Automatic owners

[finch1750]

Originally Posted by MmmHamSandwich

Pushing the pedal, by far. I drive in manual mode in excess of 99% of the time, however I must admit if you want to drop down several gears, the car will perform this much faster in automatic with "kickdown" than you can triple or quadruple tapping the shift lever.

As such, I wish that while in manual mode with sport engaged, holding the downshift command for any period of time longer than a brief tap would instruct the car to choose the lowest available gear for acceleration. This would make driving in manual mode much more engaging IMO. Maybe this is something a tuner could program in?

Thats a really interesting idea. Im local to Vishnu so Ill give them a shout and see if that is even theoretically possible

[MmmHamSandwich]

Originally Posted by finch1750

Thats a really interesting idea. Im local to Vishnu so Ill give them a shout and see if that is even theoretically possible

Please do, would be great to know if someone could pull it off.

I'll even be generous and only charge a $.05 per shift royalty for the idea!

[Suberman]

Originally Posted by MmmHamSandwich

A few misconceptions
The disparity in 0-60 times between the two transmission is almost entirely due to launch. The auto is generally 1.5 seconds slower to 60 from a standstill. When comparing 5-60 times however the auto is typically one tenth of a second slower. Acceleration curves do not adequately account for the massive disadvantage the AT has being unable to launch. Torque converter slipping is not a significant advantage in this car. Discounting launch, these cars accelerate [URL="http://www.ft86club.com/forums/showthread.php?p=616296#post616296"]

I don't think this can be correct. For example Edmunds gets the same acceleration disparity with traction control on or off and using a roll out or not. This confirms that the main reason for the difference is due to gearing. Certainly the differences in overall gear ratios correlate reasonably closely to acceleration differences.

http://www.edmunds.com/subaru/brz/2013/road-test2.html

Almost everybody reports the same delta between manual and automatic.

As for launch, well precision in achieving the exactly correct degree of wheelspin (around 15% should be perfect) is important but not that important.

The delta seems to be about half a second no matter what you try.

[MmmHamSandwich]

Originally Posted by Suberman

I don't think this can be correct. For example Edmunds gets the same acceleration disparity with traction control on or off and using a roll out or not. This confirms that the main reason for the difference is due to gearing. Certainly the differences in overall gear ratios correlate reasonably closely to acceleration differences.

http://www.edmunds.com/subaru/brz/2013/road-test2.html

Almost everybody reports the same delta between manual and automatic.

As for launch, well precision in achieving the exactly correct degree of wheelspin (around 15% should be perfect) is important but not that important.

The delta seems to be about half a second no matter what you try.

I find their 0-60 time for manual to be a bit of an outlier compared to other publications. I also only saw them compare with and without a rollout, not with and without traction control (with the exception of their tests where the car is already rolling a good speed. How traction control made a difference in acceleration at those speeds is beyond me...) Edmunds lists a 0-60 time of 6.5 for the manual FR-S, but somehow the manual BRZ as 7.3. Sounds to me like they had a driver who didn't know how to launch when they tested the BRZ.
http://www.edmunds.com/car-reviews/t...rack-test.html

Aside from that, most of their numbers seem to fall in line with other publications. Car and Driver for instance....

5-60 mph
MT: 8.1
AT: 8.2 (+.1 seconds)

0-60 mph
MT: 6.4
AT: 8.1 (+1.7 seconds)

1/4 Mile
MT: 14.9 @ 95
AT: 16.3@ 90 (+1.4 seconds)

These sorts of numbers are what make me suspect that launch is the most important factor in low speed acceleration. When these cars start from a roll they are quite similar. In some cases the auto edges out, in some it's the manual. My guess is these are due to where the shifts happen to fall. At some point (beyond 90mph perhaps) I imagine it would be impossible for the auto to have an edge with the longer gearing however.

At any rate numbers from different tests are nice, but I'll agree they're hardly conclusive. I'd like to see side by side tests of the two cars, which I am surprised no one has done. Ultimately at street speeds I doubt you'll see much difference, save for launching of course. Granted my last car was an Si which I had for 5 years and I never truly launched it, so it doesn't bother me too much.

[Kelbyat07]

Originally Posted by MmmHamSandwich

I find their 0-60 time for manual to be a bit of an outlier compared to other publications. I also only saw them compare with and without a rollout, not with and without traction control (with the exception of their tests where the car is already rolling a good speed. How traction control made a difference in acceleration at those speeds is beyond me...) Edmunds lists a 0-60 time of 6.5 for the manual FR-S, but somehow the manual BRZ as 7.3. Sounds to me like they had a driver who didn't know how to launch when they tested the BRZ.
http://www.edmunds.com/car-reviews/t...rack-test.html

Aside from that, most of their numbers seem to fall in line with other publications. Car and Driver for instance....

