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Old 05-16-2008, 11:22 AM   #1
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Default greddy wastegate woes

so, i've just spent some time looking around for some definitive info about the greddy wastegate issue i'm having (which seems common) of being able to make 12psi at like 4k, but losing 3 - 4 psi between 5 and 7k.

i know there was a lot of speculation about this, and a few of you bought replacements etc... but i wasn't finding any posts where anyone actually replaced it with something else and said "hey, that worked!"

did i just miss that, or has nobody actually remedied the problem with a different actuator? i know Ben was able to sidestep the problem with EBC, if i remember correctly, but right now I'm limited to manual boost control until i get around to modding my MS for EBC.
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Old 05-16-2008, 11:29 AM   #2
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I know of two people who simply got new actuators, adjusted the arm length, fabbed up brackets, and rocked out. Kotomile might have some pictures of his posted under his recent dyno thread. Joe Perez might have pics somewhere too, he's generally pretty thorough.

Even with the EBC maxed out, I still loose boost up to redline. But I'm also starting to wonder if it's due to not just the crappy actuator, but also due to insufficient compressor.
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Old 05-16-2008, 11:41 AM   #3
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it's probably a combination of factors. but the wastegate actuator is notoriously shitty, so i was looking to see what kind of reward i get for my effort. i feel like at least partially solving my "boost till redline" issue would snag me an extra mph or two in the traps, and generally make the car faster and more fun.
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Old 05-16-2008, 11:46 AM   #4
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It's definitely going to be a worthwhile thing to do. I've got a 16G actuator that I'm going to section and shorten the arm (with a turnbuckle for adj length) and weld up a new bracket to once I have a free weekend. It'll be a few weeks at least.
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Old 05-16-2008, 11:47 AM   #5
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I think i remember somebody using a 300zx wastegate
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Old 05-16-2008, 12:34 PM   #6
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This issue frustrates me too. Always a 1-2 psi loss before redline. We've got to come up with a good affordable solution for this..
EBC is great, but doesn't really address the problem.. if the problem is that the actuator is weak, we need to find an actuator that has a good adjustability range for our cars, and find an easy way to swap it over.
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Old 05-16-2008, 12:48 PM   #7
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Quote:
Originally Posted by JDMAflac View Post
I think i remember somebody using a 300zx wastegate

yeah rappadan did this. his holds strong to redline.
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Old 05-16-2008, 01:49 PM   #8
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THATs who it was. i knew i remembered someone dicking with something like that... guess i didn't pound that search button hard enough. :-P
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Old 05-16-2008, 02:06 PM   #9
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Old 05-16-2008, 02:15 PM   #10
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bitch! i will teabag your Ralph Macchio looking *** before you know what hit you.
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Old 05-16-2008, 02:57 PM   #11
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something interesting i took away from revisiting that thread, though, was why more of us aren't changing the location of the boost reference away from the compressor outlet and to a post-IC pre-TB location.

brain, you quoted corky's stuff about boost signal locations and the only argument against going to a post-IC signal was a potential temporary heat blast to the IC at boost onset. without trying it, i guess i won't know for sure what the tradeoffs really are, but having a signal much closer to the TB, after a flow-dependant restriction in the piping (intercooler) makes a lot more sense.

The insane boost dropoff we see with the typical installation is probably a combination effect of the craptastic greddy can and the increased pressure drop across the IC at higher boost and rpm levels.

guess i will know better once i move that signal line and make some runs to test it out...
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Old 05-16-2008, 02:59 PM   #12
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You might want to move the signal line to post intercooler, but also put a check valve in line. the check valve would not only eliminate vac on the diaphram, but should also smooth out the signal.
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Old 05-16-2008, 03:20 PM   #13
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hmm, probably won't hurt. but really think i'd see measurable vac before the tb?
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Old 05-16-2008, 03:22 PM   #14
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no, i was thinking from the manifold, especially near the rear where the signal will have the least oscillation
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Old 05-16-2008, 03:34 PM   #15
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i'm thinking about essentially where Abe put his. this way as the flow across the IC increases (which will magnify the effect of pressure drop), it'll be accounted for in the signal that makes its way to the wastegate.

between that and a helper spring, i am thinking i might be able to cut boost drop down significantly. worst case, i replace the actuator anyway.

maybe if i have a bit of time this weekend i'll pop off one of those sections of pipe and install a vac signal source, and will have some direct comparisons.
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Old 05-18-2008, 04:11 AM   #16
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I was actually wondering about EBC and boost loss. So even with the EBC the boost drops? Looks like I'll be searching for a new can. Stupid greddy crap.
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Old 05-18-2008, 12:29 PM   #17
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Quote:
Originally Posted by miataspeed1point6 View Post
I was actually wondering about EBC and boost loss. So even with the EBC the boost drops? Looks like I'll be searching for a new can. Stupid greddy crap.
the EBC can help remove it, as it will be able to close the wastegate as the rpms increase, negating the effects. However, I think Ben goes to 100% close line at redline...the actuator itself just stinks.
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Old 05-18-2008, 04:00 PM   #18
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Yeah, IIRC Ben was/is running 100% DC to redline just to maintain maybe 12-13 psi (correct me if I'm wrong Ben). My DCs don't leave the 50s and it will hold 15 psi to redline, the Greddy actuator is crap!

I bought one of these: http://flyinmiata.com/index.php?dept...umber=02-70570 used from a member, you'll also need the rod end for it http://flyinmiata.com/index.php?dept...umber=02-70571 . The thread is 1/4" x 28, which I found was impossible to locate in my town. ATP sells a WG arm extension kit for $8 (with $12 shipping..) to lengthen the arm, which you'll need unless you have other means of lengthening the arm to reach the Greddy's flapper. It is a strong can and will hold whatever you desire boost-wise to redline. After scoring those all you'd need is to make a bracket out of flatstock to mount it up.

DSCN0542.jpg
DSCN0541.jpg
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Old 05-18-2008, 10:12 PM   #19
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Lmfao meatwad ftmfw!
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Old 05-19-2008, 12:19 AM   #20
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I too am dealing with the Greddy gate woes I have a had no luck stabilizing the boost with the EBC and went back to a MBC to make sure the EBC was working right. I see a different problem from you guys, when I get in to it it hits 14-15psi than drops off to 11psi ish and then rises back up as the RPM's increase to redline. It gets back to 14 PSI by red line. Is this still the WG?

I have a helper spring on it right now.
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