[s-cars] Chip upgrades

[Kevin Day]

On Thu, Mar 19, 2009 at 8:29 AM, Scott Justusson <qshipq at aol.com> wrote:
> IME, the RS2 injector (Bosch green top) has better resolution than the
> AAN stock injector.  I too assumed this might be much, but have done
> many of these injector conversions, even on MTM stage I cars without any
> issue or CEL.  I'd venture they would work fine on a stock Motronic box.

Better resolution?  They flow more.  For a given pulse width, more
fuel will be injected.  That is the opposite of better resolution.
The ECU needs to reduce the pulse width to achieve the same AFR with
larger injectors.

> Took a while to get thru what you did there (or it's relevance), but if
> we believe Probst book that 12.6:1 A/F is 'peak power', it would appear
> your larger fuel pump is not making the resolution in A/F 'better'.
> Maybe a better test would be on the dyno.  I'm not convinced the fuel
> pump is really at issue, as many here (including me) have dyno'd over
> 300WHP with the stock pump.

You didn't understand the graphs then.  The stock fuel pump can not
keep the pressure differential across the injectors at a fixed 4 bar
above roughly 18 PSI of boost.

-Kevin