Just went a bit mental, opinions? Video added

Nice explanation exdos :thumbsup: I get you now, I thought that remapping could optimize even a bog standard set up?

I fancy getting it dyno'd stock and like this, if I'm losing power I'll probs go straight back to OEM (with bypass) most important thing to me is performance and feel, definitely wouldn't trade in power for noise :thumbsdown:

Should get a video up today jet, it really is, 4 bolts and unclip the hangers and that's them both off, OEM will go on exactly the same
 
Here's a quick video of it, this is it being started for the first time today and there is a big fence directly behind it so that will affect the sound. Sound changes quite a bit after it heats up. Definitely mad and only for weekends lol

http://m.youtube.com/watch?feature=c4-feed-u&v=zvcuNQjAnHc
 
I'd love to hear that on the road at 5000 rpm. Sounds like a beast :thumbsup: :thumbsup: :thumbsup:

Bet your be a little self conscious around town as your sound like a hooligan, but out on the country roads that will sound awesome. Your face will hurt from smiling when you get home after a trip out lol :rofl: :rofl: :rofl:
 
You've hit the nail on the head lol, when there's nobody about it's like ear porn but in a busy city centre it's a bit much haha early shifts, nice and smooth driving it's about acceptable, then you get to an open road and let loose :evil:
 
I like that :thumbsup: sounds really aggressive & I have always thought standard M cars exhausts are a little too muted anyway...it gets my vote :driving: I love TVR`s so this is right up my street, enjoy it. :)
 
That does sound good- I went for the bypass pipes only and it has a lovely cultured growl but I still crave a little bit of extra volume. That said, I had a Rogue Engineering Diablo exhaust and that only stayed on the car a week before I was sick of it being so intrusive so I should probably leave the exhaust well-alone now!
 
To be honest the video makes it seem relatively quiet it is loud as hell in real life lol!

I gave it a wee blast on the way home there with the window down, there was a few bends hence the breaks in accelerating.

Here's the link
http://m.youtube.com/watch?feature=youtube_gdata_player&v=cA4sG-ZsjJE&desktop_uri=%2Fwatch%3Fv%3DcA4sG-ZsjJE%26feature%3Dyoutube_gdata_player
 
Dean26390 said:
To be honest the video makes it seem relatively quiet it is loud as hell in real life lol!

I gave it a wee blast on the way home there with the window down, there was a few bends hence the breaks in accelerating.

Here's the link
http://m.youtube.com/watch?feature=youtube_gdata_player&v=cA4sG-ZsjJE&desktop_uri=%2Fwatch%3Fv%3DcA4sG-ZsjJE%26feature%3Dyoutube_gdata_player
Click to expand...
Just love it :thumbsup:
 
Sounds fantastic, but I bet it's really really loud! I prefer a little less exhaust and a little more induction noise with mine :thumbsup:
 
Is it just the recording that makes it sounds kind of tinny? I assume it actually has a bit of low end sound to it as well?
 
Mr Exdos, forgive me but any chance of some further info/theory on the relative impact of playing with the exhausts?

I assume the removal of the rear can to speed up the down stream loss could interfere with the pulse and or allow more of the inlet charge to exit while the valves are in overlap, is this what you were getting at?

So..

How is the RPI can really any different from a simple straight through pipe in your opinion, is the swelling (loosely call it a silencer) big enough to not impact the pulse/wave effect?

Your modification of the internal OE silencer, is this not now a straight through pipe, how is this different?

By pass pipes, could this rob any bhp or is it so minimal to be none detectable?

I know you will not have all the data so am only really asking what impact in your opinion could or could not be felt by the various exhaust mods that people commonly do. Not asking your to recommend or slag any manufacture off etc, just curious as i have not really played with the S54 engine and totally accept that there is nothing more dangerous to an engine than a determined idiot….(that could be me for clarity purposes)
 
Markcoopers said:
Mr Exdos, forgive me but any chance of some further info/theory on the relative impact of playing with the exhausts?

etc.
Click to expand...

