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Stock Twins King
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Discussion Starter · #1 ·
I have read that some people prefer to get there pressure source for a EBC from the #1 turbo nipple as opposed to the intake manifold. The most common installation is on the intake manifold. I have read that a "better" read or more accurate contol is if you tap the turbo nipple for the source.

Has anyone tried installing there EBC TPS source this way? You would have to actually "T" the turbo nipple to get this source because it is the same place you would be attaching the "IN" of the solenoid for the EBC. This may prevent over boosting and possible boost spike due to a closer "reading" on the true pressure source.

Any ideas?
 

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Boost4fun
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Mhh, my point is that I want to see the pressure in the intake mani and not right after the turbo but maybe I am wrong...
I mean due to pressure drop the reading might be wrong closely to or even at the turbo in comparison to the intake after IC, hoses and stuff like that.
Gerd
 

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Stock Twins King
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Discussion Starter · #3 ·
Ya well, thats my point. I am not concerned about the pressure drop thru the IC. I want true boost levels coming off the turbo itself. The assumption is that the boost gauge reads 18psi manifold, but in reality this could be 20+ turbo side. If one is concerned about overboosting there turbos, then I would think taking a read from the turbo is "safer"?
 

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Boost4fun
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Ok, got it. BUT if there would be such a huge pressure drop than there would most likely be a boost leak causing this I think. Then the car would stall due to measured air going to the nirvana. Different story would be with a MAP ECU or so. Than you wouldn´t recognize it.
You could add a second boost gauge for testing purposes directly at the compressor housing and compare it with the boost level in the mani... How about that?
 

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Stock Twins King
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Discussion Starter · #5 ·
A healthy system should have about a 1-1/2 psi drop on a 3-row. I would say thats about right based on my reads. Thats a good idea testing the drop via 2nd gauge, but if I am correct about the +/-2psi, then I am still thinking that could be a better source for the PS
 

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Boost4fun
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Mhh, depends on what you want to see. According to all the stuff I have learned 18psi at the mani is about right for the stockers. Most of the BPU folks are running this pressure I think.-Me also. That should assuming that (due to the drop of 1-2psi) the turbos are pumping around 20psi generally..
In principle you can do both, having the pressure measured at the turbo or at the mani. Both is a system pressure at a certain spot. The only difference is that the reading will deviate somewhat.
I have my pressure gauge tapped into the BOV line and my AVC into the line of the OE pressure sensor and both are reading equal.. That´s just as an info..:)
 

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(overspooled)
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Stu Hagen said:
I have read that some people prefer to get there pressure source for a EBC from the #1 turbo nipple as opposed to the intake manifold. The most common installation is on the intake manifold. I have read that a "better" read or more accurate contol is if you tap the turbo nipple for the source.

Has anyone tried installing there EBC TPS source this way? You would have to actually "T" the turbo nipple to get this source because it is the same place you would be attaching the "IN" of the solenoid for the EBC. This may prevent over boosting and possible boost spike due to a closer "reading" on the true pressure source.

Any ideas?
I would think that the best source for pressure for the solenoid would be off the turbo nipple itself. That is how I had mine when I had twins. I would think it would be more reliable. Not sure if another source would be better with respect to overboosting. I would think you'd be more likely to overboost if you went to the manifold for pressure; afterall there will never be a boost gain over the IC.
I always adjusted my bc duty cycle referencing my boost gauge which is plugged into the back of the manifold. you could always get the source to the back of your ebc from the manifold, or the nipple from the turbo and hook your boost gauge to another source to monitor the difference...
 

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Boost4fun
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Sure that´s correct to have the solenoid pluged to the compressor housing itselve. But the question is where to read the pressure at...
 

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(overspooled)
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read the pressure from the manifold. IMO it doesn't matter how hard the turbo is working, it matters what the manifold is seeing. 20psi at the manifold might be 22-23 at the housing, but it doesn't matter IMO.
 

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Boost4fun
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Not exactly. I think it does matter. Since the more pressure the turbos producing the higher the rev´s of them will be and somewhen you will reach a critical level when aiming to 150k revs or so.
Ok, when it comes to the engine itselve it almost wouldn´t matter how hard they are working..
 

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Stock Twins King
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Discussion Starter · #11 ·
Here is the quote I was trying to find earlier. From Andi about this:

Quote:
Originally posted by Sound Performance
You cant get surge at part throttle!! What you have is a pressure imbalance between the manifold and the IC pipes because your throttle plates are half open. This causes the BOV to open and close!! Any turbo car will do this with a responsive turbo and part throttle applications.


Lar




Lar,

This is incorrect. You absolutely, 100% *CAN* get surge at part throttle. Nothing to do with the BOVs, you can get pure and simple compressor surge at part throttle. In fact it's a LOT more likely to happen at part throttle than full throttle. Let's imagine a system where there is no BOV. Holding part throttle to make, say, 1/2 a bar of boost on your boost gauge, the turbo is making upto 2 bar of boost in the IC pipes by 6000RPM. (I've measured this myself w/ boost gauges before and after the throttle plate). So the turbo is making 2 bar of boost, but it's only flowing enough air for the amount of power you're making at 1/2 bar boost part throttle (not much air flow). Unless it's a REALLY flexible turbo surgewise, this will more often than now be WAY off the surge map and cause part throttle compressor surge.

Band-aid solution #1: a push-type BOV that opens freely at part throttle boost situations, to vent all that extra air that the part-closed throtte plate isn't letting by. This helps, but doesn't totally fix the problem... in fact my testing that showed 2 bar in the IC pipes at 6000RPM when I only had 1/2 a bar in the manifold at part throttle, was done with 3 bovs on the car (2 ssbov's and 1 blitz dd, and the blitz DD was fully open whistling like a mofo steady state during this test).

