this, or at least design it better so the flapper itself doesnt block the flow path.

I'm pretty sure if you remove that extra divdier they added, you'll be able to control boost better since diverted gas can just flow through the main tube as well...

I agree. If you google image downpipe you'll end up staring at a ton of diesel and subaru dps but a vast majority of them collect into one big collector.

I'm kind of fair weather when it comes to my miata cause it's just a project but maybe some day i'll update my build thread and throw some logs in there. I understand the benefits of an EWG but since i put that spacer in my IWG has been rock solid.

The efr lineup is regarded as having a good internal wastegate right? I have been in and out the last year so unless the consensus has changed perhaps take a look at that turbo. The reason it has that long profile is in part because of how the wastegate operates. It opens inside the turbo body and flows with the exhaust unlike the gt series that needs a little porting help. At least that's my take/analysis on it at first glance.


https://www.miataturbo.net/attachmen...ine=1460659750

Yeah, the efr hotside is well designed, most here will agree that it's definitely the IWG to have.

many modern OEM"s use that design too on their non-EFR turbos

most (all?) never have creep issues

When I put my spacer In I also took my grinder to that divider. Maybe overkill but I have no creep.

yeah the idea of the divider and divided pipe is sound, but if you cant actually flow the exhaust out the tube, then like it's hurting not helping.

Accurate first glance, sir. EFR6258, full 3" exhaust (turbo to tailpipe), low-boost actuator, minimum preload:

https://www.miataturbo.net/prefabbed...2/#post1272746

If you don't speak datalog, this is a 2-3-4 pull showing 141kpa (6psi) at redline. Zero creep. EFR IWG FTW.

Attachment 231985

Yep. And once I added the spacer in I just made the divider useless anyway. No reason to not give it more room to flow together instead of leaving that divider and creating a weird pocket.

the subabroz actually did a test between the two designs.
using two units that are designed well enough to not creep
the difference was about as much as the variance between dyno pulls

...so really, it's all just theory

Is this theory worth hacking up my FM cast DP section to make it emulate a bell mouth? Maybe something to try if porting IWG doesn't work for creep

eh... i don't think it would hurt performance enough to really matter but at a glance the fm cast unit doesn't look like it has a blockage issue. The mouth is quite large and appears to have plenty of clearance.

Has your 2560 wastegate PORT been ported?

you need to port your hotside. the 2560's didn't come with any sort of channel in them like the 2871's did (newer hotside design)

make sure you do both: open up the hole, and make the channel. we have threads on this

the fm elbow shouldn't be your problem

Not yet. I just got off the phone with Stephanie at begi to talk about it. Not sure if I'm going to attempt it myself or send it to them ($75) but it's definitely the next step to solving my creep

LownSlow I think you are better off looking into porting. From my reading that seems to solve most people's creep issues on similar setups. Thats what I would do if I were you anyways.

Those EFRs are awesome. Do want.

I get carbide burrs in the mail today. Ill probably have the car back on the road this weekend and see how well opening up the wastegate hole a little and smoothing out the current port job does. I think krissetsfire is onto something though. I bet the flapper itself is blocking flow when open.

I type too slow^ thanks 18psi

When you buy a turbo kit from BEGI one of the things they do as part of their setup is port the turbo if it is one that needs it. I got my 2560r from them and Corky did a fine job with getting it to flow properly.

Before I modified my downpipe I would creep from 6 to 8 after i upgraded to 3" exhaust. 2.5" exhaust was maybe half a psi creep.

so that means good work on the turbo port.... mediocre on the dp

Your dyno suggests that yes, you will break it.

Dann

https://www.miataturbo.net/attachmen...ine=1460850167

18psi, braineack, any other smart people:
I took apart the turbo to port the wastegate begi style. My question: should I smooth out the inside of the FM downpipe while I'm in there? You can see where the exhaust hits the casting as it makes its way out the upper hole in the picture

https://www.miataturbo.net/attachmen...ine=1460850374

Quick scetch of the parts I'm considering taking out. I could also round off all the other sharp edges on the other side

Just put the car back together after opening up the wastegate hole and smoothing out the channel Begi made. Results? Car feels incredibly slow :party: Peaked at 12-14psi where it peaked at 16+psi previously and it made ~2psi less everywhere after turbo spooled. VD puts the power around 240hp on a dynojet. AFRs were very rich so I'll have to retune WOT but I assume after they are dialed in I will be right around 250 again. I can't comfortable run a MBC to help spool anymore (its kinda terrible right now) but if it keeps my motor alive I am a happy camper.

Thanks everyone for your contributions in this thread!

not really needed for your application. I honestly wouldn't make it any thinner if I were you
your wg "port" on the elbow is more than enough
:likecat: great, glad it worked