You GReddy guys all should replace your wastegates - Page 2 - Miata Turbo Forum - Boost cars, acquire cats.

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Old 10-15-2007, 04:53 PM   #21
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I relish any opportunity to use the act of cheapskating on a project as an excuse to purchase a new tool or tools. I sometimes lament that my Greddy-based turbo project has ended up costing me just as much as a complete Bell kit, but that figure includes all the ancillary bits that I picked up along the way- a full SAE open-end wrench set, a new angle grinder, a tablet PC, a ratcheting air-wrench, etc... And it's all Harbor Freight, so while it ain't the highest quality stuff it's adequate for the frequency with which any particular tool is used. I think this is the one I'll get: http://www.harborfreight.com/cpi/cta...emnumber=39424

Heck, if each die only lasts a single use, that'll more or less justify the purchase price.
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Old 10-15-2007, 05:26 PM   #22
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That actuator on FM's site was the deal of the day a few weeks back and I called and asked if it could work with the Greddy kit. I was told "probably not without welding it." Let us know how it works for you as I am still considering it. At 5psi, my Greddy is doing OK for the time being, but I'll need one eventually.

More info on this thread:
http://forums.miataturbo.net/showthr...light=actuator
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Old 10-15-2007, 05:32 PM   #23
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Buy 2 and send them to me. I'll make them work and send you 1.
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Old 10-15-2007, 05:47 PM   #24
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Quote:
Originally Posted by clay View Post
That actuator on FM's site was the deal of the day a few weeks back and I called and asked if it could work with the Greddy kit. I was told "probably not without welding it."
I'm not planning to weld on it. My thinking right now is to create a new mounting plate to go on the compressor which will then attach to the mounting plate which is on the WG. It looks like there is enough space for a couple of #8 screws.

As to the rod, the offset may prove beneficial. There is some definite side-load on the rod in my present setup. It'll probably take some trial and error but I'm hoping there's a sweet spot on that rod somewhere that makes everything line up. I will probably cut it off at the end of the straight section in the middle and thread it for an additional straight rod to make the requisite length.

The stock Greddy WG can is fine at 5 or 6PSI, but it starts to have trouble at higher boost levels. Even with a good MBC, it's apparently not strong enough to hold boost at high RPM and high load, so you have the situation where boost builds up to whatever your MBC's set level is (say, 14PSI) and then once the WG has cracked open slightly, the can cannot seem to hold it steady anymore, so boost drops.

Ben, just call FM and buy one. They're not evil people.
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Old 10-15-2007, 06:34 PM   #25
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i've had my eye on that ebay one for a while, i really just want to hold 15psi to redline and be reasonably stable. does anyone know how long the stock greddy wastegate rod is without having to go out and measure?
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Old 10-15-2007, 11:05 PM   #26
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yo,
its rapper checking in. I was waiting for you(scott) to make a post.

For all you that are wondering i actually had to lengthen it almost 2" probably. the way the bracket was offset. The greddy mounts flat. I got a wastegate acutator off an t25 from a 300zxtt. mounts up fine. Fits close to the head/valve cover. And it holds boost nice...
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Old 10-16-2007, 06:25 PM   #27
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Quote:
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<snip> I think this is the one I'll get: http://www.harborfreight.com/cpi/cta...emnumber=39424

Heck, if each die only lasts a single use, that'll more or less justify the purchase price.
That set is SAE, I think you'll need metric. I've got the metric set, had it for about 15 years. It comes in handy once or twice a year, haven't broken a tap or die yet. Worth the price to have it around when needed.
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Old 10-16-2007, 07:25 PM   #28
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That set is SAE, I think you'll need metric.
I haven't bought it yet, but I'm assuming that since Garrett is a US company, the rods they use are of SAE-friendly diameter. The end I put on it will be custom-fabbed anyway, and SAE hardware is easier to find.

But we'll see. It's supposed to be here on Thursday, and I'll measure it then. Got a couple other projects that need finishing first- one is to mount a '94+ seatbelt-tower brace in such a way that it does not interfere with seat travel. More welding...
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Old 10-17-2007, 03:01 AM   #29
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Old 10-17-2007, 03:18 AM   #30
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Define "work". Can you make it work (well)? Yes. Will it bolt up? Probably not.
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Old 10-17-2007, 11:06 AM   #31
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Quote:
Originally Posted by Joe Perez View Post
I haven't bought it yet, but I'm assuming that since Garrett is a US company, the rods they use are of SAE-friendly diameter. The end I put on it will be custom-fabbed anyway, and SAE hardware is easier to find.

