Nascar 9:1?

[Heath Parker]

Hi All,

	Busch Grand National series motors are limited to 9:1, Winston Cup cars
are unlimited compression and are usually (last I heard) around 14:1. 
Remember, this is racing, so if you go to another track, you can build
another motor . . . and say lower the CR and change the mixture . . . and I
still don't know why they aren't running FI (smooch smooch ;).  I mean,
this is racing . . . if the racers took off with this technology, then I
think production cars' cost would drop about $1000 and FI system components
would get cheaper . . . one main reason they haven't is the fear of
ignition noise, etc. screwing with more senstive components.

	This raises one of my questions, how prevalent is this problem, has
anybody in the group run into it, and is it only a Digital system problem,
or are analog systems also bothered by noise, EMI, RFI or whatever?

----------
> From: Michael D. Porter <mdporter at Rt66.com>
	<snip>
> Russ Highton Jr. wrote:
> > 
> > In regards to the "cheaper nascar engines" with 9:1 compression.  Are
you
> > sure?  Last I heard they were running 18:1 to compensate for a vacuum
> > condition caused in the intake at high RPMs from the restrictors.  Am I
> > wrong?
>  
> I would suppose an 18:1 CR is a bit beyond the pale, Russ. At that CR,
> the heat of compression would likely cause spontaneous detonation of any
> NASCAR-legal fuel. That's very close to diesel engine compression
> ratios, and the cetane rating for gasoline of any type doesn't come
> close to that of diesel fuel. Even methyl alcohol-burning diesels are
> running about 15.5-17:1 ratios. The lower compression NASCAR engines are
> probably compensating for intake restrictions by maximizing flow at
> usable rpms and so concentrating on volumetric efficiency, not
> stratospheric compression ratios. Higher compression ratios help, but
> after the limit, they hurt.
> Cheers.
> 
> -- 
> My other Triumph doesn't run, either....