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Seen on a few forums people seem to prize stainless exhausts, but why?
Back in the 70's a mild steel exhaust might only have lasted a few years so a stainless system though more expensive could work out cheaper than changing a mild steel system a few times during the life of the vehicle. These days exhausts last a lot longer but people seem willing to fit a stainless system even on an old car, the exhaust will then outlive the car but a mild steel system fitted on an old car might also outlive the car and even if the mild steel system needed replacing once again it still might work out cheaper than the stainless system. Stainless systems look nice and shiny but you can't see the system when it's under the car and you don't worry about the look of other bits you can't see under the car...

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Because pattern mild steel ones are a bit of a lottery, you may get one that lasts or you may get one that rots out in a couple of years. You know a stainless one will last and it's a lot cheaper than a genuine Land Rover one (£1,893.60 inc VAT for the front downpipes alone, a mere £401.57 for the middle box though). My original lasted the best part of 20 years before the middle box rotted out, the Britpart replacement lasted under 2 years.

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stainless might be more expensive than mild steel but it does change the note of the engine the V8 will have more of a burbble to it with stainless steel than a mild steel exhaust
me and neighbour both have 2.5td engines he on mild steel exhaust and I'm on stainless and mine is a lot deeper grumble when ticking over

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My 1962 ford consul had a stainless steel system but it sounded rather tinny so I made up a steel system for a deeper sound ---- I've noticed quite a few classic car owners fit stainless systems but I don't like the tinny sound myself ---- does stay shiny so looks nice The system on my consul been on there for 5 years and no issues --- yet

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I want to keep my car and keep it in good nick. When jobs come up I only want to do the job once.
I fitted a double SS stainless exhaust over 10 years ago when my original back box rusted through. I bought it secondhand on Ebay.

New, stainless exhausts cost a fortune. It is one thing I would buy secondhand. It should last the life of the car. Some stainless systems are very flimsy. Double SS are good. You get what you pay for.

I later replaced the middle box. The only parts that are not stainless now are some of the clamps, the diesel DPF (mild steel) and of course the manifold (cast iron/steel).

The exhaust was a bit louder when first fitted but it quietens down after a few years as it soots up with carbon.

It impresses MOT testers. LOL.

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i fitted a stainless exhaust to my classic in 1993 and its steel their, replaced the clamps and brackets 3 or 4 times , still as good as when it was put on.
it was custom made not off the shelf .

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I fitted a Janspeed Exhaust to my P38 around 8 months ago and it still looks brand new and she sounds great, much better quality than a pattern part and it'll last a good while, I guess a stainless exhaust would outlive a car you didn't care about or want to keep that long, however I want to keep mine for a good while and only doing a job once appeals.

I fitted a pattern part mild steel exhaust to my Discovery and it lasted a year before the back box began to come apart at the seams..

You pay your cash and get your quality..

The original exhaust on mine was LR original however it had been patched and patched over the years and was a right mess, and in my opinion the exhaust design for the P38 is hideous, some systems look like you have 2 briefcases with little pipes sticking out of them as the rear most silencers and its also too damn quiet I have a 4.6 V8 up front I want to hear it!!!

Mine has a deep growl which sounds great

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And lets not forget you get the nice shiny pipes out the back with certain Stainless systems, that is how it should of been from factory IMO..
I wouldn't want those quad ones from rimmers though.. yuck

enter image description here

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Odd, obviously a taste thing but the Vogue I'm half owner of has the same system on it as yours. We were sitting looking at it the other day wondering what we could do to make it look less vulgar. Considering painting the tailpipes black so they aren't as noticeable or even getting a mild steel system to put on it but the bumper has been cut to clear the tailpipes so it would then need a new rear bumper too. It's also got an aftermarket towbar on it so there's a big lump of ironwork on the back and not the nice discreet swan neck. It's a Vogue, it's supposed to be whisper quiet.....

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Hmm yes a matter of taste indeed as for the sound to be fair my old RRC Vogue was quite throaty even with the standard exhaust with all the mufflers by comparison my P38 was quiet but it sounded like it had a slightly wheezy 6pot not a V8..

The Janspeed system has all the mufflers in place, when idling there is a nice rumble, not at all intrusive even on the M'way at 70-80mph it is whisper quiet, it comes in to its own when cruising around country lanes or town pulling away its quite rumbly and through tunnels it sounds like a TVR which isn't really a bad thing..

If your exhaust is a Janspeed system they fetch good money online selling it would give you some good money towards another system, I guess an aftermarket OE style system would be better for the value and make it look more discreet.

As for the towbar yes aftermarket ones are shit, mine didn't have the towpack from factory it was fitted in 2007 and IIRC the PO payed £300 for an OEM LR swanneck.

I'm glad they didn't fit the cheapo ugly aftermarket units.

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I can see why people would save money fitting a stainless system over a more expensive OEM exhaust, in this case they're saving money.

