performance driving with the top down

adamr · 09-14-2007, 05:40 PM

is there like a huge diffference in performance racing with the top down on any convertible ... raced an E46 ///M3 with my top down from standstill, and we were neck and neck only when i hit third did i ever so slightly start to pull, 5000/6000 rpm into third, his nose was by my door handle ...

MTV · 09-14-2007, 06:38 PM

High speed it makes a huge difference.

Off the line there's actually an advantage considering there's more weight in the rear, helping reduce wheelspin...

Matt

PS: You pulled on an M3?? Are you PrOceded????

AKbmw · 09-14-2007, 06:41 PM

^^ ive acctually pulled an m3 and im stock.. just got magnaflow mufflers

Stinger · 09-14-2007, 06:51 PM

I'm not sure how weight balance effects raceability, but I'm sure others here do know.

Anyway the weight distribution is as follows with an E93:

Automatic Top Up: 51.4/48.6

Top Down: I read somewhere that distribution changes but I can't find where I found it (the brochure does not say and I googled but no luck.)

montreal_bimmer · 09-14-2007, 06:54 PM

yes.... takes a lot away from the aerodynamics of the car

2007_E93 · 09-14-2007, 07:23 PM

I think it HAS to slow us down. I raced a VW GTI with top down and A/C on and I pulled on him but not nearly as much as I would expect to. Only beat him by a car and half. The wind resistance/poor aerodynamics has to contribute a bit. Besides, our convertibles are even more heavy and definitely do not have as much quickness to them as the coupes. I still LOVE it anyway!

BMW335icDDS · 09-14-2007, 07:47 PM

Quote:

Originally Posted by MTV

High speed it makes a huge difference.

Off the line there's actually an advantage considering there's more weight in the rear, helping reduce wheelspin...

Matt

PS: You pulled on an M3?? Are you PrOceded????

The 335 is just as fast as the E46 M3 according to all car magazines. V2, and you go M3 and M5 hunting.

Taittinger · 09-14-2007, 08:00 PM

I would expect a greater performance difference on a track as opposed to straight line driving.

2007_E93 · 09-14-2007, 08:11 PM

Quote:

Originally Posted by Taittinger

I would expect a greater performance difference on a track as opposed to straight line driving.

True!

provenflipper · 09-14-2007, 08:14 PM

I was told before that Audi doesn't make hardtop convertibles for this reason, being that the weight distribution and performance difference between top up and top down was too drastic. I don't know if that's true or not...

ejazbmw · 09-14-2007, 10:18 PM

Quote:

Originally Posted by montreal_bimmer

yes.... takes a lot away from the aerodynamics of the car

+1

the way i see the E93 is when the top is up its a performance car, but when its down it's just a car to cruise around with, theres to much wind draft for it to be as good as if the top was up.

Year's_End · 09-14-2007, 11:03 PM

Quote:

Originally Posted by provenflipper

I was told before that Audi doesn't make hardtop convertibles for this reason, being that the weight distribution and performance difference between top up and top down was too drastic. I don't know if that's true or not...

That's prolly cuz they're pigs of cars already.

Year's_End · 09-14-2007, 11:04 PM

As for the top up/down issue, I think that the effects would be non-existant up to about 60mph. From then on the wind resistance would be really screwed up and'll probably cause major performance hits.

335Transformer · 09-14-2007, 11:14 PM

Quote:

Originally Posted by Stinger

I'm not sure how weight balance effects raceability, but I'm sure others here do know.

Anyway the weight distribution is as follows with an E93:

Automatic Top Up: 51.4/48.6

Top Down: I read somewhere that distribution changes but I can't find where I found it (the brochure does not say and I googled but no luck.)

Top down doesn't change as much as people think. The top itself only weighs a few hundred pounds. This is nothing when you are talking about the total weight of the car. There is also static weight in the body to stiffen the E93. Much of the added weight of the convertible does not change balance with the top down.

SteveInNC · 09-14-2007, 11:36 PM

The weight change is less of an issue than the fact that the aerodynamics get hosed. Aerodynamic drag increases exponentially with speed, so the effect of "dirtying" the airflow will become more relevant the faster that you go (even at typical highway speeds).

In simplified form:

f = 0.5 * Cd * A * V^2

force (drag) = 0.5 * Coefficient of drag * frontal area * velocity squared

It's that "velocity squared" term combined with Cd that bites you. Top down, the Cd goes up, probably significantly.

adamr · 09-15-2007, 12:48 AM

yeah it makes a huge difference, raced again but the with the top up .. but we said rolling start ... from second about 3000 rpm into second ... totally different story ... when i hit fourth i was three cars in front and stil pulling .. we then tried rolling third, same story ... very convincing win for the 335 ...

but the thing i did notice is that slight turbo lag, or delayed throttle response !?... dunno ... so the ///M always getting tht jump on you ... and i dragged with my traction on ...

