S30 RB25DET T4 Twin Scroll Turbo Manifold Design

[Jeff9727]

Some background: I work at an engineering firm as a piping design specialist.

 

For those of you interested, I am designing a turbo manifold using my piping software at work. About a 3rd of the way complete. The photos don't show the wastegates, but I plan on utilizing two 38mm v-band waste gates. I plan on sending it to a fab shop and then installing it into my 75 280z. I use CADWorx 2018 and isogen. I will be sending the isometrics to an engineer in our process department to run flow calcs. I am working to make this manifold as efficient, equal length, and inexpensive as possible while trying to minimize the welds. Not saying it's going to be perfect...this is my first attempt at it. If I am able to produce a "Full Race" quality manifold for 1/4 the price, would there be a market for this?

 

On a personal note, I'll be jet coating the manifold and then wrapping it in two layers of 5mm thick pyrogel insulation. A buddy at the plants owes me big time and he's giving me a pony roll of pyrogel insulation. 

 

Let me know your thoughts. I'm at the mercy of the forum! Have mercy on me!

 

Thanks,

Jeff

[Jeff9727]

Some progress. The collector fab details hadn't included the waste gates yet. It's getting there...

[Jeff9727]

Moderator could I move this to the fabrication page?

[Zetsaz]

@seattlejester

[Jeff9727]

At this point, I'm just chronicling my design. I hope I'm not being annoying with all the posts.

Current runner lengths (and it needs work):

1: 23.75"

2: 17.1875"

3: 18.3125"

4: 21.75"

5: 21.625"

6: 21.5"

[seattlejester]

Moved as requested.

 

I'd love to see a manifold with high wastegate priority. Seems like it always takes a back seat. An interesting trend is to make the twin scroll and add the wastegate to the turbine housing. Maximum priority, and at that point wasting the gas via merge shouldn't affect the pulse of the twin scroll in theory.

 

The twin wastegates is pretty interesting keeping it completely divorced. A bit harder for me to swallow though, even cheap name brand wastegates are going to be expensive. Two cheap ones would be more than one ver nice large one. 

 

I feel like your welder might shoot you. Trying to get a tig torch down between the flange or where some of those joints are is going to require quite a long stick out.

[HuD 91gt]

Is there a reason why you have the turbo flange more biased to one side vs the Center of the manifold? Wouldn’t getting equal lengths be a little easier that way?

[Jeff9727]

1 hour ago, seattlejester said:

Moved as requested.

 

I'd love to see a manifold with high wastegate priority. Seems like it always takes a back seat. An interesting trend is to make the twin scroll and add the wastegate to the turbine housing. Maximum priority, and at that point wasting the gas via merge shouldn't affect the pulse of the twin scroll in theory.

 

The twin wastegates is pretty interesting keeping it completely divorced. A bit harder for me to swallow though, even cheap name brand wastegates are going to be expensive. Two cheap ones would be more than one ver nice large one. 

 

I feel like your welder might shoot you. Trying to get a tig torch down between the flange or where some of those joints are is going to require quite a long stick out.

You are probably right about the welder. I'm a piper by trade and it's our job/duty to make welders hate us.

 

But seriously, I understand your statement about the turbine housing wastegate. I'm running a borgs warner EFR 7670 W/ 1.05 A/R twin scroll. I originally wanted the 0.92 A/R as it had an internal wastegate. Being that the 1.05 A/R is not available with an internal wastegate, I'm stuck using external. Poor planning on me? Maybe.

 

Is there a way we could give the wastegate a higher priority? I'm willing to make this as efficient and awesome as possible, while still being cheaper than a 6boost. Could you please please please explain to me how twin scroll is still effective in a waste gas scenario? The more I understand it, the better I could figure a work around/solution.

 

 

1 hour ago, HuD 91gt said:

Is there a reason why you have the turbo flange more biased to one side vs the Center of the manifold? Wouldn’t getting equal lengths be a little easier that way?

Quite honestly, because after much shopping around, I noticed the trend for S30 chassis to have a forward position turbo. However, I'm sure I could use a handy dandy search button to clarify this issue. If a center position turbo manifold will fit, I'd gladly re-work this and make it symmetrical! I'd imagine a symmetrical turbo would be easier to fabricate using mandrel bending as often as possible.

 

 

Thanks for your responses thus far. I'll do more work on this tomorrow.

[HuD 91gt]

Well, pending where your RB is mounted within the bay, the stock L28ET manifold is rearward based.  I haven’t mounted my manifold to the block to check clearances but you would think there would be room.

[Jeff9727]

17 minutes ago, HuD 91gt said:

Well, pending where your RB is mounted within the bay, the stock L28ET manifold is rearward based.  I haven’t mounted my manifold to the block to check clearances but you would think there would be room.

 

If I have time this weekend, I will drop the engine in and take pics. I am able to take bunches and bunches of photos and process them into something called AGISoft Photoscan Pro. This creates a point cloud I can use to import the car and engine in 3D into autocad.

 

FYI, if this gets up and running like I want, I'll be investing all profits back into getting cool stuff like a liquid sand box. That way we can anneal and PWHT carbon steel pipe. Keep in mind, every manifold I design (with all of your help...credits will go where credit is due. Might finally donate to the website!) will undergo flow calculation and finite element modeling. All documentation will be provided along the way.  

