Z4M vs. 335i "feeling"

[Dammmittt]

Originally Posted by aerobod

I'm sorry that your automotive experience seems to be rather limited. The circumstances of where a car is to be used (specific track, getting from 0-60mph fastest, 1/4 mile times, etc) will determine if there are specific circumstances where a numerically lower rear-end can produce a faster car than a higher one. In general the numerically higher rear end will be faster, but some of the specific circumstances where it can be slower are:

- 0-60mph when the numerically higher rear-end requires 2 gear changes instead of 1.
- On a track when 3rd, 4th, 5th and 6th have to be used, compared with 3rd, 4th & 5th, requiring about 25% more gear changes per lap.
- Passing other cars on the road when a gear change is required, when with the numerically lower rear end it wouldn't be.

Also, with respect to tyre traction, off the line, assuming some clutch slip and wheelspin:

A good summer tyre on a dry road surface will have a static friction of 1.7 and dynamic friction of 1.4
Assuming the tyre is wide enough to minimise any tread block distortion
Assuming a 50/50 weight distribution will change to 60% on the rear wheels due to weight transfer
For a Z4M, the total rear weight during a wheelspinning start will therefore be about 1450kg * 9.81 * 0.6 = 8535N
The friction force to overcome between the tyre and road will be 1.4 * 8535 = 11949N
The loaded tyre radius will be approximately 0.32m
Therefore maximum torque tyre can transmit during wheelspin is 11949 *.32 = 3824Nm (or 4643Nm when the throttle is feathered after launch and traction is maximised)

The Z4M with a stock 3.62:1 rear end will have a torque multiplication of 15.75:1 in first gear, a 4.11:1 rear end 17.88:1. If we assume 12% driveline loss, then the maximum torque at the wheels is 5059Nm and 5743Nm respectively.

Although we can go into more depth, the basic issue in 1st gear for the Z4M is that with good road tyres, maximum engine torque can't be used without wheelspin with either 3.62:1 or 4.11:1 gears, leading to traction as opposed to gear limited acceleration in 1st gear.

BTW, please lay off the Red Bull or other high caffeine energy drinks, there seems to be a common overly aggressive attitude in your posts, as opposed to civilised discussion.

Can't argue with that...I hope aerobod has put this to bed.

[MVF4Rrider]

Originally Posted by aerobod

I'm sorry that your automotive experience seems to be rather limited. The circumstances of where a car is to be used (specific track, getting from 0-60mph fastest, 1/4 mile times, etc) will determine if there are specific circumstances where a numerically lower rear-end can produce a faster car than a higher one. In general the numerically higher rear end will be faster, but some of the specific circumstances where it can be slower are:

- 0-60mph when the numerically higher rear-end requires 2 gear changes instead of 1.
- On a track when 3rd, 4th, 5th and 6th have to be used, compared with 3rd, 4th & 5th, requiring about 25% more gear changes per lap.
- Passing other cars on the road when a gear change is required, when with the numerically lower rear end it wouldn't be.

Also, with respect to tyre traction, off the line, assuming some clutch slip and wheelspin:

A good summer tyre on a dry road surface will have a static friction of 1.7 and dynamic friction of 1.4
Assuming the tyre is wide enough to minimise any tread block distortion
Assuming a 50/50 weight distribution will change to 60% on the rear wheels due to weight transfer
For a Z4M, the total rear weight during a wheelspinning start will therefore be about 1450kg * 9.81 * 0.6 = 8535N
The friction force to overcome between the tyre and road will be 1.4 * 8535 = 11949N
The loaded tyre radius will be approximately 0.32m
Therefore maximum torque tyre can transmit during wheelspin is 11949 *.32 = 3824Nm (or 4643Nm when the throttle is feathered after launch and traction is maximised)

The Z4M with a stock 3.62:1 rear end will have a torque multiplication of 15.75:1 in first gear, a 4.11:1 rear end 17.88:1. If we assume 12% driveline loss, then the maximum torque at the wheels is 5059Nm and 5743Nm respectively.

Although we can go into more depth, the basic issue in 1st gear for the Z4M is that with good road tyres, maximum engine torque can't be used without wheelspin with either 3.62:1 or 4.11:1 gears, leading to traction as opposed to gear limited acceleration in 1st gear.

BTW, please lay off the Red Bull or other high caffeine energy drinks, there seems to be a common overly aggressive attitude in your posts, as opposed to civilised discussion.

