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      11-16-2011, 11:43 AM   #1
soberin
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Rolling Acceleration Times?

Please give your rolling acceleration times in 3rd gear (6-MT only, E90 only) from 60-80 mph and 80-100 mph.

My "seat of the pants" time with a stopwatch is around 2 to 2.5 sec with M power mode bone stock. It is no different with my Dinan intake and basic Dinan exhaust.
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      11-16-2011, 07:09 PM   #2
soberin
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As I have had no replies, I must ask if there is something wrong with my post?
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      11-16-2011, 11:37 PM   #3
abehwang
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I don't think M-mode does anything with your times.
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      11-16-2011, 11:45 PM   #4
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You want to open things up to DCT and I might be able to contribute...
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      11-17-2011, 02:07 AM   #5
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Quote:
Originally Posted by soberin View Post
Please give your rolling acceleration times in 3rd gear (6-MT only, E90 only) from 60-80 mph and 80-100 mph.

My "seat of the pants" time with a stopwatch is around 2 to 2.5 sec with M power mode bone stock. It is no different with my Dinan intake and basic Dinan exhaust.
I NEVER drive my car that fast! Isn't that illegal?
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      11-17-2011, 05:14 AM   #6
luis_m3
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Quote:
Originally Posted by klammer View Post
You want to open things up to DCT and I might be able to contribute...
- M mode will not affect the times, the driver will...
- 1 on opening thread to DCT
- Not illegal where I am... In fact, highly encouraged!
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      11-17-2011, 10:25 AM   #7
bruce.augenstein@comcast.
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Quote:
Originally Posted by soberin View Post
As I have had no replies, I must ask if there is something wrong with my post?
Yes, sort of...

First of all, it's doubtful that many folks have ever done a test such as you described, especially with those restrictions (E90, 6-speed) which reduce the sample audience. Why would they?

Second, you say your "seat of the pants" time with a stopwatch is around 2 to 2.5 seconds with M power mode bone stock.

I personally don't fully understand what ""seat of the pants time" with a stopwatch" actually means. Let's assume stopwatch times. In addition, what does "around 2 to 2.5 seconds" mean? Let's assume two seconds from 60 to 80 and 2.5 seconds from 80 to 100. The "around" word means you're leaving things pretty open, which is OK, because it's unlikely that anybody else will get times that match, based on vehicle weight with whatever options, with driver and whatever level of gas, plus whatever meteorological conditions exist at the time, plus whatever speedometer variation between cars. Capiche?

Finally, you get to what I assume is the point of your post, which is that the Dinan parts didn't make any difference in your observed times.

OK, here's a cut at that:

Acceleration varies as per the cube root of the power to weight delta, so if Dinan claims, say, a 10% improvement in power, and they're not lying (a rarity in the aftermarket), then your two-second time would theoretically improve to a 1.94, and the 2.5-second time would improve to a 2.42. These are hardly earth-shaking improvements, and in fact are well within a normal margin of error in a stop-watch test environment, especially if the before-and-after tests were done on different days, or in fact at different times on the same day, given normal temperature and other meteorological changes on any given day or between days.

Summing up, don't worry about your observations. Next time you make a change, test 20-100 times in third, or whatever, in order to have a better chance at observing any change in times due to a change in power. If in fact your car will do 20-100 in eight seconds right now, that would convert to a 7.75 with a 10% bump in power, which is enough to show a difference on your stop watch, although still not a dramatic difference.

Bruce
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      11-17-2011, 12:36 PM   #8
soberin
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Quote:
Originally Posted by bruce.augenstein@comcast. View Post
Yes, sort of...

First of all, it's doubtful that many folks have ever done a test such as you described, especially with those restrictions (E90, 6-speed) which reduce the sample audience. Why would they?

Second, you say your "seat of the pants" time with a stopwatch is around 2 to 2.5 seconds with M power mode bone stock.

I personally don't fully understand what ""seat of the pants time" with a stopwatch" actually means. Let's assume stopwatch times. In addition, what does "around 2 to 2.5 seconds" mean? Let's assume two seconds from 60 to 80 and 2.5 seconds from 80 to 100. The "around" word means you're leaving things pretty open, which is OK, because it's unlikely that anybody else will get times that match, based on vehicle weight with whatever options, with driver and whatever level of gas, plus whatever meteorological conditions exist at the time, plus whatever speedometer variation between cars. Capiche?

Finally, you get to what I assume is the point of your post, which is that the Dinan parts didn't make any difference in your observed times.

OK, here's a cut at that:

Acceleration varies as per the cube root of the power to weight delta, so if Dinan claims, say, a 10% improvement in power, and they're not lying (a rarity in the aftermarket), then your two-second time would theoretically improve to a 1.94, and the 2.5-second time would improve to a 2.42. These are hardly earth-shaking improvements, and in fact are well within a normal margin of error in a stop-watch test environment, especially if the before-and-after tests were done on different days, or in fact at different times on the same day, given normal temperature and other meteorological changes on any given day or between days.

Summing up, don't worry about your observations. Next time you make a change, test 20-100 times in third, or whatever, in order to have a better chance at observing any change in times due to a change in power. If in fact your car will do 20-100 in eight seconds right now, that would convert to a 7.75 with a 10% bump in power, which is enough to show a difference on your stop watch, although still not a dramatic difference.

Bruce
Allow me to clarify. There are plenty of folks with E90 M3 6-MT on this forum, so I do not think there is a shortage of samples.

