BMW M3 M4 RPM Redline Visual, Finally

swamp2 · 09-30-2013, 06:39 PM

Quote:

Originally Posted by ScarecrowBoat

this is hands down the biggest nerd fest of a thread i have ever seen

Tell that to the huge "room full" of engineers that designed your 328i...

They went into some minutiae in such amazingly diverse fields of science and engineering that it would truly make your head spin. Even more so if the basics here about shift points do... You benefit from their work each and every time you step into your car. Whether or not you can appreciate these complex, intricate and beautiful concepts is an entirely separate issue, of course...

There is content here on m3post.com well beyond this. Many appreciate and participate in such content.

To each their own, I guess.

Jonjt · 09-30-2013, 07:10 PM

Quote:

Originally Posted by ScarecrowBoat

this is hands down the biggest nerd fest of a thread i have ever seen

No one is forcing you to read this thread. There is context for these discussions that does not require your attention. If you don't like our discussion you don't have to stay. Post in a less technical thread.

khanyam4 · 09-30-2013, 07:20 PM

Jon and swamp is there anyway to prove who's right or wrong. I'm glad m3 post have member like you guys to contribute, it too bad I don't have the knowledge to participate in this great discussion about the next generation m cars.

gblansten · 09-30-2013, 07:55 PM

Quote:

Originally Posted by khanyam3

Jon and swamp is there anyway to prove who's right or wrong. I'm glad m3 post have member like you guys to contribute, it too bad I don't have the knowledge to participate in this great discussion about the next generation m cars.

No need for that. This is part of an elaborate courting ritual. Just stay back and let it unfold.

khanyam4 · 09-30-2013, 08:09 PM

Quote:

Originally Posted by gblansten

No need for that. This is part of an elaborate courting ritual. Just stay back and let it unfold.

Puhahaha lol

Bimmer4John · 09-30-2013, 08:10 PM

Quote:

Originally Posted by gblansten

No need for that. This is part of an elaborate courting ritual. Just stay back and let it unfold.

Haha.

Truth be told, neither of them are wrong per se (swamp may disagree with me :P). The argument is over the nitty gritty details and who's method is "better" (more accurate, realistic, etc.) at determining what the optimal shift points are.

There is nothing wrong with some heated debate.

CanAutM3 · 09-30-2013, 08:14 PM

Quote:

Originally Posted by khanyam3

Jon and swamp is there anyway to prove who's right or wrong. I'm glad m3 post have member like you guys to contribute, it too bad I don't have the knowledge to participate in this great discussion about the next generation m cars.

I am not sure I fully comprehend Jonjt's full argumentation, but from what I understand, I believe both swamp and Jonjt are right.

To calculate optimum shift points, you can either plot resultant tractive force vs road speed or available power vs road speed for each gear. When the lines cross between gears, it is the optimal shift point (the RPM needs to be back calculated from the road speed and gear ratio). If the lines don't cross, you shift at redline.

As swamp points out, estimating parasitic losses in the process will improve the precision of the result for both methods.

gblansten · 09-30-2013, 08:26 PM

Quote:

Originally Posted by johns

Haha.

Truth be told, neither of them are wrong per se (swamp may disagree with me :P). The argument is over the nitty gritty details and who's method is "better" (more accurate, realistic, etc.) at determining what the optimal shift points are.

There is nothing wrong with some heated debate.

I think they are both good guys and probably ought to just agree to disagree.

CanAutM3 · 09-30-2013, 09:24 PM

Quote:

Originally Posted by swamp2

Here is an interesting related question. Will the shift points for the DCT be programmed for maximum performance which means essentially short shifting? Ugh...

I think this will be a key point in figuring the actual performance of the F8X. On the F1X M5/M6, the DCT ratios were clearly not established for maximum performance. However, if on the F8X, the DCT allows keeping the revs always in the power plateau (which most likely means short shifting every gear as Swamp mentions), it will be a hell a of a performer

.

gblansten · 09-30-2013, 09:31 PM

Quote:

Originally Posted by CanAutM3

I think this will be a key point in figuring the actual performance of the F8X. On the F1X M5/M6, the DCT ratios were clearly not established for maximum performance. However, if on the F8X, the DCT allows keeping the revs always in the power plateau (which most likely means short shifting every gear as Swamp mentions), it will be a hell a of a performer

.

I wonder if BMW will adjust gear ratios with some thought for fuel economy and not just performance.

CanAutM3 · 09-30-2013, 09:50 PM

Quote:

Originally Posted by gblansten

I wonder if BMW will adjust gear ratios with some thought for fuel economy and not just performance.

