 |
In order to select the correct size
injector for your application, you might wish to use one of the
following formulas. |
|
In most cases a naturally aspirated
engine will have a B.S.F.C of .50. This means that the engine will
use .50 lbs. of fuel per hour for each horsepower it produces.
Turbocharged engines will want to be at .60 lbs. per hour or higher.
|
|
Using these numbers as a guideline, you
can select the approximate injector size in the following formula
for a four cylinder, naturally aspirated engine at 200 bhp.
|
|
Most injectors will max out at 80% duty
cycle and this is the accepted industry
standard. |
|
B.S.F.C is brake specific fuel
consumption - How much fuel you are using per horsepower per
hour |
 The proper
injector for this application would be 31 lbs. / hr. or 330 cc / min
|
|
To find the HP value of the of the above
mentioned injectors use this formula:
 |
|
___________________________________________________________
To convert cc / min to lbs. / hr. - Divide by
10.5
___________________________________________________________
To convert lbs. / hr to gal. / hr - Divide by 6
____________________________________________________________
To convert cc / min to gal. / hr. - Multiply by
.015873
____________________________________________________________ |
|
To find the new FUEL FLOW rate after a fuel pressure change:
Example 1:
If a 240 CC injector tested at 43.5 PSI is run at 50 PSI. The
result would be:
Example 2:
The horsepower value of this injector would increase by the same
rate
(X 1.0721), if all other
engine management systems remain unchanged.
Flow rate at old
pressure
240 cc/Min divided by 10.5 =
22.86 Lb/Hr |
Flow rate at new
pressure
257 cc/Min divided by 10.5 =
24.48 Lb/Hr |
|
| 240 cc/Min X 1.0721 = 257 cc/Min |
22.86 Lb/Hr X 1.0721 = 24.51 Lb/Hr |
| 36.58 Hp X
1.0721 = 39.22 Hp
| |
