Fins mean more material, more material means more cost. The fins must have some value or they would be removed. Strength can be designed into the castings via ribs etc, just like the transmission using less material than fins.

How is it a "free improvement" if it takes more material?

You think the fins are there for a no cost strength reason (there are no fins on upper surface of engine case, no strength needed there?), I think they are there to aid cooling.

alistair

On 2011-07-21, at 11:23 AM, Scott Daniel - Turbovans wrote:

> the extra casting cost is nil I suspect. .
> like barely, barely more expensive to cast it with ribs or fins than without.
> and besides,
> as I said, it adds stiffness and strength.
> it's an almost free improvement.
> there is no reason not to have fins on an aluminum sump, generally speaking.
> ( though diesel vanagon does not )
> 
> Scott
> 
> ----- Original Message ----- From: "Alistair Bell" <albell@SHAW.CA>
> To: <vanagon@GERRY.VANAGON.COM>
> Sent: Thursday, July 21, 2011 7:35 AM
> Subject: Re: Watching Oil Temp (long, as usual)
> 
> 
> I have no idea, but I'd guess adding fins must make some useful difference else it would not be worth the casting costs.
> 
> 
> alistair
> 
> 
> On 2011-07-20, at 11:29 PM, Scott Daniel - Turbovans wrote:
> 
>> sorry..
>> I didn't make it clear that is just a wild guestimate.
>> 
>> what is your hunch on it ?
>> 
>> 
>> ----- Original Message ----- From: "Alistair Bell" <albell@SHAW.CA>
>> To: <vanagon@GERRY.VANAGON.COM>
>> Sent: Wednesday, July 20, 2011 3:58 PM
>> Subject: Re: Watching Oil Temp (long, as usual)
>> 
>> 
>> how the heck did you come up with that value?
>> 
>> is this based on any measurement?
>> 
>> what is the increased surface area provided by the fins? if you know that then you can start using numbers, otherwise its all hooey Scott.
>> 
>> alistair
>> 
>> 
>> On 2011-07-20, at 3:04 PM, Scott Daniel - Turbovans wrote:
>> 
>>> Like if there were no ribs..
>>> just smooth aluminum ...about a 1 and 1/2 percent difference..
>>> on other words, not much.
>