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      04-13-2011, 10:45 AM   #1
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60-130 in a DCT vs. 6MT Updated with video

Why and how everyone compare a DCT to a 6MT in doing 60-130 runs or on the drag strip ?
So i looked more into this and i had lots of help from PG
It always seemed fairly obvious to me that a driver's shift speed would affect his 1/4 mile drag race ET and trap speed. To me, this makes natural sense. So when my own meager "BMW Performance Steering Wheel" 1/4 mile drag results (about as inaccurate as it gets) came under fire, I quickly pointed out that I'm a slow shifter on my 6MT, and this would surely account for my mediocre results. To my surprise, my explanation was vigorously attacked by a self-proclaimed BMW know-it-all and self-proclaimed drag racing expert -- Sticky. He said my car was weak and that's why it performed so poorly. That was a drum he's never quit beating, in spite of all of the data to the contrary.

But I'll admit, Its a novice with drag racing...in fact I really don't know anything about it. But I do know that if two identical cars take off from the same point at the same time and one of them waits two seconds between every shift, then while it's coasting in neutral it will not be accelerating. Therefore, it will be impossible for that car to have the same 1/4 mile trap speed of the same car that shifts as fast as it can.

I sat on one end of the debate -- as a newbie who never drag raced a car in my life, and at the other end was this self-proclaimed know-it-all of everything. He insisted he was right...and I was wrong. So more than a year ago, I asked him to prove it at the drag strip by running some of his runs in D2 mode instead of D5 (or S6). No surprise to anybody who knows how he hates to be proven wrong...he refused with some flimsy excuse that he was out to set records...not run experiments. Back in my corner, I produced CarTest physics-based car modeling software results that showed exactly how shift speed affects trap speed. Back in his corner, he laughed every time I used car test. Back in my corner, I laughed everytime he laughed at CarTest because CarTest has proven dead-nuts accurate for every performance prediction on my own car. In fact CarTest has proven so accurate that it's been within a few hundredths of a MPH on my Mojave Mile results.

I believed this would be a very easy test to run...all I needed was a car owner with DCT and a vBox. The test to figure this out would be quite simple. Run the DCT in D2 and compare the vBox results against the same car running in D5. Even though the shift speed difference between D2 and D5 is only a few milliseconds, I was hopeful it would prove the results one way or the other. Now all I needed was to find the car and test it. I ended up waiting more than a year until I got my answer.

This weekend, I borrowed a guy's DCT car and took it to a remote road in the desert that was nearly perfectly flat in both direction. There are no side streets, except the ones I would use for the tests. I planned to place the car in D2 and turn on the vBox. I would run from 0-130 MPH -- as this would give me 1/4 and 60-130 MPH results. I would run the car in both directions on the same exact piece of road for three runs in each direction (six runs total), then I would switch to D5 and run the same test all over again.

The car I borrowed was nearly bone stock. Bone stock is ideal because if the results are obvious with a bone stock car, they will be even more obvious and exaggerated on a highly modified car (such as a supercharged car). So taking a near bone stock car for the test was also going to make it the most difficult for me, and give the naysayers all of the benefits.

I found the perfect road, hooked up my Video vBox and tried one practice run in each direction to make sure the road was safe. After I was satisfied, I turned on the vBox and ran in one direction. Then I ran in the opposite direction. Back and forth three times for a total of six runs. I switched to D5 and repeated the runs. I was running low on gas, so after two runs in each direction (instead of three), I abandoned the third set of runs and went home.

The results were overwhelmingly conclusive. Even though I was only changing the shift speed by a few milliseconds, the effect on 1/4 mile trap speed was obvious and I'd say even profound. Wasting a few milliseconds shifting affected my 1/4 mile trap speed by as much as 2MPH. Even the best D2 run couldn't beat the worst D5 run. Sticky was wrong...again. That's right: the self-proclaimed expert of drag racing and all automotive knowledge was proven dead wrong again.

