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Old February 12th, 2005, 08:16   #1
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Join Date: Dec 2004
Default flexing turbo vanes

Hi guys,
Just wondering if 3,000rpm and a heavy foot would be enough to keep the vanes flexed ? Seems to me that there is not a lot to be gained by going further as a 3k shift places me right on the torque curve for my Golf V 1.9 6-speed manual. After that, it's just noise.

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Old February 12th, 2005, 08:36   #2
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Location: lakewood, ohio
Default Re: flexing turbo vanes

Shouldn't be just noise above 3,000. My '98 tdi gets a good kick @2,300 and pulls great to just over 4,000 then it falls off. You might have a MAF issue if you lose power @ 3,000. People also seem to confuse the torque peak at 1,900 rpm with power peak. Max power is @ around 4,200 rpm. Your car should pull wonerfully up to that point. The reason you want a the torque to come on at a low rpm is that it gives you better pull up to the max power. It doesn't mean that you drive at 1,900rpm. As far as your turbo question goes. Yeah, heavy foot is the key. Just don't do too much at rpm less than 2,000.
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Old February 12th, 2005, 09:06   #3
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Default Re: flexing turbo vanes

my bad. You're quite right. My car does pull way past 3k, and makes good power. It does not tail off at 3k, it's just that as far as making good fwd progress, there seems to be nothing gained by waiting till after 3,000. That seems to be the majic mark for my car at least. I assume that my vanes are beginning to flex before 3k at heavy throttle loadings? I just want to make sure that I am flexing them through their range of movement, but I don't see the need to push much further than that.
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Old February 12th, 2005, 13:18   #4
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Location: Vermont, USA
TDI(s): peebs4u2
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Default flexing turbo vanes

I hope you dont REALLY mean flexing the vanes on the turbocharger. That would be very bad. Lets not forget that a turbocharger is made up of 2 spinning 'things'(Turbine ring and the compressor ring) hooked together by a common rotating shaft. If the vanes on either of these were to flex, they would quickly fatigue and break off causing the turbocharger to implode on itself.

( http://www.chuckiii.com/Reports/Physics/VNT_turbo.shtml )

Given that the vanes on the turbine ring are made of the material "iconel". They are very flex-resistant.

If what you mean to be asking is "Are the VNT vanes moving their full travel". The answer is yes. At idle, the VNT vanes are at FULL TRAVEL because of the low exhaust velocity. As the engine exhaust velocity increases, the VNT vanes "pull back" because there is excess energy in the exhaust.

This is all controlled by the engine computer based on many inputs. You are correct that beyond 3000RPM there may be no additional movement of the VNT vanes...but engine loading may change that.

This webpage desctibes the action of the vanes on a VNT (based on its original target engine design)
( http://thedodgegarage.com/5digits_turbos.html )
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Old February 12th, 2005, 21:00   #5
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Location: New Brunswick, CANADA
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Default Re: flexing turbo vanes

When I first got my golf it had sat for 6 mo.
The vane actuator was rusted solid. I sprayed it repeatedly with wd40 and flexed it with a 9/16 open end wrench till I could move it with my finger, not easily. For the past 1 1/2 years I do what you're doing and so far it's staying free.

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