<VV> Catalytic Converter for Corvair

[Lonny Clark]

I agree, the converter will run a lot hotter than it would on a modern car,
so keep an eye on it and get a heat shield between it and the engine.

On the other hand, if you converted to fuel-injection there should be no
reason not to use a catalytic converter, if appropriately mounted.

Personally, I like the factory original muffler replacement - a turbocharger
quiets down the engine just fine.

Lonny

On Mon, Mar 24, 2008 at 11:05 PM, Craig Nicol <nicolcs at aol.com> wrote:

>
> Bill said:
> <big snip>
> I brought my car to an exhuast specialist, who was a
> really nice guy.  He looked my car over and mentioned
> that all horizontally opposed engines had a sort of
> grumble to the exhaust.
>
> He tried a resonator tip on the end of the pipe, but
> it didn't make any difference.   He told me that the
> only thing that would really make a difference would
> be a catalytic converter.  those thing are supposed
> really quiet down the exhuast, but he wanted around
> $250. to custom-install one in my car.  He said there
> is no reason why it shouldn't work.
>
> Meanwhile, I saw universal, mini-catalytic converters
> for $59.00 plus  shipping.  I was willing to try that
> just to see what would happen.  The unit is very
> small, only 4" diameter at its thickest, and around
> 10" long.
>
> I kept the stock system but mounted the converter
> behind the muffler, replacing the tailpipe.  The
> exhuast now dumps behind the car instead of out the
> side.  The first thing I noticed was that the exahust
> was much quieter.  The second thing I noticed was that
> the exhaust no longer stunk with that pre-emission
> smell, but smelled more like a modern car.  It's a
> much cleaner smell.
>
> Only time will tell if it holds up, but I'll keep
> everyone in the loop as the miles roll up, G-d
> willing.
>
> Assuming that CO is reduced with the converter, I
> expect that it will be safe even with the windows
> rolled up.  My digital CO monitor inside the car will
> let me know levels in the interior as I back the car
> out of the garage and drive at different speeds in
> different weather conditions.
>
> In addition, the large diameter exhaust outlet (2")
> looks cool, even with no tip on it yet.  I'll try to
> get a picture of it when I have the chance...Bill
> Hershkowitz 69 Monza Coupe 110 PG <unsnip>
>
> Craig opines:
> The typical catalytic converter converts CO and HC to CO2 and H20,
> assuming
> the components are fed from an engine that's running neither rich nor lean
> but in exact 14.8:1 ratio of fuel to air.  Corvairs are not calibrated to
> run at this stoichiometric ratio.  Usually, they are relatively rich.
>  This
> puts the cat into the business of burning the excess HC, which is what
> creates the "rotten egg" smell (H2SO4?).  After a steady diet of excessive
> HC, the catalyst's substrate will melt, fuse, and clog the exhaust.
>  There's
> also a fire hazard, especially when they're fed excess HC, which is why
> cats
> have a heat shield on the upper side. Excessive backpressure can burn
> exhaust valves too.
>
> '68 and '69 smog engines might have the best chance of all years for this
> to
> work 'cause the carburetors have more accurate mixture control.  Since
> you're a pioneer, keep us posted!  The only other Corvair I've heard of
> with
> a cat has a 4.3V6!
> Craig Nicol
>
>