I don't claim to be an expert on this but I have read a lot about the subject and done a fair amount of practical experimentation with intakes and exhausts on my S54 cars and others. The S54 engine is a very sophisticated design where the intake and exhaust systems coupled with a Double VANOS permit a volumetric efficiency of 106% in OEM guise. I've previously seen the figures for the back pressure in the E46 M3 (same S54 engine as the Z4M) and it is one of the lowest for a production car with cats and silencers. The S54 engineers will have optimised the OEM intake and exhaust systems to each other so if you make the exhaust more free-flowing by modifying or removing catalysts and/or silencers without improving the air intake system, then you will upset the E/I flow ratio (see: http://speedtalk.com/forum/viewtopic.php?t=3266) From my own experimentation and datalogging, I found that modifying either intake or exhaust alone, gains nothing, but improving the air intake at the same time as making the exhaust more free-flowing, improves airflow, as recorded by the ECU through the MAF, which in turn, increases Volumetric Efficiency and power output.

With the S54 having a double vanos, the valve timing is adjusted dependent upon engine RPM so that the peak engine torque tends to plateau rather than peaking at a specific RPM, and this works because maximising cylinder charge may require overlap of intake/exhaust valve opening/closing at different RPMs. Therefore, simply making the exhaust as free-flowing as possible may actually reduce cylinder filling.

The RPI exhaust appears to be a simple pipe arrangement with no silencer. The purpose of my modification to the OEM silencers is to effectively convert the silencers to a straight-through system BUT retaining silencing. I have no experience of a bypass pipe so I haven't datalogged a car with it so I've no idea how it might affect performance.

Personally, I hate particularly loud exhausts especially when they drone, and unless an exhaust shows a provable performance gain I can't see the point of spending any money on aftermarket systems. From my experimentation and datalogging I've found it possible to improve the performance and enhance the sound of the OEM silencers for very little cost, and that for me, has been the fun in devising appropriate mods.

Hope this helps. :thumbsup:
 
It does indeed.

For my part I am wishing for a bit more aural drama, and willing to trade some civility for that as it is a toy and not a daily driver, but not really looking for more BHP. I get that the after market exhaust manufactures claims should always be treated with some scepticism but given that this is a heigly tuned engine to start with am quite concerned about cocking it up. That said I am with you on the point that if you are going to change a part you should do with the most cost effective you can and given this is a performance car, add to that and not take from it.

So did your internal silencer mods achieve a noticeable increase in noise, or was this really not the design idea...I sense the latter?

I know I could serch your posts, but in the interests of speed what have you done to the inlet/exhaust elements?
1) filled drain hole in air box
2) modded the silencers
3)

Cheers :D
 
Markcoopers said:
So did your internal silencer mods achieve a noticeable increase in noise, or was this really not the design idea...I sense the latter?

I know I could serch your posts, but in the interests of speed what have you done to the inlet/exhaust elements?
1) filled drain hole in air box
2) modded the silencers
3)

Cheers :D
Click to expand...

Here's a link to a video recording I did whilst datalogging my Z4MC with the 2 mods you've listed plus my "Ramcharger II" mod, which I have not publicly disclosed.
http://www.youtube.com/watch?v=-ZaDO7NbN_Y
The noise is definitely greater and more theatrical than OEM. My interest lies solely in improving performance and with regard to sound, all I'm bothered about is avoiding low frequency drone. I've found that making exhausts more free-flowing inherently makes the exhaust sound louder.
 
I will watch that when not on the iPad as it has a few issues with YouTube vids.

So modding the rear silencers looks straight forward enough, as does sealing up the air box drain hole. Next I read somewhere tonight that the air box as a convoluted air path, so cutting some plastic out of this is a good idea.....any ideas what I am on about?

Then an addition of an air scoop, and a mod to the MAF with the honeycomb replacing the wire gauze.

Any other simple and disclosable things I should do?
 
I've no idea of what you say about a convoluted path and I wouldn't cut anything from the OEM intake system. It really is an excellent design that creates a genuine ram effect (as you can see with the needle of the Magnehelic Pressure Gauge in my video) which helps the car to achieve a Volumetric Efficinecy greater than 100%, although it can be made even better.

You've covered everything. :thumbsup:
 
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