08-09-2016, 10:15 AM | #1 |
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Tips & Pointers on Launching the 1M
I've probably been losing up to 2 seconds from having a terrible launch on the 1M.
Any tips from the Autocross or Time Attack pros? Do you have your CDV removed or a modified variant? Last edited by DSCPLN; 08-09-2016 at 11:16 AM.. |
08-09-2016, 11:10 AM | #3 | |
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http://www.1addicts.com/forums/showt...amp;amp;page=3 1M gearbox is ZF GS6-45BZ It is rated by ZF at 470 NM input torque ( 346.61 lb ft) I removed links because no longer valid. Our motors are already 320 lb feet torque and 369 overboost though overboost is always in a rolling situation there is less shock than in a launch. Update. Here is current link to ZF: http://www.zf.com/corporate/en_de/pr....shtml#tabs1-1 |
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08-09-2016, 02:22 PM | #4 | |
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08-09-2016, 03:06 PM | #5 | ||
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08-09-2016, 05:27 PM | #6 |
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^ nachob, Appreciate the elaboration on your decision to not removing your CDV.
There are definitely several different schools of thought on that topic depending on who you ask. I'm more so interested on the method on how people have been launching their 1M's from the start. Provided that you performance 'racing' and are starting from 0, running through a time circuit of any sort (Autocross, drag racing, etc).. What is the best way to launch the 1M? With that, obviously keeping tire slip to a minimum is definitely up there in priority. |
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08-09-2016, 05:35 PM | #7 | |
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08-09-2016, 09:28 PM | #9 | |
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Also you will place a lot of stress on the gearbox if you remove the CDV as others had said. Not worth it. |
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08-09-2016, 10:23 PM | #10 | |
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Understanding how to properly launch the 1M provided its high torque is the entire point of this thread. I'm not looking into starting a debate about the CDV either (there are pages and pages of the ongoing debate if you search the forums) - you either understand its trade-offs, or you don't. I was just curious what high performance drivers were running and their perspective. I am still looking for relevant 1M launch advice from a competitive performance driver. Last edited by DSCPLN; 08-09-2016 at 10:30 PM.. |
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08-10-2016, 08:27 AM | #11 |
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While I don't have a 1M I am sure the CDV is the same.
I think my CDV makes my shifting less precise and leads to clunky drive line loading and unloading..which is probably worse for wear. Without the CDV I have CONTROL over engagement points. With the CDV it is a crap shoot as to when it will hook up since it is all dependent on how fast the little hole lets the pressure bleed...engaging and disengaging the clutch. It is there to stop the ham fisted from doing clutch drops. If you understand how a clutch works and don't dump it you wont have any issues.
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08-10-2016, 10:47 AM | #12 | |
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From a high performance driver friend:
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Last edited by DSCPLN; 08-10-2016 at 10:53 AM.. |
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08-10-2016, 12:14 PM | #13 |
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This is really good and really explains the art that is a good launch. You have to take into account so much. The pavement temp, tire temps, outside temp, silt or road, asphalt or concrete and rpm range and clutch release. It really is an art that can probably only be mastered by practicing with a timer and muscle memory of what worked when and where.
I am still open so some suggestions, for example a driving instructor told me to pretend there was an egg between the throttle pedal and the throttle actuator so that you press delicately. It helped a bit and there are probably tips like that that hopefully will help out. Now I go off a little bit...... DSCPLN I know the CDV keeps coming back in the discussion so I promise that this is the last mention I make. You said that there are many opinions on this which is one one of the problems with the forums and the Internet. Every opinion is weighed equally. Someone can spend days doing research, posting actual numbers and real data and engineering analysis and someone will just make an off the cuff comment and the forums weigh them equally as just another opinion. I think that is a mistake because there are many that are thorough and are on quest for the truth and try to back it up with data. For example, I stated that the the transmission in our cars is near the limit of its rated capacity and that is something to consider when increasing the shock of removing the CDV valve. Especially when the bigger issue with our cars is the triple combination of turbo lag, a crazy surge coupled with limited traction and an engine that where output seems to vary quite a bit with temperatures. For example as related to launching the 1M. I find on cool morning the motor makes more power but the tires are colder! Later when the tires are warmer, the car doesn't pull as hard....crazy! Anyway, our performance buddy is right on on every point but his last statement also goes with what I am speaking about the internet where everything is weighed equally. The e90 does not make the torque like the 1M. At 1800 RPM we are speaking about 320 lb ft going through the driveline and mounts. The e90 is more gradual and doesn't even make that much torque at full swing. Furthermore, the transmission in the e90 is much higher rating that the 1M gearbox. So he implies that his experience without CDV and launching all the time is directly related to the twin turbo 1M. If you look at the ZF link I provided the next model up is the M3 