As a final test, I input all of the actual car data in CarTest to see if it could predict the same results. If it did, it would be (yet) another slap in the face to the self-proclaimed expert who regularly mocks the use of this tool. I just happen to have the Dynojet dyno file from this exact car taken only a few weeks ago. CarTest allows the user to input the actual dyno results. After doing so, I adjusted the launch methods to match how I used the DCT. For D2, I selected a 0.20 second shift time (200 milliseconds). I chose this shift time after some research on three or four different car forums and other web sites who claimed that 0.20 seconds was about the slowest the DCT would shift (D2 mode). For D5, I selected 0.08 seconds shift time (80 milliseconds). In input the exact weather conditions I collected during my run, including elevation and wind speed and wind direction. Then changing nothing but shift speed, I let CarTest estimate the 1/4 mile ET and trap speed, along with a 60-130 MPH time as well.

Here's the results.

Weather Conditions:
Temperature: 55.9 degrees F
Pressure: 30.04 inHg
Humidity: 27%
Density Altitude: 30 Ft.

CarTest Estimates for D2:
1/4 Mile Elapsed Time (ET): _ 12.65
1/4 Mile Trap Speed: 112.55
60-130 MPH: 12.63
Actual Results for D2:
Run-1, Run-2, Run-3, Run-4, Run-5, Run-6
1/4 Mile Elapsed Time (ET): 13.208, 13.612, 13.412, 13.204, 13.177, 13.521
1/4 Mile Trap Speed: 112.93, 112.23, 112.81, 112.84, 113.26, 112.13
60-130 MPH: 12.595, 12.435, 12.512, 12.504, 12.411, 12.456

Average Results for D2 (average of three medium runs):
1/4 Mile Elapsed Time (ET): 13.276
1/4 Mile Trap Speed: 112.86
60-130 MPH: 12.537

CarTest Estimates for D5:

1/4 Mile Elapsed Time (ET): 12.48
1/4 Mile Trap Speed: 113.83
60-130 MPH: 12.20
Actual Results for D5:
Run-1, Run-2, Run-3, Run-4, Run-5, Run-6
1/4 Mile Elapsed Time (ET): 13.135, 12.987, xx.xxx, 13.034
1/4 Mile Trap Speed: 113.35, 114.09, xxx.xx, 113.62
60-130 MPH: 12.147, 12.104, xx.xxx, 12.128

Average Results for D5 (average of three medium runs):
1/4 Mile Elapsed Time (ET): 13.052
1/4 Mile Trap Speed: 113.69
60-130 MPH: 12.13

Conclusions:
To me, the results seem pretty conclusive. Even changing the shift speed by 120 milliseconds (or whatever the actual value may be between D2 and D5) created a pretty significant change in all 1/4 mile drag results, and 60-130 times as well. As I believed at the very beginning, shift speed does affect trap speed, no matter what the self-proclaimed drag race expert seems to think.

CarTest results proved to be very accurate as well. The D2 predictions vs. actual results were about as close as they could get. 1/4 mile ET was predicted to be 12.65, actual was 13.26 (4.7% difference). 1/4 Trap Speed was predicted to be 112.55, actual was 112.86 (3/10ths of 1% difference). 60-130 time was predicted to be 12.63, actual was 12.537 (less than 1/10th of 1% difference).

The D5 predictions vs. actual results. 1/4 mile ET was predicted to be 12.48, actual was 13.052 (4.4% difference). 1/4 Trap Speed was predicted to be 113.83, actual was 113.69 (1/10th of 1% difference). 60-130 time was predicted to be 12.20, actual was 12.13 (1/2 of 1% difference).

Trap speed and 60-130 MPH results were both less than 1/2 of 1% difference from the predictions for both D2 and D5. CarTest predicted 1.28 MPH trap speed difference, and the actual was 0.83 MPH difference. CarTest predicted an 0.15 second difference for 60-130 MPH runs, and the actual difference was 0.407 seconds. And even though 1/4 mile ET was 4.4% off, Cartest predicted a 0.17 second difference, and the actual results were 0.224 second difference.

VBox files will be made available for analysis to anybody curious enough to dive into the results.

