335i driver does test-drive with M3

[swamp2]

Originally Posted by bruce.augenstein@comcast.

I'm not aware of that particular comment ever coming up, either in our running commentary or in Gillespie's book.



Sorry, my poor wording. What I meant to say was that with the built-in errors in the up-front data, you're starting every run with an approximate seven tenths of a second advantage over reality, but then the car is slower all the way down the track. Your zero-to speeds are then improved by the built in seven-tenths error, but you can't match the speed at distance numbers because of the inflated effiency loss numbers.

As mentioned several times, you're not modelling any car with accuracy unless you can nail time, speed and distance. You seem to have trouble with what seems to me to be fairly obvious fact, so I won't refer to it again.

We also seem to disagree on what accuracy means in this context. With my year or so spent on helping to develop accurate modelling software (including accuracy samples from several other packages), I'm aware that unless you're coming up with under 1% deviations from actual, you're too far off. I won't refer to this again either, since your experience is in other areas where way less accuracy is OK.



Actually, your results from CarTest (and you) have been under attack from day one. I have in fact mentioned on more than one occasion that I thought the software was probably good - just not in your hands.

OK, I take back the asshole comment, as that was a little rough. Substitute "ignorant".

You don't think the author is ignorant on this topic? I don't either. If you reread my post, I spoke specifically to whomever put a one-second delay into the process, as opposed to a more realistic three tenths or so (not varying very much from car to car). I don't for a moment think the author of the software did that.

Bruce

PS - As a minor aside, let me quote from Gillespie, on page 26, where he says, in part (while describing a fairly complex formula which is used to calculate rotational inertia by gear)), "The term in brackets indicates that the equivalent inertia of each component is "amplified" by the square of the numerical gear ratio between the component and the wheels."

Hm-m-m. Big decision for me. Am I to believe a published guy with terrific credentials whose book is in use in hundreds of colleges and universities around the world, or should I believe Swamp and lucid?

Tough call. I'll get back to you on that.

What am I missing? You seem to be contradicting yourself here. You say the comment about a frequency dependent "I" never came up, which you have claimed throughout this thread and AGAIN right here at the end of the thread, directly quoting Gillespie. What it comes down to is definitions and precision. Again if he claims that I, THE MOMENT OF INERTIA (or so called second moment) which = integral of p(r) x r^2 dV, of a rotating gear shaft assembly is a function of angular velocity HE IS WRONG, PERIOD. This is a fundmental definition from physics and engineering and can not be debated. These are the options here:

• lucid and swamp with advanced engineering/physics/math degrees are wrong
• Gillespie is wrong
• Bruce is misinterpretating/misunderstanding the scope/application/meaning of a complex formula

I'd go for the third option.

You have also misread the inputs to CarTest. The "1" figure is not 1 second, it is 1 foot. This is the distance the car must move before the clock begins counting. The author simply mislabled the title of that rows entry as time, when it should be distance and that is made clear in the "foot" label on the RHS. I have verified that this is indeed a 1 foot effect, not 1 second. So your accusations of a serious error and serious inability on my end turns out to be bogus. Keep trying Bruce.

You are never going to admit that real world testing exhibits a range of results for time, distance and speed >> 1%. Refer again (for the 100th time) to our small database of test resutls here on the forum. The same thing exists for all cars. Too many variables. You just can't see the forest for the trees...

[bruce.augenstein@comcast.]

Originally Posted by swamp2

What am I missing? You seem to be contradicting yourself here. You say the comment about a frequency dependent "I" never came up, which you have claimed throughout this thread and AGAIN right here at the end of the thread, directly quoting Gillespie. What it comes down to is definitions and precision. Again if he claims that I, THE MOMENT OF INERTIA (or so called second moment) which = integral of p(r) x r^2 dV, of a rotating gear shaft assembly is a function of angular velocity HE IS WRONG, PERIOD. This is a fundmental definition from physics and engineering and can not be debated. These are the options here:

• lucid and swamp with advanced engineering/physics/math degrees are wrong
• Gillespie is wrong
• Bruce is misinterpretating/misunderstanding the scope/application/meaning of a complex formula

I'd go for the third option.

First, gearing dependent and rpm/frquency dependent seem to me to be two different things in this context.

Second, since I've simply quoted Gillespie's plain english, I have some trouble with the entire concept of misinterpreting/misunderstanding.

I think you ought to buy the book, and be humbled by some of the items in there (such as transmission rotational inertia by gear).

