<VV> New heads, an approach...

[jvhroberts at aol.com]

 IT seems that adding an integral manifold would be not much more work, but adding a bolt on manifold to use stock carbs or a stock turbo setup would be a lot more work, plus add a failure point absent in the stock design. It would definitely be 4-1s, like the 140 heads. The turbo guys can either blank the extra mounting pads off, or mill them off and weld the hole shut, or put a Welch plug in there, etc. 

Adding enough 'meat' to mill off this manifold and add a Weber or other setup would not be much more machine work over machining just the mounting pads for such a manifold. 

Once the pattern is made, it's no extra anything to cast an integral manifold. Furthermore, for the folks wanting a bolt on, the only finish machine work is boring and facing the carb pads. Given the complexity of an air cooled head like this, the manifold is no big deal. And we're not giving up a thing for the hot rod guys.

I get the feeling there's a GOOD market for a head that cools better, makes more power, has a more detonation resistant combustion chamber, etc., over stock, as in a FAR larger market than just the guys who want to build an American Porsche engine. 


 


 

-----Original Message-----
From: Bruce Schug <bwschug at charter.net>
To: JVHRoberts at aol.com
Cc: virtualvairs at corvair.org
Sent: Sun, Jul 12, 2009 3:25 pm
Subject: Re: <VV> New heads, an approach...









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

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> With some of these as constraining issues, it does help simplify the > engineering, which will be challenging enough as it is.?

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> Areas of improvement:?

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> 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.?
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*SNIP*?
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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.?
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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??
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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.?
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Bruce?
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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"?
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