Quad Exhaust set up - options discussion

[cj10jeeper]

Picking up on the cutting and fitting.
Both for pre and post facelift the lower lip has to be cut away. A lot of material is removed (yet to even get near the car to do that)
In effect your converting the outward lower lip to an inward swooping diffuser

Fastened on with about 9 bolts across the bumper and 3 or 4 underneath, no bonding though I may do different as this is a conversion of the dual to quad diffuser and may need more strength??

These scans should help - template, cut fix:

 

[mmm-five]

So, how much cleaner/dirtier will the diffuser make the air behind the car - in aerodynamic terms, rather than cleanliness terms of course

BTW, how much for the CF diffuser, as I may be wanting one (well that's not true as I do wan't one, just need to earn some money first).

 

[Breaker]

Picking up on the cutting and fitting.
Both for pre and post facelift the lower lip has to be cut away. A lot of material is removed (yet to even get near the car to do that)
In effect your converting the outward lower lip to an inward swooping diffuser

Fastened on with about 9 bolts across the bumper and 3 or 4 underneath, no bonding though I may do different as this is a conversion of the dual to quad diffuser and may need more strength??

Thanks for posting that.

Is there a cutting template?

Guess cutting the bumper is an off the car job?

Are you planning on painting yours or leaving it carbon? I'm looking at leaving it carbon when I fit one. I guess the bumper can be cut that negates the need for painting after?

Sorry for all the questions!

 

[Breaker]

So, how much cleaner/dirtier will the diffuser make the air behind the car - in aerodynamic terms, rather than cleanliness terms of course

BTW, how much for the CF diffuser, as I may be wanting one (well that's not true as I do wan't one, just need to earn some money first).

I think it's terrible when M owners fit non-M parts to their cars!!

 

[pvr]

I think it's terrible when M owners fit non-M parts to their cars!!

Where can I get front fog lights

 

[Breaker]

You can't fit them as you have "look at me I'm a race car" vents for the brakes (very handy in traffic!).

 

[mmm-five]

So, how much cleaner/dirtier will the diffuser make the air behind the car - in aerodynamic terms, rather than cleanliness terms of course

BTW, how much for the CF diffuser, as I may be wanting one (well that's not true as I do wan't one, just need to earn some money first).

I think it's terrible when M owners fit non-M parts to their cars!!

Well, BMW do it, so I'm just continuing where they left off. BMW are the ones that took the ///M off my headrests after all!

I wonder if there's a full underbody kit I can fit

I'm also planning on unblocking comletely the brake cooling duct - although it was cool enough at Oulton Park that I didn't need any extra brake cooling. And there's a last minute Anglesey Coastal date with Bookatrack which I'm tempted to attend on Sunday 8th March.

 

[jarrow]

Well 2 more bits came together on the project today.
I'm also happy that it will mate to the prefacelift bumper as they are exactly the same profile down low. The only difference is that the facelift has a feature line that the diffuser is templated along.

Looking forward to some pictures showing the feature line that you mention.

 

[Mr Whippy]

Are you planning on painting yours or leaving it carbon? I'm looking at leaving it carbon when I fit one. I guess the bumper can be cut that negates the need for painting after?

By the looks of the template in the image, the diffuser insert sits over some of the existing bumper, maybe 5-10mm in places around the cut, so looks like a relatively easy fit all said and done.

So how much is the diffuser and screws etc. Looks like a weekend afternoon job, and a steady hand


Lets watch CJ mess it up first, then learn from his mistakes and do it properly :wink:

 

[Herminator]

Are you planning on painting yours or leaving it carbon? I'm looking at leaving it carbon when I fit one. I guess the bumper can be cut that negates the need for painting after?

By the looks of the template in the image, the diffuser insert sits over some of the existing bumper, maybe 5-10mm in places around the cut, so looks like a relatively easy fit all said and done.

