The fuel system,
50% of the "food" for the engine.
I won't talk anything about the tank, the fuel pump and the filter. I hope that
you know what they are and how they work. If not! Please don't do anything with
the fuel system.
Also the basic function of the fuel system won't be inserted here.
Not now, maybe later. It's all about time.
TOC
1. The ECU
2. The FPR
3. The Injectors
4. Putting it together
The electronic fuel injection control unit(ECU):
On my car the ECU is located on the sidewall of the passenger side, behind
the carpet.
This tin box contains the magic chip that controls the injectors.
What you really need to know about the ECU is the following:
- The ECU controls the injectors
- When you exchange the "chip" you exchange the map of the fuel
distribution.
- To get optimal function the chip must be "programmed" to your
engine.
The fuel pressure regulator (FPR):
The FPR controls the pressure of the fuel in the fuel rail, and makes sure
that it always stays above a certain level of the intake manifold pressure. A 3
bar FPR will set the fuel pressure at 4.3 bar at 1.3 bar boost pressure.
The FPR comes in different shapes.
- Static (ordinary)
- Dynamic (progressive, rising rate)
<picture on it's way>
The dynamic FPR changes the fuel pressure at different intake pressures.
The injectors:
The injectors sprays fuel into the engine. A injector works best at a
specific fuel pressure. Rising the fuel pressure will add a little more fuel,
but only for a while. If the fuel pressure is to high, the spray of fuel will be
deformed and the fuel won't be as fine distributed as it should be. If this
happens the fuel will form drops instead of the wanted mist and this is not
good.
A injector will flow a specific amount of fuel at a specific fuel pressure.
Some Fuel injector specs (The cars specified is the cars that the injectors came
in):
| make |
part # |
flow
cm3/min |
test
pressure |
Ohm |
HP
/
injector |
cars |
| Bosch |
0 280
150 760 |
192 |
? |
16 |
38 |
88-92 Saab
900 |
| Bosch |
0 280
150 712 |
214 |
3.6
bar |
16 |
43 |
85-88 Saab
900, 86-89 Saab 9k |
| Bosch |
0 280
150 706 |
214 |
3.6
bar |
16 |
43 |
85-86 Saab
900 |
| Bosch |
0 280
150 749 |
218 |
3.6
bar |
16 |
44 |
Volvo
2.3L (B230F) |
| Bosch |
0 280
150 455 |
221 |
3.9
bar |
12 |
44 |
Porsche
Boxster |
| Bosch |
0 280
150 239 |
223 |
4.3
bar |
16.2 |
45 |
86-87
vette 350 |
| Bosch |
0 280
150 728 |
228 |
3.9
bar |
14.5 |
46 |
Ford
Truck 7.5L V8 |
| Bosch |
0 280
150 745 |
235 |
3.6
bar |
14 |
47 |
Hyundai
1.6L/2.0L/3.0L V6 |
| Bosch |
0 280
150 761 |
238 |
3.9
bar |
16 |
48 |
Saab
2.0L Turbo |
| Bosch |
0 280
150 432 |
240 |
3.9
bar |
14.5 |
48 |
Saab 2.3L |
| Bosch |
0 280
150 447 |
241 |
3.9
bar |
12 |
48 |
Audi
A4, VW Passat |
| Bosch |
0 280
150 737 |
305 |
3.6
bar |
16 |
61 |
Audi
2.2L Turbo |
| Bosch |
0 280
150 447 |
346 |
4.3
bar |
16 |
69 |
Audi
2.2L (5cyl) |
| Bosch |
0 280
150 431 |
395 |
3.9
bar |
12 |
72 |
Saab 2.3L Turbo |
| ? |
SD
Blue |
? |
? |
? |
? |
? |
| ? |
SD Red |
? |
? |
? |
? |
? |
My high-performance injectors...
They are Bosch 0 280 150 431, which are rated for aprox 70 hp/injector. They
will do. (I hope)
Putting it together:
Now you know the parts for the fuel system. But what should you do when you
want more fuel?
Well, it's all up to you but here is what I think.
Wanted result: More fuel to have higher boost. But not to rich at idle.
small boost rise
solution 1 (Widdes rating: Best):
- 3.0 Bar FPR
- Modded ECU chip
- Stock injectors
solution 2 (Widdes rating: so so, may damage injectors):
- Rising rate FPR
- Stock ECU chip
- Stock injectors
solution 3 (Widdes rating: so so, may be rich at idle):
- 3.0 Bar FPR
- Stock ECU chip
- Larger injectors
Large boost rise
Solution 1 (Widdes rating: Good):
- 3.0 Bar FPR
- Modded ECU chip
- Larger injectors
Solution 2 (Widdes rating: Best):
- 3.3 Bar FPR
- Modded ECU chip
- Larger injectors
Solution 3 (Widdes rating: so so, may be rich at idle and may damage injectors):
- Rising rate FPR
- Stock ECU chip
- Larger injectors