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Old 06-13-2002, 08:14 AM   #1
VetteVert
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Default A new twist on the 3/16" connector!

OK, first let me start by making sure my assumptions are correct. I drew up the following diagram to help me explain:



I'm assuming the factory bleed valve is bleeding off pressure so the wastegate arm isn't actuated. Following this assumtion I have made a small bleed hole in my current 3/16" connector. I haven't had enough time to test everything yet, but the boost seems to hold steady more so than it was. The hole is extremely small at the moment. I wanted to start small and work my way up.

So....am I ignorant and imagining that this has helped, or could this be a worthwhile addition to the $0.79 mod?

VV
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Old 06-13-2002, 10:12 AM   #2
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It should help, because you are allowing more air to bleed off before the wastegate is actuated. However, you are also increasing the risk of the wastegate not opening when it should, or as quickly as it should. How big a hole did you drill? I may try this myself as I have a spare connector.
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Old 06-13-2002, 10:35 AM   #3
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I haven't used a drill yet; figured that would be too large (with the bits I have at least). I used a very thin needle to originally pierce the hole, and I have since used a larger needle to make the hole a little bigger. It is still smaller than 1/16". I was very careful right after I put it in. I hardly took my eyes off of the boost guage. I don't think there is anything to worry about at this level, as boost just barely goes past 1 bar. I'm going to gradually make it larger and shoot for 1.1 bar peak. Boost still drops off substantially in the upper rpms, so it must not be bleeding that much boost...

VV

Quote:
Originally posted by SnortWagon
It should help, because you are allowing more air to bleed off before the wastegate is actuated. However, you are also increasing the risk of the wastegate not opening when it should, or as quickly as it should. How big a hole did you drill? I may try this myself as I have a spare connector.
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Old 06-13-2002, 10:58 AM   #4
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Under part throttle condition, the boost control solenoid isn't activated, and you normally would see 7psi or so (wastegate spring). With the extra bleed hole, you'll probably raise this level. This is an interesting idea since you can get a few more psi under part throttle without going full boost like an MBC would.

Let us know how it goes.
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Old 06-13-2002, 11:36 AM   #5
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Wow. This was definitely not the case with my car (stock). I could easily hold > .9 bar in 5th gear at half throttle (uphill). Is my car a freak, or is this the norm?

VV

Quote:
Originally posted by bobski
Under part throttle condition, the boost control solenoid isn't activated, and you normally would see 7psi or so (wastegate spring). With the extra bleed hole, you'll probably raise this level. This is an interesting idea since you can get a few more psi under part throttle without going full boost like an MBC would.

Let us know how it goes.
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Old 06-13-2002, 12:28 PM   #6
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Quote:
Originally posted by VetteVert
Wow. This was definitely not the case with my car (stock). I could easily hold > .9 bar in 5th gear at half throttle (uphill). Is my car a freak, or is this the norm?

VV

The condition you're describing isn't what I was referring to. In fact, your car sounds normal. You have a heavy load in 5th with a fair amount of throttle, so the solenoid is activated giving you higher boost.
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Old 06-13-2002, 12:29 PM   #7
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I actually did almost the same thing, but got following result:

When you gradually depress the gas, boost climbs as expected, but does not exceed the factory setting because even if the bleed hole bleeds a bit more air, FBC will open less than usual to compensate the difference to achieve 0.9bar.

When you WOT, you will be getting a long boost spike that went over 1.5bar for a couple sec in my case, but comes back to 0.9bar slowly. Very dangerous in this situation, because even if FBC does open less, it reacts sort of slower than the first case. I guess it uses pre-programmed value with gradual correction under WOT.

The result of above two scenarios actually happened to me, but FBC behavior was my speculation according to the output.

It all depends on the size of the bleed hole, but let us know how it goes when you test both scenarios.
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Old 06-13-2002, 12:59 PM   #8
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I've tested both scenarios with my current bleed hole. They both react the same way. The highest spike I see is ever so slightly above 1.0 bar in 5th. My bleed hole is very small ATM. About the size of a sewing needle. I'm going to enlarge it very gradually so (hopefully) I don't see the situation you describe. I would think there is a happy medium to be met...if I can find it.

VV

P.S. This is after 4000 miles with the 3/16" connector (no reset), so the ECU has completely learned it.

Quote:
Originally posted by GOT_WRX
I actually did almost the same thing, but got following result:

When you gradually depress the gas, boost climbs as expected, but does not exceed the factory setting because even if the bleed hole bleeds a bit more air, FBC will open less than usual to compensate the difference to achieve 0.9bar.

