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All that valve does is block one scroll. There is no big scroll, small scroll, just 2 equally sized ports. The valve can open/close one of those ports, effectively making the turbine housing bigger/smaller on demand. There are variable-geometry turbines that take a different approach and accomplish the same things.
For what i understand there are 2 scrolls. Smal and big one. The small one is for increased velocity. And the big scroll are for increased capacity
But maybe there are different designs of twinscrolls.
In this pic you can see the different size scrolls
Oh. Well I was talking about my GT3271. They were equal-sized more or less, not different as shown in your pic above. Yeah, I guess every turbo will be different.
Im not an engineer. I just started working for them because i can work with CAD software and i have knowledge of the MX-5. I originally made 3D animation for them. And from there on they asked me if i wanted to do more stuff. Everything i have and done is not by going to school or something but learning from others and trying and trying.
I just want to involve the community in making good parts and what the community wants. Of the most of us here want a top mount turbo i will design a top mount. Vice versa. No point in making a bottom mount of most of us want a top mount.
They have huge knowledge and help me trough the process and i will draw everything and i also want to understand the principle. And if you dont like the design afterwards dont complain like. ' i wished they..'
Hmm. I'd like to see that test too. I'm speculating on my post, I've tested nothing. Do you have any examples of what you're referring to?
Well of course I can't find the exact example I'm looking for now but when the quick spool buzz started somebody did a comparison of a proper tubular twin scroll setup vs. a quick spool with tubular single scroll manifold on a Mk4 Supra and the twin scroll setup performed better everywhere because the exhaust pulses aren't screwing with each other and have a much smoother flow path in the divided configuration.
Im not an engineer. I just started working for them because i can work with CAD software and i have knowledge of the MX-5. I originally made 3D animation for them. And from there on they asked me if i wanted to do more stuff. Everything i have and done is not by going to school or something but learning from others and trying and trying.
I just want to involve the community in making good parts and what the community wants. Of the most of us here want a top mount turbo i will design a top mount. Vice versa. No point in making a bottom mount of most of us want a top mount.
They have huge knowledge and help me trough the process and i will draw everything and i also want to understand the principle. And if you dont like the design afterwards dont complain like. ' i wished they..'
That's cool. but again - walk, then run. Also: "there is nothing new under the sun". So just improve on an already existing design, with a quality cast manifold. Then, if it's successful, think about twin scroll.
I'm just being realistic.
But often the "dreamers" interpret it as negative or hateful. It's not. I actually want to see you do this.
The abilities to design and test the turbo makers enjoy are tough to argue with. They make twin scroll exhaust housings because they perform another small notch better.
It is a problem to decide which turbo to design for. The simple log manifold is a joke, or so we all thought. The Mercedes F1 cars have the ugliest log manifold I've ever seen. Yet there sits Hamilton on the pole for the British GP in a Mercedes.
My 4 into 1 casting is more responsive than my previous baffled log guy. It, in turn was a notch up on my previous simple log type, and anyone else's as well. Mercedes operates in a regime unknown to me and likely to most of us. I am not willing to criticize their science. I wish that I could.
When the divided housing is needed, the tig welder and an iron (ductile iron) manifold will be an easy chore to create. Consider that approach, if you will.
I encourage you to give it your best effort. The 3D printer is probably far enough along to go from design to reuseable pattern and core box w/o intermediates. My attempts at doing so have not successfully pulled it off yet. I am hopeful the next try will be.
For the best of all information known to mankind, perhaps on any given subject, direct your communications to Mr. Consealer404. He clearly is the class act of the library of turbo knowledge, testing, the tuner, engineer, fabricator, metalurgist, driver, installer, trouble shooter, marketer, and master scientist of all aspects of turbocharging. If he disagrees with me or anyone else on any forum, I urge you adopt his view points. My hat remains off to the gentleman.
Thx for the info. I searched good time and comparing different style manifold. From OEM to aftermarket.
