Basically. Even at max travel, the actuator is going to slightly restrict flow through the orifice. Remove it and flow will increase slightly.

Sounds like I am screwed with the hardware I have. Would a large turbine housing be a solution? If I shouldn't waste my time I guess I will go right to EWG like everyone else seems to do.

Thanks again for everyones input on this!

I used an exhaust flange as a spacer because the arm wasn't able to swing all the way open. It's not preferred but until I redo my setup it works. I don't have any creep with a very similar setup.

Downside is it leaves very little room between my dp and my rear shelf and core lines.

My feeble brain can not possibly comprehend though how it makes any sense for the waste gate to open into the exhaust port. I mean the arm opens (not fully) and when it does open it opens into and plugs 3/4 of the exhaust port on my dp... anyway I digress. Maybe I should go read Maximum boost for an explanation.

This may not be your issue but it was mine. Before i motor swapped to 1.8 my 1.6 had an S style down pipe and I didn't have any creep issues like the separated dp.

If you look between my dp & turbo you can see the silver piece, the extra exhaust flange i use as a spacer

https://www.miataturbo.net/attachmen...ine=1460408253

Try hooking up the wastegate to some pressur and see if you're able to make the WG swing open at a certain PSI... see if you hear it hit metal on metal from the inside :dunno:

I'd try that before changing everything else out... Krisset makes a good point using a flange as a spacer. That'd be cheaper as long as the studs are long enough.

Have you tried wiring the gate open with it unhooked from the wastegate? See what psi you put out with it wide open :dunno:

Have you called and talked to Corky@Begi yet about this?

If you're considering EWGs, ATP sells a 2860 turbine housing with a v-band port. This is what FM uses in their FM2R setup, it lets you use the manifold you already have, although you'll need to modify the downpipe if you don't want it to dump to atmosphere.

https://www.miataturbo.net/attachmen...ine=1460409018

(edit: I don't actually know where the turbo flange is on the BEGI S4 manifold, so you'd need to check there's enough clearance to use this.)

--Ian

Theres not. But the suggestion to check and see if flapper may be binding is valid imo

Send a dyno of it doing this or a datalog on the street.

As someone who runs 18-20 psi into stock engines all the fucking time with not a single failure id be happy to look at it and tell you if its a legitimate issue or not.

Dann

This /thread problem solved.

Just tack weld the iwg arm or make up a quick bracket or buy one they are cheap and super common.

Except I can almost guarantee that that housing will not work on his manifold. I believe the wastegate will run into the shock column.

:laugh:

I have been in touch with Stephanie at begi. She has been extremely helpful actually and offered to send me a 1/8" spacer and longer downpipe studs earlier today to try. With the downpipe bolted on the flapper does hit the downpipe but it opens to the angle in the picture in my original post. I assumed that was enough for proper flow but a spacer is worth a try if it lifts the flapper even more. If that can fix it I can just have it welded on. I can hit it with an air compressor tomorrow and double check if the gate is getting hung up.

That housing would be ideal but like others have mentioned theres no way that would fit.

The car dyno'd at 250/230 at 14psi on a dynojet. Crappy picture of dyno is in my "build" thread 1st post found here https://www.miataturbo.net/build-thr...-slayer-81107/

Actually if you look at the dyno where its likely creeping the most the power dies out. I wonder if the timing is too low (I don't have a log of that dyno pull). I will have to put a few runs in VD to see if is doing that constantly. That might be an entirely separate issue though?

IME 250 on a dynojet isn't likely to break rods. My motor did around that for 40K miles before I lost it to a throttle body screw failure.

--Ian

If I can get it to stay at 14psi although still not ideal I don't think I would touch it.

Did a 5th gear pull and hit 18.9psi :eek:. Boost reading in VD is wrong..not sure why. At any rate this is why I fear for my motor. Need to turn on overboost protection on and never do that again.

This was never an issue in the warmer months. I think the whole time I have owned the car its only been on the road win 75+ degree temps. All of these issues are in sub 65 degree weather. Maybe the best solution is to not drive it in cold/mild weather.

https://www.miataturbo.net/attachmen...ine=1460422760

The new game plan is to check the flapper for hang ups again, test actuator again with air compressor, try a spacer in that order. I will post the results when completed.


Side note: 5th gear in a miata is either terrifying or I am a grandma.

I'm having the same issue with my 2560 on fm manifold and straight through exhaust back to a Honda boy fart can. That atp ewg housing won't fit a 2560r. Smallest it will fit is a gt2860rs. I've been talking with jeremy at fm for solutions. Called begi this morning and am awaiting a call from Stephanie to discuss effectiveness of IWG porting

I can only speak to my setup but the issue isn't that flapper opening all the way. It's that when it does "open" it really isn't opening. It pivots and ends up inside the exhaust port. It basically plugs the hole it's trying to exhaust to.

On my dp there is also a little flap that segregates the wastegate from the regular exhaust. So basically before I added the spacer the wastegate would open at pressure into and mostly plug the port. The partition of course prevents any kind of relief as well. Anyway anyone with half a brain can explain to you how useless this is. may as well weld it shut and just do what dan does and run 18-20psi on stock internals.. #ALLOFIT

https://www.miataturbo.net/attachmen...ine=1460655531

If you look at absurd flow or artech stuff it doesn't seem like they do anything a lot different on that flange though. They don't put that little divider in either so maybe if the wastegate is hitting on those downpipes it isn't nearly as noticable since the excess gas can escape/bleed over to the normal exhaust? I don't know... I don't have any experience with those setups but just thinking out loud.

I never understood why they don't just make a bellmouth like just about every other company ever.

the claimed flow disturbance is literally just a stupid theory that has been tested to not affect power any more than maybe 1hp, and you would never run into any of these interference or obstruction issues.

Is the fm cast piece more of a bellmouth style? I'm just trying to get an idea if the IWG porting service by begi will stop my boost creep. Obviously there is only 1 way to actually find out but I'd like some insight. (2.5" dp to 3inch straight pipe to straight through muffler 2560r)

theirs is a cast "bellmouth" on the outside but separated on the inside. I haven't really heard of too many issues with those having interference, the ports inside are much larger than the begi SGDP

your 2560 is likely unported which would explain the creep.