VBox Results (I've highlighted the shift points):

http://www.rcollins.org/m3/VBox/DCT%...Comparison.jpg

Car Test Configuration:
http://www.rcollins.org/m3/VBox/DCT%...TestConfig.jpg

http://www.rcollins.org/m3/VBox/DCT%...arTestData.jpg

Additional Information:

I did a little more digging into the results, and it's very clear that clutch engagement time is different between D2 and D5. I looked at the 60-foot times, and it's clear that the clutch engagement is faster in D5 than D2.

At the same time, I exported as much data from the runs as I thought made sense. I tried making some graphs of the data, but nothing was nearly as clear as simply presenting the data itself.

1/4 Mile results:
Even though these aren't actual drag strip results, I tried to simulate them as best as I could using the VBox tools software. I did my best to look up the NHRA rules and figure out how times, distances, and trap speeds are measured. Then using what I learned, I programmed the VBox software to simulate the same thing. For example, I used a 1-foot roll-out, and the trap speed is the average of the speed at 1321ft, and 1257ft (Q-60 ft, with 1-foot roll-out).

http://www.rcollins.org/m3/VBox/DCT%...le_Results.jpg

Gear Analysis: Time in Gears
http://www.rcollins.org/m3/VBox/DCT%...imeInGears.jpg

Gear Analysis: Distance in Gears
http://www.rcollins.org/m3/VBox/DCT%...nceInGears.jpg

Speed Analysis: Time to Speed
http://www.rcollins.org/m3/VBox/DCT%...imeToSpeed.jpg

Speed Analysis: Distance to Speed
http://www.rcollins.org/m3/VBox/DCT%...nceAtSpeed.jpg

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Last edited by IMG; 04-17-2011 at 07:29 PM.
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      04-13-2011, 11:33 AM   #2
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beats me! but I'm practicing to become a human M-DCT
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      04-13-2011, 01:17 PM   #3
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Quote:
Originally Posted by Eugene-TAIWAN View Post
beats me! but I'm practicing to become a human M-DCT
but seriously .... this is a question only Batman can answer !
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      04-14-2011, 10:31 PM   #4
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Physics based acceleration simulation can answer this question quite well. I ran the simulations. DCT is a large benefit in such a run due to both gearing and faster shifts. The DCT will have about an 0.8 second advantage over the 6MT (both cars at stock power). My 12.9 time predicted for the 6MT agrees with some of the actual test results folks have posted.
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      04-15-2011, 03:21 AM   #5
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I think the stock 60-130 for a 6spd is 12.9 and for DCT 12.5. I believe there are 3 shifts in the m3 from 60-130. just some info
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      04-16-2011, 05:33 PM   #6
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By the way the numbers above us 0.25 s (250 ms) shifts for the MT and 0.030 s (30 ms) shifts for the M-DCT. These are totally configurable in the simulation software.
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      04-16-2011, 11:12 PM   #7
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Quote:
Originally Posted by Eugene-TAIWAN View Post
beats me! but I'm practicing to become a human M-DCT
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      04-17-2011, 01:43 PM   #8
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Wow, excellent write up...however whats the simple conclusions lol.
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      04-17-2011, 02:24 PM   #9
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Wow, excellent write up...however whats the simple conclusions lol.
I think that the point is that shift speeds make a difference. Apparently there's someone on the Forum that doesn't understand that.

Anyway, thanks for all the effort.
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      04-17-2011, 03:56 PM   #10
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Quote:
Originally Posted by dcstep View Post
I think that the point is that shift speeds make a difference. Apparently there's someone on the Forum that doesn't understand that.

Anyway, thanks for all the effort.
Thank U Sir !!!
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      04-17-2011, 07:30 PM   #11
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Quote:
Originally Posted by img View Post
Why and how everyone compare a DCT to a 6MT in doing 60-130 runs or on the drag strip ?
So i looked more into this and i had lots of help from PG
It always seemed fairly obvious to me that a driver's shift speed would affect his 1/4 mile drag race ET and trap speed. To me, this makes natural sense. So when my own meager "BMW Performance Steering Wheel" 1/4 mile drag results (about as inaccurate as it gets) came under fire, I quickly pointed out that I'm a slow shifter on my 6MT, and this would surely account for my mediocre results. To my surprise, my explanation was vigorously attacked by a self-proclaimed BMW know-it-all and self-proclaimed drag racing expert -- Sticky. He said my car was weak and that's why it performed so poorly. That was a drum he's never quit beating, in spite of all of the data to the contrary.

