Exhaust manifold casting

Author
Discussion

arguti

Original Poster:

1,772 posts

185 months

Wednesday 27th August 2014
quotequote all
Have a wee problem on my Alfa 75 Turbo Evo in that the exhaust manifold is cracked inside - see photos below.

Trying to get hold of a replacement is like trying to get hold of a hen with square teeth and I am toying with the idea of getting a small run cast as I wish to keep the car original. 2nd option is to go down the tubular manifold route if getting a OE replacement is not possible.

Amy recommendations as to:
1) What the best metal for casting
2) Any companies that may do this and
3) Likely costs of the two options.

I was thinking of doing a run of 10-20 and selling some on if the cost was not too prohibitive.

The problem!



What it should look like


Riley Blue

20,915 posts

225 months

arguti

Original Poster:

1,772 posts

185 months

Wednesday 27th August 2014
quotequote all
Thanks but I already spoke to Goos last week - he has none in stock and has been waiting for 12 months for their Italian supplier to make up another batch.

There are one or two people who also have a spare manifold but, for obvious reasons, do not want to sell.

bucksmanuk

2,311 posts

169 months

Wednesday 27th August 2014
quotequote all
The killer here is pattern charges. I don’t think you will get patterns done for less than £4k. Maybe less if you can get someone to do a 3-D CAD model of it first. Where I used to work we had some compressor volutes done about 5 years ago, twice the size of your exhaust manifold, accurate internal structure required also, and the pattern charges alone were £3.3K. STL models supplied of it all.
Then you have to get it machined, although it’s only a few faces that need licking up and some holes drilling. £200 for the first one, and then the cost will plummet for quantity.
As for the actual material itself, its cast iron, but as you can imagine there are loads of cast irons available, so hopefully someone in the automotive industry can come along in a minute and tell us what type they use, and then you specify a better one. The cost of the actual material will be about £10 per manifold so specifying something very high quality is the least of your worries.
20 manifolds are going to be £250 each at this rate. IMHO I would get a tubular one made…

or just repair it properly...
http://www.castironwelding.co.uk/

spitfire4v8

3,990 posts

180 months

Wednesday 27th August 2014
quotequote all
boostedls1 (Mike of Boost Performance) gets manifolds cast, might be worth a message to him maybe ?

esso

1,849 posts

216 months

Wednesday 27th August 2014
quotequote all
To have a small quantity cast & machined will be cost prohibitive, the tubular route would be the best option, I know you are looking at originality but would this be considered a 'performance option?'

Flatinfourth

591 posts

137 months

Wednesday 27th August 2014
quotequote all
Surely just fabricate the thing? the existing manifold will make a jig tool, will provide the 2d image (rubbing)for the face plates, which can be laser or water cut, the rest is tubing. If you cast the cost will run away.

Yertis

18,016 posts

265 months

Wednesday 27th August 2014
quotequote all
Just as those above have said, it will cost a lot. A few years ago I had an exhaust manifold manufacturer in the east midlands quote to do some for the Quattro, following the original design, reverse engineered from a knackered one (of which I have several rolleyes )

I think I calculated that I would have broken even with fifty orders at £500 a go. I don't think that's bad. What actually put me off was the risk of people installing them incorrectly and bleating at me, etc. And I didn't have £25,000 knocking around.

DeltonaS

3,707 posts

137 months

Wednesday 27th August 2014
quotequote all
Maybe these guys can help:

http://www.speedshop.ch/Alfa_Romeo.htm

TheRealFingers99

1,996 posts

127 months

Wednesday 27th August 2014
quotequote all
I'd go fabricated. Take a jig from the cracked one. As said, get the flanges water or laser cut. For the rest, schedule 40 "Weld-Els": available in straight sections, pre-formed bends, etc. -- used by steam/gas fitters. Tig or Mig together, use a long nosed die grinder to remove any excess penetration.

Were you making a big run, casting would be fine, but only if you could guarantee no cracking (you can't).

Not sure what that divider actually does. Might be possible simply to chop it (and the crack) clean out with a die grinder?

Flatinfourth

591 posts

137 months

Thursday 28th August 2014
quotequote all
Flatinfourth said:
Surely just fabricate the thing? the existing manifold will make a jig tool, will provide the 2d image (rubbing)for the face plates, which can be laser or water cut, the rest is tubing. If you cast the cost will run away.
You can probably get the bends from Jetex, look on website, Burton Power are a stockist, I bought an over axle pipe from them last week

cahami

1,248 posts

205 months

Friday 29th August 2014
quotequote all
What problems is the crack causing?