No one said anything about 0-60 or 1/4 mile times or any other conventional test measures. THEREFORE EVERYTHING YOU WROTE IS COMPLETELY IRRELEVANT TO THE TOPIC. Congrats! This is simply a discussion of acceleration in the real world on real streets where timing lights and electronic timing doesn't exist. 3 days before Christmas and all this unprovoked strife and drive by shootings. You and Hack are pathetic, immature, and contentious for absolutely no significant reason other than you feel compelled to have your response deemed as superior and simply to toot your own horns at someone else's expense. Any "attitude" on my part is simply a response to someone else's contentious and unprovoked attitude.

BTW, why would you assume 12% driveline loss? Is that some magic number you use? Hope not. And hope you don't use the stated torque figure from the manufacturer either as they are never accurate. And ultimately, you don't choose gear ratios based on the affect in first gear under unrestrained maximum throttle. There is something called throttle control. And you can get wheel spin in any available final drive ratio, including the OEM ratio. You can also not get wheel spin if you exercise throttle control. Then again, who said anything about a launch from dead stopped? In any case, when I speak of "acceleration", I talk in terms of real world usage as in stabbing the throttle and feeling the result (generally speaking). There are no 1/4 mile measurements or 0-60 sprints in my driving world. Probably not yours either. But thanks for sharing. L

[MVF4Rrider]

Originally Posted by Dammmittt

Can't argue with that...I hope aerobod has put this to bed.

Except it's all irrelevant. But I agree, hope it's put to bed as I certainly don't enjoy being attacked in such a cowardly manner (Hack and aerobod). Tis not the season for this kind of childish behavior.

[Mikewarlover]

Originally Posted by aerobod

I'm sorry that your automotive experience seems to be rather limited. The circumstances of where a car is to be used (specific track, getting from 0-60mph fastest, 1/4 mile times, etc) will determine if there are specific circumstances where a numerically lower rear-end can produce a faster car than a higher one. In general the numerically higher rear end will be faster, but some of the specific circumstances where it can be slower are:

- 0-60mph when the numerically higher rear-end requires 2 gear changes instead of 1.
- On a track when 3rd, 4th, 5th and 6th have to be used, compared with 3rd, 4th & 5th, requiring about 25% more gear changes per lap.
- Passing other cars on the road when a gear change is required, when with the numerically lower rear end it wouldn't be.

Also, with respect to tyre traction, off the line, assuming some clutch slip and wheelspin:

A good summer tyre on a dry road surface will have a static friction of 1.7 and dynamic friction of 1.4
Assuming the tyre is wide enough to minimise any tread block distortion
Assuming a 50/50 weight distribution will change to 60% on the rear wheels due to weight transfer
For a Z4M, the total rear weight during a wheelspinning start will therefore be about 1450kg * 9.81 * 0.6 = 8535N
The friction force to overcome between the tyre and road will be 1.4 * 8535 = 11949N
The loaded tyre radius will be approximately 0.32m
Therefore maximum torque tyre can transmit during wheelspin is 11949 *.32 = 3824Nm (or 4643Nm when the throttle is feathered after launch and traction is maximised)

The Z4M with a stock 3.62:1 rear end will have a torque multiplication of 15.75:1 in first gear, a 4.11:1 rear end 17.88:1. If we assume 12% driveline loss, then the maximum torque at the wheels is 5059Nm and 5743Nm respectively.

Although we can go into more depth, the basic issue in 1st gear for the Z4M is that with good road tyres, maximum engine torque can't be used without wheelspin with either 3.62:1 or 4.11:1 gears, leading to traction as opposed to gear limited acceleration in 1st gear.

BTW, please lay off the Red Bull or other high caffeine energy drinks, there seems to be a common overly aggressive attitude in your posts, as opposed to civilised discussion.

From my understanding does that mean changing final gear ratio to 3.91 or 4.11 will not change acceleration in first gear but it will still make accerleration in 2nd 3rd and 4th gear much stronger that is still pretty good in my opinion cause when do u really need 6th gear.

[MVF4Rrider]

Originally Posted by Mikewarlover

From my understanding does that mean changing final gear ratio to 3.91 or 4.11 will not change acceleration in first gear but it will still make accerleration in 2nd 3rd and 4th gear much stronger that is still pretty good in my opinion cause when do u really need 6th gear.

