Quad Conversion - Project Write up

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cj10jeeper
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Quad Conversion - Project Write up

Post by cj10jeeper » Tue Apr 21, 2009 9:27 pm

I’ve had several requests to pull together a brief write up of the project to convert to a Quad system, so here we go:

My intention was to continue to develop the Zed inline with my overall theme, not replicate an ///M but bring the rear in line with the rest of the car. I set some overall criteria:
• The exhaust had to be fully functional and not dummy pipes, or a cheaper ‘T’ off the back box. Noise levels to be acceptable, net weight the same and no drop in performance (nor gains sought)
• Luggage space had to be maintained.
• I had sourced a pair of brand new M boxes (thank you Ebay £21 Vs £850) so wanted to go with them if possible.
• Controlled costs as this was experimental.
• It had to say ‘OEM’ or at least BMW could have done that.

The movement of parts

A lot of space had to be cleared to get the RHS box in as it’s a space already full of components. (Hence the reason why on the ///M BMW just lobbed the battery on a tray in the boot and hid it under carpet)

Battery had to be removed, box narrowed by 20cm heat welded back together and new Hawker battery fitted. New earth lead fitted.

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The boot floor was plated, sprayed and sealed in. Great job by MRH Autos on the plate and spray work :thumbsup:

Starter and other cables rerouted and all returned to normal in the interior, so retaining my luggage space and keeping all the OEM battery disconnects, crash sensors, etc.

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The charcoal fume breather was removed (later found to be required only for OEM emission tests, but may later slot it back in between the rear boxes)

The Carbon Diffuser

Inspired by the latest race derived look appearing on many high end cars I wanted a CF diffuser on the back, but it was only available in single outlet and for the facelift as an OEM part.

The inspiration seen on several cars like these:

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I also wanted to keep the OEM lights too, so switching to a later bumper cover would have meant bodywork around the lights, something to be avoided.

Lots of cutting, teasing, customising and moulding of a second exit and a prefacelift quad CF diffuser was born out of the OEM CF facelift version, that fitted the bumper and accommodated the proposed new pipes.

The new outlet moulded in:
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Glossed, cut down from it's assymetric shape and finished aside minor trimmong once in place.
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Not a good look though, to have been driving around for a week though with only LHS exhausts….
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The new pipework

All that really remained was to couple the new boxes to the existing system. This was entrusted the MIJ who did a great job of fashioning stainless pipes, mounting everything and threading the new RHS pipework as a mirror of the LHS. The guys even flanged their pipes so the back boxes are correctly bolt mated on and we fitted an OEM ///M heat shield above the new box and various undertrays were modified. At a later stage it will be possible to bypass the main cats if required, but this was skipped for now due to unknown noise levels and sound of the system.

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The Result

Well I’ll let the photos speak for themselves, but I love it. It has a very OEM look to it, obviously is fully functional and has a glorious sound that is not at all loud. My criteria were fully met too.

We’ve got 1,000 miles on it and all I needed to do was cut a little CF off the diffuser as the exhaust stretches by 10mm when hot and was touching the diffuser and the diffuser needed adjustment to sit square.

Thanks to all those who chipped in comments, kept me ‘true’ on design ideas and provided a sounding board.

Of course I'd not do it again and as the Iphone ads. say have shortened and missed some steps in what was an interesting little project :D

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Jaguar F-Type 3.0 Supercharged V6 S, Stratus Grey, LSD, Active Exhaust, CF wheels, Performance brakes, Sports seats and mods ongoing
Gone but not forgotten Z4 3.0i SE Roadster ///M front, Red ///M leather seats, Aero sills

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paddy wright
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Re: Quad Conversion - Project Write up

Post by paddy wright » Tue Apr 21, 2009 9:37 pm

great job- look 4ward to seeing it on sunday!
Z4 2.2 sterling grey,Msport seats,retrofit cupholders,cruise,footwell lights,sound gen and mfsw,18"ellipsoids,xenons+light washers,ZHPknob,folding mirrors,3"stubby,update wheel caps,gateway300 ipod, wind deflector to keep the wife happy!

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Re: Quad Conversion - Project Write up

Post by ksher » Tue Apr 21, 2009 9:38 pm

The quad exhaust looks awesome. How many extra bhp does the new system give?
Current BMW: Z4 sDrive23i ///M Sport (Space Grey/Black Kansas Leather with Black High-gloss Front Grille), 318i Sport (F30).
Previous BMW: 120d SE (F20), Z4 2.5i Sport Roadster (E85), 523i Sport (E60), 323Ci (E46), 523i SE (E39), 318i (E36).
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Re: Quad Conversion - Project Write up

Post by RustyZ4 » Tue Apr 21, 2009 10:03 pm

What a fantastic job, looks good :thumbsup: , out of my techinical league tho :roll:
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Re: Quad Conversion - Project Write up

Post by WLH » Tue Apr 21, 2009 10:28 pm

RustyZ4 wrote:What a fantastic job, looks good :thumbsup: , out of my techinical league tho :roll:
X2... :thumbsup:
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Re: Quad Conversion - Project Write up

