[bnj]

Originally Posted by Driver72

The MT might drop less BETWEEN each gear shift, but the AT will still be spinning more rpms as it has a "shorter" more aggressive gearing in 1st through 4th gear.

To put it short, the flaw in the above is that the shifts do not happen in the same time and you cannot just compare the gears to the respective gears in other tranny. MT has more puff in each gear enabling MT to deploy 1st against AT's 2nd, 2nd against AT's 3rd etc. Not for a long, but long enough for MT to be able to use the highest parts of the hp curve more than the AT and so being able to accelerate faster from one speed to another.

[Driver72]

Originally Posted by bnj

You need to think the big picture. Take a random speed. It is very likely that AT needs to shift sooner and thus run at low revs soonr than MT. AT starts running low revs not only sooner than MT, but also lower than MT.

Take for example 50mph. AT needs to change soon to low revs whereas MT can be kept on the high powerband a lot longer. From this speed to top speed the sum of the integrals under the power curves at each gear is much much more favourable for MT than for AT. Do some integration and you will see

This is self evident for people having spent time with competition cars. It is essential to have close-ratio gearing. Typically the first gear is tall and the subsequent gears are close to each other so that the top gear is comparatively short. This is the way for a car to deploy the highest possible part of power curve all the time. Never dropping too low in revs.

Ok. I'm going to point this out one last time.

In your 50 mph example.
The AT will need to shift from 2nd to 3rd sooner, that is correct, but because of the lower gearing it will have accelerated FASTER from the second you hit go. That will give the AT a bit of a lead (say 5 feet). Then it will change gears, the MT will gain part of that lead back (say 3 feet) because it's still in the lower gear for an extra second.
But then the MT will need to shift to 3rd.

At that point the AT again is higher up in the rev range than the MT and charging FASTER towards redline and it will start to pull a bit more on the MT (say another 5 feet).

Then the the AT will have to shift into 4th while the MT is still in 3rd for another split second and gain some back (say another 3 feet). But then the MT has to shift to 4th, again at which point the AT has been in that gear for a second and because of this and it's shorter more aggressive 4th gear it will be higher up in the rev range and accelerating faster. This will make it pull away some more (say another 5 feet).

Then at the top of 4th going 120ish mph the race ends. At this point the AT would be about 9 feet (1/2 car length) in the lead.

I don't know about you, but I've been racing for 19 years.
I've seen this played out time and time again.

The closeness of the gear ratios doesn't determine acceleration.
Sure in a car that has a HUGE gap between say 2nd and 3rd there will be a big acceleration drop off.
But in the case of the 335i MT vs. AT both cars have 6 gears.
The MT might be spaced more closely but each of the first 4 of those gears are taller in the MT and shorter in the AT.
The shorter the gearing the faster the car will accelerate.

When people/racers want their cars to accelerate faster they drop in shorter final drive ratios, they don't re-gear their tranny with closer gear ratios but make them taller/less aggressive.

I'm out on this discussion.
If you don't understand it at this point, I don't think I can explain it any further. Take care and good luck.

[bnj]

You keep repeating the same. In the example MT at 50mph is at its sweet spot almost at the flat hp curve and a lot of good-hp revs ahead of it. Your 5ft for AT will not happen. AT has lost the second it needs to shift.

Acceleration is a direct function of the integral under the deployed hp curve. Close ratio tranny is able to deploy the highest parts of the curve. As simple as that.

[Insider]

Originally Posted by Driver72

Ok. I'm going to point this out one last time.

In your 50 mph example.
The AT will need to shift from 2nd to 3rd sooner, that is correct, but because of the lower gearing it will have accelerated FASTER from the second you hit go. That will give the AT a bit of a lead (say 5 feet). Then it will change gears, the MT will gain part of that lead back (say 3 feet) because it's still in the lower gear for an extra second.
But then the MT will need to shift to 3rd.

