[Insider]

The Porsche 911 turbo automatic is faster then the six speed manual 0-60 as well as through the quarter mile http://www.roadandtrack.com/article....rticle_id=4052 No doubt the BMW 335 has the better automatic with faster shifting times and an additional gear. Shouldn't it be faster than the manual version as well? If not why?

[mkoesel]

Some possibilities:

- Final drive ratio
- transmission gear ratios
- driver


It would be helpful to compare numbers (BMW's are on their site, Porsche's may be too).

[new2the3]

autos put down less HP to the wheels compared to manual.

[BK]

VWs with DSG transmissions are faster than their manual counterparts, too. I think this is mostly true for that type of auto tranny (uses clutches and I guess no torque converter).

[ward]

the porsche system is probaby running more boost

[TheAcAvenger]

DSG is a sequential manual, the 335 is an automatic w/ torque converter.

Its the same reason why the new VW GTI is faster in "auto" than manual, even though DSG isnt really an auto but a sequential manual. I always shake my head when people get mad at vw/audi for ripping off porsche since porsche had it first, but uhh. same auto group guys. Its all VW's gadgetry.

As far as speed goes, DSG is superior to its SMG/Ferrari F1 counterparts.

[Insider]

Originally Posted by ward

the porsche system is probaby running more boost

Did you read the article? It clearly states the cars are the same except for the transmission.

[Insider]

Originally Posted by new2the3

autos put down less HP to the wheels compared to manual.

Yes that is correct. But why is the auto faster?

[kingbriani]

Originally Posted by Insider

Did you read the article? It clearly states the cars are the same except for the transmission.

no need to get hostile... im pretty sure he meant the porsche was running more boost than the bmw. auto transmissions dont allow boost to drop as much as manual transmissions during shift so the higher boost on the porsche would have a greater effect on its automatics vs. its manuals speed than the bmw.

[Insider]

Originally Posted by kingbriani

no need to get hostile... im pretty sure he meant the porsche was running more boost than the bmw. auto transmissions dont allow boost to drop as much as manual transmissions during shift so the higher boost on the porsche would have a greater effect on its automatics vs. its manuals speed than the bmw.

That make sense. It will be interesting to see some real world numbers of both.

[RiXst3r]

both the automatic and the manual 335i have been tested to be 4.8 sec 0-60 from all the auto magazines... A manual transmission turbo car tends to loose more boost between shifts, and the boost has to re-build... an auto tranny can maintain the boost... which is why the auto porsche is faster, and which is why although the manual tranny may get more HP to the wheels, the 0-60 times are the same for the auto and 6mt... the auto gets more constant boost, and the mt gets more hp to the wheels...

In a way, YES, this does apply to the 335i, but since we use much less boost than the porsche does, it only helps out enough to make up for the other transmission losses compaired to the 6mt

[Lassaxi]

Originally Posted by Insider

The Porsche 911 turbo automatic is faster then the six speed manual 0-60 as well as through the quarter mile http://www.roadandtrack.com/article....rticle_id=4052 No doubt the BMW 335 has the better automatic with faster shifting times and an additional gear. Shouldn't it be faster than the manual version as well? If not why?

The explanation I've heard about this is that the 911 turbo auto is very well calibrated and shifts at precisely calculated points designed to maximize the power band and boost points. This makes theoretical sense, because a computer should be able to shift more precisely than a human can; the problem is usually that the torque converter soaks up more power than the shifting precision adds. You'd have to figure that sooner or later someone would be able to engineer around this problem, and it sort of makes sense that you'd see the biggest benefit for a turbo engine.

I don't know if this explanation is correct, but like I said, it sort of makes sense..

Reduced wheelspin may also be a factor.

[ilkhan4]

I think with a car like that, it's just because a manual driver just can't shift fast enough. When you're getting the 0-60 down into the 3's, 10ths of a second start to matter more. The automatic may be getting less power to the ground, but the fact that it can shift faster makes up more than the difference.

[335i SH]

The driver.
I'm 100% certain I can drive my 335i with step & paddles faster than I could one with a manual trans.

[mkoesel]

Regarding the boost issue -

Here are the gear ratios from bmwusa.com:

Gear ratios - I/II 4.06/2.40 [4.17/2.34] :1
Gear ratios - III/IV 1.58/1.19 [1.52/1.14] :1
Gear ratios - V/VI/R 1.00/0.87/3.68 [0.87/0.69/3.40] :1
Final drive ratio 3.08 [3.46] :1

[] = automatic

Now, when I look at this, I don't see how anyone could possibly make any conclusions about how the boost is effecting things, when the drivelines have vastly different gearing (especially the diff). IMHO.

I'll bet the story is the same with the Porsche.

[ward]

Great find Mkoesel

[wushuhsu]

The Porsche 997 TT is a AWD. Traction is the most important factor in 0-60 times. With an automatic transmission and AWD, the computer can finely control the amount of power delivered to each wheel to minimize loss of traction.

[0700700]

its because of the variable turbine geometry on the turbos ! when combined with an automatic transmission the angle of the turbochargers can be adjusted much quicker, hence providing maximum torque quicker. Thus expect a quicker 0-60mph time and a MUCH quicker 0-100mp/h time.

dont speculate with bull$hit


http://forums.beyond.ca/showthread/t-109329.html

[Insider]

So I assume with the extra turbo boost the PROcede provides, the auto will definitely be faster than the manual. Just like the Porsche example, right?

[FirstClass]

Originally Posted by Insider

So I assume with the extra turbo boost the PROcede provides, the auto will definitely be faster than the manual. Just like the Porsche example, right?

There in only one reply in this whole thread that has the correct answer to the op's question and this is Rixt3r's. A lot of the totally incorrect replies are quite amusing.

In response to your question: The way the Porsche works is different from the way the 335i works. The 335i has really small turbos whereas the Porsche's are bigger. I'm fairly certain the Porsche is running considerably more boost than the 335i. Another question to consider is if the AT can handle the increased power without premature failure. The 335d uses an AT because it has so much power but there have been conflicting post on weather the 335i has the same tranny as the 335d. The auto 335i is afaik as fast as or faster than the manual now, so I can't imagine it becoming slower than the manual with a PROcede.

[teknochild]

LOL you auto grannies are really reaching into thin air trying to prove your slushboxes now, comparing a 335 auto to a porshe auto thats probably had close to a million more poured into it in the way of R&D


i would point out all the differences between the two cars and the actuall trannies themselves, but its like trying to get through a brick wall with some some firecrackers

[FirstClass]

Originally Posted by teknochild

LOL you auto grannies are really reaching into thin air trying to prove your slushboxes now, comparing a 335 auto to a porshe auto thats probably had close to a million more poured into it in the way of R&D


i would point out all the differences between the two cars and the actuall trannies themselves, but its like trying to get through a brick wall with some some firecrackers

The auto is the Porsche sucks hard. It's a 5 speed Imagine the how much faster it would be if it had 6 gears like the MT.