But I'll admit, Its a novice with drag racing...in fact I really don't know anything about it. But I do know that if two identical cars take off from the same point at the same time and one of them waits two seconds between every shift, then while it's coasting in neutral it will not be accelerating. Therefore, it will be impossible for that car to have the same 1/4 mile trap speed of the same car that shifts as fast as it can.

I sat on one end of the debate -- as a newbie who never drag raced a car in my life, and at the other end was this self-proclaimed know-it-all of everything. He insisted he was right...and I was wrong. So more than a year ago, I asked him to prove it at the drag strip by running some of his runs in D2 mode instead of D5 (or S6). No surprise to anybody who knows how he hates to be proven wrong...he refused with some flimsy excuse that he was out to set records...not run experiments. Back in my corner, I produced CarTest physics-based car modeling software results that showed exactly how shift speed affects trap speed. Back in his corner, he laughed every time I used car test. Back in my corner, I laughed everytime he laughed at CarTest because CarTest has proven dead-nuts accurate for every performance prediction on my own car. In fact CarTest has proven so accurate that it's been within a few hundredths of a MPH on my Mojave Mile results.

I believed this would be a very easy test to run...all I needed was a car owner with DCT and a vBox. The test to figure this out would be quite simple. Run the DCT in D2 and compare the vBox results against the same car running in D5. Even though the shift speed difference between D2 and D5 is only a few milliseconds, I was hopeful it would prove the results one way or the other. Now all I needed was to find the car and test it. I ended up waiting more than a year until I got my answer.

This weekend, I borrowed a guy's DCT car and took it to a remote road in the desert that was nearly perfectly flat in both direction. There are no side streets, except the ones I would use for the tests. I planned to place the car in D2 and turn on the vBox. I would run from 0-130 MPH -- as this would give me 1/4 and 60-130 MPH results. I would run the car in both directions on the same exact piece of road for three runs in each direction (six runs total), then I would switch to D5 and run the same test all over again.

The car I borrowed was nearly bone stock. Bone stock is ideal because if the results are obvious with a bone stock car, they will be even more obvious and exaggerated on a highly modified car (such as a supercharged car). So taking a near bone stock car for the test was also going to make it the most difficult for me, and give the naysayers all of the benefits.

I found the perfect road, hooked up my Video vBox and tried one practice run in each direction to make sure the road was safe. After I was satisfied, I turned on the vBox and ran in one direction. Then I ran in the opposite direction. Back and forth three times for a total of six runs. I switched to D5 and repeated the runs. I was running low on gas, so after two runs in each direction (instead of three), I abandoned the third set of runs and went home.

The results were overwhelmingly conclusive. Even though I was only changing the shift speed by a few milliseconds, the effect on 1/4 mile trap speed was obvious and I'd say even profound. Wasting a few milliseconds shifting affected my 1/4 mile trap speed by as much as 2MPH. Even the best D2 run couldn't beat the worst D5 run. Sticky was wrong...again. That's right: the self-proclaimed expert of drag racing and all automotive knowledge was proven dead wrong again.

As a final test, I input all of the actual car data in CarTest to see if it could predict the same results. If it did, it would be (yet) another slap in the face to the self-proclaimed expert who regularly mocks the use of this tool. I just happen to have the Dynojet dyno file from this exact car taken only a few weeks ago. CarTest allows the user to input the actual dyno results. After doing so, I adjusted the launch methods to match how I used the DCT. For D2, I selected a 0.20 second shift time (200 milliseconds). I chose this shift time after some research on three or four different car forums and other web sites who claimed that 0.20 seconds was about the slowest the DCT would shift (D2 mode). For D5, I selected 0.08 seconds shift time (80 milliseconds). In input the exact weather conditions I collected during my run, including elevation and wind speed and wind direction. Then changing nothing but shift speed, I let CarTest estimate the 1/4 mile ET and trap speed, along with a 60-130 MPH time as well.