Band-aid solution #2: a non-surgy turbo, i.e. a very flexible turbo. My old T64 was very bad at surging at part throttle, because its surge characteristics were BARELY good enough for the 2jz even at full throttle. My PT67/T04R compressor wheel is so much more flexible that it never surged even at part throttle.

Best solution: Make sure that whatever boost control method is being used references IC PIPE PRESSURE rather than manifold pressure. Boost controllers that go by manifold pressure to control boost (i.e. ones like the Blitz DSBC, SBC-iD, etc) cause such part-throttle compressor surge to occur because they allow huge amounts of boost to build up in the IC pipes at part throttle. That's one reason HKS EZ and MBC cars are so much more driveable... if you ever drive an MBC car at part throttle through the rev range, and it has open wastegate, you'll notice that you can hear the wastegate open at high revs even when your boost gauge is still at slight vacuum or just 1-2 psi.. indicating you're already above 15psi in the intercooler pipes. The way I fixed this on my car (since I have a Blitz DSBC) was that I rerouted the head unit's boost sensor source from the manifold to the nipple at the bottom of the TB just before the throttle plate. This is in direct disagreement with the blitz directions, and yes it screws up the peak hold since it reads the boost spikes from throttle let offs.. but it makes the car SOO much more driveable because it now controls IC pipe pressure and prevents such compressor surge, not to mention stopping those awful spikes I used to get when going from part throttle to full throttle (i.e. modulating to exit a corner, then nailing it).

Sorry for the long post.... just wanted to clear this issue up.

Andi
__________________
Andi Baritchi
 

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Shawn Davis
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Ideally you have a seperate pressure gauge and boost controller. You plumb the guage to manifold and the boost controller to the turbo. You then adjust the controller to achieve the boost level in the manifold that you want.

Plumbing the controller to the manifold gives power control due to pressure fluctuations when you open/close the throttle plate.
 

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Stock Twins King
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Discussion Starter · #13 ·
Ubermensch said:
Ideally you have a seperate pressure gauge and boost controller. You plumb the guage to manifold and the boost controller to the turbo. You then adjust the controller to achieve the boost level in the manifold that you want.

Plumbing the controller to the manifold gives power control due to pressure fluctuations when you open/close the throttle plate.
So you agree with me and Andi that this is a safer/better approach to the standard EBC plumbing (installing EBC PS to the turbo)
 

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Registered
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Theoretically, locating the feedback mechanism close to the control mechanism makes for a well engineered loop. However, one would need a second gauge, located in the manifold, to verify plumbing integrity. Who here runs two or more boost indicators? They are the ones who need to comment.

I cannot agree completely with adjusting boost to meet target P on the manifold gauge. This would infer that a significant P drop and/or leak would be neglected at the expense of possibly exceeding safe turbo speed.
 

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Stock Twins King
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Discussion Starter · #16 ·
If you read this post that started in 2003 to the end you will get a better understanding.

http://www.supraforums.com/forum/showthread.php?t=114179

Although I am still unsure of this. I guess the best thing is to try it. I do have a Defi gauge running manifold pressure, and If I switch my SBCiD over to the turbo, then in effect I will have both pressure sources covered. I read that you loose the ability to have peak hold though when running this to the turbo. But I have peak hold on the Defi thats using manifold pressure.

Andi swears by this set up. He and I both track our cars, and this is an issue mostly on the road course. Maybe no one hear has really felt that car "bucking" effect like I have. Like I mentioned, it feels like my turbo is going to fly off the compressor housing. I really noticed it with my new hybrid turbo's.

I am under the impression that other than Andi, and maybe 1 other, no one else runs there's like this.
 

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Supra OG
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Stu Hagen said:
If you read this post that started in 2003 to the end you will get a better understanding.

http://www.supraforums.com/forum/showthread.php?t=114179

Although I am still unsure of this. I guess the best thing is to try it. I do have a Defi gauge running manifold pressure, and If I switch my SBCiD over to the turbo, then in effect I will have both pressure sources covered. I read that you loose the ability to have peak hold though when running this to the turbo. But I have peak hold on the Defi thats using manifold pressure.

Andi swears by this set up. He and I both track our cars, and this is an issue mostly on the road course. Maybe no one hear has really felt that car "bucking" effect like I have. Like I mentioned, it feels like my turbo is going to fly off the compressor housing. I really noticed it with my new hybrid turbo's.

I am under the impression that other than Andi, and maybe 1 other, no one else runs there's like this.

It's the only way to fly. Boost control wasn't meant for manifold pressure... all that serves to accomplish is to overspin the turbo.

Control the turbo outlet pressure.

Andi
 

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Boost4fun
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This whole thread is getting interesting more and more..
I was under the assumption that the exhaust gases are only as strong as the output of the engine. So in other words: If you are going partial throttle only a small amount of air and fuel is being forwarded into the combustion chambers and therefore only less hot gas energy can exiting the engine towards the turbos. This would mean that the drive-energy for the turbos is not as big as it would be under WOT condition for instance.

So therefore I am a little irritated by now since this would be contradicting itselve..... :dunno:

But it´s really interesting to know what´s going on since I have my AVC sensor also hooked up to the mani and not pre throttle.. Most presumable like 90% of the others also...

Gerd
 

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Shawn Davis
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Stu Hagen said:
So you agree with me and Andi that this is a safer/better approach to the standard EBC plumbing (installing EBC PS to the turbo)
100%

Personally I always stuck with a MBC at the turbo and boost gauge at the manifold.
 
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