XSeries-forum

Hi

Is it possible to fit the rear boxes from a 4.8is to the 3.0d?
Has anyone done this? Looking at real oem there is only seems a very slight difference in the mid section to join them up so maybe some adaption?

Cheers

Ollie

Im sure its possible.................but whats the point ?
It won't make the same noise you know................

There is no real point at all! Haha! But I have the exhaust off a 4.8is sitting in my garage that I didn't have to pay for and like the looks of the exhausts coming out the bumper in the 4.8, so it's really just for visual purposes! My diesel is never gonna make that awesome V8 rumble

Ollie

The 4.8 exhausts will affect the back pressure and therefore engine performance due to different pipe diameters/silencer build. 

Oh really? It's only the rear box sections I will be using, having put the pipes up together they looked the same diameter, but I could be wrong, better get the tape measure out! If I put them on and then get the car remapped, would I be ok? Or am I going to kill my turbo prematurely?

Cheers

Ollie

You might be OK with the pipes...though I thought they were larger diameter, but the back box design may give issues.  The back pressure change should not kill the turbo but it will affect engine 'breathing' so a remap would be needed to get any oddities programmed out again.

Others have just welded the tailpipe end in place and kept the OEM exhaust.  It's the 4.8 tail pipe look that is what many wanted.  Might be an option?

I am going to measure the diameter of the pipes later, then I should know for certain as just looking at the pipes they seem the same size but it could be a slight a difference in size, if I decide to get them fitted then I will speak to Jason to get the car remapped to take the exhausts into account. Apart from that your right the other option would be either welding on the 4.8 tips to the existing exhaust just for visual, I have seen some people have cut  the existing exit pipe off the box and welded up and then cut a new hole in the box and welded on the pipes so they work but come out the bumper, not sure if that would mess up with the internals of the box though!

Ollie

It's illegal, no Dpf, no strait pipes...

What's illegal?

Exhausts coming out of the bumper on non dpf cars like x5 e53.

Oh right got ya!
A mate of mine is an MOT tester and said it would be fine, but will double double check!
Thanks for the heads up

I'm not sure it's an MOT issue, but it will most likely be a 'construction and use' issue under the type approvals for EU3 cars?  Hence the exhausts pointing down - as they do on our 2005 E46 with the same Diesel engine.

Not seen it written anywhere, but I accept kkx5 statement.

Could be why owners have kept OEM pipes and just welded tailpipes into place as fake exhausts?

I think dummy tailpiece/ tips are the way to go on the Diesels. When I first got mine I had the backboxes cut out and the exhaust diverted out of the rear holes, what a instate it was sounded worse and seemed to effect the low down torque. After 2 weeks I put the original backboxes on and was much happier.

Hi Guys

Just thought I would give you an update on the exhaust front, today I went to my mates garage and had the back boxes fitted, a little bit of fettling and they went on no problem, they mount in exactly the same places, to X5Sport the bores of the pipes looked the same but actually measuring them, they were slightly different with the 3.0d being 50.11 and the 4.8is being 54, but we fabricated them to fit and now the are fitted and I have covered about 100 miles I am getting no difference in performance or mpg, the sound on startup is very slightly deeper but after that you really can't tell any difference, when giving it some beans it sounds raspier but nothing that you notice with the windows up, overall I very happy with the result considering it has cost me pretty much nothing. However I am still going to get the car remapped to make sure that back pressure is not an issue. I am going to take the risk with the MOT, and see what will happen come the time for renewal.

Cheers for all the advise

Ollie

Sorry car and exhausts are filthy, but you get the idea, car will be cleaned for BMW festival