Also flow engineering a manifold will be part of the engineering. To see where the air can flow better etc.
My idea so far what i have in my mind is a equal length divided manifold. Ive seen a few of them and i m very confident in making them fit with minimal space.
I have access to a CNC 5axis milling machine to make the prototype manifold. Also 3d scanning the engine bay and fit the turbo with the manifold to see if it fits will be one of the options
It is a problem to decide which turbo to design for. The simple log manifold is a joke, or so we all thought. The Mercedes F1 cars have the ugliest log manifold I've ever seen. Yet there sits Hamilton on the pole for the British GP in a Mercedes.
It's long, sorry. You can probably skip to the final paragraph in all honesty.
I am one that believes twin scroll is way nice to have. I come from the Evo X world which is factory twin scroll. Most everyone looking at turbo upgrades, unless they are chasing absolute peak dyno numbers, make having twin scroll a priority if they use their car mostly on the street. I know the Evo X is a very different platform compared to the Miata, but their is one big similarity, small displacement. Most Evo X owners are still on stock displacement of 2 liters. Sure it's roughly 10% more than a 1.8, but it still has some of the same challenges. We don't have a lot of room between the engine and fire wall, like there isn't much room between the engine and surrounding sheet metal on the Miata. The cast twin scroll manifold idea is great in theory as it typically allows more room from a more compact design. However, even in the Evo X world where there is a greater market for such an item, there are only 3 cast manifold options currently; OEM (limited turbo options), ATP (Largely out dated, very limited turbo selection), and MAP (OEM flanged, limited turbo options). MAP has said that the cost of developement was high, and it was a long process bringing theirs to market. For a much more limited Miata market, this could be very cost prohibitive, especially with the average Miata owners budget. Most aftermarket manufacturers of Evo manifolds stick to built to order tubular manifolds. Some are much better quality than others (Full-Race and ETS for example), which use a heavier wall high quality material, skilled welders/fabircators, but are typically higher priced compared to typical bargin brands. However, Full-Race has a nearly 0 cracking rate, and is more than worth the extra cost to most Evo X owners. I know Evo X owners typically represent a different financial market, but quality costs, no matter the platform.
A well executed twin scroll manifold definitely makes a difference (as does a quality turbo). The Evo X world has a few turbos that we suck off religiously, the MHI 18K, a decent stock frame upgrade, the bolt on GTX35r, a bigger turbo but has a lot of spool up surge, and the Holy Grail EFR turbos (mostly the T4 Twin Scroll stuff). I will use my personal car as an example. A 2011 Evo X MR Touring (the fattest of all Evo X's); Kozmic Motorsports built SST trans (with Dodson Sportsman Clutches, and Dodson Sump), Full-Race Twin Scroll EFR 7670 IWG, FR intake, COBB 3-port EBCS, Modified FR and ETS charge piping, ETS 4" intercooler, ID1000's, Kozmic Surge Tank, Wally 255 lift pump (to surge tank) to Wally 255 main pump, STOCK Engine, 3" turbo back (FR down pipe to ETS out the back) STOCK Cams, Kozmic Open Source Tune. Below is the Full-Race manifold on my Evo, it's absolutely beautiful to hold in person and see the craftsmanship and detail.
Heres my dyno graph.
So what's important about this dyno graph.
1) Red is HP, Blue is Torque, Green is boost psi, and dark red is AFR's
2) This is on Kozmic Motorsports heart breaker Mustang Dyno (avg 20% lower than most DynoJets according to Kozmic), with 0 correction, and tuned for crappy 91 octane gas on a high 80's day.
3) The power is not that impressive, and I will never claim it to be, it was tuned for reliability. I'm not chasing dyno numbers to have a big internet *****.
4) Torque was kept low on purpose, and spool up was actually slowed down, due to Kozmic trying to avoid a big torque spike that could leave me with a hole in the side of my block.
