Understanding the role of Alusil

[dparm]

Long ago I read about how Alusil engine blocks are actually porous and hold oil. Does anyone know more about this trait and how it actually works? How does it impact the motor oil and overall protection/engine performance?

I know that the process to hone the bores is extremely complicated and not something any old shop can do.

 

[DannyBoyG]

Found this interesting article, hopefully it can answer your questions!
http://bmw8.us/Nikasil and Alusil article smaller.pdf

 

[dparm]

Good read, thanks. I'm wondering why the German manufacturers are the only ones using this? US and Japanese companies are using the more "traditional" materials.

 

[mechtech2]

Cosworth Vegas used aluminum bores 40 years ago.
They needed to be lapped for a final finish, not honed.

 

[WMSmotorhead]

Originally Posted By: dparm
Good read, thanks. I'm wondering why the German manufacturers are the only ones using this? US and Japanese companies are using the more "traditional" materials.


The answer is pretty simple...even with traditional matereals, an engine can usually run correctly longer than the rest of the vehicle will hold out for. It's simple economics. The "magic matereals" cost more, so they won't be found in a common commuter car.

The technology may be better suited for an industrial engine that must run 24/7...

 

[SteveSRT8]

Alusil is an alloy, not to be confused with Nikasil which is many times deposited by a wire being electrified with ridiculous voltage and thus micro-plating the stuff onto a bore.

I had a kawasaki street bike with Nikasil bores, and they lasted through 2 sets of pistons. Very durable stuff, and it allegedly is quite the friction reducer.

And yes, the Vega used a high silicon alloy in the engine block.

 

[martinq]

The Porsche 928 used an alloy block like this (aluminum / silicon) and is very durable. I worked one with 700k km on the clock, the block had never been touched, and it ran like a clock.

 

[fdcg27]

Originally Posted By: mechtech2
Cosworth Vegas used aluminum bores 40 years ago.
They needed to be lapped for a final finish, not honed.


The ordinary 2.3 liter Vega engine used high silicon aluminum bores as well.
Didn't work all that well (I owned one), but that may have been as much due to the iron head on alloy block and open deck design as with the material used for the block and bores.

 

[BMWTurboDzl]

http://www.kspg-ag.de/index.php?lang=3

 

[artificialist]

Some engine bearings are now built this way.

http://www.kingbearings.com/oem_replacement.php