But compared to what? I have no doubt that test installations show a power increase with the horiz induction sump, but why is that? I don't buy the argument that it is because the induction air is cooler.
How is the vert induction sump set up? With an air scoop to get the ram air that the horiz injector gets, or just sticking down with no induction help? I don't know the answer. If Mahlon reads this perhaps he can describe the test cell set up?
Pete
Pete,
Just saw this thread today...... So here goes:
When we tested the horse power change between the two types of sumps, for the first time, we used the same engine, at the same oil temps and cht temps, with the same ambient air temps, on the same day, a couple of hours difference in physical time apart. (the time it took to change out the sumps and warm the engine up to the same temps)
For both runs the engines were run with an inlet air screen and no other inlet air restriction. The same exhaust system was used for both configurations. The vertical sump used a forward facing collector and the horizontal one used a forward facing inlet tube.
We really tried to do it in a fashion that would produce real results with real differences. These are not engineering type cells with all the bells and whistles you would have in that R&D environment, but production cells. So we made extra efforts to keep any variables, we could, the same.
I didn't measure the difference in inlet air temp at the intake ports for comparative purposes, but there must be a difference to explain the power difference. The horizontal sump might have a little bit better flow then the vertical, but I don't have any way of knowing or proving that. All I can say is that the same engine, with a different sump configuration installed, under the same run conditions, produced that power difference. The power difference we reported was at CHT's around 400F and oil temp around 190F, I don't remember exactly. But as the engine got even hotter the power difference, between the two, increased in favor of the horizontal configuration engine.
As the engine got hotter and hotter, we saw slightly more power degradation with the vertical sump vs. the horizontal, at the same oil temps. Our conclusion there, was that the inlet air was getting hotter due to the higher oil temps in the vertical sump making the air warmer vs. not having as much of an effect on the air in the horizontal one. Maybe that wasn't the reason, but the power didn't degrade as fast with the horizontal sump, with increase in oil temp, as it did with the vertical one.
Anyway, that is how we tested it and came up with those numbers. The objective of the test was to find out if there was a difference, not to prove one way or the other for sales purposes or anything like that. We don't make any more money selling a forward facing sump engine then we do on a vertical one. The price difference in the two engines is really our parts cost difference for the two sump configurations. So there is really no reason for us to try and skew the results one way or the other, not that we would do that in the first place.
So that is how and why we did it. We did the test several years ago, but this is how it went, from my memory. Hope the information helps in your analysis.
Good Luck,
Mahlon
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