Originally Posted by swamp2

You have also misread the inputs to CarTest. The "1" figure is not 1 second, it is 1 foot. This is the distance the car must move before the clock begins counting. The author simply mislabled the title of that rows entry as time, when it should be distance and that is made clear in the "foot" label on the RHS. I have verified that this is indeed a 1 foot effect, not 1 second. So your accusations of a serious error and serious inability on my end turns out to be bogus. Keep trying Bruce.

So I "misread" the part where it says "sec" and not feet? Hmm.

Serious error and serious inability on your end remain as fact. My real-world experience matching time slips with weather conditions among several different packages shows really good accuracy as routine. Your inability to match time, speed and distance with reasonable accuracy remains unexplained.

Originally Posted by swamp2

You are never going to admit that real world testing exhibits a range of results for time, distance and speed >> 1%. Refer again (for the 100th time) to our small database of test resutls here on the forum. The same thing exists for all cars. Too many variables. You just can't see the forest for the trees...

Once you know all (or even most) of the testing parameters, then a "range" of test results is without meaning. You need to zero in on something known and see how the results pan out. Then you zero in on someone else's test procedures, and see how those results pan out, and so on...

Obviously, we'll never come to agreement on this, so I'll go on and address the OP.

Bruce

[bruce.augenstein@comcast.]

Originally Posted by hwelvaar

I currently drive a E92 335i (since 8 months) and I recently did a 1-hour test-drive with the E92 M3.

My opinion:
- I prefer the torque of 335i for daily driving (and my 335i is still stock) - it makes your car real fast in daily traffic
- when you're not revving, the M3 feels slow ; I was *really* disappointed. I was *hoping* that the M3 would blow me away, so I could convince my own brain to drop the extra bucks to get an M3. But it didn't. Not on normal roads.
- the sound of M3 engine is fantastic in high revs, but not noticable in low and mid RPMs
- the sound of 335i is very nice in both mid and high RPMs

Notwithstanding the fairly rude attacks from other noters, the 335 feels faster because it is faster in everyday driving.

It's faster because (in no particular order):

1) It exhibits a bulgy torque curve at part throttle, typical of most of today's street-centric turbo engines. That is to say, half throttle, for instance, delivers more than half boost, so the operator gets to ride the river of torque in higher gears than one might select in the M3 at the same road speed. This gives the driver a sense of effortless speed.

2) It has less rotational inertia, both because it has higher (lower numerically) gearing and because the operator will typically be in a higher gear than in the M3 at identical speeds.

3) It makes less noise under low-load cruise conditions, and *much* less noise at full throttle. Again, this contributes to the operator's sense of effortless speed. In a sense, the 335 fools the operator into thinking the car is faster because it's more or less murmuring - even when you're pushing it a bit more, throttle wise, than when in the M3. In addition, one feels one can use a bit of extra throttle because there's a smaller risk of downside notice from your significant other in the passenger seat, the general population or the gendarmes.

4) It's "jerkmeter" (great term) quotient is well down from that in the M3 - due to throttle response (longer air columns to manage) and the fact that the 335 takes time to come up on boost. In everyday driving, the operator will typically be managing smoothness considerations, so (s)he will typically be using the throttle a little more gingerly in the M3. As an observation, human G-receptors are fairly poor at distinguishing the actual rate of acceleration, but extremely good at distinguishing rate changes. Thus the tendency for a driver to throttle-manage the M3 more in an effort to maintain smoothness.

5) Based on inputs from a couple of comparison tests, the M3 is a little light on part-throttle, low-end torque - compared to the RS4, for instance. Part-throttle, low-end torque is where the 335 excels.

Notwithstanding all of the above, lucid may have made the most cogent and to-the-point remark in this string when he said, "So what?"

Indeed.

However, the effortless feel of the 335 will be appealing to a lot of drivers when they're not feeling particularly sporty.

Make no mistake, the M3 will run away and hide from the 335 in any sort of sporting engagement, and will definitely be more fun to drive in that context, suffering only in comparision to previous M3s in that arena.

Bruce

[swamp2]

Originally Posted by bruce.augenstein@comcast.

So I "misread" the part where it says "sec" and not feet? Hmm.

Yes and no. You read incompletely and made a false assumption based on a typo of sorts in an inconsequential label in a dialog box of a software package you are unfamiliar with.

Originally Posted by bruce.augenstein@comcast.

Serious error and serious inability on your end remain as fact. My real-world experience matching time slips with weather conditions among several different packages shows really good accuracy as routine. Your inability to match time, speed and distance with reasonable accuracy remains unexplained.
...
Once you know all (or even most) of the testing parameters, then a "range" of test results is without meaning. You need to zero in on something known and see how the results pan out. Then you zero in on someone else's test procedures, and see how those results pan out, and so on...