So how much is the diffuser and screws etc. Looks like a weekend afternoon job, and a steady hand


Lets watch CJ mess it up first, then learn from his mistakes and do it properly :wink:

Nah, you let him do it once, then get him to do yours as he's bound to do a better job the second/third time :wink:

So Jeeper- whats the cost of the diffuser?

 

[Breaker]

If I remember rightly, you need a small mortgage to buy the diffuser!! Think it was cheaper to buy the whole bumper!! I asked when I got my Z4 but can't remember the price now.

 

[Breaker]

I'm also planning on unblocking comletely the brake cooling duct - although it was cool enough at Oulton Park that I didn't need any extra brake cooling.

Aren't they fully open vents then?

 

[Mr Whippy]

If I remember rightly, you need a small mortgage to buy the diffuser!! Think it was cheaper to buy the whole bumper!! I asked when I got my Z4 but can't remember the price now.

That doesn't sound good.

Worth making a GRP copy by any chance, just get CJ to buy an OEM carbon one as the template

Still more than happy with a standard setup, but these diffusers do look very nice indeed... subtle but very functional looking while melding with the styling nicely.

 

[cj10jeeper]

OK so more questions ...lol

Diffuser is about £280, but I got 25% off so not too bad.

'Mess up' - not in my vocabulary.. Mr Cock-up often comes a knocking, but I rarely let him in!!!

I plan to leave it carbon. It's so elegant. Jeez this thing is a light as a fly. Should match the CF roundels, not that I plan on a CF street racer.

Already cut out for the second exhaust and plan to create a small fibreglass hood shape over the top of the exhaust. Not really needed but I like perfection

Templating it will take a little while as the facelift has a crease line that the cutting follows, the prefacelift does not so I've got to think how to mark it out. In reality I may just chop the surplus off, draw around the diffuser and trim to fit. It's not critical at all the the diffuser totally covers the raw edge.

Focus is on getting the battery box done next so the internals are ready, but Mrs CJ has other ideas of garden and the X5 needs some remedial work :thumbsdown:

 

[Mr Whippy]

Diffuser is about £280, but I got 25% off so not too bad.

That isn't cheap, even with 25% off it's fairly eye watering for what it is!


Imagine a tiny rear-end dink snapping it, ooof, not one the insurers will like either... "yes insurance provider, I have stuck a brittle £250 item at the very extent of my car"

 

[Breaker]

Actually that's not as expensive as I though it was. Carbon fibre anything is expensive!

 

[cj10jeeper]

I didn't think it was too bad and does balance out with the pair of almost new backboxes at £20 instead of £850+ and the SBS40 race battery for £55 Vs retail £150 to £200

Never said this would be a cheap project, but want to do it right

 

[mmm-five]

I'm also planning on unblocking comletely the brake cooling duct - although it was cool enough at Oulton Park that I didn't need any extra brake cooling.

Aren't they fully open vents then?

No!

Hold on I'll get a picture....

 

[cj10jeeper]

That's a great idea mmm-five. What made you think of that...lol


So here's the plan with the battery. Remove the box chop it up and fit the new battery on the LHS as positioned. This leaves room for the back box and heat shield.

Pictures with the box stripped of safety cage and partition, the relative size of batteries and how the new one will locate.

Below are a few pics of the diffuser after a bit of chopping up. Material has been cut off to make both sides the same profile below the bumper as well as to allow the 2nd set of tips to protrude. You can see in the last photo that there is no reference line to cut to on the prefacelift, but once I cut the lowere edge off I shoudl get a good idea of how it sits.

Right now it's setting after I cast a new RHS moulding above the tips, so will know later how that turned out

 

[Herminator]

Thats going to look excellent

The carbon will be a nice contrast against the grey. With the quad exhausts it will look very racey but not in your face, I love it 8)

Is there a mounting point ready for the central tab on the front edge of the diffuser?

I may have to go for this diffuser later in the year, not sure it will be very noticable against black though. I wish I could get 25% discount at my dealership, the last guy I spoke to wouldn't even give me 10% :thumbsdown: