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Author Topic: How much is transmission loss? Quattro, FWD, automatic...  (Read 970 times)
BlackT
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« on: January 31, 2021, 02:32:57 PM »

What is real power transmission loss? Can't find reliable information anywhere.
I am interesed for tiptronic, quattro and FWD on A4/A6
I think here we have guys with dyno
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nyet
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« Reply #1 on: February 10, 2021, 05:01:06 PM »

No way to tell from dyno. Period.

Only way to tell is with an engine dyno then a roller.

25% is the most commonly used number for mt 2.7t torsen, for example, but it's just a number, and has more to do with dyno variation and incentive to get big numbers than reality.

Anyone who tells you they know what number to use is lying. At the end of the day, only whp matters anyway.
« Last Edit: February 10, 2021, 05:02:41 PM by nyet » Logged

ME7.1 tuning guide (READ FIRST)
ECUx Plot
ME7Sum checksum checker/corrrector for ME7.x

Please do not ask me for tunes. I'm here to help people make their own.

Do not PM me technical questions! Please, ask all questions on the forums! Doing so will ensure the next person with the same issue gets the opportunity to learn from your experience.
GolfSportWagen
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« Reply #2 on: February 11, 2021, 03:39:11 AM »

No way to tell from dyno. Period.

Only way to tell is with an engine dyno then a roller.

25% is the most commonly used number for mt 2.7t torsen, for example, but it's just a number, and has more to do with dyno variation and incentive to get big numbers than reality.

Anyone who tells you they know what number to use is lying. At the end of the day, only whp matters anyway.

The losses on a chassis dyno compared to an accurate engine dyno vary dramatically. Chassis to chassis dyno numbers can vary drastically for some valid and invalid reasons. The bottom line is that engine dyno tuning is the only true power data if the data is collected properly on an accurate dyno with properly input data. Unfortunately there is no accurate means to convert dyno data based on engine dyno power without accurate driveline losses or reverse calculate true engine power from chassis dyno data.
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BlackT
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« Reply #3 on: February 22, 2021, 11:07:54 AM »

Thank you for answers, that is what I tought
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jcsbanks
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« Reply #4 on: February 22, 2021, 03:45:13 PM »

Losses = driven wheels * 10 + 50 * (brand == Subaru) - 10 * (trans == manual) + 0.7612 * bullshitFactor + (2021 - yearOfManufacture) + (0.01 * flywheelPower) * (wheelSpeed/150)^2 + 4 * (numberOfBlokesInBootOrTrunk)
« Last Edit: February 22, 2021, 03:55:29 PM by jcsbanks » Logged
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