Objective was the fuel injectors in my C5 Corvette (with highly modified LS1 that was using 36 lb/hr injectors to now 42 lb/hr), were functioning over the rule of not exceeding an 80% Duty Cycle Meaning they function less than 80% of their design as to flow
In even a 60 F degree weather, the duty cycle was seen in a testrun and a OBD-II scanner recording the engine parameters going to 82% DC and in hotter weather that would be even higher.
Replacing fuel injectors to a higher flow could cost $500 to $700 depending on their rated flow This project was about taking stock C5 fuel injectors and sent to a business that cleans, increases the fuel flow and flow matches them, so all 8 injectors flowed the same amount of fuel
Cost to do that was $190 which is far less than buying others and the fact by using stock ones you're assured the design of how GM set up the calibration was the same where buying 3rd party injectors adds a problem is they will have different delay/latency of the internal coil and if not knowing the countless values in the PCM tune to change to meet those then the PCM could command injector on too early or late to when the spark plug is commanded on
Before making the injectors change, the C5 was testrun 24 miles in 30 minutes, and the OBD-II scanner recorded many of the engine's parameters. That data was then analyzed and recorded results.
All 8 injectors then were swapped to install the modified GM injectors but now flowing 42 Lb/Hr, and then I tuned the PCM for that flow In the same weather temp, distance, elapsed time and road, using the same drive style to cover all 23 fuel trim cell engine conditions, including close to the rev limiter in RPMs around 100 MPH, the testrun was done, again having the OBD-II scanner record all the real-time engine conditions which I then again analyzed and end results
The results of the before and after tests are shown below
Refer to the red lines I inserted between the two, so you can see all the results differences In short the toque gain was 12 ft/lbs and the horsepower gain of 23 HP
Where the injector maximum duty cycle went from 82% to 72% and the modified fuel injectors were decreased in how long the PCM had to command them ON Where the injectors that were taken out would handle 451 flywheel HP, the modified injectors now can handle up to 538 flywheel HP.
All for $190 of cost to have stock injectors modified to higher flow and flow matched