In Chamber Testing

[Barry Bordes]

Originally Posted by NoDOHC

Peak pressure still at 38 degrees, if that engine were NA, I recommend that you advance the timing more. Turbo, you probably have it pretty much maxed out.
Actually 851psi @ 40ATDC

Are you sure that the exhaust port opening time on the chart is accurate? I would have expected the pressure to drop significantly more than 12 psi in 15 degrees of eccentric shaft rotation if the exhaust port were open. This is very close to the curve that would be followed with the port closed. I know that the exhaust port opens 75 degrees before BBDC = 195 ATDC, but I suspect that the trace may be inaccurate in scaling (which is weird, because the no-fire trace line looks Ok).
The 5000 psi sensor's error of 1% would be 50 psi. It is probably having a difficult time with resolution down there. The exhaust port opening is written into the engine spec for the program. I estimated it at 196º ATDC. The pressure still has work to do driving the turbine wheel, it probably would show a more distinct drop off if NA. We probably need another sensor on that side of the housing (hopefully in the future one each in the exhaust and intake ports).


Can you continue the trace out to 250 ATDC? Your sensor should be able to read about that long.
No that is the standard span for the program's chart.

Barry