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BMW's N55 Single Snail TwinPower
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05-27-2009, 01:35 PM | #67 |
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This image is from the 4.4L V8 FWIW. It is a good close-up and cut away of the twin scroll used there though.
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05-27-2009, 01:35 PM | #68 |
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Here's a pic of another mechanical style CBV directly on the compressor cover. Old Volvos had this in the 80s. You can basically see how it works.
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05-27-2009, 01:38 PM | #69 |
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Yeah, usually the only thing that can happen is the diaphragm the piston sits on can tear. There are already aftermarket diagrams built by APR, etc for the 2.0T cars. They usually aren't hard to replace. I imagine the turbo and CBV are very easy to access from under the car.
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05-27-2009, 01:41 PM | #70 |
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Finally, just to prove its an electronic BPV, notice the lack of all DV related hardware on the intake tubing below:
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05-27-2009, 01:44 PM | #71 |
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05-27-2009, 01:46 PM | #72 |
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Here is a link to a good close up of the best angle photo that details the turbo well. You can enlarge the photo by clicking on it as well.
http://4wheelsnews.com/images/2009/m...ries-gt-68.jpg Any thoughts as to how many mm the turbo inlet is? For that matter, anyone know how many mm the TD03-10TKs are?
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05-27-2009, 01:47 PM | #73 |
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That's not quite the case. Twin scroll has nothing to do with the turbine wheel. It's the same, only 1 size. Twin scroll refers to the turbine housing, the part around the turbine wheel that directs exhaust gases onto the turbine wheel. Twin scroll housings align the exhaust pulses from each cylinder so that they all arrive in an orderly, linear fashion on the turbine wheel thereby maximizing the accelerating force on the turbine wheel itself.
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05-27-2009, 01:49 PM | #74 | |
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That's a great pic. Steve, take a close look inside the intake of the turbo, just before the compressor wheel. You can see the exhaust port of the CBV I just mentioned above.
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05-27-2009, 02:00 PM | #76 |
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05-27-2009, 02:01 PM | #77 |
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Twin scroll improves lag.
It has little to do with maximum power though. Generally, at seriously high HP (like over 750 maybe), I've heard that single scroll will slightly edge out a dual. But it's just nickle-and-diming when you've got plenty anyways. -scheherazade |
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05-27-2009, 02:07 PM | #78 |
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Good info! So what are your thoughts on whether this is, in part, some form of tuner protection, or are they doing it purely for other engineering/cost reasons? I imagine if they encrypt the signal it would be much more difficult to bypass but I'm not sure if this has been done before.
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05-27-2009, 02:14 PM | #79 | |
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05-27-2009, 03:58 PM | #82 |
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No, the electronic CBV does not record pressure. The electronic ones work pretty dang well. They are just solenoid controlled. Your turbos are solenoid controlled. The spring pressure is also much greater, and these don't ever "blow open." Like I said, about the worst thing you'll see is a ruptured diaphragm but those are easily, and quickly taken care of by the aftermarket.
You can bet the farm that the CBV will absolutely be included in the safety and security schemes BMW comes up with to prevent unwanted boost pressures. There will be work-arounds, just like today.
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05-27-2009, 04:09 PM | #83 |
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I would be very interested to see the compressor maps for the single turbo vs the V54 twins, curious if the single will be able to push more air.
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05-27-2009, 07:37 PM | #84 | |
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Ah, come on, they will install a hidden pressure sensor in there. It will also wirelessly transmit your offending VIN back to Germany and you will receive a letter weeks later. On the later, less throttle closure but more CBV openings. IMO, I would prefer the later if I had to choose. |
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05-27-2009, 09:20 PM | #85 |
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I wouldn't be surprised if we saw both
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05-27-2009, 09:46 PM | #86 |
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I agree I would also like to see this. As I said earlier, without knowing how much air these turbos can push (via a compressor map) we won't know if this turbo can pressurize more air than our existing twin set-up. Also, the fuel system's capacity also may be a limiting factor in total HP output.
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05-27-2009, 10:03 PM | #87 |
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When I saw the press release for the GT, I figured this engine would be to shrink the parts bin BMW has as this probably shares turbo with the future ///Ms.
It will be interesting seeing how BMW markets two engines with nearly identical output. Maybe this will be advertised as having a working fuel pump and decent sized FMIC. The tuners (including BMW performance) will probably keep focus on whatever the 3 series has, which until 2012 should be the N54. I make this guess based off the lack of attention (compared to the N54) the V8 TT has received from tuners. |
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