Remember Janspeed from my boy racer days, didn't know they were still going!

Obviously if you're paying for OEM cats it'll be expensive.

Is there no in-between - A mild steel system that lasts nearly as long as OEM but cheaper than stainless? The last exhaust I bought was for a Grand Voyager, cost me £90. Went for that instead of a stainless system that would have cost many times more.

It occurred to me to bring this subject up here because I'm on another forum where the subject vehicle has a problem with failing front cats (they have 4 cats in total) causing blockages that then see cat material enter the engine wrecking it. Someone bought an expensive stainless system complete with aftermarket front cats but the engine has recently started using loads of oil and the most likely reason for that is failed front cats (which in this case would be the expensive aftermarket stainless cats). My advice would have been keep the original exhaust but decore the front cats.... It would be ironic if the owner spent over the odds for aftermarket front cats and full stainless system to prevent problems if the expensive mods caused the same problems as the original exhaust system can cause while if they'd simply kept the existing exhaust but had cats cut out they wouldn't have had any problems.

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My vogue SE got cherry bomb in place of silencer and rear boxes replaced with straight pipe --- then cut restriction boxes off inlet pipe and blanked off holes ------ deep throaty sound and pulls almost as good as my Buick 300;

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Lpgc wrote:

Is there no in-between - A mild steel system that lasts nearly as long as OEM but cheaper than stainless? The last exhaust I bought was for a Grand Voyager, cost me £90. Went for that instead of a stainless system that would have cost many times more.

As I said, it's a bit of a lottery. Having had my car for over 11 years and 210,000 miles now, I've been there. On what I assume was the original system, the middle box started blowing after I'd owned it a couple of years. I bought a Britpart middle box which lasted no more than 2 years before it looked like this

enter image description here

Box not leaking but the pipe had come away from the box and was perforated along its length.

Bought a EuroCarParts own brand Klarius middle box which lasted at least 3 years before the (original) tailpipe boxes started to go so I decided to buy a complete system from Maltings Off Road. That was around £300 including downpipes with cats. The parts were a mixture of Bearmach and Allmakes branded items but within a couple more years, one of the tailpipes had gone the same way as the Britpart pipework while the rest of the system still looks good. The replacement section Maltings supplied was Allmakes branded and appeared to be the same as the rest of the system which makes me think the bit that had failed was the Bearmach branded section but I can't be sure.

So, at the moment, if anyone asked, I would say an Allmakes system will last but they don't make them, the same as ECP don't make the Klarius systems. So who is to know if a particular reseller is using the same manufacturer or has gone to someone that can supply something that looks the same but is cheaper?

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Lpgc wrote:

I can see why people would save money fitting a stainless system over a more expensive OEM exhaust, in this case they're saving money.

Remember Janspeed from my boy racer days, didn't know they were still going!

Obviously if you're paying for OEM cats it'll be expensive.

Is there no in-between - A mild steel system that lasts nearly as long as OEM but cheaper than stainless? The last exhaust I bought was for a Grand Voyager, cost me £90. Went for that instead of a stainless system that would have cost many times more.

It occurred to me to bring this subject up here because I'm on another forum where the subject vehicle has a problem with failing front cats (they have 4 cats in total) causing blockages that then see cat material enter the engine wrecking it. Someone bought an expensive stainless system complete with aftermarket front cats but the engine has recently started using loads of oil and the most likely reason for that is failed front cats (which in this case would be the expensive aftermarket stainless cats). My advice would have been keep the original exhaust but decore the front cats.... It would be ironic if the owner spent over the odds for aftermarket front cats and full stainless system to prevent problems if the expensive mods caused the same problems as the original exhaust system can cause while if they'd simply kept the existing exhaust but had cats cut out they wouldn't have had any problems.

how dose the cat damage the engine to make it burn oil, it can only bloke of the exhaust i thought or cause a restriction ?

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Simon has posted here > https://www.lpgforum.co.uk/viewtopic.php?f=27&t=14263&p=112046&hilit=elgrand#p112046 and Here > https://forum.elgrandoc.uk/threads/the-e51-catalytic-converter-problem.5443/page-9 about it. The guess would probabbly be it failing on one side (of the v6) so half the engine runs ok, whilst the other half struggles to push anything out of its blocked exhaust. In that case, I'd expect its compressing the sump as the exhaust can't escape where it should do and oil is then getting where it shouldn't?

The main problem is that the front cats break up, and then can't get out of the way as the rear cats catch the broken bits and block up, at least that seems to be the explanation in that case.