BTW my car is stock

karliejai · 09-15-2007, 01:43 AM

Quote:

Originally Posted by 2007_E93

I think it HAS to slow us down. I raced a VW GTI with top down and A/C on and I pulled on him but not nearly as much as I would expect to. Only beat him by a car and half. The wind resistance/poor aerodynamics has to contribute a bit. Besides, our convertibles are even more heavy and definitely do not have as much quickness to them as the coupes. I still LOVE it anyway!

uhhh if ur top is down... why is ur AC on? lol

2007_E93 · 09-15-2007, 08:48 AM

Quote:

Originally Posted by karliejai

uhhh if ur top is down... why is ur AC on? lol

LOL I know a bit silly but it was 98 degrees and the top down was not cool enough. Was a BEAUTIFUL day that you had to have the top down. Besides, this is my first convertible and I wanted to drive top down practically any day it doesn't rain.

DaveStinsman · 09-15-2007, 02:17 PM

It depends how she's built. I

f the breasts are large enough you may distract the other driver long enough to win.

Park2670 · 09-15-2007, 05:02 PM

Quote:

Originally Posted by 2007_E93

Besides, this is my first convertible and I wanted to drive top down practically any day it doesn't rain.

Hell ya! Thats the way I am. Everytime I am in a convert, its top down. Unless its rain or snow.

Lucky13 · 09-15-2007, 09:24 PM

adamr, I know this is slightly off topic but I have the TiAg E93 with saddle you asked about a while back. I got the Turbo Tuner and I know I can smoke an E46 M3 because I own one. My lease on my E46 runs out Sept 28 and I'm turning it it but will only miss the handling because my E93 beats it in everything else and is so much smoother to ride in.

halB · 09-16-2007, 06:20 AM

People, including myself, want the convertible becasue it can be driven with the top down, even though it is 400 ponds heavier and suffers more aerodynamic drag. If I wanted to race I would have bought a coupe instead.

An E93 M3 would offset some of the negatives!