"Seat of the pants" means using a stopwatch in the car, while looking at the speedometer. This is obviously not the same as a computerized or GPS timing system, but is a very easy way to get "ballpark" figures, regardless of the weight of the car and other variables.

Thirdly, the 60-80 and 80-100 speeds are the practical ranges for passing other cars, not the 20-100 time, which is of little practical use.

Lastly, any increase in HP or torque with Dinan's intake and exhaust are seen at wot at redline, and are incremental at best. I just wanted to get a sense of what others may have encountered.
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      11-17-2011, 07:44 PM   #9
bruce.augenstein@comcast.
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Quote:
Originally Posted by soberin View Post
Allow me to clarify. There are plenty of folks with E90 M3 6-MT on this forum, so I do not think there is a shortage of samples.
You're asking about fairly arcane acceleration tests, therefore restricting the sample size doesn't make any sense.

Quote:
Originally Posted by soberin View Post
"Seat of the pants" means using a stopwatch in the car, while looking at the speedometer. This is obviously not the same as a computerized or GPS timing system, but is a very easy way to get "ballpark" figures, regardless of the weight of the car and other variables.
Again, why restrict the sample to E90 6-MT cars if you don't care about the weight or other variables. Why not include DCT, for instance, if "ballpark" is all you care about.

Quote:
Originally Posted by soberin View Post
Thirdly, the 60-80 and 80-100 speeds are the practical ranges for passing other cars, not the 20-100 time, which is of little practical use.
My bad. I thought you were interested in the before/after picture with Dinan mods.

Quote:
Originally Posted by soberin View Post
Lastly, any increase in HP or torque with Dinan's intake and exhaust are seen at wot at redline, and are incremental at best...
Sounds like badly designed parts. Did you buy them for the noise?

Bruce
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      11-18-2011, 03:48 PM   #10
soberin
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[quote=bruce.augenstein@comcast.;10824011]You're asking about fairly arcane acceleration tests, therefore restricting the sample size doesn't make any sense.

Hardly arcane, as these are speeds used in daily driving.

Again, why restrict the sample to E90 6-MT cars if you don't care about the weight or other variables. Why not include DCT, for instance, if "ballpark" is all you care about.

DCT has different gearing than 6-MT. I drive a 6-MT

My bad. I thought you were interested in the before/after picture with Dinan mods.

You are forgiven.

Sounds like badly designed parts. Did you buy them for the noise?

Expensive parts, yes, but not badly designed.



See above comments.
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      11-18-2011, 04:41 PM   #11
bruce.augenstein@comcast.
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Quote:
Originally Posted by soberin View Post
Hardly arcane, as these are speeds used in daily driving.
Yeah, you can tell these aren't arcane tests because of the amazing number of responses you've gotten with specific results included.

Quote:
Originally Posted by soberin View Post
DCT has different gearing than 6-MT. I drive a 6-MT
This would skew the results no more than the other factors I've mentioned - and that you're ignoring.

Quote:
Originally Posted by soberin View Post
Expensive parts, yes, but not badly designed.
You have already said "...any increase in HP or torque with Dinan's intake and exhaust are seen at wot at redline, and are incremental at best."

My remark about badly designed parts was made because U.S. OEM drive-by noise rules mean that there is a lot of room for extra power via the aftermarket from opening up either intake or exhaust, or both. If Dinan is giving you incremental power at best, and only at or near red line, they're leaving a lot of power on the table.

Therefore, I assume you spent the money for either noise or looks.

Bruce
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      11-18-2011, 09:22 PM   #12
JIO
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Quote:
Originally Posted by soberin View Post
Please give your rolling acceleration times in 3rd gear (6-MT only, E90 only) from 60-80 mph and 80-100 mph.

My "seat of the pants" time with a stopwatch is around 2 to 2.5 sec with M power mode bone stock. It is no different with my Dinan intake and basic Dinan exhaust.
Here are the results from 7 road tests of various car magazines:

60-80: 2.7,2.5,2.8,2.7,2.4,2.7,2.4 Average:2.60 seconds

80-100: 3.2,2.8,3.1,3.1,2.6,3.2,3.2 Average: 3.04 seconds


The first 4 times were 6-speed manuals and the last 3 were DCT. The 3rd and 4th times were for an E90, the rest were E92's.

Hope this helps.
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      11-18-2011, 10:12 PM   #13
soberin
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Quote:
Originally Posted by JIO View Post
Here are the results from 7 road tests of various car magazines:

60-80: 2.7,2.5,2.8,2.7,2.4,2.7,2.4 Average:2.60 seconds

80-100: 3.2,2.8,3.1,3.1,2.6,3.2,3.2 Average: 3.04 seconds


The first 4 times were 6-speed manuals and the last 3 were DCT. The 3rd and 4th times were for an E90, the rest were E92's.

Hope this helps.
If these times are in 3rd gear, which it seems they are, then this is quite helpful. Thanks.
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      11-19-2011, 09:47 AM   #14
bruce.augenstein@comcast.
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Quote:
Originally Posted by JIO View Post
Here are the results from 7 road tests of various car magazines:

60-80: 2.7,2.5,2.8,2.7,2.4,2.7,2.4 Average:2.60 seconds

80-100: 3.2,2.8,3.1,3.1,2.6,3.2,3.2 Average: 3.04 seconds


The first 4 times were 6-speed manuals and the last 3 were DCT. The 3rd and 4th times were for an E90, the rest were E92's.

Hope this helps.
Made me smile.

Can you tell me which magazines these times are from. And when?

Thanks,

Bruce
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