You GReddy guys all should replace your wastegates - Page 3 - Miata Turbo Forum - Boost cars, acquire cats.

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Old 11-08-2007, 12:16 PM   #41
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Quote:
Originally Posted by PAT! View Post
If somebody wants to send me a GReddy actuator I can see about making a replacement.
I'd be happy to send you mine, but I wouldn't recommend that you use it as a gold-standard. The fit of the stock Greddy WG can is non-optimal in my opinion.

A question for you however- I have seen some WG cans that have two vacuum nipples. Typically one is connected to the boost reference and the other left exposed to atmo. I presume that this second one is equivalents to the vent hole found on the most WG cans.

Question is this- with a dual-fitting WG can, could I potentially achieve my goal (two switchable boost levels) by adjusting the WG to achieve full (13PSI) boost when the second nipple is exposed to boost, but to fall back to a lower level when the second nipple is left open to atmo? (switched by the same pneumatic solenoid I'm using right now as an MBC bypass)
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Old 11-13-2007, 12:06 PM   #42
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That is correct. All of our WGA are dual-port capable, although they ship with a grub-screw in place of the second port.

The best way (for spool) is to bleed off the reference to the primary/top port and send that to the bottom or to send ALL of the pressure to the bottom with nothing to the top. This way there is no boost to open the flapper prior to full boost.
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Old 11-13-2007, 08:05 PM   #43
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I just changed my wastegate actuator vacuum source from the port on the turbo to a ported nipple on the intake manifold and that made a BIG difference in responce and how it held boost. To anyone that is trying to make there greddy hold boost better DEFINATLY do that. It took 3 minutes to do and made alot of difference. And make sure the WGA has its own vacuum source that is big too.
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Old 12-03-2007, 02:28 PM   #44
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Absolutely that makes a difference, I went through all that a while ago - the issue seems to be restrictive intercooler and piping.

If you run it in the manifold, the turbo spins a LOT, all the time. Basically, let's say it's a miata and not a drag car, and there's a sort of... "curve" in the road. In this case, you might only give it "partial throttle". Basically, you only want 2-5 psi in the manifold, but the wastegate sees there's work to be done, and flows all the exhaust through the turbo.

Then you're turbo spools to about a billion, and you have exhaust restriction, hotter intake charge, heat soak the intercooler (which you'll want cold when you get out of the turn and floor it) etc. The only advantage is you get like 20 psi waiting for you outside the throttle plates - the downside I guess you could blow off hoses.

Anyway, I put my signal right in front of the throttle plates - after all the restrictions. That way the 3-5 psi drop (measured) across the intercooler is compensated for, but the turbo only presents the desired pressure to the throttle plates, to be used or not, as needed.

Pics:
http://abefm.smugmug.com/gallery/1164235#54351370

BTW - I spent quite a while explaining this to the folks at FM. They eventually conceded that I was correct. It makes sense when you think about it, there is a flow dependent pressure drop across the IC. So you'll get a bigger boost droop at high flow (be it RPM or boost based).

In an IDEAL world (since I like the crisp tip-in of having too much pressure in the IC piping, I want to run TWO MBC's, one in the manifold at my target boost (say 12 psi), and one in front of the throttle plates a bit higher so I get that huge inrush of air when I touch the gas (say 15 psi) to keep the turbo from overspooling and the wastegate from having to find a new, zen-like center once you DO open the throttle, since then it's only a small change for it. But I haven't tried this set up yet, so I can't say how it will work.

BTW, I have an intercooler/piping (FMII) for sale with this "mod" already done. Cheap! :-P
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Old 12-03-2007, 03:14 PM   #45
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Also, manifold references can kill diaphragms in wastegates...
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Old 12-03-2007, 03:39 PM   #46
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Really? Any idea what the mechanism is? Rapid fluctuations is all I can come up with, but it's a pretty weak idea. Interesting.
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Old 12-03-2007, 03:51 PM   #47
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Abe- that's an interesting idea and I think I'll try it. Although it seems obvious, I'd somehow failed to consider that boost drop across the intercooler is in fact a function of flow volume.

