RE: CSC Headers Pass SMOG!

[White Anthony <anthony.white@domain.elided>]

> For that matter, going to higher compression pistons 
> should also not change emissions dramatically (as far 
> as I know....), yet it is technically illegal to change your 
> pistons here as well....(not that anyone would know...).  
> I'm thinking of the small changes on the pistons -- 
> obviously if you are running 13:1 this theory wouldn't be 
> correct (or would it...?).

Assuming your cam and ignition timing is appropriate, and you have fuel of sufficient octane, increasing your compression ratio should, if anything, slightly improve carbon monoxide emissions and unburnt hydrocarbons emissions.  However, it will increase the level of oxides of nitrogen, which are created when an air-fuel mixture is ignited at high pressure.  The higher the pressure, the more oxides of nitrogen you get.  

I gather that the design of the combustion chamber can contribute to improving this situation -- Honda in particular seem to be very good at building high-compression, high-performance engines that burn really cleanly.  

Of course, I'm in New Zealand, so I have no view of how any of this might relate to California emissions regulations.  They do worry about oxides of nitrogen in the Australian EPA ...

regards
Anthony.  
'85 116 Giulietta
--
to be removed from alfa, see /bin/digest-subs.cgi
or email "unsubscribe alfa" to majordomo@domain.elided