View Single Post
WERK I WERK I is offline
Forced Induction Junkie
WERK I's Avatar
Join Date: Jan 2003
Location: Wisconsin
Posts: 3,291
Originally Posted by psalt View Post
Delivery to the injectors is also effected by the differential pressure valves and the lower chamber pressure. This is how CIS lambda effects injector delivery, maybe your test method is altering the lower chamber pressure. The chart suggests your fuel pump should support +450 hp, although some of the figures, especially the 944 turbo pump, look incorrect to me.
Originally Posted by Dr J View Post
Saw the new post. It is a good thread.

Paul, I upped the voltage as you suggested. It seemed that if flow was increased, that would tell me to source a new pump based on the data in Dave's post. I did not have 14V but did have 15.6V from a battery charger set on the jump start setting. You could here the pump vibrating at a higher frequency so it felt the juice. Here is what I got:

Volt 15.6, System pressure 5.4 bar (it increased from 5 bar), temperature 19C/67F

Result: same flow in all injectors about 160 ml/min

This must mean that most of the extra fuel was once again dumped into the fuel tank. Only thing left to do is play with the control pressures and see what happens.
The source of power for your test could be a fully charged battery with a charger, capable of delivering 15-20Amps should suffice. I believe the voltage normally is around 13.8vDC. Its good all injectors are delivering the same 160ml/min volume. I suspect they would deliver that same amount at 13.8volts.

You are right about the remaining fuel being returned back to the tank. There is a pressure relief valve that controls this function in the fuel distributor. Shims are used to elevate the pressure, which will elevate the pressure at the injector. I'm a little nervous about raising the pressure on your application since the 911 SC injector lines are plastic. I'm sure they're over-engineered as most everything else is by Porsche, but just be aware.

Because the SC is normally aspirated, the Warm up Regulator does have its limitations. It has no ability to adjust for boost as the 930 WUR does. The 930 WUR lowers the control pressure in the head when it begins to sense boost. Maybe a different approach will be necessary when it comes to a self-adjusting control pressure regulator(WUR)?
'85 930 Factory Special Wishes Flachbau
Werk I Zuffenhausen 3.3l/330BHP Engine with Sonderwunsch Cams, FabSpeed Headers, Kokeln IC, Twin Plugged Electromotive Crankfire, Tial Wastegate(0.8 Bar), K27 Hybrid Turbo, Ruf Twin-tip Muffler, Fikse FM-5's 8&10x17, 8:41 R&P
Old 01-19-2010, 07:42 PM
  Pelican Parts Catalog | Tech Articles | Promos & Specials    Reply With Quote #29 (permalink)