ASTM D6812 tandard Practice for Ground-Based Octane Rating Procedures for Turbocharged/Supercharged Spark Ignition Aircraft Engines
8. Preparation of Apparatus
8.1 The history and condition of each test engine should be known and documented by means of engine log books, test run sheets, and any other documentation issued by the original equipment manufacturers or repair overhaul shops before any octane rating tests are performed.

8.2 Only the engine accessories required to operate the engine shall be installed on the test engine when conducting the octane ratings.

8.3 The installation of the proper turbocharger controller, wastegate actuator, wastegate valve, and overboost relief valve for the specific engine model and application shall be verified.

8.4 The installation of the proper intercoolers or aftercoolers, if required, for the specific engine model and application shall be verified. The intercooler/aftercooler shall be supplied with proper cooling air pressure and any cabin bleed-air venturis shall be free to vent to the local environment.

8.5 The installation of the proper fuel control system, including the metering unit, pump, distribution manifold, nozzles, and fuel lines for the specific engine model and application shall be verified. This should also include ensuring equal fuel flow distribution through all nozzles and associated lines.

8.6 The exhaust system employed shall be free to discharge into the surrounding environment without extended plumbing, plenums, or mufflers, which may induce an improper pressure balance across cylinders.

8.7 Proper spark plugs matching the required heat range and depth for the engine model to be tested shall be verified. The plugs should be cleaned and gapped prior to octane rating. The integrity of the spark plug ignition leads shall also be verified.

8.8 Crankcase vents shall be free to vent to the local environment.

8.9 If the test engine's fuel system is designed to recirculate fuel to the tank, provisions shall be made to ensure that no fuel is recirculated to the containers with the PRFs or RFs.

8.10 The idle and full-rich mixture settings shall be set, and the resulting fuel flow rates verified to be within the engine manufacturer's specifications.

8.11 The idle stop and full throttle throw positions shall be set in accordance with the engine manufacturer's recommendations.

8.12 It shall be verified that the mass moment of inertia of the flywheel, couplers, driveshaft, and spacers and the driveshaft stiffness are sufficient to prevent operational resonance and possible engine failure.

8.13 Before any octane rating, and after all break-in and power baseline runs have been performed, a cylinder compression test shall be performed on all cylinders and the results recorded.

8.14 Prior to testing, the integrity of the fuel selection system shall be confirmed and the system flushed. The engine fuel selector apparatus shall be checked to ensure no leakage.

8.15 All engine settings shall be checked after the break-in period and before any octane rating. As a minimum, this shall include: fuel pressures, oil pressure, turbocharger waste gate controller setting, proper overboost relief valve operation, fuel flows, and magneto timing.

8.16 A systems check shall be performed, in accordance with specific aircraft engine manufacturer's recommendations, prior to starting the test engine. As a minimum, this shall include the following: idle throttle stop, wide-open throttle throw, mixture cut-off, and full-rich positions. This shall also include fuel and oil system leak inspections.

8.17 A systems check shall be performed after starting the test engine. This shall include as a minimum the following items: oil pressure, magneto ground check in accordance with the engine manufacturer's recommendations, instrumentation indications within normal ranges, and induction and exhaust system leak inspections.

9. Calibration and Standardization
9.1 The engine shall be set up in accordance with the manufacturer's specifications. The ignition timing shall be set within the engine manufacturer's specified allowable range for that engine make and model.

9.2 The fuel flows shall be set within +/- 2 % of the recommended fuel flow (or +/- 5 % of the recommended pressure when appropriate).

9.3 Proper waste gate controller operation shall be verified, which must include ensuring that maximum rated power is attained at full throttle and maximum rated speed without encroaching the limiting manifold pressure.

9.4 Instrumentation shall be calibrated and checked to ensure accuracy to within +/- 2 % of full scale, unless noted otherwise.