At that point the AT again is higher up in the rev range than the MT and charging FASTER towards redline and it will start to pull a bit more on the MT (say another 5 feet).

Then the the AT will have to shift into 4th while the MT is still in 3rd for another split second and gain some back (say another 3 feet). But then the MT has to shift to 4th, again at which point the AT has been in that gear for a second and because of this and it's shorter more aggressive 4th gear it will be higher up in the rev range and accelerating faster. This will make it pull away some more (say another 5 feet).

Then at the top of 4th going 120ish mph the race ends. At this point the AT would be about 9 feet (1/2 car length) in the lead.

I don't know about you, but I've been racing for 19 years.
I've seen this played out time and time again.

The closeness of the gear ratios doesn't determine acceleration.
Sure in a car that has a HUGE gap between say 2nd and 3rd there will be a big acceleration drop off.
But in the case of the 335i MT vs. AT both cars have 6 gears.
The MT might be spaced more closely but each of the first 4 of those gears are taller in the MT and shorter in the AT.
The shorter the gearing the faster the car will accelerate.

When people/racers want their cars to accelerate faster they drop in shorter final drive ratios, they don't re-gear their tranny with closer gear ratios but make them taller/less aggressive.

I'm out on this discussion.
If you don't understand it at this point, I don't think I can explain it any further. Take care and good luck.

+1 This is correct.

[Driver72]

Sorry, I had to post one last time because your last post was so funny.

Originally Posted by bnj

In the example MT at 50mph is at its sweet spot almost at the flat hp curve and a lot of good-hp revs ahead of it.

Dude seriously, where exactly do you think the AT would be?
It will be in a SWEETER spot, about 100 rpms above the MT's point.
With the AT shorter gearing and the fact it's 100 rpms higher in the rev range it WILL accelerate faster the second you touch the gas. That WILL give it a bit of a lead.

Originally Posted by bnj

Your 5ft for AT will not happen. AT has lost the second it needs to shift.

So the MT doesn't have to shift? What do you think will happen when the AT shifts in 100 milliseconds but a split second later when the manual driver has to shift and that shift takes .2 seconds?
I'll tell you, the MT driver will fall back further as his shift takes 10 times longer to make and when he hits 3rd his rpms will drop to a lower rpm than the auto trannies did because the AT has a SHORTER 3rd gear ratio!!!

Originally Posted by bnj

Acceleration is a direct function of the integral under the deployed hp curve. Close ratio tranny is able to deploy the highest parts of the curve. As simple as that.

Dude, you are so wrong.
If it's as simple as that, then a 335i with the following gear ratios would destroy us all.
1st - 3.00
2nd - 2.80
3rd - 2.60
4th - 2.40
5th - 2.20
6th - 2.00

Those gear ratios are so close man that car would live between 6700-7000 rpms at every shift.
That is NOT going to make it accelerate FASTER!

It is NOT about how close the gear ratios are in two cars with the same number of gears!!!! It's about the GEARING and the DRIVE ratio.

Go hit a track or drag strip, and talk to other racers.
Show them the gear ratios and final drive ratios of the manual and auto and ask them "all else being equal" which car would accelerate faster?
You'll see that every one of them will tell you the car with the gears and final drive ratio the auto has. Then tell them that car's tranny is an auto that also shift about 10 times faster than a human can do in the manual in the other car. See what they say.

Oh, btw, I've been driving manuals all my life in dozens and dozens of cars. The 335i is the first auto performance car I've owned.
I'm a big fan of manuals, but ain't blind to the facts.

Over and out for real now!

[musc]

Originally Posted by Driver72

Sorry, I had to post one last time because your last post was so funny.



Dude seriously, where exactly do you think the AT would be?
It will be in a SWEETER spot, about 100 rpms above the MT's point.
With the AT shorter gearing and the fact it's 100 rpms higher in the rev range it WILL accelerate faster the second you touch the gas. That WILL give it a bit of a lead.





