02-15-2014, 08:22 AM | #2 |
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Yes, xDrive sits higher than RWD, even with DHP
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'98 Dinan/RMS stage 2+(VAC cams, CES Cutring etc) '15 Buick Regal "T"(wife) '06 Saab 9-5 Combi 5mt (full suspension, LSD, clipped turbo etc) |
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02-16-2014, 02:35 AM | #3 |
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Thank u Jamesons Viggen, and i got confirmation on the technical data sheet from the dealer:
428i sdrive is 130 mm from the ground, total height 1377 428i Xdrive is 145 mm from the ground, total height 1392 I am pretty much decided to go Sdrive now. i just want to know if 428ixdrive manual is really doin 5,6 from 0 to 100 compared to 5,9 with Sdrive manual, which is also clearly stated on the dealer's data sheet... |
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02-16-2014, 03:15 AM | #4 | |
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02-16-2014, 04:55 AM | #5 |
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02-16-2014, 10:24 AM | #7 | |
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When you see a reported time for an AWD car, the launch has to be kind of aggressive to take advantage of the added traction. If the two cars(RWD and AWD) are launched the same way, with an softer launch, the RWD car will be faster. So if you are not going to do a semi abusive launch on the street, xDrive will not be faster from a dig.
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02-16-2014, 12:56 PM | #8 | |
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02-16-2014, 01:35 PM | #9 | ||
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For example I can just mash the throttle and I come under 5s everytime, all the time. I doubt you can do that with rwd. As a result the rwd is probably the one that needs more abusive launch techniques to get to the magazine numbers. In any case with launch control and awd, it makes the awd advantage even greater. Life is a lot more than numbers anyway but just wanted to clear this one up
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02-16-2014, 02:43 PM | #10 | |
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The seller couldn't swear what would be those measures otherwise. He *thought* they would be the same... Nothing is less sure. Last edited by Saphirschwarz; 02-16-2014 at 02:44 PM.. Reason: typo |
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02-16-2014, 04:50 PM | #11 |
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Other posts mentioned that XDrive with DHP has no drop in height, so XDrive+DHP is still 25mm higher than RWD+DHP, that's a big difference.
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02-16-2014, 05:04 PM | #12 | |
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02-16-2014, 07:08 PM | #14 | |
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02-16-2014, 07:56 PM | #16 | |
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02-16-2014, 08:00 PM | #17 | |
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02-17-2014, 09:50 AM | #18 | ||
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I am not talking about benefit or not at any other time then from a dig. Fact is, like I said, identical cars, but one carrying 150lbs more weight is simply not going to be faster than the other. It's just not. It only changes when traction is added which is what xDrive brings to the table. The other fact is, the magazine tests that some of you live and die by, they don't own these cars, they are perfectly happy to abuse them in order to get good numbers. A small amount of wheelspin is a good thing, we are talking about 328/428s here(not 335's here JDong-where traction of the RWD model is more of an issue). RWD 328/428 cars don't sit there and smoke em endlessly. So if you are going to out launch one in xDrive, to take advantage of the added traction you need more revs. 300hp, you kind of said it yourself. You can easily, with your brain turned off get a 5 second 0-60. Yes. But again, we are talking about those jaw dropping magazine times. The 4.4 with PPK. THOSE times, to get every last shred of advantage from the launch. That is what I am talking about. Those are more abusive than a RWD launch as they require more revs. I have a few hundred 1/4 mile launches. RWD cars like mind, you need about 2500rpms tops to get out of the whole. AWD, you need quite a bit more to make a real advantage out of a well launched RWD car, something like an EVO or WRX for example often require about 5k rpms. Again, this is not hypothesis or some debate. It's facts and physics. Fact is, Turbo+AWD in the real world, very easy to bog the launch when not given enough revs. This made racing EVOs and WRXs on the street fun when kids thought they could get 0-60 in 5 seconds like the mags but with a 2500rpm launch. Here is a recent example: " "And so, here’s how we hit 60 mph in 4.8 seconds: We held the engine at the 6700-rpm redline, jumped off the clutch, shifted out of first at about 5300 rpm, and held on to second until the car hit the redline in second at 61 mph. To get down to a repeatable 4.8-second time, we subjected the WRX to this mechanical mayhem 14 times. To its credit, it didn’t utter a peep of discontent. The clutch didn’t slip, no driveshafts turned into fusilli, and the six-speed ’box shifted and responded exactly as it did when we started. Will you try this with your new WRX? We doubt it. We doubt it. And if instead you just ease off the line, your times will likely be somewhere closer to our 6.3-second rolling-start 5-to-60-mph figure." " http://www.caranddriver.com/reviews/...al-test-review Now let's be clear before 300hp comes back with some kind of magazine article or defensive post on xDrive. If anything, I am pointing out the benefit of xDrive...TRACTION, and mostly at launch. My point is, there is technique to exploit that benefit and if not used, then the benefit is marginal.
