I built a tuning spreadsheet that is nice to build fuel maps with.
Spreadsheet Instructions
Line 2
Enter engine Size in Cubic Inches.
Line3
Enter RPM.
Line4
Enter PSI This is how much boost at the intake.
Line5
Enter Elevation PSI. This is found on Sheet 2.
Just add two zeros to the number column on the left.
Example line 8 would be 800’ line 60 would be 6000’
Line6
Enter Intake Air Temperature.
Line7
Enter the size of injector in lbs/hr.
Line8
Enter VE. This depends on the head. Built heads will usually have 1.0 or 100%
Stock can vary from .85 to .90
Line9
Enter how many cylinders.
Line10
Enter air fuel ratio. This should be known by the use of a W/B.
Line11
Enter Brake Specific Fuel Consumption.
This will vary on the type of engine and how efficient it is with its fuel.
Also rich air fuel ratios will have a higher numeric value.
Example: 10.5 A/F on a D16 will be around .55BSFC 12.8 A/F would be around
.50 BSFC
Line12
Enter vehicle weight.
Line13
Enter the original pulse width or duty cycle that needs to be change to target
pulse width or duty cycle.
Line14
This is what you want you’re A/F ratio to be.
Line15
This is what your actual A/F ratio is seen by using a W/B.
Line16
This is what you would change your pulse width to or duty cycle.
On the right side there is Liters conversion to cubic inches.
CC/MIN is to convert cc/min injectors to lbs/hr.
Under the “I9” column is where you can tell what the equivalent injector would be by
adjusting the fuel pressure.
CFM in is the CFM of the engine.
Lbs/min in is what the engine is flowing in lbs. I use this for turbo lbs/min flow also.
M/S MAX in is the maximum amount of time available the injectors can stay
open in milliseconds before the next cycle.
Duty cycle is what the duty cycle is with the inputs you entered.
P/W is the pulse width that the injector will be open to achieve the A/F ratio that you entered.
Hp at the flywheel.
To determine WHP you can calculate on a know drive train in % WHP
Torque is torque at the fly wheel.
W/torque whp torque
E.T. is a approximate time this vehicle at this weight and HP would run in the ¼
MPH is a approximate mile per hour this vehicle would run in the ¼
I recommend you just start entering your own cars values and make changes to see what happens.
This will teach you a ton about what each change does to the engine and its output.
Keep in mind this is just another tool for tuning. I always recommend running a W/B and start out on the rich side.
Can be uploaded below on post #9
Its also nice to just use for the what if factor.
Example:
If I have a 4 cylinder and I'm running 240cc/min injectors what would be the pulse width and how many lbs/min would each injector flow at 4500rpm, 0" of inHg, at 90*F IAT running at 500' above sea level running a 15.0 A/F ratio.
And what would would the pulse width be if everything stayed the same but I riching it up to a 14.7 A/F ratio.
And what would it be if i was running 3500rpm instead of 4500rpm.
etc etc...
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