When you WOT, you will be getting a long boost spike that went over 1.5bar for a couple sec in my case, but comes back to 0.9bar slowly. Very dangerous in this situation, because even if FBC does open less, it reacts sort of slower than the first case. I guess it uses pre-programmed value with gradual correction under WOT.

The result of above two scenarios actually happened to me, but FBC behavior was my speculation according to the output.

It all depends on the size of the bleed hole, but let us know how it goes when you test both scenarios.
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Old 06-13-2002, 02:16 PM   #9
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Shouldn't the bleed hole have some sort of locking mechanism when the manifold pressure is in vaccum state? I hope that bleed hole doesn't suck up lotz of dirt into the intake system.
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Old 06-13-2002, 03:14 PM   #10
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This concept is EXACTLY what the ABC that comes with the turboxs stage 2 is doing. That restrictor is replaced with a "Y" connector - one part of the "Y" goes to the stock boost solenoid, the other part goes to a bleeder MBC. Which is exactly what you have created.
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Old 06-13-2002, 03:26 PM   #11
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Stuff bigger than the hole I've made could pass through a K&N... If I go bigger, I'll ad-hoc a filter mechanism (possibly just some high temp foam wrapped around it.)


VV


Quote:
Originally posted by GOT_WRX
Shouldn't the bleed hole have some sort of locking mechanism when the manifold pressure is in vaccum state? I hope that bleed hole doesn't suck up lotz of dirt into the intake system.
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Old 06-13-2002, 03:37 PM   #12
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For the same $0.79 of the 3/16" connecter I already had Not a permanent solution for me, but fun to play with.

VV

Quote:
Originally posted by DarthChicken
This concept is EXACTLY what the ABC that comes with the turboxs stage 2 is doing. That restrictor is replaced with a "Y" connector - one part of the "Y" goes to the stock boost solenoid, the other part goes to a bleeder MBC. Which is exactly what you have created.
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Old 06-13-2002, 03:43 PM   #13
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oops, double post

Last edited by VetteVert; 06-14-2002 at 06:49 AM.
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Old 06-13-2002, 05:26 PM   #14
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Default Not a great idea

you can alter the factory bleed valve all you want.... bigger connectors, bleed holes, etc. These changes will affect the way the boost initially spools and may carry very slightly higher boost levels (less than 1 PSI).

However, you cannot increase the set boost level with these modifications. The factory ECU sees the increase and will adjust the solenoid duty cycle to bring the boost down to factory specs.

A bad side effect is that the transient high boost levels can freak out the ecu and bring out a more conservative boost MAP..... I have no direct evidence for this other than my own use of this 3/16th mod and some boost spiking.

The only way to effectly decrease spool time AND increase boost is to do one of the following 1) use a MBC 2) use an EBC 3) use a unichip or other electronic device to provide a boost offset so that you can run higher boost with the factory solenoid.

Bailey
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Old 06-13-2002, 10:40 PM   #15
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I'm trying this mod with a 3/16 to 1/8 tee.
I get 15psi in 2nd, 15.5 in 3rd, and 16 in 4th.
I suspect the ecu will pull these peaks closer to stock
values but there may be some lasting increase. I've run
the 3/16 connector for over a month now and max boost
is stock, but I run a little higher peak in 2nd and hold boost
a but better as well.
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Old 06-13-2002, 10:48 PM   #16
gromit
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Talking i used a vacuum tee!

i tried the same thing but used a tee instead of a straight connector. two ends were 3/16" and the other end was 1/16". i left the 1/16" end open to atmosphere. i was amazed! it worked just like a bleed-type mbc! it spiked to 17psi but dropped to around 15-16psi. unfortunately, i hit boost cut a couple times in 4th & 5th, so i put the stock piece back on. good luck and keep us posted!
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Old 06-14-2002, 03:33 AM   #17
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Quote:
Originally posted by icelatte
I'm trying this mod with a 3/16 to 1/8 tee.
I get 15psi in 2nd, 15.5 in 3rd, and 16 in 4th.
I suspect the ecu will pull these peaks closer to stock
values but there may be some lasting increase. I've run
the 3/16 connector for over a month now and max boost
is stock, but I run a little higher peak in 2nd and hold boost
a but better as well.
15 psi in 2nd?! Dude, don't run that! You'll probably pushing 17+ psi in 5th gear.. and you'll blow something up!

For you guys wanting to save money, build your own manual boost controller using parts from Lowe's and Ace Hardware/Furrows. Mine costed $25 using brass fittings. I used the stock hoses on the turbo too, and it works great. I even have a knob where I can control boost! It's a two stage, no high egts under partial to half throttle.

I forget the website that tells you how to build it, but I have all the part numbers from Lowe's that you need to get to build it. I'm running close to 16 psi in 5th gear, and that's where you want to be before the ECU starts to pull timing. I suppose you could a tad over 16 psi in 5th gear, but I didn't want to chance anything.

Jay
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Old 06-14-2002, 04:41 AM   #18
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you going to let us know what parts you used or what?
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Old 06-14-2002, 05:52 AM   #19
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I'm at work right now, when I go home i'll post the exact part numbers from Lowe's.

And post pics on how I assembled it.

Jay
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Old 06-14-2002, 08:21 AM   #20
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Old 06-14-2002, 03:11 PM   #21
icelatte
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Diversion,

I have a (gabedude) homemade MBC from Home depot parts
and with that I get 14.5-15 psi in 2nd gear and
up to 15.5 in 4th. So far (until the computer learns)
I've liked the 3/18 to 1/8 mod more because there's better
boost control at part throttle in 4th and 5th where I need it.
Even with a 2 stage spring/ball and bleed mbc, I could still
push my egts at part throttle in 4th and 5th. The boost numbers
I quoted were peaks, and then I get steady boost .5 -1 psi
lower, which is higher than stock. I never hit max boost in 5th . After a while, the ecu should adjust for some of the spiking.
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Old 06-14-2002, 03:34 PM   #22
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Default Hole in the line

Quote:
Originally posted by GOT_WRX
Shouldn't the bleed hole have some sort of locking mechanism when the manifold pressure is in vaccum state? I hope that bleed hole doesn't suck up lotz of dirt into the intake system.
Where that hole is, it'll probably only see pressure. Either it'll be pressurized by the turbo and the FBC will be closed, or the engine will be off boost, but the FBC closed it won't see manifold vacuum. I don't think there's any combination of conditions that would have the FBC open and the turbo not making enough pressure to overcome the vacuum in the line, although I could be wrong.

-B
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Old 06-14-2002, 04:58 PM   #23
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Default Re: Hole in the line

Quote:
Originally posted by bpitas


Where that hole is, it'll probably only see pressure. Either it'll be pressurized by the turbo and the FBC will be closed, or the engine will be off boost, but the FBC closed it won't see manifold vacuum. I don't think there's any combination of conditions that would have the FBC open and the turbo not making enough pressure to overcome the vacuum in the line, although I could be wrong.

-B
Actually, it shouldn't have anything to do with whether the boost control solenoid is activated or not. The hose comes right off the turbo outlet. There's no way you can get vacuum. All of this is upstream of the throttle plate.
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Old 06-21-2002, 12:59 PM   #24
thejean
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Question Bleed or Wastegate Controller?

Ok guys, I need some help here. We're all talking about creating a better bleed valve so the wastegate sees less pressure...

Question 1 - why not just go to an MBC that intercepts the pressure to the wastegate? Answer - because you would be concerned about high EGT's.

Question 2 - why not just install a bleed valve to vent off more bleed before reaching the stock bleed valve? Answer - because boost spiking occurs more frequently.

OK, some have said that boost spiking is common with a better bleed off however, the stock system runs with some spiking anyway. A Manual boost controller such as the Dawes Devices unit is supposed to eliminate much of the boost spiking - apparently. Therefore, Dawes says that the stock fuel system can handle up to 20% more boost without high EGT's. Well, this may be true at WOT but I doubt its true at partial throttle.

So, my question is - which is better when you don't have the resources to adjust fuel mapping?

Seems to me that both essentiall y do the same thing.

So, my next question is - how much boost increase can the stock fuel system handle overall (i.e, 20%? 30%?) and which system (ie, manual bleed controller or manual wastegate controller) permits lower EGT's at partial throttle?

I'm leaning towards the bleed controller as it allows the wastegate to always "see" some pressure whereas the manual wastegate controller prevents any pressure from getting to the wastegate until it reaches its setpoint and opens.

So, if anyone can answer these questions in some informative manner, I will owe you my engine.

Thanks,
JC
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Old 06-21-2002, 01:39 PM   #25
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Well, I believe we are also talking about 2 different types of bleed valves. My suggestion (small bleed hole in the connector), and a new bleed valve that completely overrides the factory unit. With the small bleed hole, I have to try to get high boost at partial throttle. It will rise more than it did stock, but it comes back down....since the FBC is still seeing most of the boost. I can't help but think this would be the safest, but also the slowest. I haven't had the chance to go bigger than 1/32", but at that size, I hold at ~ .95 bar until ~5600 rpms, when it falls all the way back to .6-.7 bar.

VV
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