So the MT doesn't have to shift? What do you think will happen when the AT shifts in 100 milliseconds but a split second later when the manual driver has to shift and that shift takes .2 seconds?
I'll tell you, the MT driver will fall back further as his shift takes 10 times longer to make and when he hits 3rd his rpms will drop to a lower rpm than the auto trannies did because the AT has a SHORTER 3rd gear ratio!!!




Dude, you are so wrong.
If it's as simple as that, then a 335i with the following gear ratios would destroy us all.
1st - 3.00
2nd - 2.80
3rd - 2.60
4th - 2.40
5th - 2.20
6th - 2.00

Those gear ratios are so close man that car would live between 6700-7000 rpms at every shift.
That is NOT going to make it accelerate FASTER!

It is NOT about how close the gear ratios are in two cars with the same number of gears!!!! It's about the GEARING and the DRIVE ratio.

Go hit a track or drag strip, and talk to other racers.
Show them the gear ratios and final drive ratios of the manual and auto and ask them "all else being equal" which car would accelerate faster?
You'll see that every one of them will tell you the car with the gears and final drive ratio the auto has. Then tell them that car's tranny is an auto that also shift about 10 times faster than a human can do in the manual in the other car. See what they say.

Oh, btw, I've been driving manuals all my life in dozens and dozens of cars. The 335i is the first auto performance car I've owned.
I'm a big fan of manuals, but ain't blind to the facts.

Over and out for real now!

You're a better man than me. I would have given up on trying to explain it a long time ago.

[bnj]

Originally Posted by Driver72

Dude seriously, where exactly do you think the AT would be?
It will be in a SWEETER spot, about 100 rpms above the MT's point.
With the AT shorter gearing and the fact it's 100 rpms higher in the rev range it WILL accelerate faster the second you touch the gas. That WILL give it a bit of a lead.

It will not be a SWEETER spot for AT. At 50mph AT shifts quite soon away from its powerband. At 50mph MT has more good revs left than AT.

Originally Posted by Driver72

So the MT doesn't have to shift? What do you think will happen when the AT shifts in 100 milliseconds but a split second later when the manual driver has to shift and that shift takes .2 seconds?
I'll tell you, the MT driver will fall back further as his shift takes 10 times longer to make and when he hits 3rd his rpms will drop to a lower rpm than the auto trannies did because the AT has a SHORTER 3rd gear ratio!!!

I told you already that it takes more time to shift MT, but I'm just educating you to find out what are the reasons for AT being fast. It is NOT gearing. It is its ability to shift fast!
MT uses partly 2nd against AT's third, and because AT's third is short as you said, it needs to shift to fourth when MT can still enjoy its third gear!

Originally Posted by Driver72

Dude, you are so wrong.
If it's as simple as that, then a 335i with the following gear ratios would destroy us all.
1st - 3.00
2nd - 2.80
3rd - 2.60
4th - 2.40
5th - 2.20
6th - 2.00

Those gear ratios are so close man that car would live between 6700-7000 rpms at every shift.
That is NOT going to make it accelerate FASTER!

It is NOT about how close the gear ratios are in two cars with the same number of gears!!!! It's about the GEARING and the DRIVE ratio.

Everyone knows that it is about BOTH the final ratios AND gear ratios. Assuming you are not changing the final drive at the same time as you are accelerating , you can be pretty certain that the gear ratios above would represent a closed ratio gearing. And yes assuming that the shifting does not take time, the close gearing means you deploy the highest part of the power curve. So you would put the highest amount of power to the ground. In practice that gearing is so close that it is effective only at a very limited speed range. Also the practical trade off is that the shifts take time and the presented ratios are not optimal in practice.

Can you perhaps derive another function for acceleration or alternatively prove my function for the acceleration as wrong?

Originally Posted by Driver72

Go hit a track or drag strip, and talk to other racers.