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Not sure what car it is that Simon is talking about but I suspect Japanese and someone has come up with the same implausible theory that affects early versions of the Toyota 1ZZ-FE engine fitted in the MR2 Roadster. The theory is that the cat innards start to break up and somehow make their way back into the engine so wear the bores. My daughter bought an early MR2 Roadster with a blown engine, owner had driven it about 250 miles across country and it had ran out of oil. He reckoned it had been using a bit of oil and after it had stopped with a bang, he had checked the oil and none was showing on the dipstick. We got a replacement engine, put that in and I pulled the old one apart to see how bad it was. One big end had seized and the conrod on that cylinder had snapped due to it being run with insufficient oil.

The MR2 Roadster has two cats and after a period they will start to burn oil and a number of people have suggested the same happens with them. Now I found it hard to believe bits of the cat could get sucked into the engine against the flow of the exhaust, it didn't seem to make a lot of sense. A lot of websites quote this as the cause of high oil consumption and recommend gutting the front cats to prevent it. However, only pre-2003 cars suffered this problem, later ones didn't and when you looked it seemed pretty obvious that Toyota didn't think this was the problem either. Pre-2003 engines had two tiny holes in the pistons behind the oil control rings and the recommendation was to use semi-synthetic oil. If the oil wasn't changed regularly, the holes got blocked and the oil control rings stick in the grooves so did nothing, hence the thirst for oil. On the engine I pulled apart, the oil control rings on the 3 pistons that remained in one piece were all firmly gummed into their grooves. From 2003, the pistons got 4 larger holes behind the oil control rings and Toyota recommended fully synthetic oil and these don't suffer the problem even though they still have the same cats fitted which would suggest the cats have nothing to do with it, it's the fast and furious generation that don't seem to understand the benefit of oil changes and routine maintenance....

Brian has now identified the car but I would still suspect it's the same problem as affects the Toyota engine.

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Can someone post a link to where or who sells the best non OEM exhaust system for a 4.6 P38?
Mine has finally suffered from the dreaded Northeast corrosion corner road salting program with rear boxes and center pipes rotted and now the manifold gasket leaking.... all seem to have snuck up on me as I would normally consider myself one who keeps up to date on the mechanics of my vehicles.
Rains it pours.....

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GEMS, https://www.ebay.co.uk/itm/range-rover-p38-exhaust-system-p38-V8-exhaust-system-complete-front-rear-94-99/272214722398 or Thor https://www.ebay.co.uk/itm/range-rover-p38-exhaust-system-p38-V8-exhaust-system-complete-front-rear-99-02/262391772282 or direct from Maltings website https://www.maltingsoffroad.co.uk/parts/4570888410

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On Richard's recommendation I have just fitted a new Y pipe from Maltings to the CVC and it feels good quality and fitted without any problem.
https://www.maltingsoffroad.co.uk

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https://stainlesssteelexhausts.co.uk/range-rover-p38-2-5l-bmw-diesel-1997-2002-exhaust-system/

Not going to be cheap. Made to order from any grade of stainless you specify. I know they are well made.
It seems you have to login and register to get a price.

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Gilbertd wrote:

Not sure what car it is that Simon is talking about but I suspect Japanese and someone has come up with the same implausible theory that affects early versions of the Toyota 1ZZ-FE engine fitted in the MR2 Roadster. The theory is that the cat innards start to break up and somehow make their way back into the engine so wear the bores.

Talking about the Elgrands.

I didn't think it very plausible myself at first either but now I know for fact that it does happen and have suffered it myself.

I reckon the way dust from blocked exhaust makes it's way back into the engine (where it acts as a grinding paste) is due to the excess backpressure and the exhaust valve remaining open past TDC on the exhaust stroke into the beginning of the intake stroke, at which point the inlet valve will have already opened a bit dumping some of the cylinder pressure* into the intake plenum... Now there's a situation where the exhaust is under far more pressure than the cylinder and the exhaust valve is open.

*At this point in the cycle the cylinder would usually be at low pressure, the exhaust valve has been open during the entire upstroke of the piston, pressure should be low enough for intake charge to start flowing in through the intake valve as soon as it opens. Except now because of the blockage the exhaust itself is still under pressure, the cylinder cannot be below exhaust pressure so cylinder pressure is at high exhaust pressure, so when the inlet valve does open cylinder pressure flows the wrong way into the intake... which lowers the cylinder pressure, which (since both valves are open) allows exhaust to flow at least into the cylinder and some will even flow into the intake plenum.

Like Bri says, the above effect will be worse on a 2 cylinder bank engine than on a 1 cylinder bank engine... the 1 bank engine might not run with a really severe exhaust blockage but the 2 bank will because one bank's exhaust isn't blocked. And some of that exhaust that's being dumped back into the plenum will be a high dose of EGR for the other cylinder bank on a 2 bank engine but not a high enough dose to vastly limit that bank's power. Or put another way - on a single cylinder bank engine it isn't only the exhaust restriction that lowers power output but also any backpressure can see the intake getting a lot of EGR further reducing it's power, but on a 2 bank engine the EGR couldn't lessen the amount of fresh air getting to the bank without the exhaust restriction by much more than maybe 50%.