135i tuning

[dvst8]

How do you get the flywheel readings ?

 

[bmsportzn135i]

Its the way the dyno is setup, it will give you fly wheel readings, not wheel readings!

 

[Rolf]

As explained many times:

P (flywheel) = P (wheel) +P (loss) multiplied with ambient correction factor

If the dyno is technically in order and calibrated, you can put the very same car on any dyno anywhere in the world and P (flywheel) will always read the same

P (flywheel) = Engine Power at flywheel
P (loss) = Power losses from flywheel to dyno roller (gearbox, diff, tyre drag)
P (wheel) = Power taken from dyno roller
Ambient correction factor = multiplier depending on temperature and air pressure to achieve same conditions as in controlled environment

 

[Gav Grey]

Great looking car that, :thumbs: If i may ask where did you get that front spoiler. looks great

 

[dvst8]

So is the power loss calculated per individual car or is it a standard that is used for all cars ?

 

[Rolf]

Take a wild guess when you look at KAR dyno sheet and then on above pic :idea:

 

[dvst8]

Take a wild guess when you look at KAR dyno sheet and then on above pic :idea:

Im not asking about the internet pic posted above.

And Im not clever enough to guess.

But if you dont have an answer, its still cool in school


:thumbs:

 

[Rolf]

Yes power and loss are calculated individually per car and that is the norm ... oops SHOULD be the norm :idea:

 

[dvst8]

Okay, that wasnt so hard.

So basically you saying that this power run took wheel size, gear ratios of this specific car and ambiemt temps to calculate flywheel power ?

Was estimate tyre slip and gearbox oil viscosity also taken into the calculation ? Would this also have an impact on the accuracy of the conversion ?

 

[Rolf]

And Im not clever enough to guess.

Really?

Okay, that wasnt so hard.

Tried to make it simple for you

.... and you are not paying attention ... just like in school :nonono:

 

[dvst8]

And Im not clever enough to guess.

Really?

Okay, that wasnt so hard.

Tried to make it simple for you

.... and you are not paying attention ... just like in school :nonono:

If you see the hot chick sitting next to me you would understand why Its hard to pay attention.

:inlove:

Okay but seriously, what am I missing here ? :fencelook:

 

[dvst8]

Okay, let ,me explain and maybe Rolf can set me straight.

My post is not to stir and my questions are not directed at a specific car or power output. It is to learn.

I was always led to believe that the only way to achieve accurate Engine or Flywheel power output is to remove the engine and run it on an "Engine Dyno".

Any "Roller Dyno" will read power output generated literally "At the wheels".

To get the output of power from the Engine or Flywheel when the car is run on a "Roller Dyno", one would have to take the output " At the wheels" and calculate the Engine or Flywheel power.

Sounds easier than it is. A lot of factors need to be considered for this calculation ie. gear ratios, wheels sizes etc.

And, it would be different for different cars eg. A rear wheel drive M3 would be different to say a Front wheel drive Golf GTi. An M3 with 18" wheels would be different to the same car with 19" wheels.

Am I correct ? If not please can you explain in simple terms.


:thumbs:

 

[Rolf]

100% correct down to the "any roller dyno" passus!

From there onwards you're drifting off

The flywheel result is not calculated or as one would read between your lines "estimated" but rather messured as drag losses.

It doesn't matter if you have bigger or smaller wheels or what car or what oil because losses are losses this way or that way and they get added.

The whole thing gets influenced by two more factors:

- ambient conditions
- engine system (N/A, Turbo and Diesel)

The latter are fixed values whereby amient conditions are variable and change even within and during the day!

The rest you can read further up in the thread
Sent from my GT-I9000 using Tapatalk

 

[AM Salie]

Rolf where do u recomend one should dyno in cape town? Im using meth and ethonol now snd would love some accurate readings?

Sent from my GT-I9300 using Tapatalk 2

 

[Rolf]

We make use of Dynotech in Brackenfell Industria, 24 Goud Crescent

Book with Izak: 021 - 981 9170

The run their dyno according to DIN specification :idea:

 

[tcal69]

100% correct down to the "any roller dyno" passus!

From there onwards you're drifting off

The flywheel result is not calculated or as one would read between your lines "estimated" but rather messured as drag losses.

It doesn't matter if you have bigger or smaller wheels or what car or what oil because losses are losses this way or that way and they get added.

The whole thing gets influenced by two more factors:

- ambient conditions
- engine system (N/A, Turbo and Diesel)

The latter are fixed values whereby amient conditions are variable and change even within and during the day!

The rest you can read further up in the thread
Sent from my GT-I9000 using Tapatalk

:slow: Just take it to the track and race that's the best way to find out how fast it goes:rollsmile:

 

[Rolf]

And even there you have "slow" drivers and "fast" drivers who outperform guys in more powerful cars and ride circles around them :joy:

Fact is: If I go to a dyno, I want to know as accurate as can be what my power output is, no matter where I am with this car

 

[AM Salie]

thank rolf ill call tgem

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