..bad thing is, after years with cracks and leaks on the most rear end of the manifold my LH one now 'eats up' the turboflange gaskets within months.

 

For a comlete rebuild of the exhaust system I would need to repair, or replace this one for sure. 

 

Even one of those odd manifold studs in the head disappeared, or more exactly the outer portion sheared off by itself under heat expansion. So it looks like a 'engine out' next summer, with additional cambelt change.

 

My question is -are those manifolds still available somewhere as NewOldStock ?

  ...or is there by any chance a welded-type 'refabrication' vs. those cast originals going round somewhere ?

(like for the 4 pot Esprit versions)

I have not seen anyone who made or fitted their V8 with aftermarket turbo exhaust manifold like the 4 pot.
I wish someone can fabricate an exhaust manifold so I can use a much bigger turbocharger.
I've been looking at that too but it seems there's no place to plumb a pipe - it's really so tight (no room) below the engine block.
 
Try to bring your stock exhaust manifold to someone who has a welder that can weld cast iron. You probably need to find a welder that uses Lincoln Softweld 99Ni stick electrode for single pass, high dilution welds. There's a special process to weld cast iron.

I know that there is a process of heatcycle involved..

Thing is to find a company near enough to get all stuff back within short time. For now I try to replace as much rotten stuff as possible with the 'engine in' ..and plan additional operations for next summer. As the engine could come out anyway for cambelt-service.

On the other hand it would be good to know that there is replacement ..just in case that the welding fails even more badly

Given their experience with the Esprit and the replacement radiator and exhaust systems they have developed (no V8 manifolds yet though) I'd suggest having a chat with Alunox. 

 

http://www.lotusespritworld.com/EGuides/EModifications/UpratedChargeCooler.html

year after year it gets bigger and bigger  ..the cracklines are there on the LH manifold, now even a hole on the top side is evident.

additionally two manifold studs in the cylinderhead just sheared off by unequal expansion -on the lower end of the cylinderhead-flange the manifold is notable deformed 

 

..the corrosion on the rear manifold-nuts on the other hand is normal, just what we can expect from the exposed conception in the rear wheelhousing

Edited August 7, 201410 yr by Günter

I have never tried to buy the exhaust manifolds because I haven't needed them yet.  So did you try to call the normal suppliers of Lotus parts already and they said they are unavailable?

 

What were the symptoms of these cracks?  Did you have exhaust smells in the cabin?  Horrible noises from the exhaust?  Or did you just find them on inspection?

The exhaust manifold nut condition is common due to galvanic corrosion of the steel nut on the stainless steel stud.

you would think so ..but there is a hughe difference between front end and rear end of the engine

 

 

..on both sides of the engine the corrosion can only take place as for all the wet-dirt from the wheels.

In a normally dry environment (as for the heat of the exhaust) no galvanic reaction can run so fast.  Think you know that it needs a type of electrolyth.

 

My car was in use in every condition, even in the winter (with lots of salt on the motorway)  ..so a galvanic reaction is what I have to expect -thin is that you can find those differences there

 

@Philip: 

Lotus-price

Table Number: 40_21b

Position: 01

Part Number: B918E0155K

Description: Exhaust Manifold, LH

Notes:   Qty on Car: 1

Price (each): £748.70

 

Stock: Factory Order

 

 

I asked ALUNOX for possible reengineering in a 'compact' but more efficient style .. so as a tube design , with equal lenght pipes.

 

..i this special case, with a cracked turbo flange (the crack lines are there to) means the life-cycle of the turbo flange gasket is short, really short  ..expecially if you run your car on trackdays. That is why I fabrikated my own gasket and use some type of *HoLTS manifold cement* there to equalize the surface.

 

..the cracks there on the top side are just a problem on German road certification (MOT)  ..if the engineer notices them, or the emission tester sees it as a 'leak' with additional air 

Edited August 7, 201410 yr by Günter

Cold engines get condensation on them when their temperature is at or below the dew point thereby providing the electrolyte. I have seen the nuts corrode away in a variety of positions on Lotus engines. It's almost as if Lotus intended them to be sacrificial.

Edited August 7, 201410 yr by sailorbob

in terms of general notable corrosion on our 'plastic' cars you are right -lots of bit's n pieces rust away there 

 

..thing is that I can see the different state of corrosion of the same type of nuts just there on the engine -compared both ends

 

same is for the turbos, there I had often redone the studs for the catalyst flange and the catalyst flange itself within the last 110.000km

So no joy back from Alunox on a replacement system then?