I say give us 1st to 6th for performance

and 7th for fuel economy

.

turbolag · 09-30-2013, 09:57 PM

Quote:

Originally Posted by CanAutM3

I say give us 1st to 6th for performance

and 7th for fuel economy

.

Alright let me launch my car in 7th speed from a standstill in traffic.

Uh...

gblansten · 09-30-2013, 10:02 PM

Quote:

Originally Posted by turbolag

Alright let me launch my car in 7th speed from a standstill in traffic.

Uh...

Invite some friends and then roast marshmellos over what is left of the DCT. Make a day of it.

CanAutM3 · 09-30-2013, 10:22 PM

Quote:

Originally Posted by turbolag

Alright let me launch my car in 7th speed from a standstill in traffic.

Uh...

swamp2 · 09-30-2013, 11:12 PM

Quote:

Originally Posted by gblansten

No need for that. This is part of an elaborate courting ritual. Just stay back and let it unfold.

I'd like to be insulted by that but I am also too busy laughing at your clever comment!

Kadema · 09-30-2013, 11:17 PM

I am very curious if it turns out that swamp2 overestimated rpm dependent parasitic losses for the f8x (to force his point that turbo engines are inferior and always need to be short shifted) or his (from my perspective) rather pessimistic approximation is (annoyingly) absolutely correct (again).

Keep going, guys!

swamp2 · 09-30-2013, 11:27 PM

Quote:

Originally Posted by CanAutM3

As swamp points out, estimating parasitic losses in the process will improve the precision of the result for both methods.

Not quite. If you have reliable dyno information (which anyone in the know will admit is pretty much a non-sequitur) losses are not needed. For my process, losses absolutely are required for the calculation. My calculation is almost entirely a-priori (no test data required).

swamp2 · 09-30-2013, 11:32 PM

Quote:

Originally Posted by Kadema

I am very curious if it turns out that swamp2 overestimated rpm dependent parasitic losses for the f8x (to force his point that turbo engines are inferior and always need to be short shifted) or his (from my perspective) rather pessimistic approximation is (annoyingly) absolutely correct (again).

I never said that turbo engines are either inferior or always need to be short shifted. Also the numbers are not entire "my" numbers they have been gleaned from both defaults in the software, the literature, papers and books (which of course is based on testing) and a small bit of curve fitting. That along with tons of validation efforts on predicted vs. simulated performance results. Either way the numbers are the same I used for the majority of my E9X M3 simulations. I did not purposefully make the numbers larger to reflect personal engine biases. That would be massive scientific dishonesty. Cheers.

CanAutM3 · 09-30-2013, 11:33 PM

Quote:

Originally Posted by swamp2

Not quite. If you have reliable dyno information (which anyone in the know will admit is pretty much a non-sequitur) losses are not needed. For my process, losses absolutely are required for the calculation. My calculation is almost entirely a-priori (no test data required).

Agreed if we have chassis dyno results. All we have now is bench dyno plots.

swamp2 · 09-30-2013, 11:35 PM

Quote:

Originally Posted by CanAutM3

Agreed if we have chassis dyno results. All we have now is bench dyno plots.

Another reason why I like the more purely a-priori type of calculation.

CanAutM3 · 09-30-2013, 11:36 PM

Quote:

Originally Posted by swamp2

Another reason why I like the more purely a-priori type of calculation.

You do need test data though. Those initial dyno graph need to come from somewhere

gblansten · 09-30-2013, 11:40 PM

Quote:

Originally Posted by swamp2

Quote:

Originally Posted by gblansten

No need for that. This is part of an elaborate courting ritual. Just stay back and let it unfold.

I'd like to be insulted by that but I am also too busy laughing at your clever comment!

I kid.

09-30-2013, 07:20 PM	#157
khanyam4 Ring Leader of G8X Trolls 802 Rep 1,762 Posts Drives: NA Join Date: Jun 2009 Location: 33.7743° N, 117.9380° W iTrader: (0)	Jon and swamp is there anyway to prove who's right or wrong. I'm glad m3 post have member like you guys to contribute, it too bad I don't have the knowledge to participate in this great discussion about the next generation m cars.
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09-30-2013, 11:17 PM	#170
Kadema Private First Class 1 Rep 116 Posts Drives: 123d Join Date: Sep 2013 Location: Rothenburg ob der Tauber iTrader: (0)	I am very curious if it turns out that swamp2 overestimated rpm dependent parasitic losses for the f8x (to force his point that turbo engines are inferior and always need to be short shifted) or his (from my perspective) rather pessimistic approximation is (annoyingly) absolutely correct (again). Keep going, guys!
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