WG options on Divided Twin Scroll Header

[Dynamohum]

Hi I would like to run a Twin Scroll GT35r and I’m wondering what others are doing with their Waste Gate piping setup when running a Twin Scroll Turbo on a Divided header.

I purchased a SS OBX header off of Evil Bay for $379.00 +shipping, it was relatively inexpensive compared to one of the Premium brands, this saved me building one from scratch and for that price I could live with cutting it apart for modifications.

Overall quality is not a bad unit until you get to the poor fitting of the secondary pipes and divider to the T3 flange. I will be reworking this connection and port matching it to the turbo divided turbo housing to ensure proper flow.

As you can see by the photos, they cut into the divider for the WG pipe which pretty well defeats the purpose of the divider which segregates the exhaust gases.

A few thoughts come to mind

1: cut the present WG pipe off and weld on 2 separate WG connectors off each separate secondary after the merge collectors.

2: divide the current WG pipe by welding in a divider to segregate the gasses all the way up to the waste gate.

3: forget about the gains of the Twin Scroll clean up the welds at the flange and use it as is.
4: do # 3 and cut and shorten the WG pipe

I would appreciate your input, thanks

Photo showing Poor Welding and unequal port size

Poor Quality welding, I can only assume that this was a OBX second and why I got it so cheep? Well I was not expecting much and I haven't been disappointed


Does the WG pipe need to be that long and would this not increase lag?

[Dynamohum]

Found this photo of an equal length 4 cyl twin scroll header. As you can see they merge the 2 wg pipes into one, assuming far enough away from the header that the gases do not cross contaminate the pulses?

Do you think this is a good option for running a single WG and not cross contaminating the gases?

[930gt-40r]

This is how I did mine- Because I used a T-4 turbo (modded B&B headers) on stock style B&B's, it boost creeped like a mo-fo. I also upgraded to a Tial V-44 and still got some boost creep.
For your setup I would throw twin 38's on either side with a nice 35r. No- you dont need that long a$$ wastegate tube- that is so you could run the wastegate in the stock position.
I am having new headers made from scratch to help eliminate the boost creep problem. (that is going to be twin valute as well)

Oh and as for the second picture- my buddy has a 700 horse Eagle Talon that has a twin valute with a single gate and it works well

[mark houghton]

Originally Posted by 930gt-40r

This is how I did mine- Because I used a T-4 turbo (modded B&B headers) on stock style B&B's, it boost creeped like a mo-fo. I also upgraded to a Tial V-44 and still got some boost creep.
For your setup I would throw twin 38's on either side with a nice 35r. No- you dont need that long a$$ wastegate tube- that is so you could run the wastegate in the stock position.
I am having new headers made from scratch to help eliminate the boost creep problem. (that is going to be twin valute as well)

Oh and as for the second picture- my buddy has a 700 horse Eagle Talon that has a twin valute with a single gate and it works well

Stupid question, but wouldn't a Tial 46mm help with boost creep? Get them exhaust gasses outa-there faster?

[JMA-RUF]

I have a TiAL 46mm gate, GSF headers and GT35R and I get absolutely no boost creep. Boost is pinned at 1.0bar every single time (well, when the EBC is off, that is).

[gumba]

Dynamo, you want somemo? Haven't heard that song in ages.

[Dynamohum]

Originally Posted by gumba

Dynamo, you want somemo? Haven't heard that song in ages.

Dynamo Dynamo Hummm, want to rotate my finger on her sugar plumb! Oh sorry got caught up in the song.

Actually the sound, that Dynamo hum of the Engine and Turbo screaming her lungs out is the sound I'm after. It's music to my ear's, Oh what a beauty-us Maximus Erectus Grandis sound!

Thanks guys for your help

[BoxxerSix]

WOW, obx really buggered that flange there. Looks like it was cut with a hack saw. It WAY overported in comparison to a t3 TS flange. I'd personally buy a new flange and redo the mockup.

I responded to your message on this topic

[Dynamohum]

Originally Posted by BoxxerSix

WOW, obx really buggered that flange there. Looks like it was cut with a hack saw. It WAY overported in comparison to a t3 TS flange. I'd personally buy a new flange and redo the mockup.

I responded to your message on this topic

Thanks Adam, Your input is well regarded and much appreciated. I was hoping you would have a look at these photos and comment.

Yes its a Hack Job alright! and about right for some of that high quality evil bay merchandise. I can't imagine all OBX headers being built like this? I'm assuming that this was a reject and why it was flogged so cheap on ebay.

Well like I said before for the price " I wasn't expecting much and I haven't been disappointed"

[930gt-40r]

Originally Posted by mark houghton

Stupid question, but wouldn't a Tial 46mm help with boost creep? Get them exhaust gasses outa-there faster?

This is not a stupid question- the V-band 44 flows more than a 46 due to the difference in technology- Tial only makes the F46 (our Porsche waste-gates) only for the Porsche market, no-one else really uses the F46. The V-44 has a much better design then the original type.

Originally Posted by JMA-RUF

I have a TiAL 46mm gate, GSF headers and GT35R and I get absolutely no boost creep. Boost is pinned at 1.0bar every single time (well, when the EBC is off, that is).

James- this is because my turbo is bigger than yours and also has a T-4 housing with tiny little stock sized primaries. Because my hot side flows a lot more, the stock waste-gate setup is in-effective because the turbo is even easier of a path for the exhaust gasses than the waste-gate is. This is also a product of the ridiculous velocity I had with the stock sized primaries.
Your turbo (35R w/T3 hot-side) is the last step before really having to do something creative with the waste-gate/ primaries/ turbo flange/ etc.