Stop the insults and exaggerations Bruce it is getting so old. What part of our previous lengthy debate on this topic did you miss? Drag out all of those old sims on the TRS-80 and timeslips per my previously unanswered challenge to you and put your money where you mouth is. Show the world how much better you are at automobile performance simulation than swamp...

Even given precise control of an event like a 1/4 mi run, variations will still exist and those will be larger than the accuracy that you keep claiming is "required" and that you claim you have obtained (.01 seconds, consistently and across the entire 1/4 mi was your claim...). If you have a robot drive a infinitely precisely prepped vehicle in a vaccuum on virgin, chemically precise asphalt and can do that over and over again with very little variation and then adjust unknown or unmeasureable input parameters to ex post facto match a simulation to a test that is called cheating, not simulation. I have agreed that professional drag racing is generally more precise than magazine automobile performance testing and the goal of simulation in such a scenario is different than the goal of making A-B comparisions between consumer vehicles and trying to match reported results from either owner runs or magazine results. The goal here is to even out natural variations with the precise control that simulation offers, thus you can judge the CAR, at it's best, and not the driver or weather or track or whatever. Quite simply is car A faster than car B, all things equal.

I agree that I did not know exactly what transmission loss values to use in CarTest. I suspected and agreed that the defaults were a bit too high. But I also stick to my belief that the values you have suggested are too low. In fact in this very thread you admitted you made up one of your figures. What is better ignorance or fabrication?

How much difference did this terrible, gross, unforgiveable error of mine make, let me remind you, .2 seconds to 60, .4 seconds in the 1/4. Some will continue to view this as gross and "a mile off" others will look at the range of reported results and see that both predictions approximately bracket the reported results and conclude, as I have, that the drivetrain losses are almost for sure somewhere between the default values I initially used and the ones you pulled from Gillespie. Again I would argue that the defaults the CarTest author chose may be more appropriate for lower performance transmissions as opposed to an M or Porsche boxes or the like. Hence the defaults in CarTest being not nearly as bad as you believe for the range of vehicles in the CarTest database (thousands!).

I also disagree with your statement that you must match time, distance and speed to obtain a validated simulation. This too goes way back to one of our very old arguments. All you need is one curve, any of (position, speed or acceleration) vs. time as a continuous variable. Then along with proper initial conditions you can take derivates or integrate and derive the other curves perfectly. If you can match any one of these curves with good accuracy the others will fall right in line. If you understood the physics a bit more you would realize this.

So we simply come back to the same old points. My older sims were within the ranges reported by magazines for most cars I did work on. An exception was a clear and admitted underprediction of 1/4 mi trap speeds. With your revised drivetrain loss figures the few sims I have ran are also again within the range (albeit more toward the level of the outliers - and understandably so) of results reported by magazines and the traps are now significantly closer.

Keep on beating those bloody, pulverized, expired horses Bruce.

[swamp2]

Originally Posted by bruce.augenstein@comcast.

Notwithstanding the fairly rude attacks from other noters, the 335 feels faster because it is faster in everyday driving.

It's faster because (in no particular order):

1) It exhibits a bulgy torque curve at part throttle, typical of most of today's street-centric turbo engines. That is to say, half throttle, for instance, delivers more than half boost, so the operator gets to ride the river of torque in higher gears than one might select in the M3 at the same road speed. This gives the driver a sense of effortless speed.

2) It has less rotational inertia, both because it has higher (lower numerically) gearing and because the operator will typically be in a higher gear than in the M3 at identical speeds.

3) It makes less noise under low-load cruise conditions, and *much* less noise at full throttle. Again, this contributes to the operator's sense of effortless speed. In a sense, the 335 fools the operator into thinking the car is faster because it's more or less murmuring - even when you're pushing it a bit more, throttle wise, than when in the M3. In addition, one feels one can use a bit of extra throttle because there's a smaller risk of downside notice from your significant other in the passenger seat, the general population or the gendarmes.

4) It's "jerkmeter" (great term) quotient is well down from that in the M3 - due to throttle response (longer air columns to manage) and the fact that the 335 takes time to come up on boost. In everyday driving, the operator will typically be managing smoothness considerations, so (s)he will typically be using the throttle a little more gingerly in the M3. As an observation, human G-receptors are fairly poor at distinguishing the actual rate of acceleration, but extremely good at distinguishing rate changes. Thus the tendency for a driver to throttle-manage the M3 more in an effort to maintain smoothness.

