<VV> New heads, an approach...

[Bruce Schug]

On Jul 12, 2009, at 11:35 AM, JVHRoberts at aol.com wrote:

> As with all things, if one were to design a new head for the Corvair  
> engine, there needs to be a rational and sound approach to it. Given  
> that, here's my thinking:
>
> 1. Not everything GM did was wrong.
> 2. Most of what GM did works pretty well!
> 3. To maximize marketability of this, the new design needs to be as  
> close to a direct bolt on as possible.
> 4. With these in mind, identify the shortcomings of the factory  
> head, and identify the areas that can be MATERIALLY improved.  
> Essentially, improve the factory head.
>
> With some of these as constraining issues, it does help simplify the  
> engineering, which will be challenging enough as it is.
>
> Areas of improvement:
>
> 1. Cooling. Increase the number of fins to increase cooling area.  
> Increase the open area. As contradictory as these two may sound,  
> many aircraft engines have VERY thin machined fins to achieve these  
> goals. With modern casting techniques (even some not so modern  
> techniques!), I believe this can be achieved.
> The other cooling issue is the fan. Improving this is ESSENTIAL for  
> a high output, especially a turbo engine. I looked at some 911  
> heads, and although they are more heavily finned than the Corvair  
> head, they are not so, in proportion to their power output.  
> Something line 30% more fin area on engines making 2-4x the HP. So,  
> the fan, although a separate issue, needs to be addressed.
> 2. Flow through the intake ports. CLEARLY this stinks on ice in a  
> Corvair engine. Straighten the ports, add metal to allow bolt on  
> manifolds, etc. Personally, I'd keep the original cast on manifold,  
> and simply machine it off and drill and tap the bosses for those who  
> want something else. Eliminates the need for a separate manifold for  
> those who want to keep it easy and simple. Offer it both ways.

*SNIP*

I understand your rational for this, but I wonder, it seems like  
eliminating the cast-on manifold would simplify the head casting quite  
a bit. This might be reason enough to make the head without intake  
manifolds. Then, separate manifolds could be made for a variety of  
induction systems.

If you cast the manifold on the head, somebody's still going to make a  
manifold for 1. Webers 2. 6-1 4bbl - that's two manifolds and you  
haven't even touched fuel injection. Also, if you cast the manifold on  
the head, would it be for 4-1's or would you also provide a 2-1's  
manifold?

Overall, it seems simpler to me to cast the heads sans intakes, then  
offer at least a manifold for Webers, 6-1 4bbl, and 4-1's. As  
expensive as this head would be, I doubt that many would use 2-1's  
with it.




Bruce

Bruce W. Schug
Treasurer & Membership Chairman
CORSA South Carolina
Greenville, SC
Stock Corvair Group
Performance Corvair Group
bwschug at charter.net

CORSA member since 1980

'67 Monza. "67AC140"