So, we with that in mind, I reach full boost just after 4,000 rpms on a 7670 with a twin scroll housing. That's a 57.2 mm (inducer) turbo on a 2 liter reaching 24-26 psi of boost just after 4,000 rpms on a dyno (target psi is 24.5, but spikes 26 on spool up). On the street it is marginally sooner. This is partially because of the twin scroll housing and partically because of the turbo's inertia characteristics/wheel weights. It is worth noting that another company, CBRD, is now manufacturing an EFR kit for Evo X's that uses a single scroll V-band manifold with a 7163 and they report roughly a 4400 rpm full boost figure (26 psi). The 7163 is supposed to spool better than the 7670. The 7163 specs out at 57 mm inducer, 71 mm exducer, 63 mm turbine OD and 60lb/min, where the 7670 is a 57.2 mm inducer, 76 mm exducer, 70 mm turbine OD and 64 lb/min. So the 7670 has more mass to get moving.
Twin scroll, and a high quality turbo IMO are worth the gains in area under the curve. The problem for this particular market is cost, and size of the market, from what I've seen. For most wanting more power and the turbo route, it seems they want to stay in the "Safe for Stock Block" area, and don't want to dive into the big turbo/forged internals/bigger supporting mods area, which is of course higher cost. And for the majority of the Miata Turbo market, a basic kit and cheap journal bearing turbo will suffice, especially if it's their first turbo vehicle.
I think that twin scroll is a waste of time and money in 99.999% of situations.
In Subaru land (where i am from) twin scroll pops around a bit on random builds and almost never do you see real gains when you overlay graphs/compare time slips/driveability. Often twin scroll setups (example a pte6262 on a Subaru) choke up top because of the design.
Ok now lets think when you will actually use the benefits of a twin scroll setup.
When is the last time you were going wot at say 2,500 rpm?
Why were you going wot at 2,500??
High load low rpm situations are very stressful to many components IE the weak rods in these cars even upgraded stress is stress I have managed a bend turbo tuff I beam rod/bolt with enough will power in my Subaru when with enough playing around we got spool of the average 62mm turbo but then made the power of a 68mm turbo that was actually on it (mid 30psi at 4,900 rpm in only 3rd gear).
What about traction? A linear powerband that comes on smooth will not only save stress on every component in the entire driveline but it will also help aid in actually being able to use the power your trying to make.
I only seeing this useful in situations where people are using turbos so large for the car that being able to create a nice solid powerband actually becomes a issue considering your not actually racing at 3,000 rpm and it only hurts top end.
I think that twin scroll is a waste of time and money in 99.999% of situations.
In Subaru land (where i am from) twin scroll pops around a bit on random builds and almost never do you see real gains when you overlay graphs/compare time slips/driveability. Often twin scroll setups (example a pte6262 on a Subaru) choke up top because of the design.
Ok now lets think when you will actually use the benefits of a twin scroll setup.
When is the last time you were going wot at say 2,500 rpm?
Why were you going wot at 2,500??
High load low rpm situations are very stressful to many components IE the weak rods in these cars even upgraded stress is stress I have managed a bend turbo tuff I beam rod/bolt with enough will power in my Subaru when with enough playing around we got spool of the average 62mm turbo but then made the power of a 68mm turbo that was actually on it (mid 30psi at 4,900 rpm in only 3rd gear).
What about traction? A linear powerband that comes on smooth will not only save stress on every component in the entire driveline but it will also help aid in actually being able to use the power your trying to make.
I only seeing this useful in situations where people are using turbos so large for the car that being able to create a nice solid powerband actually becomes a issue considering your not actually racing at 3,000 rpm and it only hurts top end.
Waste of time for 99.999% of situations huh? Maybe it's just a waste of time on Subaru engines with their 50 miles of piping then because that's definitely not true.
Did you know that twin scroll designs with the same A/R actually flow more air? Having something choke on the top end probably has to do with some other change in the system. When have you seen an actual fair comparison?
