Had The Car Dyno'd Today Stock w/ K&N Filters Awesome Numbers!

[gal662]

Originally Posted by CanAutM3

I am sorry to say, but your interpretation is just as flawed.

As I posted previously, the vast majority of chassis dynos are inherently innacurate at producing absolute power numbers. Further, you simply cannot take a random "drivetrain loss" factor to corroborate crank numbers.

Without a proper baseline obtained on the same chassis dyno, there is no way to accurately establish how much power you gained from your exhaust and filter. All you know is that you made 402whp on that dyno on that day. You cannot really use that number to compare to other chassis dynos or, even worse, to the factory rating.

What you should have done, is run your stock car on that dyno, do the mods and then run it again on the same dyno. This would have given you a decent appreciation of the relative gains.

Read what i have written again, for god sakes it just doesn't get through to people here!!!

What the whole argument is is that the OP has in NO WAY got a car that runs 442 WHP as a stock car!!

I am not trying to claim big figures here! My explanation is not about bragging rights about how much BHP i have!, it is showing the relation of BHP to WHP!!

I know exactly how RR's work I know they are not a true science that cannot be exact every time and I also know that parameters can be set on the dyno to produce heightened figures!!!

So if my explanation is flawed and remembering this is not an argument about what BHP i have, as tgats not what my reply was about. My thread was about the relationship between BH and WHP using my cars dyno as an answer.

Please answer the following statements just to clarify...yes or no will suffice!

1. BMW state 425-431 BHP for a stock car!
2 . BHP is measured at the crank/flywheel
3. WHP is measured at the wheels
4. BHP is higher is a higher figure than WHP
6. WHP can be viewed as a figure that is a relation of BHP that is lost at the wheels.

Now you will have probably answered yes to all them.

So tell me numbnuts...how the hell do you ever think a stock car could make 442 WHP???? Maybe 442 BHP...

Look at the facts!!

The terminology used by the OP who has argued the case and been supported by many others (and some surprising endorsers) is wrong!

So tell me where why theory is flawed?

I think the really problem is severe lack of knowledge when applying terminology here!!

Chasing numbers is a game, but when you cant get the basics right in the first place then there is a problem.

OP - drag race your car with another car. Both stock..you claim your car is 442 WHP but with filters and the other car will claim 431 BHP , total stock car from a factory!!

Believe you me you will not be leaving him for dust!!!!

[melvyn]

Hellooooooo, helloooooooo down there, am still up in my cloud here Mate as the SW wind is slow in coming.I will drop down my rope if you want and pull you up, we can be home in 2-3 days.Back to sanity , thank fook

[Powaup]

[melvyn]

Originally Posted by Railgun

It's not an exact science. Drivetrain losses have been argued for years. It's a total swag and, also mentioned countless times in other threads, a chassis dyno is best used for measuring differences.

Now, you get several cars in the same dyno at about the same time and you can compare relative difference. A one off and using that as absolute? No.

And a drag race? Really? Because that removes all other variables, doesn't it.



No one knows wth you're taking about anymore. Go to another dyno and compare notes.

Am not bothered, my point was to show the difference the Evo made before and after fitting,8hp at peak but average of about 20 hp from 5k.
Then I get baffled with science

[CanAutM3]

Originally Posted by gal662

Read what i have written again, for god sakes it just doesn't get through to people here!!!

What the whole argument is is that the OP has in NO WAY got a car that runs 442 WHP as a stock car!!

I am not trying to claim big figures here! My explanation is not about bragging rights about how much BHP i have!, it is showing the relation of BHP to WHP!!

I know exactly how RR's work I know they are not a true science that cannot be exact every time and I also know that parameters can be set on the dyno to produce heightened figures!!!

So if my explanation is flawed and remembering this is not an argument about what BHP i have, as tgats not what my reply was about. My thread was about the relationship between BH and WHP using my cars dyno as an answer.

Please answer the following statements just to clarify...yes or no will suffice!

1. BMW state 425-431 BHP for a stock car!
2 . BHP is measured at the crank/flywheel
3. WHP is measured at the wheels
4. BHP is higher is a higher figure than WHP
6. WHP can be viewed as a figure that is a relation of BHP that is lost at the wheels.