5) Based on inputs from a couple of comparison tests, the M3 is a little light on part-throttle, low-end torque - compared to the RS4, for instance. Part-throttle, low-end torque is where the 335 excels.

Notwithstanding all of the above, lucid may have made the most cogent and to-the-point remark in this string when he said, "So what?"

Indeed.

However, the effortless feel of the 335 will be appealing to a lot of drivers when they're not feeling particularly sporty.

Make no mistake, the M3 will run away and hide from the 335 in any sort of sporting engagement, and will definitely be more fun to drive in that context, suffering only in comparision to previous M3s in that arena.

Bruce

Let the speculation continue... Although I am not saying it is totally false, without a test, real data and real results I call 100% speculation on many of your points above. Have you seen a part throttle torque curve of the 335i or the M3. I'll answer for you - you haven't.

Hmmm what's next, contradictions, contradictions. We agree that a humans can feel jerk (the time derivate or rate of change of acceleration) more acutely than actual acceleration. But then you continue to say the M3 will have more jerk than the 335i and hence the 335i will feel faster. That is completely backwards for one and for two it is not about the perception of speed, but about speed. I did not realize this lengthy discussion was to the fairly ridiculous point of lauding the 335i over the M3 because it feels fast. Ugh. A similar contradiction exists with your point about noise - the car "is faster", as you open your post with, becuase is is quieter. Get real Bruce.

Your point 5 - totally meritless. Speculation with zero test data to back it up. Some terrible journalist driveling on to hear his own voice or read his own words about feel and other touchy feely crap is the likely explanation. What about the real observation and reason for BMW M going with NA compared to FI because it offers instant throttle response (hence more jerk). Yeah I guess BMW M got it wrong and made the 335i the faster and more responsive car compared to the M.

[lucid]

Originally Posted by swamp2

Let the speculation continue... Although I am not saying it is totally false, without a test, real data and real results I call 100% speculation on many of your points above. Have you seen a part throttle torque curve of the 335i or the M3. I'll answer for you - you haven't.

I tend to agree with Swamp here. Although what Bruce is saying is entirely possible, I have not seen any data to suggest that is indeed the case.

I am also not clear on some of the other points Bruce made. I can see how those issues might all factor into a perception of speed and acceleration, but not necessarily in the way he describes them. But those are subjective issues, so I woudn't say more.

I still think Bruce is overestimating the effect of the differences in the final drive ratios on rotational inertia related torque "loses". I actually chatted up one of my friends who is a dynamics/controls PhD the other day on this--very solid guy. He also did not think the effect would be significant (anywhere near 10%) between the two cars. I presented him the problem as objectively as I can without presenting my opinion for what it's worth.

Hey, but I will order a copy of Gillespie. I'm sure I can learn from it. And, when I find the time, I'll even check out that section/equation Bruce has referenced to see what it's about.

I'll try this drinking bit again.

[Ronno111]

The '08 M3 produces slightly more torque and the E46 but about 80 more HP. No one ever complained about the e46 before and that car was THE KING OF THE ROAD as far as bimmers and most other cars are concerned.

Feeling fast and being fast are 2 different things. Some of you guys are making it sound like you hit the pedal on the m3 and not much really happens unless you gun it. I think that is total BS.

Bottom line,,, any non M owner is insanely jealous of M owners. They will mod their cars with juiceboxes and fruit rollups to the point they can say they are faster than a totally stock M car. Sorry, I was in that group when I ordered my 335xi with dinan upgrade, m-tech kit and all the fixins until I woke up one morning in a cold sweat after 2 months of terrible sleepless nights and said "HOLY Shit, what am I doing- spending $57k on a modded 335 and it will NEVER be an M!!!"

That day I canceled my order and now waiting for my M car. It will be stock and I won't change a thing. I will drive my High rev car, guzzling up all the gas I can, and looking like a super star.

POINT and MORAL: I have never slept better since I changed my order to an M3. Buy an M and set the standard EVERY ONE on the road strives to beat.

[GregW / Oregon]

Originally Posted by Ronno111

Bottom line,,, any non M owner is insanely jealous of M owners. They will mod their cars with juiceboxes and fruit rollups to the point they can say they are faster than a totally stock M car. Sorry, I was in that group when I ordered my 335xi with dinan upgrade, m-tech kit and all the fixins until I woke up one morning in a cold sweat after 2 months of terrible sleepless nights and said "HOLY Shit, what am I doing- spending $57k on a modded 335 and it will NEVER be an M!!!"

That day I canceled my order and now waiting for my M car. It will be stock and I won't change a thing. I will drive my High rev car, guzzling up all the gas I can, and looking like a super star.

