boost pressure on engine brake

[Hammerhead]

What motor?
What CPL?

In my understanding
My CM871 CPL 2919 has the big turbo and is approx 1.7:1 efficiency. What does that mean you ask. It always takes more pressure to drive the turbo than it actually creates, the bearings and resistance to compression in my turbo takes 1.7psi of exhaust pressure to create 1psi of boost pressure. The engine compresses the gasses in one cylinder, then the jake opens the next cylinders exhaust valve, allowing the compressed gas to be "intaken" via the exhaust, thus re-compressing the already compressed gasses which makes the Jakes so strong.

My truck holds at 28psi during hard jaking downhill at ~1700rpm. With a 1.7:1 factor, that means the equivelant of 47.6psi on the exhaust side...this is the actual boost pressure entering the cylinder. Considerably higher than the MAX recommended 38-40psi around this site. I use stock turbo tables in jake application.
Now this sounds like excessive pressure numbers that need to be lowered, but during jaking there is no power stroke. That means there is no fuel injected, so there is zero thermal combustion expansion which is why I assume this would be acceptable boost pressure by Cummins.

Video showing how the system works https://youtu.be/JF6ZeybmQ1U

So to know if you are still in the "safe zone", we would need to know your engine type and turbo (CPL) to know the efficiency rating to calculate the actual boost numbers in the exhaust tract. If the exhaust tract numbers get too high, then the valve closing can become delayed because of the excessive pressure, and you run the risk of the piston hitting the valve before it closes.