The Big 3 on one truck/Dyno

SpartanDieselTech

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Interesting thought. I see where your going with this.

Put up with the hiss or have a laggy turbo off the line?


I already know it causes issues like this, just waiting on 3rd party empirical evidence.

Having vanes open at idle, with absolutely no backpressure, then having them slam shut causes overshoot. They close all the way, and spike drive pressure through the roof. With no turbo shaft speed, everything stalls and lags. It's one of the most basic principles of VGT transient response tuning. Intentionally causing closed loop control error, such as forcing open at idle, goes against every principle of it.
 
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bigrpowr

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I already know it causes issues like this, just waiting on 3rd party empirical evidence.

Having vanes open at idle, with absolutely no backpressure, then having them slam shut causes overshoot. They close all the way, and spike drive pressure through the roof. With no turbo shift speed, everything stalls and lags.

jomax- have you experienced this ?
 

ckrueg

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I already know it causes issues like this, just waiting on 3rd party empirical evidence.

Having vanes open at idle, with absolutely no backpressure, then having them slam shut causes overshoot. They close all the way, and spike drive pressure through the roof. With no turbo shaft speed, everything stalls and lags. It's one of the most basic principles of VGT transient response tuning. Intentionally causing closed loop control error, such as forcing open at idle, goes against every principle of it.
What if one were to command 0 percent boost and vane position at idle then gradually bring the boost and vane position up right above idle?

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sootie

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What if one were to command 0 percent boost and vane position at idle then gradually bring the boost and vane position up right above idle?

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smoke
 

jwalk09

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I already know it causes issues like this, just waiting on 3rd party empirical evidence.

Having vanes open at idle, with absolutely no backpressure, then having them slam shut causes overshoot. They close all the way, and spike drive pressure through the roof. With no turbo shaft speed, everything stalls and lags. It's one of the most basic principles of VGT transient response tuning. Intentionally causing closed loop control error, such as forcing open at idle, goes against every principle of it.



So would you say this open vane setup at idle would cause complications down the road? As in mechanical failures with the vanes slamming shut or problems that could arise from the spiking back pressure at take off


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CATDiezel

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I already know it causes issues like this, just waiting on 3rd party empirical evidence.

Having vanes open at idle, with absolutely no backpressure, then having them slam shut causes overshoot. They close all the way, and spike drive pressure through the roof. With no turbo shaft speed, everything stalls and lags. It's one of the most basic principles of VGT transient response tuning. Intentionally causing closed loop control error, such as forcing open at idle, goes against every principle of it.

I agree in theory of control loop PID tuning. The overshoot is absolutely normal to establish a baseline.
 

SpartanDieselTech

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So would you say this open vane setup at idle would cause complications down the road? As in mechanical failures with the vanes slamming shut or problems that could arise from the spiking back pressure at take off


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Nope, just drives like ****. People running these who claim not to notice just either aren't very picky, or don't pay attention.
 

SpartanDieselTech

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What if one were to command 0 percent boost and vane position at idle then gradually bring the boost and vane position up right above idle?

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Go blip the throttle off idle and tell me how gradual the increase from 600 to 800RPM is. It's almost instananeous. This is how fast the vanes need to react.

It just doesn't work right because it's not designed to do that.
 

ckrueg

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Go blip the throttle off idle and tell me how gradual the increase from 600 to 800RPM is. It's almost instananeous. This is how fast the vanes need to react.

It just doesn't work right because it's not designed to do that.
But what is the difference between going from idle and accelerating and smashing the throttle while cruising. In both cases the commanded boost goes from very low to very high. The vane position might not have to go from 0 to 100 but it would have to jump quite a bit. I'm sure the control is different but on my 6.4 the vanes Instantly go from 2 to 95 percent off idle but ebp only spikes a few psi past commanded. Like 10-15 when it only commands around 8. Is this because the 6.7 turbo controls are boost based rather than ebp?

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CATDiezel

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Nope, just drives like ****. People running these who claim not to notice just either aren't very picky, or don't pay attention.

ThanK you for pointing this out. All too often many are "satisfied" but that doesn't make it RIGHT.

A nice muffler will kill the hiss.
 

bigrpowr

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Go blip the throttle off idle and tell me how gradual the increase from 600 to 800RPM is. It's almost instananeous. This is how fast the vanes need to react.

It just doesn't work right because it's not designed to do that.

i havent heard of any issues of the first few have received the open vanes at idle, good thing its an easy flip flop if someone doesnt like it !
 

Jomax

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jomax- have you experienced this ?


Haven't drove the truck much. But around town. I haven't noticed a difference. Trust me, I'd know if the EBP was high taking off.

And I'm SUPER picky when it comes to vehicles, I notice everything...


Talking a trip to CA here shortly. I'll make note on everything people are saying it will do. I'll watch everything. Smoke output etc. Will be towing 12k so I'll notice if there is lag..


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bigrpowr

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Haven't drove the truck much. But around town. I haven't noticed a difference. Trust me, I'd know if the EBP was high taking off.

And I'm SUPER picky when it comes to vehicles, I notice everything...


Talking a trip to CA here shortly. I'll make note on everything people are saying it will do. I'll watch everything. Smoke output etc. Will be towing 12k so I'll notice if there is lag..


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we've sent out a bunch of them like that and no complaints yet . keep us posted .
 

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