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Why HP/TQ difference when using seat timing to duration at .050" lift

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Old 02-22-2010, 07:18 AM
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F6
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Why HP/TQ difference when using seat timing to duration at .050" lift

I’m using my engine analyzer and trying to find out what HP/TQ I might be getting when I’m finished with my engine update. SR and LE 210 AFR heads
I know these simulations are not going to give me the exact numbers, but I thought at least when using seat timing and then duration at .050" lift they would be about the same +- 2-3 HP.
Why do I have such a big discrepancy, although it fits at 4900-5400 rpm???

RPM…..seat timing……050”
2400……..375…………364…TQ
3400……..399…………379…TQ
4900……..525…………524…TQ
5400……..537…………540…TQ
6400……..604…………618…HP
6900……..593…………609…HP
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Old 02-22-2010, 05:29 PM
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It is cheap inaccurate software that doesn't know the true complete lobe profile. Don't waste your time with such things.
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Old 02-23-2010, 05:09 AM
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F6
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You are right about the software not asking or knowing the exact lobe profile. I tried a 10 trial offer from EA 3.09 which is really not bad, but still there was a big discrepancy in numbers.
I recall someone on a different forum asking the same question but no one really knew a good answer.
I'll just take an average of the HP/TQ numbers and see how it compares to the real world dyno numbers.
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Old 04-03-2010, 02:13 PM
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Well, you can infer what assumptions the software makes, FWIW. If it shows more power using adv. duration it implies that the software is modeling a more aggresive lobe and vice versa. I am not a software engineer, but it seems like it shouldn't be very much more difficult to write the program to use at least the three commonly published durations (0.006, 0.050, and 0.200) for a better sim.

Rich
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