09-14-2007, 05:40 PM	#1
adamr Major 71 Rep 1,032 Posts Drives: 997 GT3 RS Join Date: Dec 2006 Location: Johannesburg iTrader: (0) Garage List 2007 Porsche 997 GT ... [8.50] 2005 Mercedes Benz ... [0.00] 2008 E92 M3 (Bought ... [0.00] 2007 E93 335i conve ... [0.00] 2006 E92 325i Coupe ... [0.00] 2001 E46 M3 (Sold S ... [0.00]	performance driving with the top down is there like a huge diffference in performance racing with the top down on any convertible ... raced an E46 ///M3 with my top down from standstill, and we were neck and neck only when i hit third did i ever so slightly start to pull, 5000/6000 rpm into third, his nose was by my door handle ... __________________ 2007 Porsche 997 GT3 RS \|PCM with NAV and GSM\|Roll Cage\|PCCB\|Xenons\|Sports Chrono Plus\|PASM\|Leather Pack\|Silver Seat-belts\|
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09-14-2007, 06:38 PM	#2
MTV Banned 241 Rep 1,906 Posts Drives: E60 M5, Volvo S60R Join Date: May 2007 Location: Montreal iTrader: (1)	High speed it makes a huge difference. Off the line there's actually an advantage considering there's more weight in the rear, helping reduce wheelspin... Matt PS: You pulled on an M3?? Are you PrOceded????
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09-14-2007, 06:41 PM	#3
AKbmw Brigadier General 246 Rep 3,253 Posts Drives: M-Sport LCI Join Date: Dec 2006 Location: LA iTrader: (13)	^^ ive acctually pulled an m3 and im stock.. just got magnaflow mufflers __________________
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09-14-2007, 06:51 PM	#4
Stinger Major 112 Rep 1,040 Posts Drives: 2007 335i Convertible Join Date: Apr 2007 Location: Southern California iTrader: (1) Garage List 2007 335i E93 [7.00] 1993 318is [0.00] 1996 Z3 1.9 [0.00]	I'm not sure how weight balance effects raceability, but I'm sure others here do know. Anyway the weight distribution is as follows with an E93: Automatic Top Up: 51.4/48.6 Top Down: I read somewhere that distribution changes but I can't find where I found it (the brochure does not say and I googled but no luck.) __________________ http://e93fanatic.blogspot.com
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09-14-2007, 06:54 PM	#5
montreal_bimmer OEMconcept 174 Rep 5,593 Posts Drives: BMW Join Date: Feb 2006 Location: Canada \| USA iTrader: (6) Garage List 2006 325i [10.00]	yes.... takes a lot away from the aerodynamics of the car
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09-14-2007, 07:23 PM	#6
2007_E93 Captain 19 Rep 604 Posts Drives: ? Join Date: Jun 2007 Location: ? iTrader: (0)	I think it HAS to slow us down. I raced a VW GTI with top down and A/C on and I pulled on him but not nearly as much as I would expect to. Only beat him by a car and half. The wind resistance/poor aerodynamics has to contribute a bit. Besides, our convertibles are even more heavy and definitely do not have as much quickness to them as the coupes. I still LOVE it anyway!
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09-14-2007, 08:00 PM	#8
Taittinger Major 57 Rep 1,019 Posts Drives: Monaco Blue E92 Join Date: Sep 2006 Location: NJ iTrader: (0) Garage List 2007 335i Cpe [0.00]	I would expect a greater performance difference on a track as opposed to straight line driving. __________________ '07 Monaco Blue 335i ordered 9/4 built 9/21 shipped 9/28 arrived 10/12 at dealership 10/18 vroom 10/19 christened 11/3...
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09-14-2007, 08:14 PM	#10
provenflipper Private First Class 106 Rep 143 Posts Drives: Garage is currently empty Join Date: Jun 2007 Location: Inland Empire, CA iTrader: (0)	I was told before that Audi doesn't make hardtop convertibles for this reason, being that the weight distribution and performance difference between top up and top down was too drastic. I don't know if that's true or not...
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09-14-2007, 11:04 PM	#13
Year's_End Lieutenant General 1138 Rep 12,444 Posts Drives: 2020 Shelby GT350 Join Date: Feb 2007 Location: FL iTrader: (0)	As for the top up/down issue, I think that the effects would be non-existant up to about 60mph. From then on the wind resistance would be really screwed up and'll probably cause major performance hits. __________________ Past: '08 E92 335i\|ZPP\|ZSP\|6AT Past: '15 Mustang GT\|401A\|PP\|6MT Current: '20 Shelby GT350\|6MT
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09-14-2007, 11:36 PM	#15
SteveInNC Enlisted Member 0 Rep 42 Posts Drives: 2007 335i Sedan Join Date: Jul 2007 Location: RTP, NC iTrader: (0)	The weight change is less of an issue than the fact that the aerodynamics get hosed. Aerodynamic drag increases exponentially with speed, so the effect of "dirtying" the airflow will become more relevant the faster that you go (even at typical highway speeds). In simplified form: f = 0.5 * Cd * A * V^2 force (drag) = 0.5 * Coefficient of drag * frontal area * velocity squared It's that "velocity squared" term combined with Cd that bites you. Top down, the Cd goes up, probably significantly.
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09-15-2007, 12:48 AM	#16
adamr Major 71 Rep 1,032 Posts Drives: 997 GT3 RS Join Date: Dec 2006 Location: Johannesburg iTrader: (0) Garage List 2007 Porsche 997 GT ... [8.50] 2005 Mercedes Benz ... [0.00] 2008 E92 M3 (Bought ... [0.00] 2007 E93 335i conve ... [0.00] 2006 E92 325i Coupe ... [0.00] 2001 E46 M3 (Sold S ... [0.00]	yeah it makes a huge difference, raced again but the with the top up .. but we said rolling start ... from second about 3000 rpm into second ... totally different story ... when i hit fourth i was three cars in front and stil pulling .. we then tried rolling third, same story ... very convincing win for the 335 ... but the thing i did notice is that slight turbo lag, or delayed throttle response !?... dunno ... so the ///M always getting tht jump on you ... and i dragged with my traction on ... BTW my car is stock __________________ 2007 Porsche 997 GT3 RS \|PCM with NAV and GSM\|Roll Cage\|PCCB\|Xenons\|Sports Chrono Plus\|PASM\|Leather Pack\|Silver Seat-belts\| Last edited by adamr; 09-15-2007 at 04:12 AM..
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09-15-2007, 02:17 PM	#19
DaveStinsman Private First Class 6 Rep 147 Posts Drives: 2003 Tiburon Join Date: Mar 2007 Location: PA iTrader: (0)	It depends how she's built. If the breasts are large enough you may distract the other driver long enough to win. __________________ 2008 Montego Blue Sedan- Black leather with alum. trim, Step, Active Steering, Paddles, Comfort Access, Sun Shades, Park Distance Control, Nav, HD Radio, IPod & USB adapter, Cold Weather, Premium, Sport.
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09-15-2007, 09:24 PM	#21
Lucky13 Lucky13 212 Rep 1,762 Posts Drives: 2014 M235 manual, 2020 X3 30X Join Date: Mar 2007 Location: Columbia, S.C. iTrader: (0)	adamr, I know this is slightly off topic but I have the TiAg E93 with saddle you asked about a while back. I got the Turbo Tuner and I know I can smoke an E46 M3 because I own one. My lease on my E46 runs out Sept 28 and I'm turning it it but will only miss the handling because my E93 beats it in everything else and is so much smoother to ride in.
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09-16-2007, 06:20 AM	#22
halB Colonel 53 Rep 2,384 Posts Drives: W211 E350 4M MkV GTI 987.2 S Join Date: Jan 2007 Location: Just north of Toronto iTrader: (0)	People, including myself, want the convertible becasue it can be driven with the top down, even though it is 400 ponds heavier and suffers more aerodynamic drag. If I wanted to race I would have bought a coupe instead. An E93 M3 would offset some of the negatives! __________________ 07 E93 335i - Returned at lease end 09 W211 E350 4Matic Avant Garde - Blk/Blk, AMG pkg w/18". Sport Susp. F1 Asym. Debadged. 09 MkV GTI w/Leather & 18" Huffs. F1 Asym 10 987.2 S w/Leather sport seat, Sport Chrono, 19" Carrera S II wheels
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