Re: [Amc-list] Comb chamber grooving

[Frank Swygert <farna@xxxxxxx>]

I've worked with a lot of engineers. The majority of them suffer from "NIH" syndrome (not invented here), especially if it's an idea offered up by some non-degreed low-life mechanic, especially from what's considered by most as a third-world nation (India is "up and coming", not quite third world any more). Rather than take the idea and really examine it, they tend to scoff and discount it as some nut who stumbled on something that worked only under specific conditions -- like the "100 mpg carburetor" (yes, they existed, but only worked under ideal situations, not practical for every day use and widely varying conditions). 

Singh appears to have something though. Looks good for retrofit, but probably not for new engines. Why do I say that? Combustion chamber and intake port design induce a lot of swirl now, no need to add anything. Manufacturers can design the swirl in without resorting to such things as grooves, and can precisely control ignition with ECUs. So the grooves work well on a carbureted engine with a chamber that doesn't induce much swirl and ignition isn't precisely controlled. They don't make many more of those, but Briggs & Stratton might be interested. Most of the oil companies aren't that concerned about older engines (note our oil situation), so they wouldn't be that interested either. 

Tom, the grooves COULD induce cracking, if made too deep in a thin area. Most of the grooves are shallow for that reason. For the most part combustion chamber walls are pretty thick though, so I don't think there's any reason to be concerned. The grooves are usually 1/16" deep or so (Randy suggested Greg go 0.060-0.080" -- 1/16" is 0.0625", 5/64" is 0.078")

-------------------
Date: Tue, 18 Mar 2008 08:38:35 -0400
From: "Bruce Hevner" <scramblr@xxxxxxxxxxx>

> But I can't find a single photo! I'm not clear from the descriptions just what this grooving looks like, how critical >dimensions are, or
> anything of a practical nature. I can understand if it's subtle and
> complicated, but there's got >to be SOME rule of thumb here....
>  
>  While I think the basic idea has merit I REALLY doubt that it can
> "reduce the idle speed of an engine using a 280'@.050 cam to 500 RPM"
> (as claimed). He is making some absolutely ridicules claims for this
> modification! But there are patent issues at stake and that could mean
> $$ so there ya go. 
> I question why this idea has been around for YEARS but NONE of the
> Shell engineers had even HEARD of it. And what about the Mfgrs?? Seems
> THEY would be interested in it,, heck they are spending MILLIONS trying
> all kinds of ideas to reduce emissions and increase fuel economy.
>  I'll keep an open mind till I see some back to back tests done by an
> independent party.
>
> But HEY,,, that's just me!
> Bruce Hevner
>   
-- 
Frank Swygert
Publisher, "American Motors Cars" 
Magazine (AMC)
For all AMC enthusiasts
http://farna.home.att.net/AMC.html
(free download available!)

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