Honestly I would try to merge your pipe in. It could create enough turbulence to fix the problem.

it could very well fix it or it could not...and what I don't like is the possibility that it doesn't...then I try something else....still doesn't fix it....then im back to square one, but now with a recirculated wg flow, high flow cat and who knows else (all stuff i originally didnt want), and still creeping and still have to go EWG. I think going EWG now will just be less headaches overall, and a sure way to fix the issue? Overkill? I would have definitely thought so prior to seeing my own creep on this turbo, but meh, at least with EWG I can swap springs and stuff too.

You can still get creep on an external waste gate, and seeing as how your making 12psi with an open internal wastegate, you should definitely consider modifying that downpipe.

well, still, EWG gonna do a lot more than recirculating the bypass gasses. While Abe is doing my EWG stuff, I may have him make the new dump tube recirc into it though- im not sure, i have a few days to think about it. open dump is cool, but the sound is losing its.....cool factor already- i'll sleep on it.

I'm just saying. Garret designed that turbo with an internal wastegate, so it's not the turbo's fault or the wastegate, it's the things around it. The downpipe is the number one culprit - it's just far too efficient for that turbo. Like if you put a gt30 or something on there it would probably work great, so personally I would either a) change turbo, or b) change downpipe. It's not like you won't be able to find a buyer for either of them.

I still don't see how it can prevent the car from making any reasonable amount of boost at WOT all the way until ~4500, then it simply can't?

The exhaust was obviously bypassing through the wastegate, then it was like, fuck this time to spool this shit.

Recirculating the WG gasses didn't do shit. I didn't get any hard datalogs of it- I feel like maybe it's creeping a little less slowly... it's also a cooler night tonight, so perhaps it's helping, but only marginally. Still hit my 16psi overboost pretty easily. Here's a pic... looks funny cuz the guy sprayed it with some of that high temp paint stuff (since its aluminzed and not stainless...whatever it's not like you can see it anyways). Also, open dump got old really fast, this is much better anyways :).

Apparently one of my turbo water lines decided to develop a small hole too. So tomorrow, gonna replace the water lines, then go to get this Magnaflow cat welded in (Metallic spun). In my previous experiences.... high flow cat made a huge difference in boost creeping, I just hope it helps enough to allow me to continue tuning from here.

Attachment 189599

Thought you were going EWG?

I've got the same setup on a chinabob2870.... I hits around 16psi even with the wastegate locked wideopen.

I had a chinabob3071 with fm's cast downpipe before and got "zero" boost creep.

I'm treating it as the car is telling me to run that boost setting.

After watching your video, I think your flapper has a certain number of degrees where it isn't opening completely into the dp channel for the gate. Instead of opening 90 degrees at full open into the WG tube on the dp, it is opening say 80 degrees which in essence diverts the WG gas into the wall of the wg tube and also actually closes that tube up a fair amount. That coupled with the 90 bend for the WG tube once it approaches the fire wall gives you a bigger restriction on the WG tube than you think. That would also cause creep with the WG disconnected. While a bellmouth designed DP does introduce some turbulence, it also allows the WG to dump into a larger chamber.

I would mark the distance of full open with the DP on and with the DP off and see if there is a difference in the movement of the flapper arm. See if it opens less with the DP on.

It also appears that when your actuator is attached, you are limiting the travel of the flapper even more. That would explain the lower creep with it detached vs attached.

I believe this statement is the truth.
There is less room for the wastegate flapper to open into and therefore less room for the air to travel with the seperated gasses DP.

Hell...just look at the size of the flapper, and the size of the hole that it is in. The flapper takes up a huge chunk of the opening.

looked at the video one more time, it really does look like the flapper is covering most of the outlet once it's open. It opens into the dump tube, and since it's a small round tube and not the size of that entire cavity, there's a huge restriciton.

I bet if you could bellmouth the tube like show below you could solve the issue.

Can't argue with your guys' points... those would definitely help.

Regarding flapper movement, yes eventually it hits the downpipe, but the wastegate actually restricts its movement slightly more (pretty close though)...so basically, the wastegate actuator fully actuated, it wont ever open far enough anyways to hit the downpipe. With that in mind, I think something like what Brain posted would probably help the most... just giving the gasses larger path to flow around and out thru the flapper.

I just got back from getting a high flow spun cat welded in... it helps, but does not solve the issue. In 3rd gear (I have pretty long gearing, 5 speed, 3.9 rear end), I can stay below 16psi.... perhaps it's just a sign I need to run moar boost :). I think I would be alright with that, I was planning to push the limits a little anyways.

Right now I'm not motivated at all to remove the downpipe again start trying more stuff, or just going EWG...but I will be out of town for awhile, maybe when I get back, I might, we'll see. Downpipe slightly annoying to remove....turbo and manifold have to come out first.

Anyways I'll keep this thread updated on what I do next. At least I need to now hook up the EBCS and get some low end torque...supercharger/creep mode ftl.

edit: the only other thing that bugs me is that there's plenty of others, running ARTech stuff....both catless and catted I'm sure, that aren't boost creeping (that I know of)...What about all the other guys running similar or the same turbo, with same downpipe flange design- why aren't they getting this? So I don't know, maybe there is something we are overlooking.

I had this dp below with a 2560 and it did not creep at all. Maybe Abe's manifolds are just that much better!

https://www.miataturbo.net/miata-parts-sale-trade-5/fs-stainless-turbo-manifold-fm-downpipe-exhaust-gt2560-t25-54735/

Oh hey, my old stuff happens to be for sale too.

Well if anything you could put some spacers between the wasteagete actuator bracket and compressor housing and move the wastegate actuator closer to the firewall a few mm. That should allow it to open further with the wastgate attached. This way you can at least see the minimum boost level you hit when you wired the wastegate open (13psi).

The rod length is adjustable, I could make it longer, but then the flapper will be slightly open at idle/cruise....before it was open dump so I stayed away from this....I could do it now, exhaust might be a little louder, but any reason why I shouldn't do this?

that's why i suggested moving the the physical location of the wastegate. so even if you need to shorten the rod to keep it tight, the amount it can extend doesn't change...so moving it closer to the wastegate flapper should allow the flapper to open that much further.

Well, looks like I'm just going to live with 16psi for now :).

Feels great, pretty aggressive, but I dont drive/beat on the car daily... will just continue to keep an eye on things the best I can. Got the boost curve/response decent today with the help of EBC and messiahx. Nice to finally have some low end torque back...and not running the turbo is supercharger/creep mode.

I know when the weather gets colder the creep will get worse, I'll just have to see by how much...and figure it out when the time comes.

Attachment 189517

Don't see any creep whatsoever in that plot. ?? If EBC gives you that much control, it means your wastegate is pretty effective. Is the complaint that you can't achieve that control at a lower boost setting?

yep exactly- I just can't really run anything less than 16 consistent. I could target 14 ish, but it would creep a little then from 6000-7000. In the above logs, my boost duty starts around 62 percent, then slowly walks up to around 90 by redline, and boost 16 to 16.8-9 at redline. I have exactly 16.0 psi set in the boost target table- I'm pretty happy with it but i may tweak it some from here.