Now you will have probably answered yes to all them.

So tell me numbnuts...how the hell do you ever think a stock car could make 442 WHP???? Maybe 442 BHP...

Look at the facts!!

The terminology used by the OP who has argued the case and been supported by many others (and some surprising endorsers) is wrong!

So tell me where why theory is flawed?

I think the really problem is severe lack of knowledge when applying terminology here!!

Chasing numbers is a game, but when you cant get the basics right in the first place then there is a problem.

OP - drag race your car with another car. Both stock..you claim your car is 442 WHP but with filters and the other car will claim 431 BHP , total stock car from a factory!!

Believe you me you will not be leaving him for dust!!!!

Whoa, buddy, tone it down. Numbnuts? There is no need to get insulting. You made a lengthy post full of blatant mistakes and got called out for it.

The main point I keep repeating is that the vast majority of chassis dynos are inherently innacurate at producing absolute numbers. So yes, the OP's 442whp is probably optimistic due to an optimistic dyno. That number is utterly useless for comparison to other cars. However, if the OP uses the same dyno in similar conditions after he mods his car, he will have a decent appreciation of the relative gains he got from his mods.

The difference between the 425 and 431 BMW ratings for the S55 is simply the units used. 431 is in DIN, the German/European unit for power often referred to as PS for pferdestärke (german for horsepower). 425 is in SAE, the unit used in North America. 431ps(DIN)=425hp(SAE). European publications will use 431 and North American publications will use 425.

As for your 4th question, it cannot be answered by yes or no since it depends on operating conditions. As a general principle, you are right, at any given moment in time, power at the wheel will always be less than at the crank due to losses. However, most manufacturers use steady state conditions (constant RPM) to obtain their official ratings. Engines behave differently when operating in steady state vs operating in transient, especially modern FI engines that have a tendency to produce far more power when accelerating at mid to high RPM. Since the vast majority of chassis dyno runs are done with the engine accelerating, the engine can be producing more power and therefore it is quite possible that the resulting peak power at the wheels can be higher than the official manufacturer rating at the crank.

Which brings me back to my original point. Since the power produced by the engine can vary with acceleration rate and that the acceleration rate is controlled differently on different chassis dynos, it will only exarcebate the difference of the results obtained on different chassis dynos.

I agree, there is quite a lot of lack of knowledge regarding dynos and power ratings. But it is a complex topic .

[JoeFromPA]

I have a headache.

One last note:

AFAIK, there's two things that need to be reinforced about drivetrain loss between engine and wheels:

1. It's not a linear number. It doesn't soak up 10% of engine output at 2000 rpms and 10% of engine output at 7000 rpms. As a percentage, it takes less engine output to continue pushing the power through the drivetrain at max output than it does at min output.

2. 40 years ago, RWD platforms had 15-20% drivetrain losses at max. They are more efficient nowadays.

[brian30tw]

Originally Posted by JoeFromPA

I have a headache.

One last note:

AFAIK, there's two things that need to be reinforced about drivetrain loss between engine and wheels:

1. It's not a linear number. It doesn't soak up 10% of engine output at 2000 rpms and 10% of engine output at 7000 rpms. As a percentage, it takes less engine output to continue pushing the power through the drivetrain at max output than it does at min output.

2. 40 years ago, RWD platforms had 15-20% drivetrain losses at max. They are more efficient nowadays.

I refuse to contribute to the idiocy going on above, but wanted to agree with you here. Building on #1, I also don't see how drivetrain loss can be a fixed percentage of output, but rather a fixed level of output. In other words, it takes X horsepower to turn gears in the transmission and the wheels, not Y% of the engine's output at any given time. If you think drivetrain loss is a fixed percentage of output, that implies the drivetrain somehow requires more horsepower to turn gears as the power of the engine grows, which can't be true (e.g., 10% drivetrain loss would imply the drivetrain requires 40 horsepower to operate when the engine makes 400 horsepower, but somehow the same drivetrain would take 50 horsepower to operate when the engine makes 500 horsepower).

[TR930]

I am going to the dyno today (same one and same tank of gas) to measure the delta of my newly installed Dinan Stage 2. I will post uncorrected results.

