tbm
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« Reply #15 on: November 27, 2014, 02:42:01 AM »
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Dave87VRS, what spec your engine has? I mean - turbo, portings etc.
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nbdiy
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« Reply #17 on: November 27, 2014, 02:52:54 AM »
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In my opinion:
On turbocharged engines it makes no sense, only in the range the range the turbo makes no/ or small boost.
Its a misbelief that you need overlapping on charged engine, because the pressure in the manifold will in case of overlapping press fresh air into the exhaust and thats not what you want (only if you want to cool down your exhaust/turbo), you want it in the engine, to get good efficiency.
Let the exhaust valve close at TDC (not before, because you have old exhaust gases in you engine<- internal egr) and open the inlet Valve directly after. Only on small pressure or low volume flow you can make a small overlapping.
Its an other way on noncharged engines, there you can use overlapping to get more air in the engine, but also can make internal egr with it, if you make the overlapping in a wide range, or much before tdc.
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Dave87VRS
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« Reply #18 on: November 27, 2014, 03:37:00 AM »
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Dave87VRS, what spec your engine has? I mean - turbo, portings etc.
Still running ko3s. I misread your first post. I thought you had managed to activate the vvt for a performance increase. Your correct in saying its used for cold starts only however it can and has been utilized for performance gains. |
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tbm
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« Reply #19 on: November 27, 2014, 04:13:49 AM »
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What turbo do you use? How much turbo spool was increased with overlapped settings? |
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tbm
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« Reply #20 on: November 27, 2014, 04:21:25 AM »
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In my opinion:
On turbocharged engines it makes no sense, only in the range the range the turbo makes no/ or small boost.
Its a misbelief that you need overlapping on charged engine, because the pressure in the manifold will in case of overlapping press fresh air into the exhaust and thats not what you want (only if you want to cool down your exhaust/turbo), you want it in the engine, to get good efficiency.
Let the exhaust valve close at TDC (not before, because you have old exhaust gases in you engine<- internal egr) and open the inlet Valve directly after. Only on small pressure or low volume flow you can make a small overlapping.
Its an other way on noncharged engines, there you can use overlapping to get more air in the engine, but also can make internal egr with it, if you make the overlapping in a wide range, or much before tdc.
I'm also pretty sure if you increase camshaft overlapping you move torque peak at higher rpm range. That is the main reason for this adjustment in my opinion. |
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tbm
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« Reply #21 on: November 27, 2014, 04:25:46 AM »
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BTW: does anyone know stock camshaft overlapping settings for AGU, AUQ and BAM engines?
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nbdiy
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« Reply #22 on: November 27, 2014, 04:39:29 AM »
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I'm also pretty sure if you increase camshaft overlapping you move torque peak at higher rpm range. That is the main reason for this adjustment in my opinion.
On naturally aspirated engines I agree. But I think on turbocharged engine´s I think you shoot to much air in the Exhaust. Your Maf-readings go wrong, because you have less air in engine, then measured, and the turbo has to spin lot more to get the same boost, and in this case it will die if you drive the same boost-pressure than before, that are my thought´s to this... |
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littco
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« Reply #23 on: November 27, 2014, 04:42:04 AM »
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BTW: does anyone know stock camshaft overlapping settings for AGU, AUQ and BAM engines?
What do you mean? With VVT active its around 23 degrees open and when not active its around 1 degree, |
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zillarob
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« Reply #24 on: November 27, 2014, 04:57:59 AM »
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If a compressor is making enough psi/flow to overcome what it takes to drive the the turbine (that drives the compressor), wouldnt that be like one of those free energy contraptions  |
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tbm
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« Reply #25 on: November 28, 2014, 12:52:55 AM »
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On naturally aspirated engines I agree.
But I think on turbocharged engine´s I think you shoot to much air in the Exhaust.
Your Maf-readings go wrong, because you have less air in engine, then measured, and the turbo has to spin lot more to get the same boost, and in this case it will die if you drive the same boost-pressure than before, that are my thought´s to this...
The best solution to solve over discussion is return back stock camshaft settings and create several log sessions  |
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tbm
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« Reply #26 on: November 28, 2014, 12:55:20 AM »
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What do you mean?
With VVT active its around 23 degrees open and when not active its around 1 degree,
It is 23 and 1 degrees in addition to default settings. But I can't find how much is default camshaft overlapping settings for these engines. I believe it should be about int: 0,5mm and ext: 0,3mm. |
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nokiafix
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« Reply #27 on: November 28, 2014, 01:44:41 PM »
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Tfsi the inlet can be used to make the engine sing and dance reduce dynamic cr aid spooling move kr windows ect, not much on the 1.8t just can use it to aid spooling. Not like the JBS claim of 40hp gains from vvt attack. |
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byzan a4
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« Reply #28 on: November 29, 2014, 06:12:30 AM »
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The vvt on k04 cars is for spool etc and only emissions on k03 as std. The change point can be changed but it can't be altered incrementally sadly. I have thought of using a vvt mechanism from an alt engine to see if it's adjustable like a tfsi one as they mechanically look the same
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4ringpieces
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« Reply #29 on: November 29, 2014, 11:09:04 AM »
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Run on dyno with vvt active all time
Then run on dyno again with vvt deactivated.
Where the lines cross is where you should have the change over point.
Only really moves with cams and/or intake/exhaust manifold changes
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