Off with the old and on with the new Quad...

[cj10jeeper]

Very much like what you've done, but then again having a quad and CF diffuser - no surprise..

Quality of work and fitting looks good. Tips seem a bit too close to the diffuser, but if they don't touch under any temperature and driving conditions then should be fine. CF will stand up to it. I actually like the look

Def. have reservations about a silencer on one side and not the other. Everything tells me it's wrong to off balance a system. Sound, pressure, gas flow, effect on the engine (unless you have a balancer).

Nice job overall

 

[PawnSacrifice]

Glad I used a heat resistant resin for the CF Anyway, good work - look forward to the next system in a month or so 8)

 

[bmwangler]

Whole set-up looks great, well done

 

[billygilly]

Looks excellent, great mod and also stops anyone saying it's copying the //M

 

[AlanJ]

Def. have reservations about a silencer on one side and not the other. Everything tells me it's wrong to off balance a system. Sound, pressure, gas flow, effect on the engine (unless you have a balancer).

You and me both then.......

 

[Hotride]

I think it looks good. Those tips are definitely not my first choice, but they are growing on me.

Only concern as others have mentioned is the rear muffler on 1 side only, otherwise I think you have done well!

 

[Friengineer]

Looks awesome! I would be a little concerned about heat causing damage to the carbon and would lower the tips slightly out of caution. It depends entirely on the cure cycle the manufacturer used. I assume they'll have used a decent high temperature epoxy and cured it at upper 100s to lower 200s. A decent epoxy should be good for lower 200s.

I Would definitely ask what glass transition temperature (temperature at which the resin system matrix starts to break down) it's spec'd to.

Either way, looks amazing.

 

[JDM]

Thanks for all the comments people.. Sorry I've only just got around to replying, I have been rather tied up all weekend and just got round to turning the laptop on..

So as requested i've attached a picture of the car from the rear showing the diffuser aswell. Hope this is what people were after. Also uploaded a video trying to show how it sounds but its pretty hard with an iPhone.

As for peoples comments with regards to the unequal balancing of the system by having one rear silencer on the LHS and not the RHS I mentioned this to the exhaust specialist when they were undertaking the works. I am assured that it wont upset the balance as all the silencers are straight through, I.e there are no twists or turns in the silencers it is just a straight through baffle within the box with wadding surrounding the baffle within the box. I am also informed that all back pressure is determined at the cats at the bottom of the headers?

With regard the carbon diffuser as this is a BMW part made to be next to the exhaust tips then I would hope that it would be up to the job. All this talk of glass temperature resin is confusing me. I guess all I can do is keep an eye on it and make sure theres no damage being caused?

Thanks for all the positive feedback guys, I was expecting alot more negative to be honest with me stepping outside the safe zone!!

Video Sound Clip Below

http://img84.imageshack.us/img84/3585/cb5.mp4

 

[Bradders75]

I'm another one in the thumbs up camp - looks great and I think the DTM tailpipes really suit a diffuser set up. Having followed you in the past, I thought your last system was way too loud and ruined the character of the engine a bit so if your new one is quieter, even better!

 

[JDM]

I'm another one in the thumbs up camp - looks great and I think the DTM tailpipes really suit a diffuser set up. Having followed you in the past, I thought your last system was way too loud and ruined the character of the engine a bit so if your new one is quieter, even better!

Thanks Bradders.

New setup is still quite loud. It's not quite as loud as the other one but its alot deeper sound, more bassy ( is that how you spell it )?

What it has done is take the edge off at motorway speeds which is what I was after. I like it loud, its what the car is missing IMO, gives it more sense of occasion and drama with the pops and bangs etc..

 

[cj10jeeper]

I guess if the box is no more than a straight through tube with perforations, then it should have minimal effect

 

[JDM]

I guess if the box is no more than a straight through tube with perforations, then it should have minimal effect

Thanks for clearing that up Phil, was a little worried about it. Having said that these guys really know what they are doing. I can't praise them enough. Brett is an utter perfectionist in everything he does.

 

[Leatherneck]

Nice, your cars certainly looking mean now JDM (in a good way) think the diffuser and DTM pipes suit your paint colour to a T.

Brett showed me the pics he has of your new set up when I took my Z4 Coupe in last week, for the quad conversion you originally made famous (basically silencer delete and new pipework behind the bumper). I went for the usual oem look round tips, and for my car (silver colour with the original bumper cut) I think this set up looks fantastic.

Can't say I am quite so sure about the sound as yet, I know you mentioned about the pops and bangs in your original posts, but I wasn't quite prepared for the amount / volume. Interesting to note that you say you still get these with your new set up. Is it still the same in this respect or have the pops and bangs been reduced at all for you?

I am a little worried about the reason for the pops and bangs too, and it definitely seems to me that my car has lost some of its previous performance / 'urge'. I think I will look into a rolling road tune to see if anything is amiss. Would appreciate any feedback you (or anyone else reading this) may have on the subject, especially regarding whether a rolling road tune (or remap even?) is likely to regain the cars previous 'oomph' / reduce the pops and bangs. I am wondering whether the car is running to rich for some reason after the exhaust mod and whether the pops and bangs could be damaging the engine?