It'll make it quicker in every gear, although you may have to exercise a little more throttle control in first (which takes practice to optimize). Options to take if experiencing excessive wheel spin is either to back off the throttle a slight bit to regain grip or change up. From there the lower gearing is nothing but a plus save fuel economy. Hopefully no one will roll in with out-of-context 1/4 mile or 0-60 BS.

[aerobod]

Originally Posted by MVF4Rrider

No one said anything about 0-60 or 1/4 mile times or any other conventional test measures. THEREFORE EVERYTHING YOU WROTE IS COMPLETELY IRRELEVANT TO THE TOPIC. Congrats! This is simply a discussion of acceleration in the real world on real streets where timing lights and electronic timing doesn't exist. 3 days before Christmas and all this unprovoked strife and drive by shootings. You and Hack are pathetic, immature, and contentious for absolutely no significant reason other than you feel compelled to have your response deemed as superior and simply to toot your own horns at someone else's expense. Any "attitude" on my part is simply a response to someone else's contentious and unprovoked attitude.

BTW, why would you assume 12% driveline loss? Is that some magic number you use? Hope not. And hope you don't use the stated torque figure from the manufacturer either as they are never accurate. And ultimately, you don't choose gear ratios based on the affect in first gear under unrestrained maximum throttle. There is something called throttle control. And you can get wheel spin in any available final drive ratio, including the OEM ratio. You can also not get wheel spin if you exercise throttle control. Then again, who said anything about a launch from dead stopped? In any case, when I speak of "acceleration", I talk in terms of real world usage as in stabbing the throttle and feeling the result (generally speaking). There are no 1/4 mile measurements or 0-60 sprints in my driving world. Probably not yours either. But thanks for sharing. L

I'm sorry that you seem incapable of civilised discussion. You seem to be highly irritated by anyone that has a difference of opinion to yourself. BTW do you understand what Immature even means? You have all the traits of immaturity: http://www.merriam-webster.com/dictionary/immaturity

When you have more experience, you will find that the whole package (transmission ratios, rear end ratios, engine torque profile, etc) is important. Having the right gear ratio at the right time in real world situations for best acceleration doesn't always mean the lowest rear-end ratio if you have to make more gear changes during the acceleration.

The 12% driveline loss figure is a reasonable estimate for BMW manual transmission cars, based on quoted power and torque values vs rear wheel measured values. BMW quoted torque values have also been shown in the past to fall in the range of -1% to +10% of nominal values.

[Dammmittt]

Again, I agree.

[Mikewarlover]

I think both of u guys have some impressive and important points but all said and done. Changing the final gear ratio along will still improve the performance greatly in gears that we will actully get to use everyday. Plz stop all the personal attacks

[MVF4Rrider]

Originally Posted by aerobod

I'm sorry that you seem incapable of civilised discussion. You seem to be highly irritated by anyone that has a difference of opinion to yourself. BTW do you understand what Immature even means? You have all the traits of immaturity: http://www.merriam-webster.com/dictionary/immaturity

When you have more experience, you will find that the whole package (transmission ratios, rear end ratios, engine torque profile, etc) is important. Having the right gear ratio at the right time in real world situations for best acceleration doesn't always mean the lowest rear-end ratio if you have to make more gear changes during the acceleration.

The 12% driveline loss figure is a reasonable estimate for BMW manual transmission cars, based on quoted power and torque values vs rear wheel measured values. BMW quoted torque values have also been shown in the past to fall in the range of -1% to +10% of nominal values.

This is comical. Yeah, you win the prize for being civilized and your first para I guess is just a slip up to your norm. 14 posts and you're picking a fight with someone? I'm more than happy to discuss things in nothing but a civilized manner. But that doesn't mean I appreciate cowardly personal attacks...completely unprovoked...because someone disagrees with anything I write.

Ultimately, the real world isn't a road corse. You can't set up your gearbox to deliver the perfect terminal speed per gear for every situation you encounter. Sure, a shorter final ratio will cause you to shift more often and you might run out of a gear at a less optimium point. Who cares? Deal with it. That's a trade off for the increased acceleration. But it doesn't change the fact that the car will accelerate quicker with shorter final drive gearing in the vast majority of situations. Put it this way. Two identical Z4Ms other than one has stock final drive and the other a shorter final drive. Which do you think would be quicker around Nurburgring, same driver?