Next time around I'm kicking boost-creep in the face with twin V-44s (over kill, but I got a second one for cheap)

[mb911]

we use the twin 38V band(tial) for the twin scroll setup on our 993 single turbo setups

[Dynamohum]

Thanks for the info Guys.


Picked up my heads yesterday from the machine shop (valve grind) and mated the head to the heater for the first time.
Uncovered another problem, the port i.d. is 1.645" and the small collar on the header that goes into the head has an o.d. 1.505" There is .140" difference in size, way to sloppy for me. So now I need to remove these collar which is fine because it will make it much easier to abrade the id of all the tubing in preparation for the TBC. I will have to see what it looks like once they are removed and if possible counter bore the flange for the proper size collars or just leave them off?

What are you thoughts on this?

The reading moved while taking the shot, the correct reading is 1.645"


This is the head sitting on the header. Not a great shot even with the macro, but if you look carefully under the guide you can see the huge gap between the head and the collar.

[RarlyL8]

This is a common problem with ported heads. If you do not want to purchase a set of larger ID headers then the collar can be stretched to fit using a metal cone and mallet.

[Dynamohum]

I'm going to coat the exhaust ports and the inside of the header with this product from Tech Line Coatings Inc. once the header modifications are complete.
The Technical rep assures me that when this product is applied at the correct thickness of 0.001" that it will not mud crack or peel off.
I'm willing to take my chances and be the Ginny Pig!

Prier to measuring the id of the head and od of the collar I was worried about maintaining a acceptable clearance between the two. After measuring I see that I will need to do allot of work to correct this huge gap

[Dynamohum]

Originally Posted by RarlyL8

This is a common problem with ported heads. If you do not want to purchase a set of larger ID headers then the collar can be stretched to fit using a metal cone and mallet.

That is a good suggestion, Thanks

[Dynamohum]

Ok here are some mock up photos on where I'm thinking to cut the WG pipe

Will weld in a V band flange for the WG and thinking of going with the WG002

Can I still go shorter than this? How short can I go and still have clearance?
Any input welcome, Thanks

http://www.synapseengineering.com/

[beepbeep]

Don't mount WBO2 sensor on pressurized side (before turbo), it will fail quickly and exhaust backpressure will mess with readings. Mount WBO2 sensor after the turbo. The port on collector is for EGT probe, not lambda.

Regarding turbo flange, it looks OK to me. It's hard to make perfectly clean welds when hand-welding. The important thing is that it doesn't crack.

I'm also mildly sceptic to coating. If it's done with plasma it will probably stick...but home-coating sounds like a good way to ruin the turbo, if flakes would come off.

[voitureltd]

This is a set of OBX that have been on the wall for years. By comparison to the current ones, the old seem to be more carefully done. Still not enough confidence to use them on something . Everthing is smooth as far as the fingers go. As I recall they were a bit more expensive back then so cost cutting / higher production must take its Lb of flesh. Next photo is of a Norwood TT solution for waste gate. No long tubes to waste gate there. Also two turbos, one waste gate ( why two waste gates 1 turbo as on some posts? Couldn't that create a unbalance of back pressure from one bank to the other? ). I would suspect the Norwood set up is to equalize the pressure between the cylinder banks as each turbo pressurizes 3 cylinders.

[Dynamohum]

Originally Posted by beepbeep

Don't mount WBO2 sensor on pressurized side (before turbo), it will fail quickly and exhaust backpressure will mess with readings. Mount WBO2 sensor after the turbo. The port on collector is for EGT probe, not lambda.

Regarding turbo flange, it looks OK to me. It's hard to make perfectly clean welds when hand-welding. The important thing is that it doesn't crack.

I'm also mildly sceptic to coating. If it's done with plasma it will probably stick...but home-coating sounds like a good way to ruin the turbo, if flakes would come
off.

Thanks for your input Goran.

I will make sure to mount the WBO2 after the turbo.

Whats your opinion on the WG pipe length and the length of the divider to insure no cross contamination of the segregated exhaust pulses when using a Twin scroll turbo?

Its hard to see the weld from the photo, trust me when I say it is poor quality, there is even a small crack in one of the corners.

The ports are not the same size, not square and I suspect will not line up with the turbo housing properly. I can correct all this by building up with weld and grinding it to a proper finished size to match the turbo housing. Lots of work but it will be corrected.

Re the home TBC coatings, I'm using the same process that the big name companies are doing. I know that there are many that are Skeptical about these products and will stay clear of them, until they are well proven.

I realize the risk, but I'm willing to test it out and find out for myself first hand.
I will set up a few test pieces first, coat them, heat them till they fail and report my findings back here when I'm done. I will also take a test piece and hammer it to simulate a dent to the header tubing and check for cracking and bonding issues. If at that point I still have doubts then I will not coat the id of my header. Nothing ventured nothing gained, I will not risk a new turbo without testing to satisfaction.

Thanks for your concern

[Dynamohum]

Originally Posted by voitureltd

This is a set of OBX that have been on the wall for years. By comparison to the current ones, the old seem to be more carefully done. Still not enough confidence to use them on something . Everthing is smooth as far as the fingers go. As I recall they were a bit more expensive back then so cost cutting / higher production must take its Lb of flesh. Next photo is of a Norwood TT solution for waste gate. No long tubes to waste gate there

Thanks for your input and the photos.

Yes yours seems like its has better welds, yours looks smooth mine are bubble gummed and ground in some places to try and hide there mess, your divider is centered, where as mine is crooked. You really need to see the inside of mine where I can't seem to get a good photo of to see how bad a job they did.