I have been telling that from a speed to another speed close ratio tranny is better for acceleration. However, AT has shorter first gear, so it has an edge during the first feet. This might be the source for your one-sideness since you might be thinking that acceleration takes always place only from stand still...

Also, talking to racers is what I do quite often, but being an educated guy, I usually know a lot better what is the theory behind a specific phenomenon. Often people do not understand what causes what and by how much at the presence of multiple variables. There are guys with multiple decades' experience, but it seems they still don't see the relational weights of different factors.

[x7original4x]

so the verdict is....i dont want to read all of this....

[bnj]

Originally Posted by x7original4x

so the verdict is....i dont want to read all of this....

This was only about which ratios in a tranny put more power to the ground and induce better acceleration. We have not yet been discussing about which is faster, AT or MT. It, in turn would depend on the traction coefficient. With tuned cars acceleration is more dependent on the traction than with stock cars. This is because the traction dependent part is relatively more important and, of course consequently, the power restricted part is less pronounced. So MT might not be able to utilize its power advantage (more power to the wheels due to less transmission loss than AT), and AT shifting faster than MT, AT is at better position when compared to comparing purely stock cars.

Also the possibility for driver error in shifting stick is increased with more power.

Edit:
A good generalization would be though that most of the time AT is faster from stand still, and most of the time MT from a roll. Depending on many factors...

[rallycobra]

bnj - Driver 72 has it completely correct. You have it entirely wrong.

[bman5150]

Originally Posted by Kenny H

I laugh when I read about other people thinking a tranny is 'notchy.' They don't know notchy until they have tried shifting all that power through a tremec. Its enough of an issue for me to consider a built AOD-E at this point....or atleast a T56....

Thank you for the input, I'm thinking automatic more and more....

Amen to that. My '01 GT stang has the horribly notchy tremec 3650. Even the T-56 in the Cobra shifts far better than the 3650 in the late '01 - 04 GTs!

I'll be in the market in early 08 for either a 335i, G8, or EVO X. I need to do an auto this time around for a variety of reasons, which was kinda bumming me out until I test drove a step 335i. It's by far the best true auto I've ever driven. I like VWs DSG a little better, but it's darn close. It's a very smart trans - it was difficult to confuse it - and I tried. Always seemed in the right gear and always was quick to get into the right gear when needed. Sport mode was noticeably better, but even in regular mod it was very nice.

I'm very curious to see how the new EVO's version of the DSG will feel. Ditto for the 6-speed auto that will be available in the upcoming G8. The G8 appeals to my muscle car interest as it's going to come with GM's L98 6.0L V8 with over 360 hp and around 390 torque. I'm worried about overall weight, however.

The only thing that kinda bugs me about the 335i is the lack of an lsd, but I know that topic's been discussed all over this board. At least the aftermarket has a solution now - a pricey one, though!

[bnj]

Let’s have a hypothesis that having short gears makes wonders in acceleration. Specifically, if you compare two trannies, of which one has systematically shorter gears, it must be a lot better acceleration wise. Even more so if there is a huge difference at each gear!

(We know that according to the theory, what accelerates the car fastest is putting the most power down, which happens by deploying only the highest output range in our dyno curve, which can be achieved by tranny that has close ratios so that at upshifting you do not fall too far from the peak power. But let's forget the theory for a while.)

Let’s see if we can test our hypothesis.

Let’s take 3 trannies. AT, MT and SLOW. SLOW is an extreme example of really really tall gearing as opposed to a typical one. Here we have the contenders and respective rear diff ratios multiplied by gear ratios:

Tra: AT MT SLOW
1st 12,8 12,5 7,21
2nd 7,21 7,39 4,68
3rd 4,87 4,68 3,39

Now our experiment has gearings really close between AT and MT and we cannot assume that this makes a difference, but if our hypothesis is true, it is self evident that SLOW having extremely tall gearing would be left far behind the others. Several seconds probably, because some could argue that even the tiny difference between AT and MT could make a difference. But SLOW gearing is so TALL that it is almost out of this world.