gearbox and it is a 53BZ rated at 600 NM (442 lb/ft). You have a higher rated gearbox with less torque. The opposite is true with the 1M. You have a lower rated gearbox handling more torque so driveline jolt is a bigger concern in our cars. Also the part about BMW only one using CDV valve, I will not speak to because I only speak about things I research and don't know off-hand if that is true. What is true is that BMW uses expensive dual mass flywheels. The dual mass flywheel is a two piece flywheel where both pieces can move respectively with springs to absorb engine vibration. While this design makes for smoother running, it is another piece that is impacted severely by a jolt and they can soften over time, overheat and fail. You will notice the 1M has a clutch temperature sensor. This piece is expensive and another reason engineers use CDV to reduce the driveline jolt. https://en.wikipedia.org/wiki/Dual_mass_flywheel I see a lot of these testimonials all the time. In another thread discussing direct injected turbo oils and 15k oil change intervals, someone chimes in and says my old 328i has 250K miles and I changed the oil every 15K miles totally discounting all the research posted about direct injection spraying cylinder walls and some fuel mixing with oil, etc. Again, everyone just weighs this off the cuff irrelevant statement the same. The 328i is a normally aspirated, port injected motor. The 1M is a twin turbo direct injected motor and the oil is taking a bigger beating than his 328i. Another poster says on an F80 says I didn't break-in my e46 and 80K miles it doesn't burn any oil. Again, if that's true, lucky for him but his car used iron cylinder walls, the F80 used a new process where metal is welded directly on the aluminum block. Not the same material on the new cars. So that is all I will say about it anymore and I apologize if your thread went off. I wish the CDV hadn't been the first silver bullet mentioned in it. I assume with your mods that you are OK incurring the additional risk to the driveline but I just want to make sure that people don't just think taking off the CDV is going to give them 2 second faster launches with no impact to the durability of the Dual mass flywheel and gearbox. I hope you understand the spirit of why I posted this. Humbly.... done. Thank you. |
08-10-2016, 04:14 PM | #14 |
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^ nachob Very well put.
Lots of questions raised regarding the capability of the stock gearbox to support tunes set to higher levels of torque. And the impacts of a removed CDV Last edited by DSCPLN; 08-10-2016 at 05:00 PM.. |
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08-11-2016, 02:09 AM | #15 |
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I had drag hundreds of time (not on the 1M) and its all trial and error. Same day same road but different tyre temp and clutch temp will require adjustment.
Past cars I drove that had CDV is Lancer Evolution and AP2 S2000 and it never bothers me a bit as I know I can hammer the gearbox harder with the extra cushion from CDV. If you lost 2 seconds on launching that is some serious traction problem to me. Anyway each to their own. |
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08-12-2016, 10:55 PM | #16 | |
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Maybe others will recall some examples, but I personally only remember hearing of one transmission failure here on the forum and I don't think the guy was running a lot of mods. There are lots of people putting out 450-500 ft-lbs for years now with no transmission issues. . . Clutches, well that's another story. Now back on the original topic . . . I find that there is no need to rev beyond about 2000-2500 RPMs for a good launch. Slight hold at the friction point, and as it grabs, right foot to the floor. For me, the variation is in the feel for traction while briefly holding at the friction point and how quickly to get it fully engaged. There is not much variation in the starting RPM's. My autocross club usually has about 150' lead in (usually with a gate) prior to the timing start, so perfect launch from the line is less critical then being able to put full power down through the start. My approach to a straight line all out 0-60 run or 1/4 mile may be different, but I don't really do that. Last edited by CarJunkie; 08-12-2016 at 11:02 PM.. |
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08-13-2016, 12:28 AM | #17 | ||
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Great tips on launching! Very relevant to my needs (Autocross) |
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08-14-2016, 11:05 AM | #18 | ||
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I agree with your launch technique. It takes quite awhile to realize that you don't need to launch it at high rpm.. And it's really difficult to keep dialing back. Most of the autocross events I do have a 5 foot roll out to the timer so it's pretty much an immediate launch ... a little bit of wheelspin is fine but less is more. Getting into the boost off the line just means you will roast the rear tires. The best way to improve rear traction is bigger rear tires. I run 10" rear wheels and 285/30/18 really helps and 315/30/18 (on a 10.5) makes you go " wow.. I was roasting the 285s.." .. |
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08-14-2016, 07:23 PM | #19 | |||
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Quicker engagement will make it worse. BUT IF it does take it away please report back so I can eat some crow cake. Tjamks |
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08-15-2016, 12:02 AM | #20 |
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I lean toward nachob's point of view.
And I typically notice the CDV effect more with basic moderated driving and less with spirited driving. Haven't removed it to see what the difference is. Also you have to consider that this car's forte wasn't meant to be launching and making a quick 1/4 mile, but to be quick around a track or through twisty roads. If you learn to anticipate the effects of the CDV, it's not much different than learning to drive a manual in the first place. |
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