Here's the results.

Weather Conditions:
Temperature: 55.9 degrees F
Pressure: 30.04 inHg
Humidity: 27%
Density Altitude: 30 Ft.

CarTest Estimates for D2:
1/4 Mile Elapsed Time (ET): _ 12.65
1/4 Mile Trap Speed: 112.55
60-130 MPH: 12.63
Actual Results for D2:
Run-1, Run-2, Run-3, Run-4, Run-5, Run-6
1/4 Mile Elapsed Time (ET): 13.208, 13.612, 13.412, 13.204, 13.177, 13.521
1/4 Mile Trap Speed: 112.93, 112.23, 112.81, 112.84, 113.26, 112.13
60-130 MPH: 12.595, 12.435, 12.512, 12.504, 12.411, 12.456

Average Results for D2 (average of three medium runs):
1/4 Mile Elapsed Time (ET): 13.276
1/4 Mile Trap Speed: 112.86
60-130 MPH: 12.537

CarTest Estimates for D5:

1/4 Mile Elapsed Time (ET): 12.48
1/4 Mile Trap Speed: 113.83
60-130 MPH: 12.20
Actual Results for D5:
Run-1, Run-2, Run-3, Run-4, Run-5, Run-6
1/4 Mile Elapsed Time (ET): 13.135, 12.987, xx.xxx, 13.034
1/4 Mile Trap Speed: 113.35, 114.09, xxx.xx, 113.62
60-130 MPH: 12.147, 12.104, xx.xxx, 12.128

Average Results for D5 (average of three medium runs):
1/4 Mile Elapsed Time (ET): 13.052
1/4 Mile Trap Speed: 113.69
60-130 MPH: 12.13

Conclusions:
To me, the results seem pretty conclusive. Even changing the shift speed by 120 milliseconds (or whatever the actual value may be between D2 and D5) created a pretty significant change in all 1/4 mile drag results, and 60-130 times as well. As I believed at the very beginning, shift speed does affect trap speed, no matter what the self-proclaimed drag race expert seems to think.

CarTest results proved to be very accurate as well. The D2 predictions vs. actual results were about as close as they could get. 1/4 mile ET was predicted to be 12.65, actual was 13.26 (4.7% difference). 1/4 Trap Speed was predicted to be 112.55, actual was 112.86 (3/10ths of 1% difference). 60-130 time was predicted to be 12.63, actual was 12.537 (less than 1/10th of 1% difference).

The D5 predictions vs. actual results. 1/4 mile ET was predicted to be 12.48, actual was 13.052 (4.4% difference). 1/4 Trap Speed was predicted to be 113.83, actual was 113.69 (1/10th of 1% difference). 60-130 time was predicted to be 12.20, actual was 12.13 (1/2 of 1% difference).

Trap speed and 60-130 MPH results were both less than 1/2 of 1% difference from the predictions for both D2 and D5. CarTest predicted 1.28 MPH trap speed difference, and the actual was 0.83 MPH difference. CarTest predicted an 0.15 second difference for 60-130 MPH runs, and the actual difference was 0.407 seconds. And even though 1/4 mile ET was 4.4% off, Cartest predicted a 0.17 second difference, and the actual results were 0.224 second difference.

VBox files will be made available for analysis to anybody curious enough to dive into the results.

VBox Results (I've highlighted the shift points):

http://www.rcollins.org/m3/VBox/DCT%...Comparison.jpg

Car Test Configuration:
http://www.rcollins.org/m3/VBox/DCT%...TestConfig.jpg

http://www.rcollins.org/m3/VBox/DCT%...arTestData.jpg

Additional Information:

I did a little more digging into the results, and it's very clear that clutch engagement time is different between D2 and D5. I looked at the 60-foot times, and it's clear that the clutch engagement is faster in D5 than D2.

At the same time, I exported as much data from the runs as I thought made sense. I tried making some graphs of the data, but nothing was nearly as clear as simply presenting the data itself.

