09-18-2019, 02:34 AM | #155 |
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Interesting. Whether the results should be trusted 100% is a different story (especially since this is an advertisment video straight from XDelete's website), but it could be indicative.
Question is how much of that is managed to be transferred to the road in a 2 driving wheels setup and whether you would still not be better off with less WHP but more transferred into acceleration. That's probably very situation-dependent. If you could hypothetically do FWD only, I'd expect even less losses / higher WHP, but the traction in real life would be even worse. One thing is certain - 0-100 is always faster with AWD. I think people tend to go to a goat for wool, when discussing the advantages of RWD over XDrive (from an XDelete point of view)... The answer is all given in the very first sentence of XDelete's Manual: "BMW’s with xDrive are great vehicles, except when it comes to having fun with your car." That says it all, IMO.
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Last edited by Skyhigh; 09-18-2019 at 04:42 AM.. |
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09-18-2019, 04:53 AM | #156 | |
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Having the option is pretty cool, there's that, but then again, I have another make that is rwd. |
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09-18-2019, 05:00 AM | #157 |
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Anyone having issues w/ the app crashing while trying to "Log in or Create Account"? Payed up and can't make it past this step. Phone appears to be compatible.
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09-18-2019, 08:54 AM | #158 | |
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Pixel 1, Pixel 2, two different model of Huawei with usb c. I wasnt able to connect. The Ethernet setting was missing. The Huawei phones were crashing on "Log in or Create Account" screen. I have success with Samsung galaxy 9, probably all Samsung phones with usb c will be ok. |
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09-18-2019, 10:33 AM | #159 |
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You cannot do fwd only. (Unless you disconnect rear driveshaft)
The transfer case is a shaft directly connected from the transmission to the rear wheels' driveshaft. It is always driving the rear wheels. The transfer case actuator simply tightens some clutches inside a side gear to apply power to the front driveshaft or releases to remove torque application. Removing awd would not free up any more power, nor give you significant acceleration. You are still carrying all the extra weight, and the friction losses are still there whether the front wheels are actuated or not. Also (bonus info) the front differential is a fully locked differential, no limited slip, and not open. The wheel rotation difference gets released through the front driveshaft and inside the transfer case by the clutches. It's a great system, but some people here have way too many expectations of this xdelete software. I've been running 2wd mode for one and a half years now, and there is no additional benefit besides being able to spin your rear wheels and get the car really sideways.
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09-18-2019, 11:13 AM | #160 |
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You lost me there... front diff is not fully locked, that would not make any sense. You can definitely rotate one front wheel on its own when it is in air. Perhaps I misunderstood your terminology.
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09-18-2019, 11:48 AM | #161 |
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It's fully locked, meaning all the differential action is done through the transfer case.
Hold the driveshaft from spinning, and try that test again. Or better yet, spin the driveshaft by hand while having someone apply counter pressure on one and both wheels. Driveshaft will drive both wheels every time. It's a simple gear differential, which behaves a lot like a torsen, but without any slip at all.
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09-18-2019, 11:54 AM | #162 |
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That info is especially relevant when the transfer case actuator malfunctions and leaves the front wheels active even on slow speed turns.
The front wheels will skip and hop because they want to spin together.
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09-18-2019, 01:05 PM | #163 | |
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As for the actual topic it would be very interesting to see how much if any difference there is in acceleration times once you have enough speed to not have wheelspin in RWD mode. |
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09-18-2019, 02:23 PM | #164 |
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How can it not free up any power if no torque from the engine is sent through the drivetrain to the front wheels? As 100% is sent through to the rear there is no longer as much dissipation through the moving of the front drive train parts. Carrying the weight isn't what causes the ~20% power loss we see between xdrive and rwd. It's the friction and inertia from having to send torque through those parts directly. Once the tcase is disengaged you are only dealing with the external Friction of the road to move those front parts. The engine output doesn't take nearly as much of a hit from this since you measure power from just the rear two and only accounting for a bit of extra weight. On a dyno this is essentially neglible.
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09-18-2019, 02:47 PM | #165 |
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You have to realize that all the torque is applied to the transfer case shaft, which is always connected to the rear driveshaft. It doesn't actually pull power from the rear wheels, ever.
When all 4 wheels are spinning at relatively the same speed, there is hardly any total force loss because the power is always used to move the vehicle as a whole. Just friction losses. The 20% "loss" is falsely apparent when dynoing on the rear wheels, because the front wheels stay still. There are a lot of friction losses, from fluid and bearings. This is because it is in an "unnatural" condition of moving the rear wheels while fronts are stopped. This never happens in real world driving conditions. Additionally dynos calculate the force applied to the roller by the wheels, and it gets complex when they have to estimate engine power from 4 wheels, especially when it's not a full time awd system. Dynos use different calculations for 2wd/4wd systems, and across different brands. Actual numbers are probably some 5-10% losses at most from fluid and friction on dyno.
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09-18-2019, 02:52 PM | #167 |
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Now the F3x might be different, although I really doubt it, the E53 X5 certainly has a front differential.
https://www.bimmerfest.com/forums/sh...11&postcount=1 |
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09-18-2019, 07:05 PM | #168 | |
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It pops up "Sorry, xDelete can't connect to your car, make sure ignition is on" even though it is on and IP is set to theirs. I believe they haven't gotten the support of all xDrive ECU versions yet. I'm pretty close to asking for a refund or selling my license if they don't offer it.
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09-18-2019, 08:40 PM | #169 | ||
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09-18-2019, 09:06 PM | #170 | |
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However, E53 has a completely different type of system. It is a full time awd system. F30 can variably add and remove drive to the front wheels.
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09-18-2019, 11:19 PM | #171 |
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Honestly, seems to me some xDrive version aren't supported at all, mine hasn't connected at all so I can't even have my car added onto the app so I can flash full stock like they tell me too.
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09-18-2019, 11:25 PM | #172 | |
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09-19-2019, 12:42 AM | #173 |
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Ok so as I thought it was a terminology issue after all, when you said earlier "the front differential is a fully locked differential" you were talking about what I call center differential (i.e. transfer case / transfer box).
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09-19-2019, 12:57 AM | #174 |
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The app can' even do the basics of logging in, yet we are supposed to trust it to reprogram our $45k+ machines?
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09-19-2019, 03:07 AM | #175 | |
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09-19-2019, 04:33 AM | #176 |
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No worries - the anonymous developers from the Austrian company with no company website said/wrote it is perfectly safe! It must be then. I am sure they have all the competence and design data they need to make that assessment.
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