spdracerut

iTrader: (2)

Some pretty interesting numbers from a WRX on internal vs. external dump WG:
http://www.motoiq.com/MagazineArticl...Wastegate.aspx

JohnBradley

iTrader: (30)

Good article but something we had seen a few years ago. Back to back, 90% WGDC on the tru boost, dump vs no dump. Pretty easy to guess which one is which is which.

Evo8cy

Its all very relative, there are applications where an external dump makes a difference, as it alleviates back-pressure, gas turbulence, and aids in gas velocity and speed. There are other applications where it makes no difference at all.


It is all down to how well designed the turbo system in relation to the turbo used is.


Back in the day, when I changed the evo oem turbo setup to an externally gated one, I picked up about 25-30whp on a low reader, as I was able to run/hold more boost in the upper rev range and at the same time add a few more degrees of timing without any sign of knock.



Also there are some inaccuracies in the article such as : there is no need for twin gates on a twin scroll manifold. As an intended example I will use the evo oem setup which as we all know has a twin scroll manifold and a twin scroll exhaust housing. One can use a 38mm tial gate i.e, on the stock manifold attributed and installed on a specific point ( there are at least 2 good places) on the manifold where is common for all 4 cylinders, thus relieving equal amount of pressure from all four. Another way to an external gate setup is on a fabricated O2 housing-downpipe configuration. Both ways yield better results if the excess gasses are dumped into the atmosphere.

Another inaccuracy is that OEM turbo setups are created with internal gates, due to the reasons they have listed, which is not true as several Porche models for example come with external gate configurations.










Marios

spdracerut

iTrader: (2)

Correct, it all depends on the setup and that is addressed in the article and the comments of the article.

You can use a single gate on a twin scroll configuration and that is addressed in the comments of the article.

As for the use of external gates on OEM configurations, yes, there were a few back in the day. But you will not find an external gate configuration on a modern car due to the reasons listed in the article; I'll take that back if you can provide an example. I am not aware of any.

Evo8cy

I did not read the whole article, nor go by magazine articles in general, besides of some exceptions, as there is no need to do so, my 25 year old on cars and turbos study and experience is enough for me on the above subject and in general. So I did not know what was entirely covered in it or in the comments.





It matters not if you can find or not contemporary cars with the use of an external gate by OEM manufactarers, the technique, technology and complete applications are there to be used if the choice is made. Besides none of the car companies, ever produced mass production cars with external wastegates vented to atmosphere, which is a factor that makes a difference in power in certain applications. Car companies produce cars based on max profit and that's the main reason they have almost abandoned the use of an external gate. Most aftermarket tuning houses though still keep offering upgraded packages with external gates, where it is needed, whether vented or not to the atmosphere, and that should tell you something.



My advise is do not go by what and how car companies design and produce their turbocharger systems, as although they do what it says on the tin, 90% of them can be improved in one way or another.











Marios

spdracerut

iTrader: (2)

You know..... if you would have read the article, it says exactly why OEMs use internal gates: emissions and cost.

Evo8cy

I already know what the article should say, but if it says emissions, that is a lie produced by car companies, in an effort to further justify things, if it is referring to external gates plumped in and not vented, obviously a vented system is about emissions but would also cost less as a system compared to a re-circulated one. I assume though that it must be referring to a non vented system as car companies do not produce mass production cars with a screamer.












Marios

LetsGetThisDone

iTrader: (1)

They say emmisions because all OEM's need all the exhaust to go through the cat. They then say, yes, it is possible to recirculate an external wastegate back into the exhaust. That then leads in to a discussion on cost, complexity, and packaging. All of which is very valid.


MotoIQ is a solid source. They right well thought out, quality, articles. The article says exactly what it should say. But you came here to run your mouth without even reading it.

03whitegsr

iTrader: (8)

This seems to be missing the boost curve for one of the runs though? I'm guessing the external is likely higher on boost across the RPM range?

Don't get me wrong though, externals are absolutely better. I hate internals. Pick one or two of these traits for any given internal gate:
Transient boost spikes
Drop boost with engine speed
Blow open limiting peak boost
Boost creep


As for only needing one external gate on a twin scroll setup...good luck.
I'm not saying it's impossible, but I've seen nothing but poor results trying to do it and the few tests that have tried both, back to back in fair tests, have shown the dual gate setups are better.

LetsGetThisDone

iTrader: (1)

Even if the external gate made more boost, it did so at the WGDC, which means the boost increase due to less back pressure, so the extra boost you got was "free", it did not take any more power to drive the turbine wheel and spin the turbo faster.

LetsGetThisDone

iTrader: (1)

I find it funny that you're calling me out for "hiding behind a key board".


You said negative things about a good article, without even reading it. I pointed that out and I'm the *******. Some with little to no knowledge of wastegates and how they work could read that article and come away with good information to use in the future.