If you prefer to keep your stock gear ratios instead of having the increased acceleration benefit then by all means. Personally I'm keeping my stock ratios as I'm satisfied with the acceleration and don't want to reduce the fuel economy any more than it already is. But that doesn't mean I can't appreciate the difference shorter gearing makes. In fact, in my last 2 Ducatis I shortened the gearing by adding 2 teeth to the final drive sprocket and the difference in acceleration was amazing. No way would I do that to my MV Agusta as it's too quick as it is. My MV already hits 150 mph in the 1/4 mile.

Anyway...feel free to attack me some more!

[Dammmittt]

Originally Posted by MVF4Rrider

This is comical.

Yes it is, but only because of the way you're reacting to his posts.

Originally Posted by MVF4Rrider

Anyway...feel free to attack me some more!

He's not attacking you, he's pointing out what you're failing to consider, and all you've done is blow him off and freak out. Chill out man.

[MVF4Rrider]

Originally Posted by Dammmittt

Yes it is, but only because of the way you're reacting to his posts.



He's not attacking you, he's pointing out what you're failing to consider, and all you've done is blow him off and freak out. Chill out man.

It just isn't necessary to add-in the little digs that are only there to belittle someone. It's just rude and unnecessary. If you don't make a point of it then you're condoning it. It's not freaking out as you put it. It's a desire to stop the digs which serve no useful purpose. I guess I could have told you to chill out after O-Cha called you an idiot (more or less) and you responded with both barrels. The legal term "standing" has application here.

Regardless, happy holidays and my apologies for anything considered rude on my behalf.

[Dammmittt]

Originally Posted by MVF4Rrider

It just isn't necessary to add-in the little digs that are only there to belittle someone. It's just rude and unnecessary. If you don't make a point of it then you're condoning it. It's not freaking out as you put it. It's a desire to stop the digs which serve no useful purpose. I guess I could have told you to chill out after O-Cha called you an idiot (more or less) and you responded with both barrels. The legal term "standing" has application here.

Regardless, happy holidays and my apologies for anything considered rude on my behalf.

True, I've been known to argue pointlessly about something that I just happen to be knowledgeable about, and try to beat it into the other person's head that they are wrong.

And on that note cheers!

[aerobod]

Originally Posted by MVF4Rrider

This is comical. Yeah, you win the prize for being civilized and your first para I guess is just a slip up to your norm. 14 posts and you're picking a fight with someone? I'm more than happy to discuss things in nothing but a civilized manner. But that doesn't mean I appreciate cowardly personal attacks...completely unprovoked...because someone disagrees with anything I write.

Ultimately, the real world isn't a road corse. You can't set up your gearbox to deliver the perfect terminal speed per gear for every situation you encounter. Sure, a shorter final ratio will cause you to shift more often and you might run out of a gear at a less optimium point. Who cares? Deal with it. That's a trade off for the increased acceleration. But it doesn't change the fact that the car will accelerate quicker with shorter final drive gearing in the vast majority of situations. Put it this way. Two identical Z4Ms other than one has stock final drive and the other a shorter final drive. Which do you think would be quicker around Nurburgring, same driver?

If you prefer to keep your stock gear ratios instead of having the increased acceleration benefit then by all means. Personally I'm keeping my stock ratios as I'm satisfied with the acceleration and don't want to reduce the fuel economy any more than it already is. But that doesn't mean I can't appreciate the difference shorter gearing makes. In fact, in my last 2 Ducatis I shortened the gearing by adding 2 teeth to the final drive sprocket and the difference in acceleration was amazing. No way would I do that to my MV Agusta as it's too quick as it is. My MV already hits 150 mph in the 1/4 mile.

Anyway...feel free to attack me some more!

If you go back through the thread, you will realise that your attitude was condescending towards my post, before I reacted in the same way to yours. I may have only posted 14 times here, but across bimmerfest (as jsc), bimmer.org (as jsc), zpost and bimmerforums I have well over 1000 posts.

Anyway, it is pointless for me to argue any more with you, I have my opinion, you have yours and as I prefer discussing and debating the points as opposed to arguing about them, I won't add any more to this particular post. In life there are very few binary outcomes, most things are positioned somewhere on an infinitely sliding scale from one extreme to the other, but rarely at the extremes.

