Where did you plumb your boost controller into ? UIM is no good !
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How is that possible? The MAF sits between the compressor and the throttle body, there is nowhere for that air to escape anywhere inbetween besides via the blowoff valve (which at this point shouldn't be open at all). Anything that passes the MAF must enter the engine.
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However, I begin to see what MM is saying about flow vs pressure...
One would infer that your MAF should be pegged at whatever amount of air your turbo can flow at a given shaft rotation speed. All other variables remaining constant, you should be flowing a constant g/s from your turbo. This is why Jeff is saying the turbo is still spooling/lagging.
I know for a naturally aspirated engine, the MAF reading should increase as RPM increases, because the engine is operating under a vacuum and sucking in air...
For a supercharged application, the MAF reading should increase as RPM increases, because airflow is dependent upon RPM for a supercharger.
But for a turbo, the flow should remain constant (all other variables being held steady)...
As more air enters the engine, more exhaust must exit, which would speed the turbine faster, however your boost controller should be mitigating that by keeping the output at a constant 10 PSI and bypassing that additional exhaust past your turbo via the wastegate (since you are at target boost), so why does your MAF reading change?
Again, I'm mulling this over while sitting at my desk, I'm sure I'm overlooking something or greatly oversimplifying things, but bear with me.
One would infer that your MAF should be pegged at whatever amount of air your turbo can flow at a given shaft rotation speed. All other variables remaining constant, you should be flowing a constant g/s from your turbo. This is why Jeff is saying the turbo is still spooling/lagging.
I know for a naturally aspirated engine, the MAF reading should increase as RPM increases, because the engine is operating under a vacuum and sucking in air...
For a supercharged application, the MAF reading should increase as RPM increases, because airflow is dependent upon RPM for a supercharger.
But for a turbo, the flow should remain constant (all other variables being held steady)...
As more air enters the engine, more exhaust must exit, which would speed the turbine faster, however your boost controller should be mitigating that by keeping the output at a constant 10 PSI and bypassing that additional exhaust past your turbo via the wastegate (since you are at target boost), so why does your MAF reading change?
Again, I'm mulling this over while sitting at my desk, I'm sure I'm overlooking something or greatly oversimplifying things, but bear with me.
VFR = ((DISPLACEMENT) x (RPM) ÷ 1728) x (VOLUMETRIC EFFICIENCY)
VE changes with compress air and temp.
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How is that possible? The MAF sits between the compressor and the throttle body, there is nowhere for that air to escape anywhere inbetween besides via the blowoff valve (which at this point shouldn't be open at all). Anything that passes the MAF must enter the engine.
at part throttle the compressor circulates (with a plum back BOV) air between the maf and TB. the engine sips at the air being circulated.
at full throttle the compressor only flows what the engine can breath - not what the compressor is capable of flowing.
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Here is a chart I did that demonstrates how flow and whp are closely related
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Actually - at part throttle there is no air recirculating . The throttle is what controls how much air the turbo produces .
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the MAF sits out front
at part throttle the compressor circulates (with a plum back BOV) air between the maf and TB. the engine sips at the air being circulated.
at full throttle the compressor only flows what the engine can breath - not what the compressor is capable of flowing.
at part throttle the compressor circulates (with a plum back BOV) air between the maf and TB. the engine sips at the air being circulated.
at full throttle the compressor only flows what the engine can breath - not what the compressor is capable of flowing.
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it probably depends when your BOV closes. if the BOV is open then I reckon the compressor will flow more air than the engine needs. With the amount of air my compressor (SC) flows at idle it is hard to believe there isn't recirculation happening at part throttle at 3000rpm.
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A lot of other BOVs are closed pretty much at all times except between gear changes .
It is people with this type of BOV that I directed this thread at because there are times that this setup will cause excessive pressure buildup before the throttle plate if your BC is plumbed into the UIM .
I would like to drive a car with the Synchronic BOV on because I think throttle control would be more precise than with any other type of BOV.
Last edited by Brettus; Sep 18, 2009 at 01:52 PM.
Not to step on even more toes, but the Synchronic sucks IMnsHO.
It opens way too easily and, even in recirc, tends to make the turbo chase its tail by setting up an oscillating cycle in the intake tract.
I'm still quite sold on the HKS in recirc.
It opens way too easily and, even in recirc, tends to make the turbo chase its tail by setting up an oscillating cycle in the intake tract.
I'm still quite sold on the HKS in recirc.
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Just to rehash - what exactly did you try ?
Have you tried the setup I have been describing ?
IE
something like a Greddy type RS bov or a turbo xs VTA with the BC hooked into the UIM. Then monitored pressure guages either side of the the throttle plate in a partial throttle load situation - around 5000rpm
Have you specifically tried that ?
Have you tried the setup I have been describing ?
IE
something like a Greddy type RS bov or a turbo xs VTA with the BC hooked into the UIM. Then monitored pressure guages either side of the the throttle plate in a partial throttle load situation - around 5000rpm
Have you specifically tried that ?
Last edited by Brettus; Sep 18, 2009 at 03:48 PM.
