hybrid_944

Im having a forman argument with one of my friends. He swars up and down that the blocks of the 944 are steel, or cast iron. and Im trying to get him to listen to me on the fact that they are a aluminum / slycone composite.

can any one confirm this to me so he will just shup up and conciede to my knoledge

oh. and im looking for a shop to hone the cly walls. any one know of a place?

Doug944s2

Tell your friend to shut up! 944s definitely use a non-sleeved, "alu-sil" block, just like the 928's V-8 from which it's derived. I believe that the aluminum pistons need to be coated with iron or other metals to work against the hard silicon surface. Sorry, but I can't help with the other question.

IceShark

You are basically correct except it is a silicate compound (sand, oxygen, metal) that gets added to the aluminum, certainly not silicone which is the rubber like stuff.

In any event, they certainly aren't made out of iron. Bet him the farm on that one if he thinks he is so right. <img src="graemlins/roflmao.gif" border="0" alt="[hiha]" />

Dan in Pasadena

Hey, Ice! I don't want to hijack this thread but I need to speak to you about my headlight. I assume you got my check finally - sorry for the delay. Can you send me a private email please?

Danno

"He swars up and down that the blocks of the 944 are steel, or cast iron."


Uh, have your buddy put a magnet up to the 944 block and check it out himself!

Some people point back to the GM Vega using Reynolds-390 aluminum as one of the predecessors of the 944 block.

The particular alloy used by Porsche is trademarked material called Alusil made by Kolbenschmidt AG. It is composed of roughly 30% silicon (not silicone, popular for personal-flotation devices in So.Cal chics). Since the solution (eutectic) limit for silicon dissolved in aluminum is around 11%, the excess silicon percipitates out as crystals. So technically, the Alusil material used in our blocks is really a metal-matrix composite (MMC). Some more info from the manufacturer: <a href="http://www.kolbenschmidt.de/KSWebGate/KSPG_WG_51.nsf/vwFiles/lpdc_engine_blocks/$FILE/lpdc_engine_blocks.pdf" target="_blank">Alusil engine blocks</a> (PDF file)

Then you're all familiar with the 4th extra step in the block-preparation requiring lapping with a fine abrasive to remove the softer aluminum from between the harder silicon crystals.

The Boxster uses a different material with less silicon (around 15-21% IIRC) with some copper added (presumably to make the molten mix easier to flow into molds). This is called Lokasil. Here's some more info from the manufacturer: <a href="http://www.kolbenschmidt.de/KSWebGate/KSPG_WG_51.nsf/vwFiles/aluminium/$FILE/Dg_e.pdf" target="_blank">Lokasil info</a> (PDF file)

hybrid_944

ok. good. so thats why the blocks last so long. now for the next thought. hum.

can you weld on this alusil to fill in the gaps left by removing the balance shafts. There are 3 on ether side. and id rather not try to tap and plug them.

thanks.

Larry Dumoff

You may want to check with a shop working on Chevy racing engines. I believe these use a similar material.

Danno

"can you weld on this alusil to fill in the gaps left by removing the balance shafts. There are 3 on ether side. and id rather not try to tap and plug them."

I guess you could weld up the holes. Easier just to get the "Balance Shaft Delete Kit". These are just block-off plates that bolt onto the block. The driver-side plate also has a tapped hole so you can keep the oil-supply flowing to the turbo. I think <a href="http://www.andersonmotorworks" target="_blank">Anderson Motorworks</a> or <a href="http://www.paragon-products.com" target="_blank">Paragon Products</a> carries these. That way you can just leave the block in the car and remove the balance shafts.

hybrid_944

i was thinking about the kit. but the engine is already out of the car and im looking for a shop to resurface / mod my block.

K27

Interesting article on this subject.
<a href="http://waw.wardsauto.com/ar/auto_boring_trutheverybodys_ideas/index.htm" target="_blank">http://waw.wardsauto.com/ar/auto_boring_trutheverybodys_ideas/index.htm</a>

Danno

"i was thinking about the kit. but the engine is already out of the car and im looking for a shop to resurface / mod my block."

Sure you can weld the block. Just make sure you use someone who does quality aluminum welding. Here's a guy that welded in an entire block-brace on this 928: <a href="http://www.928sg.com/block.htm" target="_blank">http://www.928sg.com/block.htm</a>