V8 Exhaust Advice Required

Aye Up All,

Renovation work continues on my ‘97 D1 V8 and which now has to include attention to the exhaust system.

The whole system including lambdas looked fairly new on pre purchase inspection so I didn’t give it too much attention.

It is presently fitted with what I thought were a standard Y pipe with cats; a centre silencer; over-the-axle pipe and a rear silencer.

I first noticed that something might be amiss when days after purchase a small amount of ‘soot’ appeared on the driveway. Closer inspection identified a leak at the coupling flange of the Y pipe and centre box and what looks like a slightly crumpled middle box. My suspicions were that the truck had been reversed into something, catching the tailpipe and pushing the whole system forwards.

It was only whilst recently laying around under the vehicle waiting for the TX box oil to drain that I discovered that the flange on the end of the Y pipe where it joins the centre box has been bodge welded right around the circumference of the pipe. I’m not sure whether this too was a result of the previously assumed collision.

To add insult to injury at the end of a recently long journey an annoying ‘tinny’ vibration has developed when moving at low revs roundabout 10 - 15mph and which disappears with further acceleration. I’m hoping it’s the centre box baffles and not the auto box!!

With replacement in mind I’ve been toying with doing away with the centre box altogether and running a straight pipe through to an over-the-axle section and onwards to the rear silencer but having trawled through a number of threads on the site I’m also reading of keeping the centre box and running a pipe out to the rear/rear side and doing away with the rear silencer.

Whilst I do like the idea of ‘tweaking’ the sound of the V8 I’m more interested in saving brass on not having to fork out for two silencers as well as maintaining performance.

I have heard a V8 with a straight through pipe and no silencers at all which sounds nice (but yes, legally questionable) and one with only a rear silencer which sounds a fair bit quieter but in no way excessively loud.

So is there a definitive answer as to which way around to do it - i.e. is one way more likely to affect back pressure more than another and hence interfere with the engine performance or will there be no difference?

Thanks

The definitive answer, ok.
All 300 series D1s had a one piece exhaust system, with a flange joint where the system meets the down pipe, so with out any sleeve style joints when the vehicle left the factory.
The first box in the system is the muffler (silencer) the second tail box is what changes the sound of the exhaust.

I change my exhaust system when the tail box fell apart 11 + years ago, and fitted a Janspeed cat-back system, it came in two parts and was pleased to see it was a perfect fit and with welded flange joints for each part, although the flange was in steel and not stainless.
The exhaust volume is similar to the factory system but the tone out the tail pipe is a lot deeper, so certainly more noticeable, also an improvement in acceleration.
Pictures from last year of the system which has never been touched since fitting, other polishing the tail end now and again, so well worth the expense.

Thanks for that Discool, I will look into the janspeed system in due course.

Enzian said:

Thanks for that Discool, I will look into the janspeed system in due course.

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What ever you do just make sure you don't get something too loud, I speak from experience here and trust me when I say that it's fun on a blast to the shop but if you are travelling any distance a noisy exhaust actually becomes quite irritating.

discool said:

The definitive answer, ok.
All 300 series D1s had a one piece exhaust system, with a flange joint where the system meets the down pipe, so with out any sleeve style joints when the vehicle left the factory.
The first box in the system is the muffler (silencer) the second tail box is what changes the sound of the exhaust.

I change my exhaust system when the tail box fell apart 11 + years ago, and fitted a Janspeed cat-back system, it came in two parts and was pleased to see it was a perfect fit and with welded flange joints for each part, although the flange was in steel and not stainless.
The exhaust volume is similar to the factory system but the tone out the tail pipe is a lot deeper, so certainly more noticeable, also an improvement in acceleration.
Pictures from last year of the system which has never been touched since fitting, other polishing the tail end now and again, so well worth the expense.

Click to expand...

looks like new under there

dieseldog69 said:

What ever you do just make sure you don't get something too loud, I speak from experience here and trust me when I say that it's fun on a blast to the shop but if you are travelling any distance a noisy exhaust actually becomes quite irritating.

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Nah you want it Balls out..

Pfft.

Quiet exhaust!!!!!!!!!

Henry_b said:

Nah you want it Balls out..

Pfft.