[The HACK]

Originally Posted by MVF4Rrider

You want a real beat down, let me know. In the meantime, quit being such a forum chicken s**t by talking big from thousands of miles away. You wouldn't do that to my face... Reagrdless, it's just unnecessary and shows a lack maturity to turn what anyone says into a personal attack. You can disagree without resorting to this kind of adolescent behavior.

BTW, what you wrote is incomplete and misleading. Acceleration comes from the amount of multiplied torque across the rpm range being used in each gear. That means for first gear it's the multiplied torque at each and every rpm from launch rev/clutch disengagement rev to redline, and each gear thereafter from the point the rev counter lands after shift to redline. It's also the combination of the elements working together that affects this (engine torque output per rpm and engine efficiency (from design to tune), gear ratio, final drive, rear tire circumference, mass, aero efficiency, tire grip).

By simply changing the final drive to any available shorter gear in the marketplace (given), you will produce more multiplied torque at every rpm in which your rev counter experiences. All things remaining equal (all other variables), your car will accelerate quicker. Case closed.

The other theoretical hogwash (aerobod) about too short of gearing causing adverse affects isn't something that could or would happen considering the aftermarket gearing options under discussion, unless your tires no longer have any grip and/or your car is sitting on ice. You have to assume during these discussions that conditions are somewhat normal (dry and warm) and that people know how to drive their cars and the car is in passable safety condition (ie, the tires are within wear limits).

Really? I've talked down to ignorant fools like this in person. Stupidity is stupidity...Like your claim that replacing US headers and cats with Euro headers and cats will magically gain you 17hp and umpteen ft-lbs.

http://www.bimmerfest.com/forums/sho...3&postcount=64

Or your claims that TORQUE is the only thing that matters to acceleration.

http://forums.bimmerforums.com/forum...=908998&page=3

Or your bogus claims that 335i gearing is shorter than E46 M3?

http://bmwcca.org/forum/showthread.php?t=1013&page=2

You have absolutely no understanding of how engine, gear, torque, and RPM works. Stop posting your BS on these boards unless you have actual REAL insight.

[Hawkeye]

Originally Posted by The HACK

Really? I've talked down to ignorant fools like this in person. Stupidity is stupidity...Like your claim that replacing US headers and cats with Euro headers and cats will magically gain you 17hp and umpteen ft-lbs.

http://www.bimmerfest.com/forums/sho...3&postcount=64

Or your claims that TORQUE is the only thing that matters to acceleration.

http://forums.bimmerforums.com/forum...=908998&page=3

Or your bogus claims that 335i gearing is shorter than E46 M3?

http://bmwcca.org/forum/showthread.php?t=1013&page=2

You have absolutely no understanding of how engine, gear, torque, and RPM works. Stop posting your BS on these boards unless you have actual REAL insight.

Oh snap. Just to let y'all know... I don't know what you are saying or who is right but this thread sure is entertaining

[Dammmittt]

Originally Posted by Hawkeye

Oh snap. Just to let y'all know... I don't know what you are saying or who is right but this thread sure is entertaining

[Burt Reynolds]

easy fellas. get a brew and lets all relax a little. Happy holidays to all fellow Z enthusiasts.

[Mikewarlover]

Originally Posted by Burt Reynolds

easy fellas. get a brew and lets all relax a little. Happy holidays to all fellow Z enthusiasts.

+1

[MVF4Rrider]

Originally Posted by The HACK

Like your claim that replacing US headers and cats with Euro headers and cats will magically gain you 17hp and umpteen ft-lbs.

My God, you never quit. Already stated two things. One, Turner Motorsports makes the claim to the torque loss by those figures due to the difference to the US and Euro exhaust systems only. Go jump in their case if you think they're stupid. As for the gearing between the 335i and M3, I made a calculation error on my spreadsheet which through off the whole outcome. I came clean on that, but I guess that doesn't count. All else is dead on.

Not sure why you and O-Cha seem to disregard the normal forum etiquette that keeps everyone from doing nothing but what you both do, which is to take disagreement to the disparaging level.

Quit being pathetic and giving life to this crap. You must really have masculinity issues. Probably the worst thing about car ownership these days is forums and the few idiots which allow their unhappy lives to spill over unto others. For the last time, there's no reason to make anything personal. Now go sign up for an anger management class.

I really wish age was visible for all to see. It would explain a lot.

[BZZZE]

I'm with Hawk...this thread is entertaining but someone posted this in another thread at it applies here.