Stay "tuned".....

[CanAutM3]

Originally Posted by brian30tw

I refuse to contribute to the idiocy going on above, but wanted to agree with you here. Building on #1, I also don't see how drivetrain loss can be a fixed percentage of output, but rather a fixed level of output. In other words, it takes X horsepower to turn gears in the transmission and the wheels, not Y% of the engine's output at any given time. If you think drivetrain loss is a fixed percentage of output, that implies the drivetrain somehow requires more horsepower to turn gears as the power of the engine grows, which can't be true (e.g., 10% drivetrain loss would imply the drivetrain requires 40 horsepower to operate when the engine makes 400 horsepower, but somehow the same drivetrain would take 50 horsepower to operate when the engine makes 500 horsepower).

Hmmm, seems like you need to go study Engineering.

While you are correct stating losses are not a fixed % of output, the multiple different losses in a drivetrain vary in many different ways. Some are fixed, some are load dependent and some are speed dependent.

When running in transient (engine accelerating), you also need to factor inertial impacts that are not losses per-se.

[CanAutM3]

Originally Posted by TR930

I am going to the dyno today (same one and same tank of gas) to measure the delta of my newly installed Dinan Stage 2. I will post uncorrected results.

Stay "tuned".....

Looking forward to see those results

[melvyn]

Originally Posted by CanAutM3

Looking forward to see those sensible results

How you getting on with your brakes , all up and running

[CanAutM3]

Originally Posted by melvyn

How you getting on with your brakes , all up and running

[melvyn]

Originally Posted by CanAutM3

Sorry, wrong guy.

[brian30tw]

Originally Posted by CanAutM3

Hmmm, seems like you need to go study Engineering.

No doubt! Not my comparative advantage in this world, to be sure.

Understanding I'm probably oversimplifying things, in your mind (I respect all the knowledge you typically convey), is it fair to say that, as the power output of an engine increases (and the drivetrain stays constant), the percent of that output lost to drivetrain loss decreases? I.e., for a fixed drivetrain, would a 500 HP engine suffer from a lower percent drivetrain loss than a 200 HP engine in the same car? That's the real point I was hoping to convey, if it's correct.

[CanAutM3]

Originally Posted by brian30tw

No doubt! Not my comparative advantage in this world, to be sure.

Understanding I'm probably oversimplifying things, in your mind (I respect all the knowledge you typically convey), is it fair to say that, as the power output of an engine increases (and the drivetrain stays constant), the percent of that output lost to drivetrain loss decreases? I.e., for a fixed drivetrain, would a 500 HP engine suffer from a lower percent drivetrain loss than a 200 HP engine in the same car? That's the real point I was hoping to convey, if it's correct.

It is really not possible to say without a complete understanding of the configuration and losses of the entire drivetrain and the power characteristics of the two engines in question. Also, since most chassis dynos are rolling road type dynos, tire rolling losses also need to be factored in.

As I mentioned previously, different loses vary depending on different parameters. For example, gear meshing losses do indeed vary with load since the friction between gears is directly dependent of the load being transmitted between them. The same holds true for some of the bearing losses. Tire rolling losses have an element that varies with the square of speed; so as the engine RPM increase on a dyno run, those losses increase exponentially. Same goes for windage losses that increase with the cube of speed.

That is why I maintained so many times that trying to put a number on drivetrain losses is a futile exercise. It can only be done with elaborate simulation models. And even then, it remains an approximation.

Sorry, there is no black or white answer here.

[brian30tw]

Originally Posted by CanAutM3

That is why I maintained so many times that trying to put a number on drivetrain losses is a futile exercise. It can only be done with elaborated simulation model. And even then, it remains an approximation.

Sorry, there is no black or white answer here.

As is the case with so many things in life! Thanks for your detailed responses.

[Who's on first]

So, no new Dinan results?

[TR930]

I have a dyno sheet for the stage 2, I will post here tomorrow.

[TR930]

Got it. Check the "Dinan Stage 2" thread, dyno posted there.

[stranger]

Originally Posted by TR930

Got it. Check the "Dinan Stage 2" thread, dyno posted there.

link?

[TR930]

http://f80.bimmerpost.com/forums/sho....php?t=1145367