POINT and MORAL: I have never slept better since I changed my order to an M3. Buy an M and set the standard EVERY ONE on the road strives to beat.

While I choose my cars based on the best performing car that meets my other needs, I must admit that driving an M car gives another kind of satisfaction. It is not the fastest or best at everything, but it is a car you will never be embarrased by. I'm not constantly shopping, but when I buy something it will be researched and the best. That gives satisfaction whenever I use the item, whether it is a car, a watch, a camera or whatever.

[swamp2]

Originally Posted by Ronno111

The '08 M3 produces slightly more torque and the E46 but about 80 more HP. No one ever complained about the e46 before and that car was THE KING OF THE ROAD as far as bimmers and most other cars are concerned.

Feeling fast and being fast are 2 different things. Some of you guys are making it sound like you hit the pedal on the m3 and not much really happens unless you gun it. I think that is total BS.

Bottom line,,, any non M owner is insanely jealous of M owners. They will mod their cars with juiceboxes and fruit rollups to the point they can say they are faster than a totally stock M car. Sorry, I was in that group when I ordered my 335xi with dinan upgrade, m-tech kit and all the fixins until I woke up one morning in a cold sweat after 2 months of terrible sleepless nights and said "HOLY Shit, what am I doing- spending $57k on a modded 335 and it will NEVER be an M!!!"

That day I canceled my order and now waiting for my M car. It will be stock and I won't change a thing. I will drive my High rev car, guzzling up all the gas I can, and looking like a super star.

POINT and MORAL: I have never slept better since I changed my order to an M3. Buy an M and set the standard EVERY ONE on the road strives to beat.

Honest, brash, well written and well thought out. Maybe a bit extreme, but more or less I agree. Good post.

[e36jakeo]

I guess I am a bit confused why you guys have spent hours, or perhaps days, at this point arguing back and forth about some pretty nitty gritty details regarding how to guess how fast a car will be. As far as I can tell if you have:

1) Car's HP
2) Car's weight
3) Assume mnft will gear it in a way that takes advantage of its torque curve
4) A benchmark of a car of similar weight and HP

you can get to numbers that are as close as your complex simulators.

Example: C & D tests a 3240 lb Porsche GT3 and achieves 1/4 mile in 12.0 @ 118 MPH. The M3 makes identical HP and torque, is geared a bit shorter in 1st-3rd, and weighs about 10% more and has a bit less traction off the line due to less weight over the rear wheels. Yeah, I'd guess about 12.7@114 MPH. I guessed very similar figures even before the car came out based upon projected weight and HP (and comparing it to what the M5 has achieved with a bit better HP to weight).

Anyways, I guess you guys like typing a lot, and it is fun to read the banter.

[GarryF]

It's even simpler than that, if the OP had changed throttle response on the M3 to highest setting he'd have found it just as responsive I bet pushing the M button made a big difference to throttle response on my test drive

[lucid]

Originally Posted by e36jakeo

I guess I am a bit confused why you guys have spent hours, or perhaps days, at this point arguing back and forth about some pretty nitty gritty details regarding how to guess how fast a car will be. As far as I can tell if you have:

1) Car's HP
2) Car's weight
3) Assume mnft will gear it in a way that takes advantage of its torque curve
4) A benchmark of a car of similar weight and HP

you can get to numbers that are as close as your complex simulators.

Example: C & D tests a 3240 lb Porsche GT3 and achieves 1/4 mile in 12.0 @ 118 MPH. The M3 makes identical HP and torque, is geared a bit shorter in 1st-3rd, and weighs about 10% more and has a bit less traction off the line due to less weight over the rear wheels. Yeah, I'd guess about 12.7@114 MPH. I guessed very similar figures even before the car came out based upon projected weight and HP (and comparing it to what the M5 has achieved with a bit better HP to weight).

Anyways, I guess you guys like typing a lot, and it is fun to read the banter.

Sure, I do 1/4 mile runs during my commute every single day! And I guess we also like typing although I'm pretty worn out on this one.

[bruce.augenstein@comcast.]

Originally Posted by swamp2

...Stop the insults and exaggerations Bruce it is getting so old. What part of our previous lengthy debate on this topic did you miss? Drag out all of those old sims on the TRS-80 and timeslips per my previously unanswered challenge to you and put your money where you mouth is. Show the world how much better you are at automobile performance simulation than swamp...

Strange as it may seem, in my own mind I haven't viewed this as a competition. Disagreement as to what routine accuracy is, yes. Competition? No.