[seattlejester]

Less 90* off the collector would be nice. Ideally putting the waste gates where the turbo flange is and curving the turbo flange further down stream, although I'm sure packaging comes into play and with adequate boost control probably a fairly moot point.

 

^a really nice example, although pretty much infinite room to play with compared to ours.

 

The AR size seems quite large, I feel like a drop in 0.1 wouldn't be an issue with a twin scroll setup would probably even help spool. I don't have my sizing chart to compare, but what are we looking for power band wise and flow wise? To me that seems like a bit of a peaky setup with a power band in the upper RPM's if memory serves.

 

I'm not sure I understand your question. Do you mean how the twin scroll is working when you waste through the turbine housing? I mean the stock wastegate on the EFR turbos waste through the turbine housing, more in line then on the outer portion of course though. I imagine you get most of the benefits of the exhaust being separated all the way to the turbine housing so you benefit from not having interfering pulses and gain the benefits of the exhaust speed. Once you have to bleed the waste gas you are essentially past your desired turbine speed, so loosing the benefits of the twin scroll by having a single wastegate port that more or less merges them in the waste stream is almost more beneficial in that you loose that divorced benefit as well as removing the volume. 

[Jeff9727]

11 hours ago, HuD 91gt said:

Well, pending where your RB is mounted within the bay, the stock L28ET manifold is rearward based.  I haven’t mounted my manifold to the block to check clearances but you would think there would be room.

Thanks for that!

[Jeff9727]

Awesome vid @seattlejester ! Inspired me to do this. See images. 

So far...:

1: 19.75"

2: 19.75"

3: 19.375"

4: 21.75"

5: 21.625"

6: 21.5"

 

I will probably need to repipe all of it and especially runner 2 as this thing will put the turbo itself up wayyy to high. Will hit it again monday. I will have the engine in hopefully tomorrow and check clearances. I will also do a symmetric design including "prioritizing the wastegate" to show @HuD 91gt

[seattlejester]

Definitely better at least in waste gate priority and transitions.

https://www.theturboforums.com/attachments/wastegateplacement-jpg.660044/

https://ls1tech.com/forums/attachments/forced-induction/337259d1327631255-does-mount-orientation-wastegate-matter-precisionmanual.jpg

 

The question or concern is if that gets in the way of feasibility in either manufacturing or locating it is probably going to take a back seat.

 

Your welder is definitely going to be planning your murder.

[Jeff9727]

A little progress report:

I took @HuD 91gt's advice and centered up the manifold. All pipe lengths are equal as of now. The connection for the wastegates are 45 degree branches off the collecter with 90D ells welded to those. 

I will be 3D scanning the borg warner tonight so I can create an autocad model of it. If anyone wants a Borg-Warner EFR 7670D autocad model, message me.

I am interested in a specific manifold design done by CRG Turbo Manifolds out of Australia. Here's a link and let me know what y'all think:

 

[seattlejester]

It looks pretty, but your downpipe running is going to be a bit awkward with the waste gate in the way.

[Jeff9727]

So...I got this quote today...LOL! And that's the minimum length of pipe I can purchase with them.

[mtnickel]

I’d be interested in one of these. I also commend you on your ambition. As has been mentioned however, is that I think the welding and working with the welder, planning assembly and order of welds will be key. Have to remember this will be HOURS of welding. Plus machining both flanges. It’s a lot of work. Hard to keep cost down. The CX racing one is even $600us and they hardly pay for labour. Haha

[Jeff9727]

Thanks for the comment! To all, I have revised the design...again. But, I've ordered the parts and I've committed to the design. Attached is a picture of the final revision. You will notice that I have left the waste gate connections off. That my friends, is proprietary. Just know that it will be a true twin scroll design and I definitely will be posting a picture of the wastegate kit I intend to manufacture for selling purposes.

The design has again been through a flow check only to make sure the short radius ells do not cause excessive back pressure. They don't. I don't have a stress model yet, but my mechanical engineer says that I should not gusset anything because I could possibly crack welds. He will perform a thermal growth analysis when he has time.

Also different from the attached plan, I went with a different and more simple style of collector. I am using a 3" weld cap with a flat plate welded to it. Hard to explain but there is one little detail showing it on the plan.

If you plan on fabricating this, please note that the final height of the turbo flange can change. I will probably leave this piece for last and do a "field cut".

What are your thoughts?  Pics to come. It might be another couple of weeks before my next post, BUT WE HAVE PROGRESS!

[seattlejester]

Interesting evolution. Almost like a twin turbo setup that goes into a single twin scroll. 

 

Should be fairly potent and your welder won't be giving you the evil eye.

 

The question obviously would be, is there room for the steering shaft? That dips quite a bit more overall. I do like how it hugs and the tilt for the turbo so that you can run the dump pipe very close. 

 

Also raises the question is the long pipe after the collector needed? What if you merged closer or had the turbo mounted not flat? Would be a bit more compact. Overall I really like the slight tilt to the wastegate, loads better than just a flat 90 off of it that a lot of people run.