Re: [DML] Re: PRV Performance - Set me straight please

[Martin Gutkowski <martin@xxxxxxxxxxxxxx>]

endotex23 wrote:

>Finally, while I'm no great fan of emission standards I accept the
>very real benefits they provide to the environment. It seems you do
>not. Until you and a few others accept that gobs of power can be made
>and still keep the air clean you're doomed to drive clunkers. Put
>another way there *is* a substitute for cubic inches...it's called
>technology.
>  
>
I'm going to take you to task here. While you're absolutely correct in 
what you say, have a look at www.journeytoforever.org and chase down the 
statistics on pollution produced in the production of these modern, 
"cleaner" cars and compare it to the emissions kicked out by a 20 year 
old car in 20 years...

Over here in Europe, we're now sitting on cars such as the Renault Clio 
182 and the Honda Civic type R (is this in the US yet?) both of which 
are small, relatively economical runarounds that through some really 
clever VVT are pushing the 100bhp/litre goal, normally aspirated. 
engines over 2 litres make up (I would guess) fewer than 5% of cars on 
the road, and probably around 33% are diesels. North America really is 
behind the times.

>
>For Martin: A D with emissions equipment is speced at 1% (measured
>pre-cat with the lambda loop open) because the cat needs it there. 
>With no cat 2% CO is still leaner than best power, a bit higher on the
>CO will get you more. If you're looking for max power than 2% is too
>low but it'll still be less than your max when you get there. Do some
>dyno pulls (if you can) to get it dead on but generally speaking it
>should end up around 4%.
>  
>

According to my friend and PRV expert, anything over 2% is not a healthy 
mix and you'll start experiencing bore-wash. Remembering of course that 
the mixture adjustment screw is only the "+C" in your fuelling graph and 
what really counts is shimming up the primary pressure regulator and 
tuning it up using a wideband lambda probe. You can also use this 
method, to a certain extent, to tune up a turbo'd D. After all, the 
K-Jet system is a crude air-mass meter, just a restrictive one. Shim it 
up to account for that restriction and all you have to worry about is 
the ignition (sigh)

Martin






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