It would've been nice if I had saved all that old data, but I haven't. However, I do in fact have some old spreadsheets I used to list various runs, and with the newfound copy of QJ, I thought I'd take a crack at modelling one of those runs. Unfortunately, the spreadsheets largely lack those back-of-timeslip notes, but I do in fact remember one particular run fairly well, since it was the first time I ran my old (stock) E36 M3 into the thirteens. I know that QJ is the loss-leader, Quarter lite model (and if memory serves, they say it's accurate to within "only" a tenth), but what the heck.

Herewith the results:

Timeslip Data---------------Actual---------------------Quarter, Jr.
60’-------------------------2.035----------------------2.04
330’------------------------5.814----------------------5.79
660’------------------------8.968----------------------8.95
MPH------------------------78.09----------------------78.1
1000’-----------------------11.68----------------------11.66
1320’-----------------------13.993---------------------13.96
MPH------------------------98.41----------------------98.3

(I have the full data, but don't know how to include it in this document.)

So even with this tool, the accuracy is very good, without any shenanigans on my part. In fact, with this simplistic tool, there isn't any room for shenanigans. My belief is that CarTest will be at least that accurate when matched against an actual timeslip.

Originally Posted by swamp2

Even given precise control of an event like a 1/4 mi run, variations will still exist and those will be larger than the accuracy that you keep claiming is "required" and that you claim you have obtained (.01 seconds, consistently and across the entire 1/4 mi was your claim...). If you have a robot drive a infinitely precisely prepped vehicle in a vaccuum on virgin, chemically precise asphalt and can do that over and over again with very little variation and then adjust unknown or unmeasureable input parameters to ex post facto match a simulation to a test that is called cheating, not simulation. I have agreed that professional drag racing is generally more precise than magazine automobile performance testing and the goal of simulation in such a scenario is different than the goal of making A-B comparisions between consumer vehicles and trying to match reported results from either owner runs or magazine results. The goal here is to even out natural variations with the precise control that simulation offers, thus you can judge the CAR, at it's best, and not the driver or weather or track or whatever. Quite simply is car A faster than car B, all things equal.

So accuracy that is substantially better than what you're claiming is reasonable is...cheating?

OK, you're as much as calling me a liar already, so I can live with cheater. I assure others that cheating is not part of the deal. I just plug the numbers in, and see what happens...

Originally Posted by swamp2

I agree that I did not know exactly what transmission loss values to use in CarTest. I suspected and agreed that the defaults were a bit too high. But I also stick to my belief that the values you have suggested are too low. In fact in this very thread you admitted you made up one of your figures. What is better ignorance or fabrication?

What? Fabrication? OK, that's the second time you're calling me a liar, and enough is enough. I made a simple mistake (taking numbers from a chart that really doesn't address the issue), and when I discovered that, I mentioned it. "Admit" it? I guess, but nobody beat it out of me. More like "stated" it. Back off a little, please. The other figures are simply lifted as standard sample fare from a sample problem.

Originally Posted by swamp2

How much difference did this terrible, gross, unforgiveable error of mine make, let me remind you, .2 seconds to 60, .4 seconds in the 1/4. Some will continue to view this as gross and "a mile off" others will look at the range of reported results and see that both predictions approximately bracket the reported results and conclude, as I have, that the drivetrain losses are almost for sure somewhere between the default values I initially used and the ones you pulled from Gillespie. Again I would argue that the defaults the CarTest author chose may be more appropriate for lower performance transmissions as opposed to an M or Porsche boxes or the like. Hence the defaults in CarTest being not nearly as bad as you believe for the range of vehicles in the CarTest database (thousands!).

Gillespie didn't have any particular brand name in mind when he constructed those charts with sample information. Four tenths of a second off is ugly, compared to the accuracy deliverable by even a simple tool such as QJ.

Originally Posted by swamp2

I also disagree with your statement that you must match time, distance and speed to obtain a validated simulation. This too goes way back to one of our very old arguments. All you need is one curve, any of (position, speed or acceleration) vs. time as a continuous variable. Then along with proper initial conditions you can take derivates or integrate and derive the other curves perfectly. If you can match any one of these curves with good accuracy the others will fall right in line. If you understood the physics a bit more you would realize this.

The point is, they didn't fall in line for you.

Originally Posted by swamp2

So we simply come back to the same old points. My older sims were within the ranges reported by magazines for most cars I did work on. An exception was a clear and admitted underprediction of 1/4 mi trap speeds. With your revised drivetrain loss figures the few sims I have ran are also again within the range (albeit more toward the level of the outliers - and understandably so) of results reported by magazines and the traps are now significantly closer.

