Silumin..(Rob,Brian,Mark&anyone else)

[210bhp]

Can I ask you guys a few things from our previous thread 'the rarest version of the carrera RS?' I hope you don't mind this to try to improve my education!!
Brian
The homologation papers in May 73 refer to chassis 1490 and it's odd engine number as being the start of silumin cases yet Mark details his previous car 1382 with a 633 engine stamp as having an aluminium case. Have I got this right? Where is 1490 now? Can the owner confirm engine stamp as 663 or 633
Does 1490 definitely still have a silumin case? Was 1382 the first silumin case?
Robert
You say aluminium cases were used back in '64. Was this in the 356(which I know little about) or 901? Was this straight aluminium or silumin or some other alloy?
Mark
You say silumin was really homologated for use in the 3 litre development for extra strength. Is the 2.7 casting for the silumin case the same as the mag case i.e. do the cases look the same but just a different colour? How else can I confirm if my case is mag or silumin?
Regards
Mike

[andyjboy]

Mike -

aluminium was used for the early 2.0 litre crankcases from its introduction up until the spring of 1968 when the magnesium crankcases were introduced.

As far as I am aware, the silumin crankcases were introduced in May 1973 - around the same time that the shorter rear trailing arms were installed - so the chances are that your car originally came with silumin crankcases.

[andyjboy]

As far as previous experience with Silumin goes, Porsche had been using various silumin alloys (aluminium alloys containing between 4 & 20% silicon) for their tractor engines (& I think some of their automobile transmission cases) since the '50's.

Silumin alloys had also been used extensively by other manufacturers - in particular Ferrari.

[parced@telia.co]

On the issue of Silumin I have tried to do some research. I have found 2 cars with Silumin engine-cases on the -73 Carrera RS. Closer inspection of these show that the case is a 911/83 BUT look like a RS 3.0 case with the smaller spigot diameter. The two cars that I know of has been built/rebuilt to rally spec at the factory. One of the cars is 1570, the other one I don't have any paper of. My encounter with that one was in the early 80's. I have tried to find "evidence" on the subject but the trail has gone cold....

[fryardds]

I thought it was odd too that the VIN and engine # mentioned in the homologation papers is significantly past those of #1382. I hope Jeff or Rob will weigh in on these questions. Here are the pages that we have talking about all this time.

[kenikh]

Is the Silumin case the same as the sometimes referred to "Aluminum 7R" case? I believe Steve at Rennsport built a 2.8RSR engine out of one of these once. He had an extensive post either here or on Pelican, with photos, of the car.

[Flat Six, inc.]

It sounds like the factory just started using the early sand-cast 2.0L cases with the 80mm stud spacing again......rather than the '74 RS/RSR 3.0L cases that had 83mm stud spacing.

That would make sense right?

Interesting stuff.....

Aaron

[parced@telia.co]

The two cases I have seen had the feet for the MFI-pump so it was later design. I also remember that you can see the foot for the spigot and that the spigot was off center in that foot. I have failed to think of checking the pressing number but that would confirm, or not, my theory. I will try to get the number from 1570.

[210bhp]

2+2=5? I have discovered..................
The first record of a silumin engine case that I have been able to find is in the Russian T34 tank. This is not too suprising as the technologies the Russians were trying to expedite in the 30's included new foundry techniqes especially the use of electronic crucibles for casting new alloys including silumin. The engine was light and strong and this tank became a thorn in the German's side during the WW2. The tank's development began in 1931 when the Russian's bought two American Christie tanks to study(especially the trans. and suspension). The foundries and engineering works were all in the Ukraine. The tank factory was in Kharkov.
Where did Ferdinand Porsche visit during late 1932...?......when the Russian's tried to tempt him to become 'chief State engineer'.......according to the records he visited factories, engineering works, foundaries and tank and tractor lines in and around the Ukraine....Kiev in particular which is not far from Kharkov. FP declined their offer and returned to Germany to continue with his newly formed design studio. Of course he went on to help design and build tanks for Germany notably the Tiger.
Did FP see the new techniques for casting on his visit.....did he see one of the first silumin cases made? Was this technology used after the war at Porsche?
Regards
Mike

[MarkH]

I had no idea this subject would generate so much interest, great.
I have been waiting to see #1490 surface for years. I worked for
several years with Fred Hampton to assemble a list of RS/RSR's
for a registry but as is often the case, it ran out of gas. We did
assemble a pretty good list but #1490 was not on it.

I owned RS 3.0 9114609027 for a number of years and agree with
Par that the surface color and texture of the case was the same as
#1382. I never investigated beyond that. I wish I had.