But we'll see. It's supposed to be here on Thursday, and I'll measure it then. Got a couple other projects that need finishing first- one is to mount a '94+ seatbelt-tower brace in such a way that it does not interfere with seat travel. More welding...
I figured you would cut the shaft, die both ends, and insert a threaded coupler. Done.
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Old 10-17-2007, 12:10 PM   #32
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Quote:
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I figured you would cut the shaft, die both ends, and insert a threaded coupler. Done.
Well, the shaft on that WG can looks like this: ---\___/---

Whereas what I need is more like this: ---\______

We'll just have to see when it arrives. Probably not going to happen this weekend as I've got plans, and then I'm out all next week.
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Old 10-17-2007, 06:32 PM   #33
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I just did the measurements extra well, did not tap/thread the shaft and all i needed was 2 small washers to set the preloaded tension on it. It felt like the same tension i had on the greddy that was tightened all the way
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Old 10-17-2007, 09:37 PM   #34
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I'll look into it probably when I upgrade the downpipe and exhaust.
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Old 11-07-2007, 12:51 PM   #35
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Well, I finally got that new WG can installed this weekend. It's the one with the kink in the middle of the rod, and is rated for 5 PSI.

Here's a shot of the new can next to the stock Greddy can. Obviously, some fabrication will be involved. FM claimed to clay that it would not fit without welding. Well, I didn't have to break out the MIG welder, but the angle grinder and drill press got a decent workout.

For one thing, note the positions of the mounting bracket relative to the vacuum nipple. Mounted in the same orientation as stock, the nipple nearly hit the head, no way a hose would fit on there.





First, I cut off the folded-up part of the new WG bracket, then I notched it to clear both the head and my breather filter. Next, I cut the rod into three pieces, sectioning it at the third and fourth bends (the one closest to the can being the first). I discarded the middle piece, and threaded the ends of the two remaining pieces. They were exactly 1/4", so I used a 1/4-20 die. A pair of hex couplers and a piece of 1/4-20 straight rod, and I now had a WG with an offset and adjustable rod, which improved the fit dramatically, allowing me to mount the can very close to the compressor body:




Then I fabricated an adapter bracket to mount the new can onto the compressor. Relative to the mounting of the Greddy can, this one is rotated a bit more than 90 counter-clockwise, so that the bracket faces up. In the process of notching the can's attached bracket for clearance I lost one of the two mounting holes, so I re-drilled a new one very close to the body of the can. Here's a shot from the front showing some detail on the bracket:




Using a hand-operated pump, I extended the rod by about 3/16" before screwing everything together, to pre-tension the WG somewhat.

And the results? Well, I'm not as impressed as I'd hoped I'd be.

With the MBC bypassed, the system makes a steady 7 PSI. Not bad.

With the MBC in, I'm still getting some spike. Or more precisely, some droop at higher RPMs. This morning I drove up a long hill, in 5'th gear, at WOT, at about 60 MPH. The system held a rock-steady 13 PSI. But blitzing through the gears in a more realistic fashion, I'd see the boost initially go up to 14 PSI and then gradually droop down to about 12 PSI. (I'm basing this on eyeballing the mechanical gauge, as the logging PC is not in the car right now.)

It's definitely an improvement. The old setup, even with the spring, had slightly more droop, and produced a slightly higher pressure with the MBC (I consider this a bad thing, since electronically bypassing the WBC is my failsafe for the WI system)

I'll probably keep it. Just wish I could have gotten that nice rock-steady line that Brainey posted initially.
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Old 11-07-2007, 01:07 PM   #36
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Maybe it needs a little more pretension? Still that is some nice work Joe.
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Old 11-07-2007, 09:13 PM   #37
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I could try increasing the pretension, however that will also increase the "base" boost- ie: the boost when the MBC is bypassed.

I'm a bit nervous about that owing to the fact that I'm relying upon the ability for the system to automatically drop boost in the event that my WI system should ever fail. (the presence of pressure in the WI line closes a pressure switch, which powers a solenoid, which closes the bypass around the MBC. No water pressure = no activation of solenoid = base boost)
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Old 11-08-2007, 11:03 AM   #38
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If somebody wants to send me a GReddy actuator I can see about making a replacement. If you don't mind making your own bracket I could sell them to you guys for $100 (retail on a bracketless WGA is $150). I can build them with 5-10, 9-14, 14-18 or 19-24 psi springs. Lifetime warranty blah blah blah.
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Old 11-08-2007, 11:33 AM   #39
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Joe I get the similar boost action after adding in the MBC on my internally gated t3. It's rock steady (after I added the helper spring) with actuator only. Add in the "diy MBC" and I see nearly a 2 psi fall after peak boost. The helper spring DID reduce that fall by nearly 1 psi with MBC installed. Is the MBC causing this peak and drop? It looks like it to me.
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Old 11-08-2007, 12:12 PM   #40
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Is the MBC causing this peak and drop? It looks like it to me.
It's hard to say, since I have not adjusted / spring either WG can to achieve 13PSI all by itself. I have always tried to aim for a 2-stage system, with "full" boost activated by the operation of the WI system.

But I can say that the lower levels of boost I've achieved without the MBC have always been stable, whereas the higher levels of boost achieved with the MBC have not.
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