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centre silencer removal


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I've read good things about the removal of the centre silencer box & replacement with a straight through pipe, on a TDi.

Does this apply to the V8 also?

Has anyone done it with positive results?

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Take it out. You will release loads of extra power, torque, improve emissions and get unheard of fuel economy. Landrover, despite spending literally 100s on testing and development of things like the engine, exhaust and emissions bunged a carp silencer on to make their cars slower and less economical.

OK, I am kidding you, it will just make the car noisier. If that is your bag then fine; I put the boxes back into my exhaust as I got sick of the row every time I put my foot down - which is quite often in a Tdi! :) If you want more power you may be able to get it by spending out on top line 4 branch manifolds with insulating wrap and then a larger bore free flowing pipe.

Sorry for the sarcastic tone of the first paragraph. ;)

Chris

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I wouldn't remove the centre box, it will only serve to make a lot more noise, the only way it will possibly reduce your fuel consumption is by making it so unpleasant to put your foot down.

The reason diesels run slightly better without the boxes is that the turbo can run up slightly quicker. (This is what i've been told anyway)

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I've done this on my Discovery rally car (std 3.9). It is a lot louder, but not as bad as I expected - fine for a competition car, would be a nightmare as a daily driver.

I removed the centre box for a couple of reasons - I kept bending the silencer, by making contact with the ground, I wanted to help improve flow and hopefully release a bit of power and I wanted it to be bit noiser to stop spectators stepping out in front of me! ;)

I have been pleasantly surprised with the difference - throttle response feels a bit crisper, mid range it feels like it has more pull - but it could all be an illusion, I haven't had it on a rolling road and can't really quantify.

It does pop and bang a bit more now too.

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On a race car I expect it would help a bit with improved flow as you're probably driving a lot more aggressively than one would on the road. I'm with Chris - manufacturers spend a lot of money designing these things with people far cleverer than the rest of us (and whose job is to design exhausts).

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The center box was replaced with the rear box on my 4.2 90 and the rear and Cats were removed all together.

much crisper, much quicker pick up, Don't know about fuel economy but by reducing the back pressure there should be a small improvement.

The V8 is not as dependant on back pressure as a 4 pot and will not lose power like a 4 pot by reducing the back pressure.

The exhaust of a Range Rover V8 removes a massive amount of power from the engine and sound.

Land Rover spent Millions keeping in as quit as possible and get as much power as possible. The law will not let them sell a snarling fire breathing V8 as a every day car even TVR have to quieten them down but removing the CAT's and middle box is a known way to improve the performance..

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I removed mine from my 2.5, I know it's not a V8 but it's a petrol so same idea. Main reason was that I kept knocking it off road, breaking the seal and making it leak, but I also wanted to make it a bit louder as I was spending so much filling it with fuel I might as well hear it disappear! I later fitted a PTO so it won't fit back there anyway.

It sounds nice at idle but does drone a fair bit at higher revs and I've been considering putting a smaller silencer back in, to clear the PTO and stay above the chassis level. Not really bad but after a few hours you start to wish it was a little quieter.

Mine failed an MOT without it, but I'm not sure whether that was because of the noise or because the particularly fussy MOT station read the bit that it "should have the same number of boxes as when made" (or something like that). They made me buy another silencer and then told me how to take it off again afterwards and store it for the next MOT! Needless to say I haven't been back there again and it's passed the last two MOT's with no problems with just the rear box.

Give it a go if it won't cost you much, with a V8 it'll sound better than mine at higher revs too :D

Richard

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The MOT regs don't say anything about the number of silencers, they say that the exhaust noise should "not be above a level which would be considered normal for this type of vehicle" or something to that affect. It's very open to interpretation. I guess if in doubt, drive into the MOT centre before you book and ask them if it'll be problem. If they say yes, try another one!

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I also wanted to make it a bit louder as I was spending so much filling it with fuel I might as well hear it disappear!.....It sounds nice at idle but does drone a fair bit at higher revs and I've been considering putting a smaller silencer back in,

...and it now sounds like a Morris Minor. :) Sorry Dicky but it does! :)

Mine failed an MOT without it, but I'm not sure whether that was because of the noise or because the particularly fussy MOT station read the bit that it "should have the same number of boxes as when made" (or something like that). They made me buy another silencer and then told me how to take it off again afterwards and store it for the next MOT!

I would certainly be finding a better trained MOT station!

Chris

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Hi,

My 3.9 has tubular headers & Y piece, this feeds into a straight through centre box that I made up from parts from Milner Conversions then into a 2.5" tail pipe. The box is the largest ovel they did and is surprisingly rather quite for a V8. It does have a growl when you gas it but it's not excessive.

Cheers,

Andy

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The 3.5 90 uses the same exhaust as the 2.5 normally asthmatic oil burner, and to be fair, its very restrictive. A slightly better option is to fit the round centre box from a 2.5TD ….. but it makes the exhaust note too high pitched, and also got in the way of my PTO pump.

So in the end I fabbed up a centre pipe and done away with the centre box. I left the rear silencer on and fabbed a new tail pipe from 3 inch…………… yes its louder, but not excessively so, and passed the MOT OK.

It has made absolutely no difference to the MPG but the top end is now a lot more lively. It also resonates nicely at 2000 - 2500 rpm :D

Ian

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...and it now sounds like a Morris Minor. :) Sorry Dicky but it does! :)

I would certainly be finding a better trained MOT station!

Chris

Yep, but seeing as it isn't running at the moment that's the least of my worries! I think I've passed my boy racer stage now, it'll probably quieten it down a bit when it eventually gets a TDi shoved in it.

Certainly not going back to that MOT station again, the local garage seem far better despite not specialising in 4x4's.

Richard

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As Dicky will confirm the 109 wasn't quiet :D , that had one teeny tiny back box which I think had seen better days. Passed the MOT no problem even with the picky tester. The noise got really dull after about 10 miles though - combined with the overdrive wail it was like being in a war zone :blink: drove up to Billing once, that decided it for me and the new exhaust will be towards the quieter end of things.

I think I've worked out the fuel map for flames on over-run though so audio drama can be replaced by fireworks instead :lol:

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Surely though if you remove the silencer then and you get the gutsy noisy V8 then you would have to change it back for mot

mmmm can't be worse than jules's lightwieght v8 that had two cherry bombs and no slincers at all. passed a couple of real MOT's easy.

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Hmm, mixed bag of responses there.

I think if i have some spare minutes & pipe i will experiment.

I don't want to make it too loud on cruise as i occasional do long road trips.

thanks everyone.

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