I think you’re right. At least, that’s where the data is leading. I just need a few more examples to come to a conclusion. So, the other L2501 Turbo w/ the injection pump timing mod basically made the same power as my tractor. However, it required a greater load from the dyno to reach the same gains. He’s also generating a bunch more smoke on startup and more smoke just before the turbo becomes efficient.It's starting to make the case for keeping the fuel timing retarded (stock) when planning a turbo upgrade.
You would think that the method of removing gasket material to advance the fuel timing would not only advance the timing, but also increase the travel on the cam, which would also increase the potential fuel volume per cycle.
Did this latest dyno result use a turbo kit with the latest changes:
Allowance for hood shock.
Reduced exhaust pipe diameter at the sharp bend coming off the turbo unit?
Just curious at this point.
His Turbo setup is identical to mine. So, no, he doesn’t have the new reduced diameter downpipe, but does have the new charge pipe. I’ll be testing and posting the results of the reduced diameter downpipe modification sometime in the near future.
To me, that would indicate your thesis is correct.