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Ummmm ..................... you guys were saying that my setup should not work , does not work , and will never work and I was scratching my head wondering why it works so damn well .
I forget the rest of the detail
I forget the rest of the detail
Your setup could "work" and obviously does "work", except it isn't optimal, it allows for several bad scenarios and is pointless since it can be done the "correct" way with better, more accurate and more repeatable results.
As I said a billion posts back - coincidence is not correlation.
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Is your reading comprehension really that low? Seriously?
Your setup could "work" and obviously does "work", except it isn't optimal, it allows for several bad scenarios and is pointless since it can be done the "correct" way with better, more accurate and more repeatable results.
As I said a billion posts back - coincidence is not correlation.
Your setup could "work" and obviously does "work", except it isn't optimal, it allows for several bad scenarios and is pointless since it can be done the "correct" way with better, more accurate and more repeatable results.
As I said a billion posts back - coincidence is not correlation.
You are stuck in your own paradigm ....
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Demostration of a really laggy turbo - sorry about the quallty
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This second one is the boost controller hooked in behind the throttle plate - that is why you see pressure as i slowly accelerate then hold it at about 5000 before flooring the throttle.
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This second one is the boost controller hooked in behind the throttle plate - that is why you see pressure as i slowly accelerate then hold it at about 5000 before flooring the throttle.
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Last edited by Brettus; Sep 22, 2009 at 01:52 AM.
Video #1 - Tells us nothing since you are already moving.
Video #2 - If that was the boost onset delay under the exact same conditions as the first video, you had your boost controller set up incorrectly. Ask ChickenWafer about that.
Video #2 - If that was the boost onset delay under the exact same conditions as the first video, you had your boost controller set up incorrectly. Ask ChickenWafer about that.
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what do you mean by Already moving ?
What scenario would tell you something ?
It was under similar conditions yes - gradual acceleration to 5000- held at 5000 for a few secs then foot to the floor . I don't see any issue there, I plant my foot at 12seconds in and boost almost instantly goes to 10psi+ . Where is the issue ?
And the reason you see some boost before that is that the BC is plumbed in before the TP and I'm slowly accelerating .
The video below is a little more complex so pay attention .
The first part shows part throttle acceleration up to approx5000rpm . At 5seconds I nail it and you see boost drop below 10 for a nanosecond . The rest is just WOT to redline and boost drops off as rpms climb due to other factors.
This situation is the crux of what I've been saying in this thread . If I plumb my boost controller in the UIM and put the boost gauge before the UIM I will see 20PSI on the boost guage in this scenario (unless BOV is tuned to conteract it) .
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What scenario would tell you something ?
And the reason you see some boost before that is that the BC is plumbed in before the TP and I'm slowly accelerating .
The video below is a little more complex so pay attention .
The first part shows part throttle acceleration up to approx5000rpm . At 5seconds I nail it and you see boost drop below 10 for a nanosecond . The rest is just WOT to redline and boost drops off as rpms climb due to other factors.
This situation is the crux of what I've been saying in this thread . If I plumb my boost controller in the UIM and put the boost gauge before the UIM I will see 20PSI on the boost guage in this scenario (unless BOV is tuned to conteract it) .
[embed]<object width="425" height="344"><param name="movie" value="http://www.youtube.com/v/dIu_Jmnx5BU&hl=en&fs=1&"></param><param name="allowFullScreen" value="true"></param><param name="allowscriptaccess" value="always"></param><embed src="http://www.youtube.com/v/dIu_Jmnx5BU&hl=en&fs=1&" type="application/x-shockwave-flash" allowscriptaccess="always" allowfullscreen="true" width="425" height="344"></embed></object>[/embed]
Last edited by Brettus; Sep 22, 2009 at 03:49 PM.
Because even a giant, missized turbo will spool instantly at 5000 RPM while you are cruising and already putting 40 - 50 g/sec through it.
That isn't the point of the boost controller.
No wonder you think it works. Don't forget how tiny your turbine is.
Do it from a stand still.
That isn't the point of the boost controller.
No wonder you think it works. Don't forget how tiny your turbine is.
Do it from a stand still.
Last edited by MazdaManiac; Sep 22, 2009 at 06:02 PM.
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Because even a giant, missized turbo will spool instantly at 5000 RPM while you are cruising and already putting 40 - 50 g/sec through it.
That isn't the point of the boost controller.
No wonder you think it works. Don't forget how tiny your turbine is.
Do it from a stand still.
That isn't the point of the boost controller.
No wonder you think it works. Don't forget how tiny your turbine is.
Do it from a stand still.
What do you mean from a standstill , I presume you mean accelerating from 2000 rpm or something ? I know spool is slower from down there - of course it is . If you agree to demonstrate what yours does at that rpm i'll do the same test here . But I'm not going to post my one without some commitment from you to do a test as well .
Last edited by Brettus; Sep 22, 2009 at 07:48 PM.
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hmmm- looks like your boost control could do with some work
Yes I know this is not a good boost control test - funny all the same though
Yes I know this is not a good boost control test - funny all the same though
Last edited by Brettus; Sep 22, 2009 at 07:14 PM.