As far as external gates on OEM vehicles, maybe a boutique manufacturer is doing it. I have yet to see one on a massed produced vehicle. Audi, BMW, Nissan (GTR), McLaren, Porsche, Ferrari, Ford, Chevy, Mitsubishi, etc. Porsche did use them way back in the day, but not on their new stuff. And Ferrari did use an external on the F40. But the new 488 uses internals.

Evo8cy

For sure the external gate is running more boos at the same duty cycle.



I also prefer external gates, although on some internal applications, i.e the stock turbo system, the internally gated system works quite well. Running it externally gated though, over here there are many stock turbo , or stock frame turbo setup evos that run an external gate with any issues of boost creep mainly, that were existent with an upgraded internal gate, alleviated. And although peak boost might have been ok and held to the desired rpm point with a stronger internal gate, the external gate system, when done right, helps the turbo recover faster and have a better transient response.




It is all about getting the right amount of gasses out at the right time. Maybe the gate you tried was too small, or the placing of the gate along and in relation to the design of the exhaust housing and piping was not the optimal. This type of problems easily disappear when two gates are incorporated into the setup as more gas volume is moved at the right time. But the beauty of it, is to build a system with one gate that works, and it is more than possible, because I have done it many times, and as far as the evo is concerned, stock turbo, fp green, fp red, fp black, and now I'm running a custom 6868 billet dbb, all on a single external gate with no issues whatsoever.





If/when you decide to change turbo setups, try building a single gate system, put some more careful study and research on it and I am sure you will be able to do it.











Marios

03whitegsr

iTrader: (8)

Not really.

There is a certain amount of "mechanical advantage" to any given wastegate system that the valve has in relationship to the EBP and boost pressure. Change that mechanical advantage and it will change the boost pressure.

Case in point, put a stiffer wastegate spring in an external and that same 90% duty cycle will increase the boost pressure without affecting the backpressure at all.


Evo8cy, I'm curious about the setups you speak of. Got pictures.

Honestly, the issues I speak of have less to do with it working and more to do with long term reliability and just general manufacturability. To fully maintain the benefits of a TS turbo, you have to keep the passages divided all the way to the face of the wastegate valve. Doing that, you have one piece of steel that divides the two flow paths being exposed to the full exhaust flow. Usually it means the functional temperature limits of the material are exceeded. There is also usually a high differential temperature between that divider and the outer wall tubing.

The divider ends up cracking and buckling, from what I've seen. Once it does that, boost response usually goes to hell.

Evo8cy

Listen if you are in the habit of creating such discussions because you have nothing else to do, try doing it with someone else, as I am not interested. As for calling you out, nothing of such has happened, and the only thing that is funny is that you thought that could be possible through a pc monitor. I answered back in the same way you responded to my post. But you can bet your sorry *** that if the reason was worth it and we were face to face I would call you out as I have 100 of times up to now in my life.



You did not point anything out, you merely tried to be a smart-*** and impolite.


As I said, learn to accept other people's opinions, and think before you type. There is nothing to point or not point out here, it is an article that everybody who is able to read can and will if he/she wishes do so, and everybody in entitle to their own opinion.





I'm not interested to know what you have seen or not on the matter, I know what I have seen and it is enough for me. I also did not mention any of the above manufacturers apart from porsche which I have worked on and yes that was many moons ago. I am not aware if porsche still makes externally gated cars, but whether it does or not, it makes no difference to any of the gearheads on here i.e, as the proven technology and application exist, and it can be used by anyone. Also there are truck manufacturers that still do use external gates in their very contemporary trucks.



Also many aftermarket tuning companies do incorporate external gates in their designed kits for cars of the manufacturers you posted, kits that are superior to the oem ones.











Marios

Evo8cy

There are more than one way to do this. Since you can understand metallurgy and how to built such a system then I'm sure you will figure a way to do it.



I will give you a couple of hints on it, since you think what you have either seen, or believe will happen is the case, and the way things should be done. There does not need to be a divided section anywhere in the piping going to the gate. The only divider should be in the manifold and in the exhaust housing.


Two ways to do this, two pipes merge to one that bolts up to the face of the gate, the other way is to place the gate on the existing divider of the manifold or the merge collector, either immediately straightforward or with the use a a very small pipe. Which way you'll use depends on the type of manifold and space that you have.



Here is a pic I found on the web showing what I am saying. It is not a twin scroll setup, but the principal is the same.

http://www.turbosmartusa.com/news/mi...-evo-turbo-kit




On the evo/dsm stock cast manifold, the gate can be mounted on top straight on the divider.





Also the exhaust housing can be modified and attach the wastegate there, i.e the stock evo exhaust housing can be modified (welding an additional special piece on it that carries the external gate) , and of course you can run a downpipe that is divided and carries again the wastegate.





If all the above applications and setups are done the right way, using good material, proper welding process, no real issues of long term durability will exist.












Marios