Quiet exhaust!!!!!!!!!

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I had 3" straight through made for my old RRC and it was a hoot for a blast but tedious after more than 30 minutes and especially on the motorway.

I don't mind them a bit throaty but if they are just loud and tinny they sound rubbish and you wind up needing ear defenders which takes the fun out of driving it.

We got a young lad on the island with a moped that you can hear long before you see, it sounds crap and I find it rather offensive when I've just got the baby to sleep and he decides to come ragging it round this end of the island, his mate has the exact same ped and it has a standard exhaust on it and you can barely hear it running, even on full chat it is very quiet.

dieseldog69 said:

I had 3" straight through made for my old RRC and it was a hoot for a blast but tedious after more than 30 minutes and especially on the motorway.

I don't mind them a bit throaty but if they are just loud and tinny they sound rubbish and you wind up needing ear defenders which takes the fun out of driving it.

We got a young lad on the island with a moped that you can hear long before you see, it sounds crap and I find it rather offensive when I've just got the baby to sleep and he decides to come ragging it round this end of the island, his mate has the exact same ped and it has a standard exhaust on it and you can barely hear it running, even on full chat it is very quiet.

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odd when they're ragging the tits off it and it's only doing like 5mph lol

pricks.

Enzian said:

Thanks for that Discool, I will look into the janspeed system in due course.

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Don’t hold your breath, I haven’t seen a D1 system for sale in years.

Rimmer bros or SS were the others I compared Janspeed with, but the workmanship (welding and kinks in the bends) put me off, and l’m no expert but had the opportunity to compare the two other systems at the Billing LRO show once.

Years ago LRO did a bit in their Mag on fitting a new SS system on a RRc but wasn’t straightforward, the bend over the axle the bend was wrong, fortunately they had the vehicle on a ramp and all the skills plus kit to cut and modify and weld the stainless pipe to fit, which took a bit of time they weren’t happy and said so. Imagine have to face that issue when fitting DIY on the drive.

Aye Up,

Yes Discool, I haven’t come across anything yet other than standard pipes and having helped to fit some recently they weren’t accurate over the rear axle.

I’m going to have to sort a new y pipe with cats and from what I am reading a new centre box, followed by a pipe to the rear. Whether I put owt else on is still under consideration.

The work will have to be done underneath on the drive as far as possible but I may have to twist the arm of a local exhaust guru for the bit over the axle.

PS

I get yer point dieseldog - the rattling coming from the centre box area at the mo is a pitn and I’m either feathering the loud pedal to keep the revs below rattle point or gassing it to get quickly through it!
Thankfully its not occurring at cruising speed.

Would it really be a pain to make up a twin exhaust with a cross pipe/joining pipe (can't remember the technical name for it). It should only need one box on the far end and should sound great without being a pain. If you are a half-decent welder then a few straight bits and a few bends from a pipe supplier should help you make one. Even in stainless.

Stanleysteamer said:

Would it really be a pain to make up a twin exhaust with a cross pipe/joining pipe (can't remember the technical name for it). It should only need one box on the far end and should sound great without being a pain. If you are a half-decent welder then a few straight bits and a few bends from a pipe supplier should help you make one. Even in stainless.

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Um I’m interested, Does a D1 V8 auto have provision for an additional pipe plus exhaust hangers on the offside?

discool said:

Um I’m interested, Does a D1 V8 auto have provision for an additional pipe plus exhaust hangers on the offside?

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Of course not!
Stupid me! Coming from the Kit Car world, where you have to make it up as you go along half the time, I would just have got hold of various bits of steel, mostly from my stock of offcuts and made up hangers etc then welded the ones to hold the rubbers to the chassis or the floor of the tub. (Oops, kit car term there). So I tend to forget that other people don't think like that. All it takes is a stick welder and a bit of measuring up. I'd be tempted to look at a system made for a twin pipe V8, like an old Rover or something and see if that would yield sufficient bits to get started, then cut and shut it with a few other bits to make one up. Remember, in the Kit Car world, V8s reign supreme, from Marlin Roadsters and Berlinettas, to Morgan V8 copies, to Cobras. And they have the additional problem of ground clearance which really isn't a problem under a Disco.
Sorry about that!