5-60 mph
MT: 8.1
AT: 8.2 (+.1 seconds)

0-60 mph
MT: 6.4
AT: 8.1 (+1.7 seconds)

1/4 Mile
MT: 14.9 @ 95
AT: 16.3@ 90 (+1.4 seconds)

These sorts of numbers are what make me suspect that launch is the most important factor in low speed acceleration. When these cars start from a roll they are quite similar. In some cases the auto edges out, in some it's the manual. My guess is these are due to where the shifts happen to fall. At some point (beyond 90mph perhaps) I imagine it would be impossible for the auto to have an edge with the longer gearing however.

At any rate numbers from different tests are nice, but I'll agree they're hardly conclusive. I'd like to see side by side tests of the two cars, which I am surprised no one has done. Ultimately at street speeds I doubt you'll see much difference, save for launching of course. Granted my last car was an Si which I had for 5 years and I never truly launched it, so it doesn't bother me too much.

That's pretty interesting that the MT and AT time from a roll is pretty close. With launch for the AT, it is close to 7.9

[Suberman]

Factory figures support the gearing argument.

What we really need is someone who has fitted the 4.55 final drive to his automatic to publish acceleration figures.

[mike_ekim1024]

Originally Posted by Suberman

Factory figures support the gearing argument.

What we really need is someone who has fitted the 4.55 final drive to his automatic to publish acceleration figures.

There are a few members who have done 4.5X here. I have the Weir performance 4.56 but I haven't had it installed yet.. Waiting to finalize a tune before introducing more variables

It might be interesting to start a thread specifically for 4.5X and 4.88 final drive for automatics. I'm getting more and more excited to do mine.

[KayC]

I went for a MT because my last car had a dual clutch gear box and when I test drove the AT FRS, I feel it was no where near the dsg in my Audi A3.

[Alamexico]

Bought mine as an A/T to use as a commuting car/slightly modify to my taste. Second so the wife can drive it when I don't feel like it. After 5 years of commuting(150-175k miles) I will retire it and do an engine swap of my liking and it will have a M/T. Got it semi planned out. lol

[MmmHamSandwich]

Originally Posted by Suberman

Factory figures support the gearing argument.

Except they don't...

http://www.ft86club.com/forums/showp...77&postcount=1

[Suberman]

Originally Posted by MmmHamSandwich

Except they don't...

http://www.ft86club.com/forums/showp...77&postcount=1

Not sure what you're getting at with the graphs. I'm just using Subaru Canada figures: 0-100 km/hr (62 mph) takes 8.4 seconds with the AT and 7.7 seconds with the MT. This is the same delta everyone seems to get, about half a second.

Because the delta is pretty much the same regardless of which figures you use it has to be mainly gearing.

Top speeds are 211 and 221 respectively proving that the AT top gear gearing is too tall to pull top speed.

People think launch is so critical to better acceleration timed but that's only true if you have lots of excess torque to deal with, not the case with the BRZ.

Also, awd is often quicker off the line because it reduces wheelspin.

Drag racing on wrinkle slicks is a whole other ball game. There wheelspin affects overall gearing due to the wrinkled sidewalls.

[Suberman]

Originally Posted by KayC

I went for a MT because my last car had a dual clutch gear box and when I test drove the AT FRS, I feel it was no where near the dsg in my Audi A3.

That's because it isn't a DCT. Its a torque converter tranny with a lockup clutch.

However, torque converter trannies are a bit lighter than DCT types for similar torque capacities, and can be made to shift as quickly for street use.

In some ways the PDK DCT solution is looking for a problem to solve already solved by the planetary torque converter automatic.

Generally speaking it is cheaper to build a planetary automatic for high torque loads.

Mercedes has even developed a planetary automatic with no torque converter which uses a computer comptroller lock up clutch only.

Finally, ZF and others have hybrid ready planetary automatics with space to fit an electric motor where the lockup clutch and torque converter would go. This transmission will dominate the market very soon because the DCT cannot do this.

[mike_ekim1024]

Tye300 just posted videos of his auto on track. Sounds and looks good!

http://www.ft86club.com/forums/showp...&postcount=223

[Freeman]

1. Mpg is better
2. I prefer an AT to MT

sent from my locker... help!