Anyway, back on topic, I think any quad conversion for the Z4 really enhances the looks of the car, I always think symetrical looks 100% better on a car. I even think the looks of such a conversion are worth a small loss of performance, although it would be nice to 'have my cake and eat it'

Regards

LN

 

[JDM]

Hi Leatherneck..

Yeah Brett told me that he had got another Z4 coming in last week for the quad setup.. It seems that I have started something of a trend here lol. Thanks for the complement on the new system, I love the look of the DTM pipes. Just looks like nothing else that Ive seen before on a Zed.

With regards to the noise of your system I would say give it a few thousdand miles, it gets better and mellower with age. Before mine was taken off it sounded at its best.

The new system is still the same in terms of pops and bangs so I wouldnt say its anything to do with that particular setup with the t section behind the bumper. I think its just with having big factory silencer removed which will deaden most of these noises. IIRC my original factory system popped and banged sometimes on lift off its just louder with the silencer removed.

With regards to the car running rich I cant see how changing the exhaust will effect this as all of the fuel air mixture is done before the cats and the cats will determine everything after such as back pressure etc. I may be wrong though.

Its funny that you mention the system affecting the power. Mine felt the exact opposite. Felt alot more free and rev happy. I put it down to removing the silencer. It definately didn't make the car any slower, not noticably anyway.

You are right in what you say about the quad finishing off the car though. It just looks so much more balanced. If you havn't debadged the rear yet then I would definately recommend that just to balance it up that bit more

Hope this helps you out a bit. Your more than welcome to come and see my setup though if you want to compare if you arent too far away.

Cheers

John

 

[Leatherneck]

Thanks for the reassurance JDM, will deffinitely give it some time, not only for the sound to 'mellow' but also for me to get used to the new sound. Anyway, as I hinted at before, I think the looks of the thing will let me forgive the system from being a little louder than my ideal. Yes, I debadged the car same day I bought it

I also have a theory (and hope) that the quads sound better outside the car than in, so I plan to test this theory by letting a (trustworthy) mate loose with the car while I stand outside and listen.

Unfortunately I am not local, well not anymore, I travelled down from Darlington, County Durham to have the exhaust done, partly after reading your posts and also because I recall getting an exhaust done with Brett a few years ago, when I was local (I am originally from Sheffield and still have family there).

Regarding the 'science' behind the cause of the pops and bangs and performance impact of my new exhaust set up, I have very little knowledge to base any theories on. Only reason for pops and bangs that I can think of would be unburnt fuel in the exhaust system, hence my fuelling issue concern, but I agree with you that (short of any type of sensors on the engine somehow being affected by the difference in flow of exhaust gasses or something) I don't see how fuelling could be influenced by the mod.

Regarding performance, a couple of weeks ago I filled up with Shell V power petrol which really seemed to sharpen up throttle response (the 'urge' thing I was talking about) especially when accelerating at motorway speeds / from around 3000rpm. This is the kind of urge I feel has been reduced. I think I might try standard shell this week, just in case the higher octane in the V power could have any bearing on the performance and pops and bangs of the new exhaust.

Do you ever recall asking Brett about the pops and bangs or performance implications of the quad set up yourself?

Thanks again

LN

 

[JDM]

I think the quads definately sound better outside than in.. Ive had the opportunity of driving a mates car behind mine and also watching the GF drive off in it (told her to give it some) lol.

I guess your theory of unburnt fuel creating the pops and bangs is possible but as said I cant see how changing things from the mid silencer back can affect this. I still think its purely down to the removal of the silencer. I would also say its nothing to do with the t section as I said it still pops and bangs on my new setup which is two individual pipes from the mid section.

No I didnt ask Brett about the effect on performance to be honest. I guess if I had noticed a loss in power I may have gone back to pick his brains but like I said mine felt quicker.

Hope you manage to get it sorted to your satisfaction and if you are ever up these neck of the woods visiting family the invitation is still there to come have a look at mine if you want.

Cheers

John

 

[Leatherneck]

Thanks John

I will try and remember to let you know / arrange something when I am next down, would be good to compare the 2 exhaust set ups in the metal.

Cheers

LN

 

[oli445]

I wouldn't worry about pops and bangs, I used to have a racing puma that popped and banged from the factory. The exhausts on them were janspeed full systems. I think the pops and bangs sound awesome, really miss them!

 

[koolchris99]

where did you get the CF diffuser?

 

[JDM]

I wouldn't worry about pops and bangs, I used to have a racing puma that popped and banged from the factory. The exhausts on them were janspeed full systems. I think the pops and bangs sound awesome, really miss them!

Thanks for your input oli445. I love the sound of them.

where did you get the CF diffuser?

It's a BMW part that is sadly no longer available. I searched high and low for mine including speaking with BMW in Germany and they couldnt source me one. It was part of the BMW aero package for the facelift cars.

I luckily managed to drop on one from a fellow forum member (pawnsacrifice) who had one lying around that he had decided not to fit.