1/4 Mile results:
Even though these aren't actual drag strip results, I tried to simulate them as best as I could using the VBox tools software. I did my best to look up the NHRA rules and figure out how times, distances, and trap speeds are measured. Then using what I learned, I programmed the VBox software to simulate the same thing. For example, I used a 1-foot roll-out, and the trap speed is the average of the speed at 1321ft, and 1257ft (Q-60 ft, with 1-foot roll-out).

http://www.rcollins.org/m3/VBox/DCT%...le_Results.jpg

Gear Analysis: Time in Gears
http://www.rcollins.org/m3/VBox/DCT%...imeInGears.jpg

Gear Analysis: Distance in Gears
http://www.rcollins.org/m3/VBox/DCT%...nceInGears.jpg

Speed Analysis: Time to Speed
http://www.rcollins.org/m3/VBox/DCT%...imeToSpeed.jpg

Speed Analysis: Distance to Speed
http://www.rcollins.org/m3/VBox/DCT%...nceAtSpeed.jpg

Updated
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      04-19-2011, 10:30 PM   #12
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OP: Did you edit the orginal post after making it? Perhaps I was being careless and just entirely missed the original post. Great work anyway. I'm also a big fan of CarTest. I've ended up getting in quite a few deabtes around CarTest centered topics here on the forum. Both those who believe in Physics and those who don't...

A few comments:

Without exact knowledge of the shift speeds, which are still not known I don't think you can claim a "victory" here. Undoubtedly faster shift times (say over a MT) will improve nearly any performance results, often by the amout of time saved per shift with a DCT which is about 1/4 sec per shift. My past efforts have also shown that DCT is about equivalent to 20 hp over a MT (obviously it is not real hp so top speed won't be improved by this).

Shift speeds: I have always believed that Drivelogic modes that include some surge (i.e. S4-S6) should perform slightly better than any other modes that do not include the surge because surge is essentially like power shifting in a MT. I also made some attempts to measure shift times (posted on that long ago). Although the effort was not entirely conclusive, it indiated that low D mode shifts are actually faster than higher S mode shifts. I'm not sure about D2 vs D5. D modes lack the extra bit of momentum kick from the surge in the shift but were still faster overall. I believe the M-DCT can shift in as fast as 30 ms. I suspect 200 ms is a very worst case shift but upshifts probably never get that slow, perhaps some downshifts or multiple downshifts. A better test might have been S5 vs D2. In short, I do not think 200 ms for D2 is a good guess at all.

Note: Do not confuse a jerky shift (one with surge like S4-S6) with a fast shift. They can be fairly uncorrelated!

Weight: To get really accurate results you need the actual car weight. If you had nearly an empty tank you can't use official BMW curb weight numbers. You need to adjust your numbers down due to this. Also I think CarTest uses total weight minus driver for the "weight" field. Another reason to adjust your numbers down.

Losses: It is pretty clear both from literature as well as from various 1/4 mi trap speed correlation efforts with test that CarTest has some overly conservative numbers for losses. If you used actual dyno results that should be superior. I'd trust the results from rri.se over any inertial dyno.

60-130 timing. I don't think this is typically tested by passing through 60 on the way to 130. It is done by beginning at 60 mph even/steady then going WOT. This will obviously have an impact on both testing and simulation. As long as the comparison is "apples to apples" it should be fine.

ET's: Without getting great traction and a great launch there is no way you will match the "ideal" prediction from CarTest. Especially with little to no drag racing experience and on a less than ideal surface from a traction perspective. This does not mean your CarTest predictions here are not what that car is actually capable of.

Trap speeds: Indicate you probably have a pretty good match between the car's actual power and the dyno results.

In short, besides a very nice validation effort for CarTest I don't think you proved that D5 is faster than D2 due to quicker shifts. Nice work either way. Congrats.



P.S. Arguing with Sticky is a totally useless activity... You are 100% correct on why a fast shifting DCT (apples to apples) will outperform a slot shifting DCT or a slow shifting human in a MT. It is obvious from basic physics and simulation demonstrates it as well.
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