I am finishing up stripping the intake & vlve covers on my S4. I don't think you could find a casting this bad on a vega or a pinto. There was an Edlebrock manifold at the shop that did the stripping. If the quality of it was a "10" my 928 is at beat a "2." I had a hard time figuring out why it was painted ALL over. Now I understand.

 

Carlos,
What did you strip your parts with ?
Certain chemicals can have a nasty effect on Magnesium to the point of melting them, also the Edelbrock intake is aluminum which may look better because it's density is higher and it is a more expensive material.
Density of Aluminum (6061) is .098 lbs/in3
Density of Magnesium is .065 lbs/in3
What you lose in appearance you gain in
Strength (Yeild) VS. Weight (Density)
And if you look at the cubic inches of material in your intake and do the math I think you will see why it is the chosen material for our already FAT GIRLS.
Not trying to sound like a no-it-all, It's just that I deal with these issues daily, especially with the German designs.
Sorry to ramble, I bead blasted my intake last week and it is at the powder coaters now, I will post some pics when it comes back.
I had it done in Black Chrome with a Clear coat.

Tim

 

Tim,
Carlos is correct. The castings for some of the intake pieces is really bad. I was amazed as well. Crevices and valleys all over the place. I have no idea why a car that cost as much as the 928 did would have such pathetic castings -
But hey! it goes like stink!!!!!!

 

Bernie,
I agree totally that they look like crap when stripped, my worst spots were on the top where the script is ( go figure ). By the way your intake turned out awesome!!!
Was that a straight black with clear?
I relate the cost of the car with cheap castings right next to the junky looking plastic air intake! I am almost done with a new air intake made from polished aluminum tubing and the same turbo hoses you used on your intake.
It should be done within a week or 2.
Tim

 

I think that may be the reason so many of them peel. The bad surface in addition to thickness they must paint/coat it does not make it good at holding up under high temps.

Here are mine refinished.

<a href="http://boards.rennlist.com/upload/intake_valvcvr2.JPG" target="_blank">http://boards.rennlist.com/upload/intake_valvcvr2.JPG</a>

 

Abby,

Did you swap your motor for an S4's did you adapt the S4 intake to fit your S3?

 

Although I'm not a metallurgist, I do know that casting MAGNESIUM is both harder and more dangerous than casting aluminum or steel. Also, it is very hard to get paint to stick to magnesium, as it tends to form a thin oxidized film as soon as it's exposed to air. Most automotive manufacturers won't even mess with magnesium based on cost and on difficulty working with it. I think if the 928 intake manifold were made today, they'd most likely be made of rubberized-plastic, similar to the ones used in the Boxster and 996. YMMV.

 

Hey Jim,

I actually ended up buying a new block, brand new. Interesting story behind it, 928Intl had a brand new block that had never been fired. It was a Porsche Tech training motor(never in a car) complete and he sold me the block for a reasonable price. I had some scratches in one of the cylinders in my original block so rather than re-work, I bought the one from 928Intl..

 

Abby how did you put a six speed in your car? I always wonderd in the 968 one would be adaptable.