Post by klarky » Tue Apr 21, 2009 10:33 pm

looking good, probably looks even better in person id bet

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Re: Quad Conversion - Project Write up

Post by cj10jeeper » Tue Apr 21, 2009 10:40 pm

Cheers guys
Of course .. public outing on Sunday so you can judge in person. I cannot take photos of it, so you can't really see the shape of the CF nor the pattern, etc.

ksher - no idea if it gives more HP. The capacity of the system is greater, backpressure should be lower, but dyno aside I'd not guess as it's all to complex getting exhausts right. If it's the same (and it does feel better, but but dynos are unreliable...) then I'm happy.
Jaguar F-Type 3.0 Supercharged V6 S, Stratus Grey, LSD, Active Exhaust, CF wheels, Performance brakes, Sports seats and mods ongoing
Gone but not forgotten Z4 3.0i SE Roadster ///M front, Red ///M leather seats, Aero sills

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Re: Quad Conversion - Project Write up

Post by paddy wright » Tue Apr 21, 2009 10:47 pm

paddy wright wrote:great job- look 4ward to seeing it on sunday!
bump- i am really looking forward to hearing it
Z4 2.2 sterling grey,Msport seats,retrofit cupholders,cruise,footwell lights,sound gen and mfsw,18"ellipsoids,xenons+light washers,ZHPknob,folding mirrors,3"stubby,update wheel caps,gateway300 ipod, wind deflector to keep the wife happy!

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Re: Quad Conversion - Project Write up

Post by fasterthanyouCJH » Tue Apr 21, 2009 11:53 pm

Hello, new to the forum. 3.0i Z4, where is this meet?is it open to newcomers? thanks.

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Re: Quad Conversion - Project Write up

Post by paddy wright » Wed Apr 22, 2009 12:04 am

check out the midlands breakfast club thread in meets section. Oh and welcome :D
Z4 2.2 sterling grey,Msport seats,retrofit cupholders,cruise,footwell lights,sound gen and mfsw,18"ellipsoids,xenons+light washers,ZHPknob,folding mirrors,3"stubby,update wheel caps,gateway300 ipod, wind deflector to keep the wife happy!

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Re: Quad Conversion - Project Write up

Post by GP20 » Wed Apr 22, 2009 12:10 am

Looks awesome. I had my doubts before you started the project, but it's great to see when someone isn't afraid to go the extra distance to have the job done properly. Your Z is becoming one of my favorite modified Z4's.

Btw, are your wheels refinished in a dark gray?
'08 BMW Z4///MC 18" & 19" BBS RGR's|Michelin PSS'|TCK DA's 450/500|OEM CF spoiler|Aero side-skirts|ZHP gear-knob|OEM STB|
'06 BMW Z4///MR (sold)
'04 BMW Z4 3.0i 6sp SMG (lemon)
'03 BMW Z4 2.5i non-sport (sold)

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Re: Quad Conversion - Project Write up

Post by GP20 » Wed Apr 22, 2009 12:12 am

And here's another suggestion. I think the exhaust muffler boxes are now standing out a little too much with the contrast of the rear diffusor. Maybe you would consider powercoating them black. :thumbsup:
'08 BMW Z4///MC 18" & 19" BBS RGR's|Michelin PSS'|TCK DA's 450/500|OEM CF spoiler|Aero side-skirts|ZHP gear-knob|OEM STB|
'06 BMW Z4///MR (sold)
'04 BMW Z4 3.0i 6sp SMG (lemon)
'03 BMW Z4 2.5i non-sport (sold)

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Re: Quad Conversion - Project Write up

Post by cj10jeeper » Wed Apr 22, 2009 8:56 am

Hey GP20 - thanks for the feedback and comments. You were one of the guys that 'kept me true' by ensuring I did not slip into the T pipe route and kept an eye on net weight :thumbsup:

You are bang on the money re toning down the boxes. I already had a discussion on the forum on that point and indeed have some high temp matt black paint ready for the job (found some matt black barbeque paint, that's for spraying direct on bare metal and good for extreme temps). I decided to run it for a month and see what I thought before painting as the cans are brand new and will mellow and it's hard to revert once sprayed.

Wheels are self customised jobs with the centres being done in smoked chrome. A 3 part process of black base, wet chrome and lacquer over.

paddy - not really much to hear as it's well silenced. There is a meaningful growl once the revs rise and things get serious, but I did not want a 'ricer' box. Equally I like to 'play' without drawing too much attention via the noise. I also had a warning from Mrs CJ who gets pissed that the Hamann quad on the X5 shakes windows and makes babies cry :rofl:
Jaguar F-Type 3.0 Supercharged V6 S, Stratus Grey, LSD, Active Exhaust, CF wheels, Performance brakes, Sports seats and mods ongoing
Gone but not forgotten Z4 3.0i SE Roadster ///M front, Red ///M leather seats, Aero sills

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Re: Quad Conversion - Project Write up

Post by gannet » Wed Apr 22, 2009 9:12 am

just awesome and a great look :thumbsup:
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Re: Quad Conversion - Project Write up

Post by Mr Whippy » Wed Apr 22, 2009 9:18 am

Nice work :D
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