More on S4 fuelling

[Malcolm White <M.White@sni.co.uk>]

I had a fairly lengthy discussion with the technical department at Bosch
today to talk about injectors and pumps. I also found a list of Bosch
injectors and their flow rates on a Finnish Web site
(http://www.co.jyu.fi/~rax/suutin.htm) which lists some part numbers
together with some vehicle applications. They also have a formula which
shows the required flow to be cc/min = (7*KW)/#cyls.  For an Audi 5 cyl
engine, this equates to 1cc flow per bhp. If so, the standard Bosch S4
injector (0 280 150 951, interestingly listed as a Porsche Turbo
injector on the above Web site) is rated at 346cc/min which seems to tie
up with the max bhp that the standard fuel injectors can cope with. I
know that there are numerous other factors to consider in every
application but this appears to be a guideline. There are numerous
alternative injectors (anyone know the part number and flow rate of the
RS2 injectors....Dave E?). Some I were given are as follows;

0 280 150 967	386 cc/min	3.8 Ford Mustang
0 280 150 669	387 cc/min	Peugeot 205
0 280 150 689	411 cc/min	Fiat Tipo
0 280 150 984	444 cc/min	Porsche Carrera RS
0 280 150 690	444 cc/min	VW

These are all of a similar design and spray pattern to the standard S4
injector. The Bosch guy also suggested a standard additional parallel
fuel pump to provide increased flow (and offer some redundancy). He
didn't feel that additional fuel pressure was required at the required
boost pressures. He did suggest a rising rate fuel regulator/pump if
higher boost pressures were required. Anyone have any experience or BTDT
in this area.

Would I be better aiming at flow rates on the higher side to assist
cooling?

Does anyone know the flow rate and pressure of the standard S4 fuel
pump? The man at Bosch implied that Audi run their fuel pumps towards
the upper limit.

I hope that the relentless hammering of this topic isn't boring too many
listers!

Regards, Malcolm.