cis Cheap power

[quk@sievers.com (Phil Payne)]

In message <199705101909.MAA09531@f29.hotmail.com> "joe espana" writes:

> It's great to see Phil with all the answers. On my last post I couldn't exactly 
> tell what was going on, but as Phil did say cis does measure air density and not 
> flow. I hope he can confirm this, ...

I sure hope he can't - it's wrong.  CIS assumes air density of 1 bar at input - 
that was my precise complaint about "fooling" it by making the input air more 
dense.  You'll notice that _no_ current injection systems measure air 
quantities at any point other than atmospheric input.
 
> Cis is tuned for economy rather than performance, but it does work quite 
> well despite that. When I suddenly take my foot off the throttle at high speed, 
> there really is no air buffeting through the compressor or flapper problems. No 
> backfires....etc. My old 5ks had it for it's last 30 k miels and my newer T has 
> had it for the last 10 with NO problems. I am open for criticism, though. Oh, 
> the people that don't know about CIS and would like to know more can pick up the 
> Bosch Automotive Handbook at their local libraries or wherever 
> else....Later....Steve

Nah.  The _only_ economy/performance tradeoff is the one under your right 
boot.  You get maximum energy out of a fuel/air mixture at a quite specific 
ratio - the stochiometric ratio.  You get maximum performance by using a _lot_ 
of both components at this same ratio - you get maximum economy by using just 
enough of both components - but again - at the same ratio.  The trick is to get 
the ratio right (with minor deviations for things like cold engine surfaces) 
across the entire load/rpm/temperature/pressure range.


--
 Phil Payne
 phil@sievers.com
 Committee Member, UK Audi [ur-]quattro Owners Club