Keep on beating those bloody, pulverized, expired horses Bruce.

Again, we can agree to disagree, apparently while we both beat those bloody, pulverized, expired horses together.

Bruce

[bruce.augenstein@comcast.]

Originally Posted by lucid

I tend to agree with Swamp here. Although what Bruce is saying is entirely possible, I have not seen any data to suggest that is indeed the case.

Since I haven't driven a new M3, I agree that it's all speculation. I probably should have said the 335 is probably faster than the M3 in everyday driving.

Still, since I've been interested in and been a close observer of these everyday driving dynamics over the years, let me say that it's informed speculation.

Originally Posted by lucid

I am also not clear on some of the other points Bruce made. I can see how those issues might all factor into a perception of speed and acceleration, but not necessarily in the way he describes them. But those are subjective issues, so I woudn't say more.

PM me if you feel like it. I've surrepticiously studied every driver I've ever ridden with, from race tracks to granny in her Buick, with the closest attention to how the driver interracts with the car. It's a fascinating topic (for me).

Originally Posted by lucid

I still think Bruce is overestimating the effect of the differences in the final drive ratios on rotational inertia related torque "loses". I actually chatted up one of my friends who is a dynamics/controls PhD the other day on this--very solid guy. He also did not think the effect would be significant (anywhere near 10%) between the two cars. I presented him the problem as objectively as I can without presenting my opinion for what it's worth.

I get a 5% penalty, netting 20% of the M3's 25% advantage.

What I was actually hoping was for hwelvaar and footie to tell me I was full of it, that I was correct, or some mixture of the two.

Their observations are in effect unassailable - because it's not whether the M3 is faster or slower than the 335 in the daily slog, it's how it feels.

...although your "So what?" reaction made me laugh out loud.

Bruce

PS - My bet is that if you were in your shiny new M3 at a light, and your evil twin in a 335 was also at that light, with a 100 yard long wall between you (to keep testosterone levels down), after a normal launch and shift procedure you'd clear that wall with him ahead of you and pulling away.

The bastard.

[swamp2]

Originally Posted by bruce.augenstein@comcast.

...
Herewith the results:

Timeslip Data---------------Actual---------------------Quarter, Jr.
60’-------------------------2.035----------------------2.04
330’------------------------5.814----------------------5.79
660’------------------------8.968----------------------8.95
MPH------------------------78.09----------------------78.1
1000’-----------------------11.68----------------------11.66
1320’-----------------------13.993---------------------13.96
MPH------------------------98.41----------------------98.3

Great Bruce, that is step 1. By the way you are a long way off from your claim of .01 seconds or better! I don't suppose you cherry picked this match at all right this is probably the worst Bruce the simulation god has ever done, right . Now the seconds step is to post multiple slips to show that they are more consistent than the difference between this single run actual vs. simulation. The next step is to explain how you can get a match of BETTER accuracy than the level of uncertainty of the unknowns. You admit you don't know the diff loss. If you can not adjust it how do you know it is right? The same argument applies to all of the inputs for the car. Did you account for the hp change as the car breaks in or did you use the factory numbers? Did you use a worn tire diameter or a new tire diameter? The list of questions that limit the accuracy to which you can simulate is much longer than this list and I have pointed these out many times in the past. Deviations from each one of these effects would be larger than the "routine" accuracy you claim you can get (or than the accuracy shown above as well). What does this all boil down to? Possibly luck, possibly being right for the wrong reasons. These have been my points all along and you still just don't get it.

Originally Posted by bruce.augenstein@comcast.

OK, you're as much as calling me a liar already, so I can live with cheater. I assure others that cheating is not part of the deal. I just plug the numbers in, and see what happens...

What? Fabrication? OK, that's the second time you're calling me a liar, and enough is enough. I made a simple mistake (taking numbers from a chart that really doesn't address the issue), and when I discovered that, I mentioned it. "Admit" it? I guess, but nobody beat it out of me. More like "stated" it. Back off a little, please. The other figures are simply lifted as standard sample fare from a sample problem.

I did not say you are cheating nor that you are a liar. Perhaps you can't read? I simply provided my definition of cheating with simulation. If you tune parameters to match a test to a greater degree of accuracy than is either a) repeatable in test or b) is more accurate than results with reasonable ranges of uncertainty in input parameters, then yes you tuned ex post facto which is a nice way of saying "cheated", if the shoe fits, put it on if not, just humor youself with my terrible and unreasonable definitions of cheating.

