<VV> More on valve seat failures

[jvhroberts at aol.com]

 Well, in part, Marc. The other economy at work here is the cost to engineer a good solution, even if it was cheap to produce. 

Aircraft engines use alloys other than simple steel for the intake seats, and as I recall, it's a high manganese alloy. The CTE is actually not much different than aluminum. Also, aircraft valve seats are much thicker wall and much deeper than a Corvair, as I sit here looking at a cracked head from a Pratt and Whitney Wasp radial. Yeah, my garage has some weird stuff in it. <G>

Now, if GM made the seats at least dimensionally similar to an aircraft engine's seats, would we have the same problems? Probably not. Would it cost more to produce? Probably not, although in the 60s, Detroit was notoriously cheap. 

Anyway, aircraft engines are way different beasts in their operation and use. Other air cooled passenger car engines are more fair comparisons. 

 

John Roberts
 

 

-----Original Message-----
From: Marc Sheridan <sheridanma1966 at gmail.com>
To: Virtual Vairs <virtualvairs at corvair.org>
Sent: Tue, May 8, 2012 5:27 pm
Subject: Re: <VV> More on valve seat failures


I think it all comes down to economy. You do things differently when
building an aircraft engine versus one for an economy car. Years ago I went
to Trusports Indycar shop for an open house. We were told how valve seats
were done in the race engines. The exotic alloy seats were left in liquid
nitrogen, while the heads were heated in an oven. With the two temperature
extremes, the seats simply fell  into place. Once temperatures equalized,
the engine builder told us nothing would get them out. Not even a heavy
crash that ripped apart the engine.

A race engine isn't an aircraft engine, but I imagine they do something
similar.

Marc Sheridan


On Tue, May 8, 2012 at 4:23 PM, Kerwin Nailor <kerwinnailor at verizon.net>wrote:

> How do the air cooled aviation engines, flat and radial, deal with keeping
> seats in place? They get some pretty dramatic changes in temp, like heavy
> rain.
>
>
> Kerwin Nailor
> kerwinnailor at verizon.net
>
>
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