Flywheel HP Calculation from WHP

[SilverRings]

I know this one is tricky, but what percentage should S4 Dual Clutch guys use to get Flywheel from Wheel HP? Factors that I see effecting that percentage would be AWD and a Dual Clutch Automatic.

[MrFunk]

Typically AWD cars have 20% drive-train loss... I'd use that for a rough estimate.

[shoe3k]

Calculating from WHP to crank doesn't work out like you think.

Using 20% drivetrain loss.

400hp (crank) * 20% = 80hp loss
320whp*1.20 = 384, which isn't 400hp.

[LINDW4LL]

15-20%.

Calculating from WHP to crank doesn't work out like you think. Using 20% drivetrain loss:

400hp (crank) * 20% = 80hp loss
320whp / .8 = 400

The proper calculation would be 320 / .80 = 400

[mmm def]

I use 20% for awd and 15% for rwd as a ballpark.

[eurotic]

Calculating from WHP to crank doesn't work out like you think.

Using 20% drivetrain loss.

400hp (crank) * 20% = 80hp loss
320whp*1.20 = 384, which isn't 400hp.

Yeah, LINDW4LL has the right math on this.

Although I thought these cars were not nearly as bad as 20% drivetrain loss. I though it was closer to 15%.

Although all that really matters (to me anyway) is how much power gets to the ground.

[mmm def]

Yeah, LINDW4LL has the right math on this.

Although I thought these cars were not nearly as bad as 20% drivetrain loss. I though it was closer to 15%.

Although all that really matters (to me anyway) is how much power gets to the ground.

These cares are closer to 350 crank.

[jimrobbington]

These cares are closer to 350 crank.

This x2. Which means you can't even guesstimate a percentage based on wheel vs OEM claimed HP of 333. And no one knows the true crank figure from the factory since it's all just guesstimates based on wHP dyno readings. Lol.

Someone needs to throw a spare engine on the crank dyno.

I've always thought the figure for AWD, manual was like 20-23% loss and normal auto was more like 25-27%. This coming from the A4 b7 world

[Hellahashtags]

From APR's website data, it's 15%-20%. For example, Stage 2 (91 pump) is claimed to be 373 WHP and 448 HP.

[shoe3k]

15-20%.


The proper calculation would be 320 / .80 = 400

How embarrassing. I"m sitting looking at my post and realized that I never included the last sentence, which was the exact part you added. Thanks for the catch.

[s5stocky]

Just put car on dyno it pulled 373 whp so my calculations are 466 hp at the crank.
Stage II EPL tune with SC pulley
Runs like a beast :)

[blackfunk]

Because you bumped a 4yrs old thread I'll add this.....APR is the only tuner that I'm aware of that has an engine out dyno for testing. Everyone else is guessing (through calculations) but they all fall within percentage points of each other.

I won't even get started on different dyno's giving different numbers LOL