AS21 or AS41 - What's the difference??

[DKK Ted]

Ok, what is the difference between the AS21 and the AS41 case, is one better than the other? The way it's made, the matrial, who manufactured it, German, Brazilian, or Mexican or what??

[j-f]

21 and 41 give the amount of magnesium included in the alloy of the case, for what I know.

[nicolas]

AS21 cases are german cases and are indeed of a different material. they had the patch on the fywheelside from the factory, 8mm stud inserts. they are supposed to be made of a better material, but i have heard also that many of these AS21 cases are warped. another downside is that there is no provision for the factory fuelpump.

i have never experienced a difference compared to a stock (mexican or german) case, but i have never been in a situation where the limitations of the case become apparent. the only thing i missed was the hole for the pump as the electric one make more noise.

[Zach Gomulka]

AS21 cases are german cases and are indeed of a different material. they had the patch on the fywheelside from the factory, 8mm stud inserts. they are supposed to be made of a better material, but i have heard also that many of these AS21 cases are warped. another downside is that there is no provision for the factory fuelpump.

This is true because the AS21's came on fuel injected motors that usually ran very lean (hot) to comply with emissions. I would never use an AS21 unless it was NOS, personally.

[javabug]

they had the patch on the flywheelside from the factory

Mine does not.

[Jesse/DVK]

AS21 cases are german cases and are indeed of a different material. they had the patch on the fywheelside from the factory, 8mm stud inserts. they are supposed to be made of a better material, but i have heard also that many of these AS21 cases are warped. another downside is that there is no provision for the factory fuelpump.

This is true because the AS21's came on fuel injected motors that usually ran very lean (hot) to comply with emissions. I would never use an AS21 unless it was NOS, personally.

In the US yes, but in Europe you also have AS21 with provision for a fuel pump. As far as I know Gene Berg preffered AS21 cases because they are stronger.

[Bruce]

21 and 41 give the amount of magnesium included in the alloy of the case, for what I know.

It's actually the amount of aluminium.
AS-21 = 2% Al, 1% Si
AS-41 = 4% Al, 1% Si

[red baron]

The ideal percentage amount of Si in Al-alloys is at 11.7%. Its the so called eutectic mixture. This means at this point about 90% of the material consits of mixtures crystals of AlSi. These are very tough. only about 10% are Si crystals wich are very brittle and tend to suddenly collapse.

So a little less amount of Si helps to keep the alloy tough. But then there are many factors to recon, when it comes to the process of casting. So the guys at VW hat probably chosen to put some more Si in there, cause it helps to cast very complex models with thin walls, and prevents rough crystals to exude.

You see ver compley thing. I think - from the material side the AS21 should be a bit tougher. But who knows wich reasons what have and if everybody ever gets to the point where the case collapses...

[notched]

21 and 41 give the amount of magnesium included in the alloy of the case, for what I know.

It's actually the amount of aluminium.
AS-21 = 2% Al, 1% Si
AS-41 = 4% Al, 1% Si

So, a AS-21 case is 2% aluminum, 1% silicone, and the rest magnesium?

[Ivan]

Greta thread - is the answer 20?

[DKK Ted]

How about this one, Brazilian AS41 and the Mexican AS41, any big difference if any??

[JIMP]

O.K. maybe it's the same thing like racecraf asked, what's the difference between the older AS41 cases with the 10mm studs and the new ones you can get today still AS41 but with 8mm studs, as far as the code looks the same but doesn't look the same by eye, any inputs on this?

Friendly

Dimitrios

[Felix/DFL]

21 and 41 give the amount of magnesium included in the alloy of the case, for what I know.

It's actually the amount of aluminium.
AS-21 = 2% Al, 1% Si
AS-41 = 4% Al, 1% Si

So, a AS-21 case is 2% aluminum, 1% silicone, and the rest magnesium?

1% Silicium! Silicone would be a bit weak 

I have got two AS21 both with the cooling patch.
One german with fuel pump mounting, and a new mexican FI case without pump mounting AND manily filled behind 3rd cyl.
The mex. case needed a lot more work for deburing, the german casting is much more smoother...

What I don`t understand is that it`s said that the AS21 is stronger. Why?
It has less aluminium and more mag! And aluminium gives more strenght...And if you look at the heat conductance tha alu is even at the first place.

Anyhow never had any problems with my used german As21. But always wondered about the tale that AS21 is better.

Another thing to bear in mind is that the older cases have smaller oil galleries, so less oil volume going throu...
The cases with 10mm studs screwed direct into the case tend to fail cause the studs pull out of the case.So I would always convert to 8mm case savers.

