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elRey
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« Reply #15 on: February 02, 2017, 04:24:58 PM »
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Maybe once you get past the 'switch-over' hang-up we can revisit controlling both turbos with 2 targets. There's also part-throttle control.
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prj
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« Reply #16 on: February 02, 2017, 11:42:35 PM »
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Maybe once you get past the 'switch-over' hang-up we can revisit controlling both turbos with 2 targets. There's also part-throttle control.
There is nothing to get past. I have tuned and engineered many compound turbo setups. You simply do not understand. End of story. But go ahead. You don't seem to care. You also don't seem to understand compressor maps. Look at the shaft RPM at high flow, but 1.0 pressure ratio. You will exceed acceptable shaft RPM and destroy the turbo. |
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« Last Edit: February 02, 2017, 11:45:23 PM by prj »
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fgtskofd
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« Reply #17 on: February 02, 2017, 11:50:42 PM »
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lol Please explain, mechanically, how a manual boost controller can hold a wastegate closed tighter than completely closed. If that was sarcasm, kudos  Some pressure will always be in the waste gate line on boost. because you can't get 100% duty cycle, anything above atmospheric pressure I would consider to be helping the waste gate spring. Basic Engineering |
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fknbrkn
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mk4 1.8T AUM
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« Reply #18 on: February 03, 2017, 12:26:49 AM »
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Some pressure will always be in the waste gate line on boost. because you can't get 100% duty cycle, anything above atmospheric pressure I would consider to be helping the waste gate spring. Basic Engineering
show us spooling logs with wgdc 95% and with unpluged wg line. im very interesting ^) elrey, blowing a huge hot air masses thru tiny k03 isnt a good idea anyway and what happens at the top end? id say there is a point when comp wheel produces more rotating power than turbine wheel. thats really weird setup for me, just think about bypassing it |
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nyet
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« Reply #19 on: February 03, 2017, 12:35:55 AM »
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Some pressure will always be in the waste gate line on boost. because you can't get 100% duty cycle, anything above atmospheric pressure I would consider to be helping the waste gate spring. Basic Engineering
If there is ANYTHING causing your wg to leak during spool, you have a design problem that a MBC will not fix. |
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ME7.1 tuning guideECUx PlotME7Sum checksumTrim heatmap toolPlease do not ask me for tunes. I'm here to help people make their own. Do not PM me technical questions! Please, ask all questions on the forums! Doing so will ensure the next person with the same issue gets the opportunity to learn from your ex
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elRey
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« Reply #21 on: February 03, 2017, 03:20:14 AM »
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 why would I have high shaft speed but only 1.0 PR? This whole idea about the small turbo being a restriction on the intake side is a VERY common misconception about compound turbos. The flow capacity of a compressor is dependent on /derived from the pressure ratio across compressor. P2/P1. Change P1 and flow capacity changes, be it by elevation, weather, or big turbo in front of it. Maybe consider mass flow vs volumetric flow capacity, where the big turbo is changing mass flow not volumetric flow. Did some ppl miss the last post on the first page? prj please describe or better yet share a link to any one of your many compound turbo projects also. Were they sequential turbo systems or compound turbo systems? The limiting factory here will be the total exhaust flow capacity thru the K03 turbine AND K03's wide open wastegate. That's something on which I doubt anyone has any hard data. Again, a compromise I intentionally made. Is there ANY way we can get back to ME7 threory instead of compound turbo theory, which there are a lot better sources on the internet than both prj and me? Thanks, Rey
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« Last Edit: February 03, 2017, 04:14:48 AM by elRey »
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fgtskofd
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« Reply #22 on: February 03, 2017, 06:04:21 AM »
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[quote author
=nyet link=topic=12095.msg100714#msg100714 date=1486107355]
If there is ANYTHING causing your wg to leak during spool, you have a design problem that a MBC will not fix.
[/quote]
Obviously my humour wasn't happening. I had issues with my waste gate bending open though on a k03 though :s
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fgtskofd
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« Reply #23 on: February 03, 2017, 06:07:40 AM »
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show us spooling logs with wgdc 95% and with unpluged wg line. im very interesting ^)
elrey, blowing a huge hot air masses thru tiny k03 isnt a good idea anyway
and what happens at the top end? id say there is a point when comp wheel produces more rotating power than turbine wheel.
thats really weird setup for me, just think about bypassing it
Why would I want to destroy my turbo by un plugging the waste gate line. |
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_nameless
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« Reply #24 on: February 03, 2017, 06:18:52 AM »
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this thread makes my head hurt. at the end of the day if you cant bipass the ko3 it will be a restriction period. id have a large wastegate before the k03 to bipass the small turbo when the the large turbo comes on line with a mechanical switch over on the cold side so when the large turbo takes off a swing check or vacuum actuator closes off the small turbo outlet so it wont bleed back. series hot side parallel cold side otherwise pointless
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Giving your mom a tuneup
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fgtskofd
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« Reply #25 on: February 03, 2017, 07:54:08 AM »
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Wouldn't it have boost creep if the waste gate wasn't big enough already ?
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elRey
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« Reply #26 on: February 03, 2017, 07:58:47 AM »
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I haven't turned up the boost enough yet for that to be a factor. As I increase overall boost and/or have big turbo make more of the boost and thus exhaust flow, it may still show itself.
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prj
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« Reply #27 on: February 03, 2017, 12:01:50 PM »
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why would I have high shaft speed but only 1.0 PR? Because air needs to go through the turbo. Look at a compressor map. I am done here. This is a waste of time arguing with someone who does not grasp basics of mechanical engineering and does not understand the concept of flow within an ICE. |
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elRey
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« Reply #28 on: February 03, 2017, 01:00:52 PM »
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I believe you are referring to the far bottom right of the compressor map for small turbo due to total flow of big turbo going thru small turbo. Is that what you are saying?
E.g. The flow coming out of the T3/T4 falls far right on the x-axis of the K03 compressor map, that right?
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« Last Edit: February 03, 2017, 01:10:35 PM by elRey »
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TijnCU
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flying brick
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« Reply #29 on: February 03, 2017, 01:40:06 PM »
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Yes like that. To visualize flow people often compare to water and pipes etc. Well, think of your k03 as that little water mill that you used to poor water on when you where a kid (or in my case the one I poor water on for my kid). The mill has to turn for the water to pass through. Lots of water will only go through as fast as the mill will turn. If you pressurize the water the mill will turn faster.
Thats why modern compound/sequential setups bypass air as soon as the large turbo starts producing boost. This can be easily achieved by means of a spring checkvalve that will open automatically as the big turbo spools up and you only need to worry about the exhaust bypass (that you can control with either a wastegate or valve).
Here is a picture of a system with this layout:
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