My hesitation to do something like this earlier was based upon Corky's recommendations. Specifically:

The intake plenum signal source will slightly improve boost response, since the turbo is free to make all the boost it can until the pressure reaches the sig*nal source and is transmitted to the wastegate. The fact that the turbo is free to make a brief spike of boost will cause the intercooler to be hit by a greater slug of temperature. Greater temperature is always to be considered a nega*tive.

(...)

All things considered, heat should be the controlling factor. Unless unusual circumstances dictate, hook the wastegate signal to the compressor outlet and call it a day.
I'm not sure I understand PAT!'s concern as to the death of the diaphragm.
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Old 12-03-2007, 05:53 PM   #48
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Let me know how it goes- I only have my theories and the one data point - my own car, which worked well. My feeling is that in the manifold, there IS going to be a lot more heat - not the initial spike he's talking about, though I guess it's a small issue) but the build of up the turbo trying to put 50 psi into the IC piping trying to force 10 psi past your partially closed throttle.
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Old 12-03-2007, 06:30 PM   #49
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I should clarify- I'm going to try post-IC, pre-TB, not the manifold.
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Old 12-03-2007, 07:11 PM   #50
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considering the relitively low boost amounts i'm running, 7-8psi. And having a decent size front mount intercooler. I think the benifits of having a manifold sourced wastegate is the way to go. I think everyone should try it at least, cause its so easy and makes a nice differance.
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Old 12-03-2007, 07:26 PM   #51
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Quote:
Originally Posted by bubbaflaat View Post
considering the relitively low boost amounts i'm running, 7-8psi. And having a decent size front mount intercooler. I think the benifits of having a manifold sourced wastegate is the way to go. I think everyone should try it at least, cause its so easy and makes a nice differance.
Where's the benefit? The main reason I put it ahead of the throttle plates was listening to my turbo spool as fast as it could go, and avoiding heatsoak, at part throttle. I guess it sounds good spinning like that, maybe it's worth going slower/getting knock for, but is it worth the turbo rebuild? I'm dramatizing a bit, but I really think you'd want to concider having the signal pre-throttle.
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Old 12-03-2007, 07:48 PM   #52
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Quote:
Originally Posted by corky bell
Wastegate Actuator Signal

...Essentially, three choices exist for sourcing the signal: the compressor out¬let, a plenum entering the throttle bodies, and the intake manifold. Each of these has merit and problems.

The signal originating at the compressor outlet offers the best control over the wastegate with regard to its response and ability to consistently control boost to a given value.

The bad side is that torque-curve rise will suffer slightly, as this source will create the earliest possible wastegate cracking point. This early cracking point will offer some relief thermally, because the entire system will virtually never see more boost than the basic setting of the wastegate. This can be important in avoiding a quick heat soaking of the intercooler.

The intake plenum signal source will slightly improve boost response, since the turbo is free to make all the boost it can until the pressure reaches the sig¬nal source and is transmitted to the wastegate. The fact that the turbo is free to make a brief spike of boost will cause the intercooler to be hit by a greater slug of temperature. Greater temperature is always to be considered a nega¬tive. For a blow-through carburetor system, where the wastegate and fuel pressure regulator must see the same signal simultaneously, the plenum sig¬nal source is best.

Sourcing the signal from the intake manifold should be considered only when turbo response is of the highest importance and the short blast of extra heat can be tolerated or ignored.

All things considered, heat should be the controlling factor. Unless unusual circumstances dictate, hook the wastegate signal to the compressor outlet and call it a day.
heres a read.
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Old 12-03-2007, 08:04 PM   #53
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If you can come up with a EBC that doesn't suck, best of all. Take it off the compressor outlet. I'm curious to see how much heat you get by taking the signal at the other side of the intercooler. It's an easy test to run, read the turbo outlet temps and move the line around.

For that matter, you could measure heatsoak by seeing how much the IC outlet varies in the two modes.