The benefit of twin scroll spooling faster is not just all about boost threshold. Lower boost threshold can be an important thing though when trying to make big power with a large turbo and still having a usable power band. But besides that, it means that it is more responsive to throttle modulation and transient throttle changes, and boost recovery time is lower when you shift to the next gear.
Traction is solved by having better tires or suspension or car setup, reducing power is the easy way out. Twin scroll setups aren't automatically violent either, and if for some reason the onset is too violent, then electronic boost control strategies can fix that.
Please go read this thread. I know it's a rotary engine and from awhile ago but it's a true apples to apples comparison.
The abilities to design and test the turbo makers enjoy are tough to argue with. They make twin scroll exhaust housings because they perform another small notch better.
It is a problem to decide which turbo to design for. The simple log manifold is a joke, or so we all thought. The Mercedes F1 cars have the ugliest log manifold I've ever seen. Yet there sits Hamilton on the pole for the British GP in a Mercedes.
My 4 into 1 casting is more responsive than my previous baffled log guy. It, in turn was a notch up on my previous simple log type, and anyone else's as well. Mercedes operates in a regime unknown to me and likely to most of us. I am not willing to criticize their science. I wish that I could.
When the divided housing is needed, the tig welder and an iron (ductile iron) manifold will be an easy chore to create. Consider that approach, if you will.
I encourage you to give it your best effort. The 3D printer is probably far enough along to go from design to reuseable pattern and core box w/o intermediates. My attempts at doing so have not successfully pulled it off yet. I am hopeful the next try will be.
For the best of all information known to mankind, perhaps on any given subject, direct your communications to Mr. Consealer404. He clearly is the class act of the library of turbo knowledge, testing, the tuner, engineer, fabricator, metalurgist, driver, installer, trouble shooter, marketer, and master scientist of all aspects of turbocharging. If he disagrees with me or anyone else on any forum, I urge you adopt his view points. My hat remains off to the gentleman.
Waste of time for 99.999% of situations huh? Maybe it's just a waste of time on Subaru engines with their 50 miles of piping then because that's definitely not true.
Did you know that twin scroll designs with the same A/R actually flow more air? Having something choke on the top end probably has to do with some other change in the system. When have you seen an actual fair comparison?
The benefit of twin scroll spooling faster is not just all about boost threshold. Lower boost threshold can be an important thing though when trying to make big power with a large turbo and still having a usable power band. But besides that, it means that it is more responsive to throttle modulation and transient throttle changes, and boost recovery time is lower when you shift to the next gear.
Traction is solved by having better tires or suspension or car setup, reducing power is the easy way out. Twin scroll setups aren't automatically violent either, and if for some reason the onset is too violent, then electronic boost control strategies can fix that.
Please go read this thread. I know it's a rotary engine and from awhile ago but it's a true apples to apples comparison.
The rotary guys at least try to make power at times.
How many Miata guys here are trying to make 5-6-700whp where spool is needed quickly so they can try to make a good powerband and stay in it.
If your having spooling issues trying to make a 250whp-300whp car its because you choose a poverty ebay turbo or some other random cheap $250 turbo you found on the forums (Miata guys are famous for this). A simple efr or bullseye turbo will make it a completely different car but turbos are turbos right only twin scroll can help .
I have seen a local buddy go with a twin scroll pte62 setup.....after talking to his tuner while his car was being tuned on the dyno (one of if not the biggest GTR/SUBARU/EVO tuners in the US) they switched over to a pte62 with a single scroll setup after that season and that's what he is on now.
He admitted that there was never a single time where twin scroll actually provided something for him and all it did was start to hurt up top.
While I admit it may have benefits with some random auto x and even less track guys what % are actually going to purchase this twin scroll setup and all the other goodies like the extra wastegate, retune ect all for 300 rpm of spool. Will they even notice the difference and actually do anything besides help you jerk off to your dyno graph?
I don't have a problem making enough power. I'm afraid to turn it up and blow up the transmission. If you want to do something productive, design some better trans options.
07-02-2015, 06:37 PM
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