[red baron]

I doubt, that the major ingerdient is magnesium....

[Bruce]

21 and 41 give the amount of magnesium included in the alloy of the case, for what I know.

It's actually the amount of aluminium.
AS-21 = 2% Al, 1% Si
AS-41 = 4% Al, 1% Si

So, a AS-21 case is 2% aluminum, 1% silicone, and the rest magnesium?

1% Silicium! Silicone would be a bit weak 

Another thing to bear in mind is that the older cases have smaller oil galleries, so less oil volume going throu...
The cases with 10mm studs screwed direct into the case tend to fail cause the studs pull out of the case.So I would always convert to 8mm case savers.

An AJ AS-21 German case has exactly the same size oil passages as any AH, AK, AE case.

Si is silicon.

[DOUG BERG]

.

[Tony M]

The story i got is that the as21 case will take more hp than the as41 - my local vw machine shop claims that it will take with a turbo over 400hp and live - even when you machine there cases the finish is very different with the as21 + they are german, back filled, and no fuel pump - i use that spot for a breather - have never had a single problem with these cases - have 2 of them - one punched out for 94's and the other stock - even used they sell for over 300.00 bucks.

[Felix/DFL]

An AJ AS-21 German case has exactly the same size oil passages as any AH, AK, AE case.
Si is silicon.
[/quote]

Sorry Bruce but that`s 100% false. Silicium gives the mag the needed strenght otherwise it would be way to soft.

Silicone would just burn up in smoke at the casting process...

I wanted to say that the oil galleries in older cases not AS21 are smaller, sorry that I dindn`t seperate that.

[Bruce]

An AJ AS-21 German case has exactly the same size oil passages as any AH, AK, AE case.
Si is silicon.

Sorry Bruce but that`s 100% false. Silicium gives the mag the needed strenght otherwise it would be way to soft.

Silicone would just burn up in smoke at the casting process...[/quote]
I didn't type Silicone.  That is a type of rubber-like sealer.  Si is the chemical formula for the element Silicon, atomic number 14.  In English, it is spelled Silicon.  What language is silicium from?

[notched]

21 and 41 give the amount of magnesium included in the alloy of the case, for what I know.

It's actually the amount of aluminium.
AS-21 = 2% Al, 1% Si
AS-41 = 4% Al, 1% Si

So, a AS-21 case is 2% aluminum, 1% silicone, and the rest magnesium?

1% Silicium! Silicone would be a bit weak 

I have got two AS21 both with the cooling patch.
One german with fuel pump mounting, and a new mexican FI case without pump mounting AND manily filled behind 3rd cyl.
The mex. case needed a lot more work for deburing, the german casting is much more smoother...

What I don`t understand is that it`s said that the AS21 is stronger. Why?
It has less aluminium and more mag! And aluminium gives more strenght...And if you look at the heat conductance tha alu is even at the first place.

Anyhow never had any problems with my used german As21. But always wondered about the tale that AS21 is better.

Another thing to bear in mind is that the older cases have smaller oil galleries, so less oil volume going throu...
The cases with 10mm studs screwed direct into the case tend to fail cause the studs pull out of the case.So I would always convert to 8mm case savers.

Ya, I added the "e" by mistake. I'm a Yank. Dan Quayle and I like to add an "e" unnecessarily... Silicon...

[JS]

An AJ AS-21 German case has exactly the same size oil passages as any AH, AK, AE case.
Si is silicon.

Sorry Bruce but that`s 100% false. Silicium gives the mag the needed strenght otherwise it would be way to soft.

Silicone would just burn up in smoke at the casting process...

I wanted to say that the oil galleries in older cases not AS21 are smaller, sorry that I dindn`t seperate that.

[/quote]

Try Googling "AS21 alloy".

[Felix/DFL]

An AJ AS-21 German case has exactly the same size oil passages as any AH, AK, AE case.
Si is silicon.

Sorry Bruce but that`s 100% false. Silicium gives the mag the needed strenght otherwise it would be way to soft.
Silicone would just burn up in smoke at the casting process...
I wanted to say that the oil galleries in older cases not AS21 are smaller, sorry that I dindn`t seperate that.

Try Googling "AS21 alloy".
[/quote]

was yust a translation mistake we both meaned the same thing!!!    In german: Silizium
Translation (GB english):
 silicium [chem.]   das Silizium   - Symbol: Si   
 silicon [chem.]   das Silizium  - Symbol: Si