My quickie CarTest runs using losses of trans/diff/axles at 4/1/3% and for the higher torque 3.1 liter model and a 3150 curb weight (driver included in sim, not curb) are as below. If your data represents one of the faster times for this model then my thoughts continue that these total losses may still be a a bit low.

As well like with your inciting and insults, I'll say the same, "back off".

[Redadair]

Originally Posted by lucid

What nonsense about the claimed higher low-end torque of the 335 being more suitable for daily driving! Stop staring at dyno charts and reaching such conclusions. Think about the final drive ratio and the individual gear ratios if you are indeed focused on feeling the instantaneous acceleration wheel torque results in.

Tq@Wheels = Tq@WheelDyno x Total Reduction

I made some quick spreadsheet calculations and plots based on dyno data for both cars. Below is the proof that the M3 has more torque at the wheels once you are over 1500 rpms in 1st gear. Who drives a sports car below that, even on public roads?

Dyno data source: http://www.rri.se/popup/performanceg...p?ChartsID=768

What? Can we get a drug test here?

The low end torque of the 335i is far superior to the M3. In fact the M3 never makes as much torque as the 335i does stock at any point in it's RPM range.

Red

[coaster]

Originally Posted by Ronno111

The '08 M3 produces slightly more torque and the E46 but about 80 more HP. No one ever complained about the e46 before and that car was THE KING OF THE ROAD as far as bimmers and most other cars are concerned.

Feeling fast and being fast are 2 different things. Some of you guys are making it sound like you hit the pedal on the m3 and not much really happens unless you gun it. I think that is total BS.

Bottom line,,, any non M owner is insanely jealous of M owners. They will mod their cars with juiceboxes and fruit rollups to the point they can say they are faster than a totally stock M car. Sorry, I was in that group when I ordered my 335xi with dinan upgrade, m-tech kit and all the fixins until I woke up one morning in a cold sweat after 2 months of terrible sleepless nights and said "HOLY Shit, what am I doing- spending $57k on a modded 335 and it will NEVER be an M!!!"

That day I canceled my order and now waiting for my M car. It will be stock and I won't change a thing. I will drive my High rev car, guzzling up all the gas I can, and looking like a super star.

POINT and MORAL: I have never slept better since I changed my order to an M3. Buy an M and set the standard EVERY ONE on the road strives to beat.

Ha ha ha ... I am still laughing from this post. I especially liked this part:

"Bottom line,,, any non M owner is insanely jealous of M owners."

But if that's how you really felt then why did you rush to place an order for a 335xi in the first place? (Sounds like a BS post to me.)

And Swamp ... stop congratulating people like this, your credibility is dropping like a rock.

Onward ...

[swamp2]

Originally Posted by coaster

Ha ha ha ... I am still laughing from this post. I especially liked this part:

"Bottom line,,, any non M owner is insanely jealous of M owners."

But if that's how you really felt then why did you rush to place an order for a 335xi in the first place? (Sounds like a BS post to me.)

And Swamp ... stop congratulating people like this, your credibility is dropping like a rock.

Onward ...

You can let me decide which posts I will support and which I won't thank you very much . Like I said, he was a bit brash in his comments but there is an enormous amount of truth there as well. Perhaps replacing the combination of "any...insanely" with "many...highly" would have been more truthful. Also I still think Ronno had quite a lot of valid things to say in his post outside of that sentence.

[swamp2]

Originally Posted by Redadair

What? Can we get a drug test here?

The low end torque of the 335i is far superior to the M3. In fact the M3 never makes as much torque as the 335i does stock at any point in it's RPM range.

Red

Ugh, have you been reading? What matters for max acceleration is power to the ground divided by weight. Torque and hp at the crank are rather meaningless until you take into account gearing multiplication. The next point of the thread was concerning part throttle torque curves which may be larger in the 335i than the M3.

[swamp2]

Originally Posted by bruce.augenstein@comcast.

PS - My bet is that if you were in your shiny new M3 at a light, and your evil twin in a 335 was also at that light, with a 100 yard long wall between you (to keep testosterone levels down), after a normal launch and shift procedure you'd clear that wall with him ahead of you and pulling away.

The bastard.

Bruce are you crazy, what the heck are you saying. If this is an actual attempt to go fast and you have even moderate skill the M3 would dust the (stock) 335i. If this is another one of your subjective "part", "half", "mellow", "average". "normal", etc. throttle situations then this is an ill formed comparison without enough clear/precise definition to have a known outcome. Ugh....

[bmwm4f82]

Perhaps we should have a separate forum -

"Why the 335i is superior to the M3"

[murellus]

Omg 335 Best Car Bmw Makes M3 Has No Chance Wtf Haxorz Roflol