MB tubular manifolds

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drcdb15
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MB tubular manifolds

Post by drcdb15 » Mon Oct 23, 2017 11:12 pm

As I am considering spending a bit of cash on MB61, my thoughts have turned to the exhaust, and specifically tubular manifolds. As I understand it, there's not a lot can be done with the 2.9i lump in sensible cost-effective mods without going to race-level expense for cams, chips and blowers etc. What *does* make sense - or does it? - is to get the air in better and get the exhaust gas out better.

Well the first bit is easy, a K&N filter in the existing air box, and better supply to the airbox. Been there, done that. Now, about the exhaust...

What's the latest thinking here? Who supplies what? Is it really worth the money? Why, when QRG (and GW too I understand, but can't confirm) list SS tubular manifolds as off the shelf, are folks going to the likes of Infinity and others to get one-offs and specials made? Is one tubular very much like another? There's mention of step-downs and adapters and designs avoiding these...

So... is it worth it at all? And if it is, what are the pitfalls, who's the 'best' supplier - and fitter? And should the manifold be bought as a whole system replacement or can the original pipes and silencers be retained?

As always, the collective experience of others who have trod this path before will be greatly appreciated.

Thanks

Chris

(Mods NB: the other two threads on here are about cast manifolds (Pete F) and pipes downstream of the manifold (AJL) so I've started a new thread but happy for you to merge if you feel appropriate)


Chris
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Post by efi_sprintgte » Tue Oct 24, 2017 7:12 am

I've had a 200 bhp 2.9 which involved a fast road cam, air filters, tubular manifolds, gas flowed heads. It was a lovely engine with great manners. I would have said this cost no more or less then doing the same to a Essex but I got more power then I would have done doing the same basic mods to a Essex. I had this fitted to a 5a.


Later on this engine was fitted to a MB with cast iron manifolds and the previously free revving and fun engine became abit flat!

Club traders (can't remember which one to be honest) supplied tubular manifolds and exhaust systems where then fitted and all the power was back. So on a tuned 2.9 the exhausts made a large difference!


As an aside the fast road cam was great in the 5a but in the heavy MB we noticed the lack of low down torque. As such a road cruiser MB I would stick with the standard cam personally.


JC

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Post by peter freeman » Tue Oct 24, 2017 8:10 am

I fitted SS manifolds - much better than the originals. The reason I mailed about it was I was told that unlike the Essex heads the studs would not snap - they do - at least three of mine did. The good news is that the studs snapped off level with the cast manifolds and the SS are thinner so I was still able to use them and get nuts fitted. I would advise anyone fitted new manifolds to cut the old nuts off rather than trying to undo them - not easy but worth the trouble IMO. I bought mine from GW as it was their turn to get my money but I think the ones from QRG will be identical.



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Post by drcdb15 » Tue Oct 24, 2017 11:47 am

efi_sprintgte wrote:
Tue Oct 24, 2017 7:12 am
As such a road cruiser MB I would stick with the standard cam personally.
As I said, I'm not trying to make a race car :) just looking to see what's worth doing and what is more towards the area of diminishing returns.


Chris
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MB tubular manifolds

Post by ronnie » Tue Oct 24, 2017 11:58 am

Have you considered

Ceramic coatings can help improve the performance of your headers



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Post by DARK STAR » Tue Oct 24, 2017 12:09 pm

Mine is Superchipped with a rolling-road re-map, which is very effective on the 2,9.
With an adapted K&N twin 40 air filter and tubular manifolds it gives about 210 bhp.
The manifolds are impossible to photograph (and it is installed in a Coupé, so irrelevant!) but were made to have the longest possible primaries going into a collector just above the chassis rail, then into a standard stainless exhaust system with no intermediate boxes.
With an Aston Martin axle (forget the ratio but it's not the same as Scimitar) the car will pull to the redline in 4th = 240 km/h.
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Post by drcdb15 » Tue Oct 24, 2017 12:49 pm

peter freeman wrote:
Tue Oct 24, 2017 8:10 am
I fitted SS manifolds - much better than the originals. ... I bought mine from GW ... I think the ones from QRG will be identical.
Thanks for the comments folks, though I stress again I am not looking for a race engine and I'm not considering special treatments such as ceramic coatings, or special tuning such as a rolling road set-up. Rather I am limited to 'bolt-on goodies' for want of a better phrase, and in the case of tubular manifolds want to establish: is it worth it? Or is it too much cost and hassle for any benefit it might give?

