Magnesium inlet manifold?

MikeP · 05-10-07, 06:17 PM

I have the oportunity to acquire a quad 48 IDA original type manifold for SBF. The manifold is in magnesium not aluminium. My question is whether mag is suitable as it will be in contact with the coolant? Will there be serious corrosion issues either in the long or short term? Are there any issues with galvanic corrosion? Maybe it would be OK for a race motor which sees little use with regular stripdown. Can the mag alloy be protected by adding something to the coolant or a special type of antifreeze? I would really like to use this part as the price is good and it would be really light. Any info gratefully received.
Thanks
Mike

Doc Watson · 05-10-07, 08:57 PM

Mike,

I cant answer all your questions but magnesium is the most active anode in the electrolytic scale. It will corrode when in contact with steel or aluminium and even more so with water present. I can understand your desire to use it but would a good reproduction in aluminium be better? Do you have a block already?

In the aircraft industry they sometimes paint all bolts just prior to assembly to minimise any steel to mag contact and also paint the bolt heads but always try and keep moisture away. If the underside of the manifold and water passages were painted and you were very careful when assembling the top of the engine this would help minimise the galvanic action but it will always be corroding to some extent unless you can be sure the manifold isnt touching steel or the coolant. Anybody else help?

Andy

Andy

Paul Thompson 'Hooligan' · 05-11-07, 05:32 AM

We use Kinsler magnesium bodies on Roy Smart's GTD and if the water is allowed to touch the manifold metal, it corrodes like mad!!

The bodies are nicely coated (powder i think) and whilst intact, there are no issues, but if water had to pass through it, you'd have to be doubly sure that there are absolutely no bare areas, or it would corrode itself apart...

Roys tb arrangement is 2x4 body sections that bolt directly onto each head and a flat centre valley plate to cover the 'void' between.

It doesn't have any water flowing through it, but where a temp sensor was initially located, sticking into one end of the TFS head, the bit around the sensor corroded badly in its first season... It has now been repaired and sealed and the sensor located elsewhere.

Another thing to always remember is that you have to be pretty carefull when inserting and removing threaded bolts/inserts and not overtighten. I guess again a reaction can take place between mag and the insert/bolt? does anyone know whether this is so? or whether there is a preferred 'protection' method for such fittings?

It is nice and light though!!

Malcolm · 05-11-07, 02:32 PM

Can you seal the inner surface of the waterways of the manifold effectively "painting" them so no contact with water? Cam coat or something?

MikeP · 05-11-07, 07:26 PM

It looks like this mag manifold might just be rather too soluble without some serious sealing and protection. Probably too much aggro for a few pounds lighter.
Cheers
Mike

Scott Calabro · 05-11-07, 08:23 PM

Mike,

If you don't want it, can you PM me with the acquisition info ?

Regards,
S

David Morton · 05-12-07, 10:42 AM

Mike,
Walk away from it or use it as a buck/pattern to cast some more in Aluminium if it differs significantly. There is even water in the fuel which can/will erode Mag sinificantly UNLESS its fully sealed. The slightest ding or nick or crack in the sealant and your in trouble. Fine if you have a race car engine and its in strip down regularly but otherwise an always impending problem.
Dave M

Scott Calabro · 05-13-07, 09:07 AM

There are several aviation specific coatings and chemicals that can be utilized to stop any corrosion. They are expensive and a significant health hazard. Google MASTINOX. For those who don't have access to these type of products, stick with cast aluminum. Maybe paint the bottom with GE Glyptal.

Best,
S

BruceLambo · 05-13-07, 07:59 PM

Just a question here, how does one tell the magnesium from aluminium?

woodz428 · 05-13-07, 08:32 PM

As far as determining by appearance I would say the color is more "grey". Also, at the age of the manifold discussed, I would be willing to guess there are areas already corroded. I've seen magnesium that was corroded from the humidity in the storage they were in. They were also designed for short term racing usage, because the next best thing was just around the corner and weren't too concerned about such minor details as long term performance.
I think the suggestion made regarding casting aluminum ones is a neat idea, although possibly a little costly. It would seem to have a potential market with a set of Weber look alike electronic FI.

MikeP · 05-15-07, 09:30 AM

The mag inlet manifold I referred to is a freshly made part. Original type aluminium quad 48 IDA weber inlet manifolds are available from John Wisher in the UK as are uprights, bellhousings, BRM wheells etc. etc.
Cheers
Mike

Lynn · 05-19-07, 11:35 AM

Not sure if this is a battle worth fighting, but since magnesium, for all intents and purposes, is the the least noble-anoidic material there is:

which precludes the use of a sacraficial anode, I wonder if one of those forced current corrosion preventers would work in this case?

Bye the way, the galvanic chart was found in a pretty neat article about protecting automotive electrical connections from corrosion using zinc paste and similar products: Anti-Corrosive Zinc Paste for Electrical Connections.

Lynn

MikeP · 09-05-07, 08:36 PM

The magnesium inlets are now in production. A suitable inhibitor can be put in the coolant to guard against corrosion or the manifold can be ceramic coated. The inlet is to original GT40 spec. (photo attached - sorry about the background - it was the only one available in the pub)
The first batch of ten are now available either as the bare casting at about £700 or machined with helicoil inserts at about £850. Ceramic coating would be extra.
The contacts for the manifolds are either Bob Maynard or Nick Shrigley-Feigl at
Auto - Historic Ltd
Unit 34
Churnet Works
Macclesfield Road
Leek
Staffordshire
ST13 8YA
Tel: 01538 383683/370103
Email: info@autohistoric.com
Auto Historic - Maintenance, Repair or Restoration of Historic and Classic Motor Cars

Rick · 09-06-07, 12:57 AM

One of those was on Ebay and sold for $661 last week. Not sure if it was Aluminum or Mag.

http://http://cgi.ebay.com/ebaymotor...spagenameZWDVW

Mike Drew · 09-06-07, 03:01 AM

Quote:

Originally Posted by RamboLambo

Just a question here, how does one tell the magnesium from aluminium?

Just try to set it on fire. If it gets hot, it's aluminum. If it explodes and burns your house down, it *was* magnesium.

MikeP · 09-06-07, 10:19 AM

They are most definitely magnesium. The pattern was made from an original GT40 aluminium manifold which used 50 IDAs. The company have been using magnesium inlet manifolds on their two Formula 5000 race cars for some time. They are making the manifolds as a result of needing one for their original race cobra.
Cheers
Mike