hahah, yeah, when I called in the first time to get the WG ported, Stephanie wasn't in so I got transferred to corky and be basically said with my setup, I might have to put something in the primary exhaust just to purposely restrict flow. I went ahead and ordered a high flow cat to have handy just incase I go that route...but that's going to be last resort for me. Random side note, summit racing is awesome, ordered this thing yesterday afternoon, and it's supposed to get here today..free shipping option too.

also, messiahx is going to let me try his WG from his 2554 I think, might help narrow it down even more.

I couldn't agree more with the "disconnect actuator/wire flapper open" comments. I can also see where running the dump pipe back into the exhaust makes sense. Though it's been done on other cars, they are running different turbos and different exhausts and different manifold designs...all things that can make a difference. If it were possible, I'd try to get something like the FM elbow/downpipe (borrow?) and see if you get the same results....though that would be a PITA.

do those two dirlled holes between the two ports go anywhere? like are they drilled through the flange?

I was wondering about those as well. Sort of strange. It looks like the flange I had on my old turbo setup. It had those holes and there was a metal block off plate bolted down to divide the chambers. I don't think the holes went all the way through though.

On mine they went all the way through the flange. I had to plug them until I got a bolt in WG seperator.

The fact that Corky had a gut-feeling you would have this issue seems like a Red Flag to me. Lots of experience behind those gut-feelings.

Anyway, what we're basically talking about here is the balance between the restrictions through the turbine vs. through the wastegate. If you don't want to restrict the turbine side, then you have to figure out how to unrestrict the wastegate side. It was noted before that some race catchcans can generate 1-2psi by artfully connecting to the main exhaust in such a way that a venturi is created. That's not insignificant and much better than dumping to atmosphere. The problem is that you are in serious trial and error mode to find the right balance/angles/etc. going down this path. And doing it with a beautifully welded piece.

If the WG checks out and you have to get into a balancing act, my recommendation would be to put a cutout valve into your main exhaust. The catch is that you seal off the "cutout" port so that it dead-ends. Now you have a way to infinitely vary your main exhaust back-pressure. The way I see it, restrict a bit for street driving where you want 7psi, and then open it up and let it run wild at the track where you have better gas. Just a thought.

Do you have any Aero friends that can do some Computational Fluid Dynamics on your setup?

Yeah cause they go directly into the wastegate section of the housing.


https://www.miataturbo.net/attachmen...1&d=1302893714



before you do anything, wire the wastegate fully open and go take a WOT log to redline.

Still at work, but yep step 1 is fully open flapper test.

The holes are welded shut on the back side..I asked Abe about it before. Basically, most setups he runs a divider plate there, so he bought a bunch of flanges set up for that, but I obviously didn't need one since mines welded into turbine housing. No gasses leak past the divider, id definitely be able to hear it being open dump on the wg side.

Hornet, you're exactly right and I agree...if it comes down to a pressure difference problem, I'm gonna hate going into a guess and check way of things and hack up this awesomely made downpipe. If it comes down to it...I could still just go ewg, although that seems pretty ridiculous for a 2560

Hit the basics and keep us advised.

Those holes that are welded shut can be thought of as bleed valves or fixed "wastegates." By allowing flow through those passages, you decrease flow through the turbine. There are lots of reversible things like that (including removing the divider on the turbine housing) that you can try which don't involve cutting up that beautiful pipe.

that would result in the loudest car ever.

lol

Well, looks like the turbine just flows way too well... disconnected the flapper...took forever to spool up but in the upper rpm I got up to 12.9psi... lol. Hey it sounded cool/loud at least...right?

With WG connected I got about 17psi at redline... 4-5 psi difference- so I guess we can weigh out the WG being bad.

At this point I could: recirc the wg tube, add high flow cat...but I would be guessing and checking. I might just send the stuff back to Abe and have him modify it for EWG- I will be out of town for about 2 weeks here soon so it actually would work out pretty well.

What do you all think? Thanks for all the help thus far.

Attachment 189721

Ewg.

Already PMed ARTech about it and contacted streetunt about the actual wastegate... to me it sounds like the only real fix to the issue at hand, VS some sort of bandaid fix, but I wanted to hear your guys' opinions on it too.

First GT2560R miata to need EWG?? fml

Need? Pretty sure your car is telling you to run 17psi.

yeah...it felt pretty good, not gonna lie

that's what she said?

When are you getting a real turbo tony?

EWG is a sure fix that preserves the performance built into your exhaust. Anything else could become a long and frustrating road of hacking and experimenting.

I think the proper conclusion is that your turbine flows far too well in comparison to your wastegate. So, let's give the wastegate the flow it deserves. EWG.

As soon as my brakes, chassis, and suspension can keep up with the one I have... or when you give me a good deal on the little demon you have now. :makeout:

yep... i agree 100 percent. I'll have a good setup ready to go also if I ever go built motor/bigger turbo as well. Thanks for all the help here

My FMII GT2560 creeps pretty bad too. I upgraded to the newer style FM actuator/bracket, but haven't done the porting yet. At this point I'm living with it, and will probably do the porting when I install my '99 head. I really hope I don't have to go EWG, because I've got the FM cast o2 housing and downpipe, and it'll be allot more involved than what you have to do.

C

that creep is insane and doesn't make sense. It's obviously bypassing the turbine almost completely, then WHAMO.