So, back to the nub of the matter, viz: is i worth it? And part of that is, how long do they last? I don't want an 'improvement' that actually makes the car LESS dependable than the original equipment !

It has been suggested to me that some off the shelf manifolds have not been as long-lived as one might expect, and certainly very far from the 'fit for life of the car' expectation that most folks have in fitting stainless parts. Was that your experience too, Peter, with the item you bought from GW? Does anyone else have any long-term experience of the 'standard' off the shelf options from GW/QRG (or any other Scimitar supplier) ?

Incidentally, obviously GW/QRG don't make their parts themselves - does anyone know the source of their manifolds ?


Chris
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Post by mn757 » Tue Oct 24, 2017 12:53 pm

My SE6 had a new stainless system fitted in 1982 (but not manifolds until 2010). It was purchased through MIDAS and manufactured by Double S which is probably where the suppliers get theirs from. I have had to replace one centre box in all that time as the pipe parted company with the box. Other than that they have lasted 35 years and still going strong.


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Post by scimjim » Tue Oct 24, 2017 12:58 pm

GW used to get theirs from SS (not sure if they still do). The latest ones all seem to have the "ball" on the end to allow for misalignment - which eventually leaks in my experience. They are also made down to a price, so the stainless isn't the best.


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Post by Old and Slow » Tue Oct 24, 2017 1:00 pm

Perhaps you've seen the discussion on the performance value of tubular exhausts in the Early Sabre forum?
I Don't think anyone's quantified the benefits, but definitely seen as a big improvement.
According to a book I have, if you want "interference" working (where the flow of gas pulses interact and add some benefit) the three branches should join after 18 inches. If you want "independent" working, the pipes need to be about 5 ft long before joining. However it all depends on firing order etc. That's the theory, anyway.
Others will have better experience of life expectancy than me.


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Post by efi_sprintgte » Tue Oct 24, 2017 2:07 pm

Performance gains often go hand in hand. As I stated earlier on a tuned engine they made a big difference. On your engine, hard to tell. Without before and after rolling roads you will never actually know either.


A one word answer would be yes


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Post by drcdb15 » Tue Oct 24, 2017 3:19 pm

Old and Slow wrote:
Tue Oct 24, 2017 1:00 pm
Perhaps you've seen the discussion on the performance value of tubular exhausts in the Early Sabre forum?
I had not, but I have now. Fascinating, I love all the early history detective work, much like me trying to get to the bottom of the Webster story. If only people would be more rigorous in keeping tidy, indexed, dated records... in triplicate :D

Many thanks to everyone who has responded. The consensus seems to be, then, that tubular manifolds are probably a good idea in principle, the benefits might not seem terribly noticeable depending on what other factors might be holding back the engine's full potential (though Peter F reports a noticeable reduction in noise levels, which might be a good thing for the neighbours), and the pipes/joints might leak a little if you're unlucky, and might not last very long if you get a poor batch - but on the other hand they might!

So far I haven't heard anyone saying positively "don't do it!" which I shall take as some encouragement :lol:

Thanks again to all !


Chris
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Post by DARK STAR » Tue Oct 24, 2017 4:37 pm

Tubular manifolds are definitely worthwhile, and Stainless Systems' quality is irreproachable.
I have their full exhausts on the GTC and they are perfect after many years, the rear boxes are even mirror-finish shiny.


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