I really don't see it hurting you on the other side of the IC piping, you're talking, oh, milliseconds there. Running at part throttle you're really heating this air you're not even using.

Anyway, this is getting beat to death.
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Old 12-04-2007, 10:44 AM   #54
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Rapid fluctuations is mainly it. When tied to a constant pressure source the opening and closing of the actuator is pretty smooth. But when referenced to the manifold the moving assembly is sucked upwards much quicker and the diaphragm takes a beating when it slams into the upper part of the actuator body. Also, in some actuators, its possible for the diaphragm to lift, partially or fully, off of the perch that connects it to the rod. This can distort the surface of the diaphragm and created wrinkles or high points... we get far more warranty claims on set-ups with the actuator tied into a manifold reference.
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Old 06-01-2016, 09:13 PM   #55
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I know I'm resurrecting an ancient thread but I guess I have an ancient turbo set up.

Would this actuator be an acceptable replacement for the one people complain about on the GReddy? REV9 GT Series Adjustable Wastegate Actuator 5PSI T25 T28 G25 GT28 Turbo Charger | eBay
(Do I need to stick with a 5psi actuator if I'm going to use a MS2e and Electronic Boost Control? Is there an advantage to going up to a 7psi Actuator?)

To lengthen I could just use one of these, right? https://www.z1motorsports.com/forced...od-p-5345.html

Trying to get all my potential issues shored up before I have Savington dyno tune my MS2e / GReddy setup at the end of the month. I really don't want to have issues holding boost during the tune and then switching out parts later that will screw everything up.
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Old 06-02-2016, 11:01 AM   #56
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Hello?? Is this thing on?

Can anyone answer my question about switching around wastegate actuators?

Is the GReddy one inherently bad or was the improvement because the 300zx tt actuator is set to 7psi and its stiffer spring makes it more consistent?

Braineack , Ben , Joe Perez , Curly ??

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Old 06-03-2016, 01:27 PM   #57
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I have an ancient blow off that came with one of the earlier (c.1999) FM2's. There's no diaphragm in it. I used to have to pull it apart and clean it every few months as it would gum up.

Later, I moved it closer to the throttle body, and rotated it. We're something like 8 years later and I haven't cleaned it once. To be fair, that's probably only 30k miles, still, I've been happy with it. Never any repairs to diaphrams. It may be slower, but I'm not sure it is. Look at Synapse Engineering's valves - they can open in under 20 ms, so pistons aren't all bad. :-) They are a little spendy, though.
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Old 06-03-2016, 08:15 PM   #58
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Quote:
Originally Posted by AbeFM View Post
I have an ancient blow off that came with one of the earlier (c.1999) FM2's. There's no diaphragm in it. I used to have to pull it apart and clean it every few months as it would gum up.

Later, I moved it closer to the throttle body, and rotated it. We're something like 8 years later and I haven't cleaned it once. To be fair, that's probably only 30k miles, still, I've been happy with it. Never any repairs to diaphrams. It may be slower, but I'm not sure it is. Look at Synapse Engineering's valves - they can open in under 20 ms, so pistons aren't all bad. :-) They are a little spendy, though.
for now I'm just running a recirculating eom Bosch blow off valve. My issue is building boost with stock GReddy wastegate actuator. I think it is cracking open on partial boost. I hadn't driven it yet with the MS setup (still finishing that off). I'm sure the EBC will help but I didn't want to show up at the dyno for tuning and have to fight with the wastegate actuator and waste my money.

I found this one that is a little higher psi (7.5) with a curved actuator that should put everything in a better location on the cocked turbine housing.
Kinugawa Adjustable Turbo Wastegate Actuator Subaru IHI VF30 VF34 VF35 0 5 Bar | eBay


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Old 06-04-2016, 04:48 PM   #59
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It's not pretty, but if you're creative and on a budget (and it's accessible, I'll admit, I don't know what the part you're working on looks like) you can use a helper spring. I did that on that FMII's wastegate, it worked for years.

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