with the cats please.
If I have issue with mot's it's easy to swap out the middle section of exhaust now the corroded down pipe bolts have been replaced.
It's just a bit of fun and some extra noise when I want it unlike a back box delete and nothing is permanent and can be put back to stock easily when I have had enough or for an mot.
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Sure
The extra noise is making you think it's more powerful - 100% no doubt you have less. Remember BMW made great effort with the exhaust (within constraints of cheap cats, etc.)

You'll actually lose power due to removal of the scavenging effect that means in real simple terms the gas flow and shock waves pull exhaust out of the engine, getting more charge in the cylinder as exhaust is pulled and producing more power. At the same time it's key for smooth balanced engine operation.

The cats are fairly delicate and the shock waves from getting the noise and some extent pops ( unhurt fuel exploding) will shake them to pieces breaking up the internals.

You either need these fitting further back or secondary runs of pipe to the rear. That's the reason many folks do bypass tubes on the rear boxes.

Separately I would not want 1000c exhaust coming out mid car. High chance of damaging and melting stuff - just beware.

Totally agree it's a bit of fun and love the idea. Top end cars like Astons have it but done correctly.
 
Thank you for the detailed response I won't have the valves open for extended periods and do regular checks underneath.I did want them fitted further back but there wasn't room.
Everything is reversible by replacing the middle section of exhaust so if I need to its not the end of the world, on the plus side it does sound mental.
 
I'm sure it will sound 'mental' when you dare use it
Just making you aware of the downsides and potential damage.
One good blast could see off your cats, or you may be fortunate and they hold up

As for no room - I fitted a full ///M twin back box.wuad system and custom tubing. You just have to make space by relocating and removing things
 
But surely the cats will be ok even during a good blast because the original system (from cat downwards) will be temporarily out of use and not subject to any harm or gas flow? I.e. cat downwards will be no worse off than like say the engine being switched off? Not sure if I make sense
 
RickyG512 said:
But surely the cats will be ok even during a good blast because the original system (from cat downwards) will be temporarily out of use and not subject to any harm or gas flow? I.e. cat downwards will be no worse off than like say the engine being switched off? Not sure if I make sense
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Only working from an iPhone. If these are fitted before the main cats then will only impact the precats.

If so then they are really dangerous for emissions and heat.

I want to avoid appearing negative but the more I consider this the worse the mod seems to me.
 
seems to be between primary cats and secondary cats, i.e. upstream of the secondary cats

unless thats what you meant cj10jeeper
 
RickyG512 said:
seems to be between primary cats and secondary cats, i.e. upstream of the secondary cats

unless thats what you meant cj10jeeper
Click to expand...

Yes - that's my understanding when I look at the photos.
 
the secondary cat delete and replace with straight pipes seems to be like a good option? haven't really seen anyone say anything bad about it

https://www.youtube.com/watch?v=s0JgaTc1Sys

[youtube]https://www.youtube.com/watch?v=s0JgaTc1Sys[/youtube]
 
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