Y-alloy heads? Your 2.4S has 'em

[Allen Henderson]

On a head trip gents and gals,

We've learned that Y is for "Yttrium" and this was used to add temperature robustness to the heads. Does anyone have any documentation that these were, in fact, unique to the 2.4S? Some suspect marketing department hype, i.e. that all heads are made from the same material, that is T, E and S? Below is from the factory WorkShop manual and is ONLY found for the 2.4S ((not 2.0 or 2.2 or std 2.7) (and RS in the same manual)). Thanks.
-Allen-

[Flieger]

Interesting. It would seem that the casting number would be unique if a different alloy was specified.

[Allen Henderson]

I believe, but and not sure, that the casting number is:
911.104.307.1R for 2.4S. But, the S would should, regardless of material, have a different casting number as the the ports are bigger than the T and E. So, a different casting number alone will not really indicate a different material. We need more "proof." Interestingly, folks who "play" with these, apparently, haven't noticed any material (pun intended) difference?

I'd also like to get a confirmed 2.7RS, BTW, as I believe the chamfer on the head is different than an RS. Can anyone confirm or dispute?

I have a set of 2.2S and they are:
911.104.307.0R

We need to confirm the 2.4S Casting number and THEN, HOW and IF they are, in fact, a different material from the 2.2S or other heads.

-Allen-

[Flieger]

Well, we could look for some junk heads and take them to a University or something where they could put a sample of the metal through a mass spectrometer. If only...

[Flieger]

http://www.chemistry.pomona.edu/Chem...um/yttrium.htm

[Allen Henderson]

Y-alloy: one of the first use was in Aircraft engines. Yes, you guessed it. In the heads, which of course, were aircooled!

-Allen-

[72 S Trga]

We've learned that Y is for "Yttrium" and this was used to add temperature robustness to the heads.-

I might mave missed the thread, but what is meant by "temperature robustness"?

Is it alloyed into the aluminum alloy?

Thanks

[Flieger]

Yttrium is alloyed with Aluminum and Magnesium to make the metal more stable throughout a range of changing temperature. Similar to adding silicon, Yttrium Aluminum alloys have less change in volume due to heating or cooling than does pure Aluminum.

[tom1394racing]

Allen

Looking through some of the heads on my shelf, It seem like the switch to Y alloy may have been made with the 2.7 heads.

The attached pics show various heads with and without alloy markings.

The 2.2/2.4 E and S heads look to be identical with no alloy marking.

The 2.7S through 3.2 Carrera heads (including the SC heads) are clearly marked with a "Y" in the upper right in the photos. The 3.3 turbo head also shows an alloy marking for the unique alloy used in the turbo, in the same location.

I don't have any 2.7RS heads but all of my sources say that the 2.7RS head was the same as the 2.4S head.

The pics in order of appearance:

1. 2.2/2.4E
2. 2.7S with "Y" alloy marking
3. 2/2.4S
4. 3.3 Turbo with "RR350" alloy marking

[Allen Henderson]

Tom, thanks for that great info.

I know there is a 911.104.307.1R head and I think, in fact, it was the 2.4S, which would have been the same as a 2.2S EXCEPT for a Y.

-Allen-