To be really sure that SLOW will be toasted, let's accelerate from stand still.

How could we verify our hypothesis to be true? We notice that if we take the first gear away from AT tranny, we have exactly the SLOW tranny. Let's put a tall sixth gear on top of our SLOW tranny and let's run a test.

In fact this experiment has been done and tested in the real life! (Only that in reality the first gear was not removed and the new tall 6th gear was not installed.) One guy used deliberately 2nd as his first gear, and 3rd as his second gear when accelerating to find out the truth. The results are here:

http://www.e90post.com/forums/showthread.php?t=69303

It seems that the resulting acceleration is far from SLOW. Well, let’s just forget our hypothesis. It did not get supported as the results were not extremely poor, despite our hypothesis was that our SLOW gearing is extremely poor.

[BMWPower06]

All this talk about gearing, and you guys are missing the most important point MORE DRIVETRAIN LOSS WITH AUTO!!

[gotturbo]

Originally Posted by bman5150

Amen to that. My '01 GT stang has the horribly notchy tremec 3650. Even the T-56 in the Cobra shifts far better than the 3650 in the late '01 - 04 GTs!

I'll be in the market in early 08 for either a 335i, G8, or EVO X. I need to do an auto this time around for a variety of reasons, which was kinda bumming me out until I test drove a step 335i. It's by far the best true auto I've ever driven. I like VWs DSG a little better, but it's darn close. It's a very smart trans - it was difficult to confuse it - and I tried. Always seemed in the right gear and always was quick to get into the right gear when needed. Sport mode was noticeably better, but even in regular mod it was very nice.

I'm very curious to see how the new EVO's version of the DSG will feel. Ditto for the 6-speed auto that will be available in the upcoming G8. The G8 appeals to my muscle car interest as it's going to come with GM's L98 6.0L V8 with over 360 hp and around 390 torque. I'm worried about overall weight, however.

The only thing that kinda bugs me about the 335i is the lack of an lsd, but I know that topic's been discussed all over this board. At least the aftermarket has a solution now - a pricey one, though!

Being a mustang man myself, here is my story. I bought a 92 GT in 94. It was an AOD. I wanted a manual because I always drove manuals. Always! But this thing had the leather, 21,000 miles, red paint. I just couldn't turn it down and thought, "what the hell" it will be good for driving to work with a coffe and cigarette. (and also a mullett, at that time, LOL) I built that car for 7 yrs, putting a Kenne bell supercharger on it and everything in the book. It was fast. I started to really want a manual again and a clean slate with a better starting point. So I bought an 01 with a 5-speed. Yep! 3650! What a pos when it came to notchy shifting. I never could stand it! Everyone was having problems. Some were replaced to no avail. Some like my sister's 03 were buttery smooth. That is when I decided that I just had a shitty one and couldn't live with it any longer. I hadn't got my 92 sold yet and pretty much could have probably swung it with the wife to keep both. Instead I said to my wife let's trade the 01 in on a new A4 2.0T. So we went to the Audi dealer. We wanted an S4, and were waiting for the new one to come out, but when it did and it was a V8 costing 50 large instead of 41, we were pretty much not wanting to spend that much. It ended up coming down to a brand new 2.0T and a used CPO 01 S4 with about 40,000 miles on it. She picked the fast one. The S4. She felt so sorry for me that she had no choice but to let me convert my AOD to a 5-speed. I did all the labor on my 92. Always. I put in a tremec 3550 and fell in love all over again. I might as well have had a brand new car. Sorry your's is notchy Kenny(OP) but I loved mine. It was sweet. (centerforce dual friction clutch) I finally got the car done in every way. Painted it, minted out the interior, 5-lug conversion, Chrome 18" Saleen's, everything. That is when I decided I was over it. Let somebody else tear it up. Sell it now, while I can get something for it. Brand new 4 wheel disc brakes of Cobra decent, new tires, etc. It sold at the end of last year for 12,900 with 110,000 miles on it. It was a consignment lot so I pocketed 11,500. I saved another 8,500 and put 20,000 down on my 335 E90.
I'm sure all would agree that I am a die hard manual man. That being said, I LOVE MY NEW STEPTRONIC! The whole car is the best of all worlds and I wouldn't trade it for a loaded 750! Hope this helps you Kenny.

