S5 stock maniold, external dump

[sen2two]

Here's a sneak peak at this for now. I have been seeing here, and other places, where people want to fix the whole boost creep, and boost dropping off before peak RPM. One way is to get an upgraded Garrett internal gate that is very similar to our stock wastegates, and port the wastegate areas on the turbine housing. This works well for a lightly modded car, but some still need more. Especially if the motor is ported, running higher compression, or runnning a hybrid turbo.

Now it has been done a few times on the much larger S4 manifold. But with the very small compact S5 manifold, and divided runners, making an external dump far more complicated. A few people have also kept the stock wastegate area but separated the down pipe area and wastegate area for an external dump. This still poses a problem with releasing enough exhaust pressure through the holes in the turbine housing. Making creep and drop off less noticeable, but not getting rid of it.

Here is what i am going to do to fix the problem. A one inch hole in each runner, meeting at one point with a 38mm external wastegate.

Pics do much better than words.

(I'll update after it's all welded up and finished, I got side tracked with another project and didn't get t finish)


Holes were done with a bridgeport mill. Now I know not many people here will have access to a machine like that. but its not hard to drill a hole with a hand drill and port it out with a die grinder.









Got some pipe and turned it down slightly in a lathe to fit very snuggly in the holes. I'm all about tight fits,














Cut some pipe and mocked it up. A little trimming and grinding, and this will all fit nicely. There's actually a pretty good amount of room below the manifold to come up with your own design. Just take some measurements and get to cutting!

[soldave]

Is a 38mm wastegate gonna be big enough? I'm going for a 50mm to be on the safe side.

[sen2two]

38mm is plenty large enough. My motor is completely factory. Hasn't even been rebuilt yet... Most people port the stock wastegate to 35mm.

I am not a fan of overly large wastegates. Here's why... In theory of course, but I would rather be safe than sorry in this case.

whether you have a large wastegate or small wastegate, they still open at the same speed. And that speed is quick. When you hit your set PSI and your overly large wastegate opens, it releases a large amount of exhaust pressure quickly. Most of the time TOO quickly. Causing exhaust pressure drop and possibly a drop in boost momentarily slamming it shut again only to open quickly again. You might not notice this, but I'm sure the motor does.

[Phoenix7]

have you done any amount of porting to maximize the exhaust flow in the stock manifold?

[sen2two]

Started on it, But havnt finished it just yet. I'll finish the port work after i finish the wastegate job.

I will be doing some port/flow work the the rear turbine housing also.

This will not go onto the car just yet though. I want to hit 12's on the untouched factory turbo first. I'm about ready for that though. So hopefully this will go on soon enough.

[Phoenix7]

keep it up man, I can't wait see what results/improvements you achieve.

[TitaniumTT]

Lemme start off by saying that this is pretty damn cool. Good job on the work so far.

Originally Posted by sen2two

38mm is plenty large enough. My motor is completely factory. Hasn't even been rebuilt yet... Most people port the stock wastegate to 35mm.

I am not a fan of overly large wastegates. Here's why... In theory of course, but I would rather be safe than sorry in this case.

whether you have a large wastegate or small wastegate, they still open at the same speed. And that speed is quick. When you hit your set PSI and your overly large wastegate opens, it releases a large amount of exhaust pressure quickly. Most of the time TOO quickly. Causing exhaust pressure drop and possibly a drop in boost momentarily slamming it shut again only to open quickly again. You might not notice this, but I'm sure the motor does.

Instead of guessing, I would datalog it. MAP and EMAP as well as WG duty. If you're running any sort of ems or electronic boost controler, you sould be able to tune it out.

[need RX7]

very interesting.

[RETed]

You've just destroying the whole reason why Mazda redid the turbo exhaust manifold and turbine section.

Seriously, you guys need to leave alone these "rare" parts and go mess with S4 stuff.


-Ted

[soldave]

What's rare in what he's done?

[Phoenix7]

Originally Posted by RETed

You've just destroying the whole reason why Mazda redid the turbo exhaust manifold and turbine section.

Seriously, you guys need to leave alone these "rare" parts and go mess with S4 stuff.


-Ted

there is no way to get better flow out of the S5 manifold?

[jerd_hambone]

Originally Posted by RETed

You've just destroying the whole reason why Mazda redid the turbo exhaust manifold and turbine section.

Seriously, you guys need to leave alone these "rare" parts and go mess with S4 stuff.


-Ted

Hey now, just because Mazda spent a million dollars redesigning something, doesn't mean it is working at it's peak. He's not trying to mess with what Mazda did exactly, he's more on the lines of trying to make his car as reliable as possible. One good boost spike can do all sorts of damage.

Relax there ol' buddy!

[RETed]

I'm talking about the "independent twin scroll" function of the whole system...

Anyone who has messed with both the S4 and S5 turbo systems knows the turbos produce power differently.
The S5 has a smoother power delivery, because it spools quicker and more linear due to the independent twin scroll.
The S4 will lag a bit and then punch you in the gut when the boost hits around 4kRPM or a little bit after that.

This has nothing to do with boost creep.
I've ported S4 and S5 turbos before, and I've never had a problem with boost creep after porting the wastegate passages.
In fact, I ported the S5 turbo so well, it ended up producing only 5psi of boost with unmolested wastegate vacuum lines, even with no cats.
(We were able to get the boost to hit 10psi with an A'PEXi AVC-R afterwards.)
Oh, and this wasn't with the stock compressor section - it was running an H-trim compressor side.

The S5 turbo parts are not easy to acquire in the states.
In fact, there's a demand for those parts for those who know about it's advantages.
There's a bazillion S4 turbos parts available, and it's easier to stuff an external wastegate on them a whole lot easier.
In the end, you're doing the same thing - remove the independent twin scroll (well, the S4 never had it to begin with) and run an overpriced and oversized external wastegate which, IMO, is not necessary if you know how to port the stock wastegates efficiently.

In the end, I call this kinda project "showing off" just to document the resources you have on hand.


-Ted

[sen2two]

Or maybe I post thing's up from time to time to impress you, only to be shot down time and time again. You have broken my hear one to many times...

Seriously man, is there any thing you do like, that hasnt come from you?

[Phoenix7]

I always like to tell people to "Read between the lines...listen to what is being said, not how it's being said." Ted comes off rather harshly some of the time but you know he means well even if it doesn't read like that. He doesn't believe the external WG is MORE effective than a properly posted twin-scroll system on our setup and therefore this mod seems redundant to him, especially on the S5.

I would take all the input you've received so far, see what benefits you can achieve and then post your findings...Ted knows what's up when it comes to these cars, their components and sometimes it takes real numbers to change his mind. As you continue to research these mods you'll be able to show what benefits you have achieved or perhaps you'll reinforce what ted has been saying all along. You won't really know/satisfy your curiosity until you finish.