Meter fuel into the intake port at the pressure, timing and duration the ECU commands.
Four injectors mounted in the fuel rail and firing into the intake runner bungs. Injection timing is configured to control the end of injection event so injection can be extended during transient conditions.
Injector evaluation emphasises maximum duty cycle, availability of characterisation data, and the size of the fuel rail injector ports. CR26I resized the injectors as one of its listed changes.
Characterised on the APR hub dyno with ramp runs, giving pulse width against fuel volume. Minimum injector pulse width is held at 1.9 ms, which is what sets the minimum manifold pressure map and keeps the injector out of its ballistic region on overrun. From the design reports and one-pagers: Duty cycle analysis, run at 12,500 rpm at 12 V against injector characterisation data from spring 2022 and the Michigan 2022 acceleration event. The optimal duty cycle is 25%, so fuel is only spraying while the valve is open, which minimises wasted fuel; the higher the fuel pressure run, the better. Using the injector data available at the time, an increase of 35 psi differential pressure from the then-current setting produced a 25% change in injector duty cycle. Fuel pressure is then validated on the dyno by sweeping 45, 55, 65 and 75 psi, running five dyno pulls at each and recording torque, power and fuel flow.
CR22: DeatschWerks 18U-138-0280, Bosch part number 0280158138, sponsored by DeatschWerks. Same size as the CR21 injectors. CR26I resized the injectors.
Shakedown 7-15-23, CR22. An injector was not receiving full 12 volts; the PDM output measured 4 volts. Continuity between wires was checked and the switch was found to be inconsistent. Fixed by soldering the switch.
Dimensions called out on the cost report drawings. These are the figures printed on the drawing, not a labelled specification; open the drawing itself for what each one refers to. Injector Bung (as drawn): 1.63, TRUE R0.44 R0.95, 2.52 Source: Cost report drawings: CR25/Powertrain/Design/Y - Cost Report Drawings/Manifolds/Intake/Injector Bung.pdf; CR26i/Powertrain - IC/Design/Y - Cost Report Drawings/Manifolds/Intake/Injector Bung.pdf; CR27i/.Powertrain/Design/Y - Cost Report Drawings/Manifolds/Intake/Archive/Injector Bung.pdf Quantity per car, as costed: 4
Nothing in CrimsonStorage covers these yet.