[gotturbo]

Here are a couple pic's just cause I'm a pic whore.

[E90Russ]

Just get the manual. You'll never have to defend your decision to your car buddies.

[rallycobra]

I love that Red Stang with white leather!!! I had a 90 5 speed that looked just like yours without the wheels, and grey cloth. Most fun I've ever had in a car! I had a 98 Cobra convertible that was eventually supercharged to 420whp. The 90 was just more fun, the 98 was a little bit impractical as a daily driver. People would get nauseous riding around in it!

I live in the city and drive once a week, which is why I have my current ride. This winter I'll ED a 335xi coupe. Steptronic

I also want to go on the record and say I can shift a manual faster than the step. At the track, I would never take my foot off the gas on the cobra. For the 2-3 shift I would push on the gearshift knob as hard as I could (I can bench 250lbs), and at 6700rpm kick the clutch to the floor and slip my foot off the left side of the pedal when it hit the floor. Try that without doing a CDV mod!

[rallycobra]

Originally Posted by bnj

http://www.e90post.com/forums/showthread.php?t=69303

It seems that the resulting acceleration is far from SLOW. Well, let’s just forget our hypothesis. It did not get supported as the results were not extremely poor, despite our hypothesis was that our SLOW gearing is extremely poor.

bnj - your observation is correct

He was having traction problems. Too much power at the wheels. He started in 2nd to reduce the power at the wheels.

If he had drag radials or AWD, he would have been faster starting in 1st.

If you don't have enough traction, the gears don't help. In 98 mustang cobra on STREET tires, 3.73 final drive was the fastest gear. You feathered the clutch out, and crossed the line at the top of 3rd gear. 13.5 in the 1/4 was a great time on stock tires.

One of the fastest stock cobra guys back in the day was Bob Cosby. He ran 4.56 or 4.88 gears depending on his transmission ratios. At launch he would pop the clutch at 7000 rpm on slicks, and cross the line at the top of fourth gear. With the gears and slicks, he dropped into the 11's with 280rwhp and a 3500lb car. He broke a lot of transmissions too!

[rallycobra]

Originally Posted by BMWPower06

All this talk about gearing, and you guys are missing the most important point MORE DRIVETRAIN LOSS WITH AUTO!!

How much? 5 or 10whp at the most? We aren't talking about a 3 speed from the 60's. Once the torque converter locks, the only increase in power loss is if the auto has more internal friction than a manual. Probably not noticible when you have a procede and 350 whp on tap. 1 or 2% power loss?

[musc]

Originally Posted by rallycobra

How much? 5 or 10whp at the most? We aren't talking about a 3 speed from the 60's. Once the torque converter locks, the only increase in power loss is if the auto has more internal friction than a manual. Probably not noticible when you have a procede and 350 whp on tap. 1 or 2% power loss?

Based on rear wheel dynos, the difference has been 5-10 hp. The difference is negligible considering the engine itself probably varies 5-10 hp.

[Jaws]

Originally Posted by BMWPower06

All this talk about gearing, and you guys are missing the most important point MORE DRIVETRAIN LOSS WITH AUTO!!

Check the dynos. The step is very efficient.

[Bubbarossa]

Originally Posted by Kenny H

My advice to you is to slow down a bit and enjoy the car. Being 16 and given a car like that is akin to your parents handing you a gun. Hopefully it shoots blanks....

Exactly. Parents these days seems so overly protective of their children, however, they'll hand them the keys to a car such as this without a second thought!!!