TheRealFingers99

1,996 posts

127 months

Friday 29th August 2014
quotequote all
Flatinfourth said:
You can probably get the bends from Jetex, look on website, Burton Power are a stockist, I bought an over axle pipe from them last week
Yeah, but they won't be the correct grade or thick enough. That thing has to be able to stand a lot more heat than a n/a manifold and support the weight of a turbo.

TheRealFingers99

1,996 posts

127 months

Friday 29th August 2014
quotequote all
cahami said:
What problems is the crack causing?
Can't speak for the owner. I hope none at the moment. But if a shard of cast iron breaks off it will destroy the turbo almost instantly.

arguti

Original Poster:

1,772 posts

185 months

Friday 29th August 2014
quotequote all
TheRealFingers99 said:
Can't speak for the owner. I hope none at the moment. But if a shard of cast iron breaks off it will destroy the turbo almost instantly.
This, manifold was taken off as turbo was damaged, this was probably the cause when you look how much of the vane has eroded over time compared to the original

Edited by arguti on Friday 29th August 18:26

MJK 24

5,648 posts

235 months

Friday 29th August 2014
quotequote all
Is it not possible to weld due to poor access?

I've had cracked cast manifolds welded before successfully but they were from non turbocharged Mercedes engines.

Flatinfourth

591 posts

137 months

Friday 29th August 2014
quotequote all
TheRealFingers99 said:
Flatinfourth said:
You can probably get the bends from Jetex, look on website, Burton Power are a stockist, I bought an over axle pipe from them last week
Yeah, but they won't be the correct grade or thick enough. That thing has to be able to stand a lot more heat than a n/a manifold and support the weight of a turbo.
You underestimate my experience. NA manifolds often run hot enough to be able to see the exhaust pulses travelling along the tubes, by comparison turbo manifolds are often blunt instruments that have no tuned length and little detail, the example above is exactly that. If you look at the cast manifold's layout, the tube design required to create a copy would result in a welded sructure strong enough to lift the car by, and if done carefully could have good paths to fixings etc too.

Edited by Flatinfourth on Friday 29th August 14:56

arguti

Original Poster:

1,772 posts

185 months

Friday 29th August 2014
quotequote all
Thank you everyone for the comments and suggestions; Mike from Boosted has got back to me saying it is possible but he has to have the original in order to estimate costing, etc.

Going down the tubular route is the other option yet understandably no one will guarantee against cracking especially in a turbo application.

Flatinfourth, I take your comments yet I seem to recall a thread on the Guy Croft forum about comparing the Alfa 155Q4/Lancia Delta Integrale OE exhaust similarly, is a crude looking thing and comparing the actual gas flow versus some aftermarket tubular manifolds and establishing that the OE manifold came out best.

I cant find the specific thread but here is a similar one

http://www.guy-croft.com/viewtopic.php?f=6&t=2...

In fact it was only recently I saw on his forum that there is now one aftermarket manifold that he endorses but it is around £2000!

http://www.guy-croft.com/viewtopic.php?f=7&t=2...

Some of Guy Croft's thoughts on exhaust manifolds (he posts under GCRE) for educational purposes. I have no connection Guy other than saying his book on modifying the Fiat/Lancia engines is absolutely fantastic!

http://www.fccuk.org/forum/ubbthreads.php?ubb=show...


thank you

Edited by arguti on Friday 29th August 18:27

mike9009

6,918 posts

242 months

Friday 29th August 2014
quotequote all
MJK 24 said:
Is it not possible to weld due to poor access?

I've had cracked cast manifolds welded before successfully but they were from non turbocharged Mercedes engines.
If access is good and crack does not run too deep, surely this is a viable option?

arguti

Original Poster:

1,772 posts

185 months

Friday 29th August 2014
quotequote all
If you look at the pictures of the new manifold versus the current state of mine there is a large crack but more importantly with time, the dividing vane has effectively been eroded away by heat and my concern is that is is this particulate matter which I believe has led to the damage to the turbo

The car is a 1987 model with only 69,000 km on the clock and the boost is factory standard with power at around 155bhp - the standard pistons, crankshaft etc are apparently strong enough for up to 400bhp so it's not like the engine has been particularly stressed. Just heat and age have taken their toll.

My preference for going down the casting route is that I am thinking of getting a second 75 turbo and I don't want to have to go through this again.