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'98 Dinan/RMS stage 2+(VAC cams, CES Cutring etc) '15 Buick Regal "T"(wife) '06 Saab 9-5 Combi 5mt (full suspension, LSD, clipped turbo etc) Last edited by Jamesons Viggen; 02-17-2014 at 10:02 AM.. |
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02-17-2014, 10:10 AM | #19 |
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^ I believe launching the WRX is a different problem, there is too much turbo lag and the engine will bog down if you don't launch aggressively. It was that way at least for the previous generation (from what I read).
My car uses launch control at around 3k RPM, where it absolutely dumps the clutch, giving a pretty violent launch. There is a counter in the TCM that logs how many times you have launched the car, and disables itself after some huge number lol. The weakest link in this case are the clutch packs, not axle shafts or differentials. But once you go up high enough power (grip with tires), then obviously the driveline becomes the limiting factor, ahem solid rear axle. Anyways, not that those are the kind of cars being discussed, but I'd guess the driveline abuse starts once you approach 400 HP to a single axle. |
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02-17-2014, 10:20 AM | #20 | |
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The WRX is of today is very different than 2002, not such an on off laggy wet noodle. I watched a 500hp 996TT run a 15.0 at E-Town with a light roll off-almost no launch lol. He got confidence through the day and after 12 passes got down to the mid 12's. But given your cars example. Again, the S4 is very different than launching a 2.0T. This thread was specific to the 4 cylinder cars. The tq and power delivery of the 6's makes launching them less likely to bog. Again, the key. Someone please explain how two identical cars, but one heavier, and maybe even making 1-2% less power due to more parasitic losses, how will that car be FASTER unless it exploits traction from AWD? And if the RWD car hooks up fine at 2500rpms launch, how again does AWD out launch it unless it sticks with more revs to get it out of the whole faster.
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02-17-2014, 10:32 AM | #21 |
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If your pavement is not perfect (e.g. too wet, too cold, etc), you WILL lose traction during a WOT launch on a RWD or FWD car. I had this happen all the freaking time in my AH3. Even on 1->2 shifts on highway onramps when hitting bumps.
You can either upgrade to track quality ultra high performance tires, or you can attempt to turn off ASR/DSC so that your car does not attempt to avoid wheelspin, which is wasteful on your tires and makes a scene out of aggressive takeoffs. A 150lb weight increase (e.g. 3% of the curb weight) is not as catastrophic a handicap as you make it out to be. The technique you quoted is virtually how EVERY magazine does their launch tests -- AWD or RWD. The manufacturer supplied number is a more accurate estimate of the car's non-brake-torqued / non-launch-controlled 0-60. The only "exploitation" here is that AWD in a sports sedan application will consistently shave off tenths of seconds due to recuperating the valuable time lost by wheelspin. And that's something that easily overcomes the marginal weight gain of such systems. Does this apply to the N20? Probably not as much as to a more powerful BMW. It's a relatively low power low torque engine. It will likely matter if you live in a climate where you choose to have all-season tires rather than the max performance compound optimized to your climate. |
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02-17-2014, 10:38 AM | #22 | |
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And I did not say 150lbs is a huge weight gain. But the general rule of thumb that gaining or losing 100lbs on a typical street car is roughly equal to about 10hp. And again, the magazine tests are not the same for RWD and AWD because again, it is about RPMS of the launch. If the RWD variant can plant power with a 2500rpm launch, the AWD car will not be faster with the same technique(unless as you said, it is wet which we are NOT talking about). You need to reach a point where the RWD car can no longer support that RPM while the AWD one can. That is how a launch advantage happens. So no, not the same technique. AWD-FWD-RWD, all three take to being launched a bit differently.
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'98 Dinan/RMS stage 2+(VAC cams, CES Cutring etc) '15 Buick Regal "T"(wife) '06 Saab 9-5 Combi 5mt (full suspension, LSD, clipped turbo etc) Last edited by Jamesons Viggen; 02-17-2014 at 10:53 AM.. |
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