This R866SC Duramax L5P does not act like a lazy, waiting-on-the-turbo diesel. With about 2.25 psi of boost showing at idle and a 4,000-rpm redline, the engine responds the instant it is hit. That is the point of the combination: immediate air supply, fast rpm rise, and a diesel that sounds and reacts far sharper than most owners expect. On first fire, the iDash display lets us watch the important data in real time, including rail pressure, rpm, and boost, so we can see exactly what the engine is doing as it comes to life.
The clip captures the end of a test sequence with the engine already under observation. Rail pressure appears stable, and the final engine speed is called out at roughly 8.50, likely referring to the measured value on the display rather than a new operating limit. The stated engine redline is 4,000 RPM, establishing the intended upper boundary for the test.
At idle, the system is showing approximately 2.25 PSI of boost pressure. That is a notable condition because boost is already present before the engine is loaded or accelerated, indicating the forced-induction system is active and producing measurable manifold pressure even at low engine speed.
Before making another throttle input, the operator decides to let the engine continue running so oil temperature can rise further. This suggests the team is avoiding a hard acceleration pull until lubrication conditions are closer to the desired operating range, which is a standard precaution during testing.
Once additional oil temperature has built, the operator prepares to make a sharp throttle application. The intent is to see how the engine responds when it is suddenly loaded or accelerated, rather than only observing steady-state idle behavior.
After the throttle input, the immediate reaction is that the engine appears to handle the event better than before. The comment indicates an improvement in how the combination accepts a quick application of throttle, implying better transient response or more stable operation under that sudden demand.
The final remark suggests the team believes the current setup may now be sufficient to achieve the desired result. Although the clip is brief and does not include the full outcome, the conclusion is that the engine's behavior, boost condition, and readiness after warming appear promising enough for the next step in testing.
