Twinscroll worth it?
 

Im thinking about designing a twinscroll cast manifold. Do you think this is worth it and would you buy it?

When the complete kit is finished it would be for sale at a MX-5 specialist.



I was thinking about a similar design like this

https://www.miataturbo.net/attachmen...ine=1435866778


What are your toughts? Worth it or not and is there any interest?

Not enough information to determine if it's worth "it."

What is "it?"

Pro tip: actually get any sort of proper cast manifold designed, built, and in production for a 1.8 miata for a reasonable price, that fits t2's and t3's, plays nice with the rest of the bay, and has a decent angle for a downpipe, and you will already "have a market".
You know why? Cause it's not easy. There's a reason only approx 2 companies make them now, with hopefully a 3rd competing in the near future. Learn to walk before you run.

also, iirc that picture won't work with the bp firing order

Worth the extra time to design and possibly the extra money for the turbo



In 2 weeks we have a new meeting for the next parts we are going to make. I think a 1.8 turbokit will be on the planning. Oh and i need a bigger turbo so thats a plus. :p

I like to create the impossible.:jerkit:

What IS the extra time and money?

Developing and testing will cost some extra time. And the twinscroll turbo's are more expensive than singlescroll

Well with that answer, i'll say that the answer to your original question is a rock solid "potentially."

There's 2 companies that offer cast manifolds right now. If you came out with a generic, nothing-revolutionary, but good (not perfect, just good) quality manifold and could undercut the competition, you would sell them.

Miata market is like this:
1. Price
2. How much it cost
3. Quality
3. Everything else

I used to rock a GT3271 twin scroll turbo, and I wouldn't have bought the manifold you're discussing building. I wanted a manifold that actually closed-off a valve and forced all the air into one side of the turbine for better spoolage. If you built that, and I had the GT3271, I prob would have bought it.

Go for it, I was considering a twinscroll 7163 but the overall cost was looking closer to 3000 for everything assuming I could find someone to fab up the manifold which was my only complication. I've read good things on those that do run twinscroll, though. Add a TS setup with a VVT head and you have a recipe for radically entertaining response.

Like this?

https://www.miataturbo.net/attachmen...ine=1435873541

Yes, like that. But in my case, with a cast iron manifold, I couldn't bolt that between my manifold and turbo without my turbo hitting the car in ways I could not trim-to-fit for. I always wanted to build that valve into the turbo itself... I even bought the stuff to do it, but when I pulled the turbo I discovered it was toast and ended up replacing it with a non-twin scroll.

Will this non divided manifold with valve spool better than a fully divided manifold?

Not quite apples to apples as it were.

This is my old Evo 3
https://www.miataturbo.net/attachmen...ine=1435873858
Built bottom end 2.0L 9.3:1 CR, HKS 272/280 cams, 24x12x3.5 AGP bar and plate, short route 2.5" piping TD05-20G with a 12.5cm^2 twin scroll housing on a short runner unequal length exhaust manifold & full 3" exhaust


And wouldn't you know it. I cannot find the boost curve for when I had the stock motor/turbo in my photobucket. I do not have the data but for what little it's worth without proof I would make 14psi at 3400-3500rpm on a stock 8.8:1 bottom end, stock TD05-16G 7cm^2 turbo, stock intercooler with stock long route hard piping, HKS 272/264 cams & 3" exhaust

spool negatives : larger intercooler, bigger exhaust cam
spool positives : shorter intercooler piping, 0.5 points of static compression


The increase in transient response between gears was noticeable but again I don't have any data. I am a firm advocate of twin scroll for anything but a drag setup.

Yes it would.

So it basically makes the turbo variable, for example like an 1.0 AR to a 0.5 AR with the valve closed right?

Yeah something like that. The valve shuts and now all 4 cylinders worth of exhaust have to go through one port, exhaust velocity goes up A BUNCH and this super fast exhaust hitting the turbine helps spin it up very quickly. Upside of this is great response, downside is turbo will choke if it stays like this. So the valve needs open once boost target is reached so turbine inlet pressure will drop and everything can breathe.

Eh let me think. The small scroll is for the spool. And the bigger scroll is for the horsepower. If you only have the small scroll it will choke.

You want a valve to open up the big scroll at certain boost level.

Those valves only open up both scrolls.

And what about a divider. Low boost everything goes to to small scroll for quick spool. And after a certain boost level the valve switches from the small scroll to the big scroll. So instead of both scroll opened.. al the air goes only to the big scroll

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.

Would like to see this test because on most vehicles a fully divided manifold coupled with a fully divided turbine housing will perform better than a non-divided manifold with a quick spool valve.

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?

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

https://www.miataturbo.net/attachmen...ine=1435876674

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.

Ah i see. Different designs of twinscroll. But designing the manifold for a 3071/3271 or something would be better.

"I want to build and sell a twin-scroll cast manifold. But first, will you please explain to me how it works?"

:giggle:

Yeah, this thread is sort of comical.
Maybe he works for someone that actually know what they're doing.
Otherwise just another troll thread.

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..'

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.

Then see post 8. You don't need to specialize your manifold to sell it, in fact doing that would limit your customer base a lot.

Best bet is build a cheap and reliable manifold. Cheap and reliable is a winning combo.

google "sound performance quick spool valve".
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.

it's not that hard to figure out. don't get caught up on the cross section of the volutes on paper. Just pair cyls 1&4 then 2&3.

https://www.miataturbo.net/attachmen...ine=1435881300

https://www.miataturbo.net/attachmen...ine=1435881300

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.

corky

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

This is a Honda D16, but a good comparison for seeing what it does with a big turbo.

Here is something Mazda published in a SAE paper a few decades ago:

https://cimg3.ibsrv.net/gimg/www.mia...d2d24a750b.png

I would love to do a build using the Evo VIII turbo. Ive seen some impressive 300hp plots put out from that turbo on sub-2 liter engines.

https://www.miataturbo.net/attachmen...ine=1436051622
https://www.miataturbo.net/attachmen...ine=1436051622
https://www.miataturbo.net/attachmen...ine=1436051622
https://www.miataturbo.net/attachmen...ine=1436051622
https://www.miataturbo.net/attachmen...ine=1436051622
https://www.miataturbo.net/attachmen...ine=1436051622
https://www.miataturbo.net/attachmen...ine=1436051622
https://www.miataturbo.net/attachmen...ine=1436051622

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.

https://www.miataturbo.net/attachmen...ine=1436079781

https://www.miataturbo.net/attachmen...ine=1436079781


Heres my dyno graph.

https://www.miataturbo.net/attachmen...ine=1436079781


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 penis.
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.

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.

Mazda scientifically tests single scroll vs twin scroll turbos - RX7Club.com

So many available flavors, and you chose salty.

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 :facepalm:.

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?

Twinscroll worth it?
 

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.

-sincerely,
less than 300whp.

They must be doing something wrong.

I dont doubt that it probably doesnt make much of a difference on your typical drag car that never leaves boost, but if it doesnt show up on a dyno its either a fucked up setup, or they started the dyno pull at 4k rpm. It seems like most dyno shops do this (because theyre stupid).

Pretty sure if they can build and tune GTRS and subarus that trap 170+ mph they can figure out when to start a pull on the dyno.

No the car we are talking about is not a drag car it is just a fun weekend car. I said yes it shows spool gains but only for you to jerk off at the dynograph (slightly 300rpm or so isn't ANYTHING) on the street there will never be a noticeable difference. The weather outside and DA at the time will probably effect your butt dyno more then twin scroll vs single.

Gains yes..on paper...reality very small while also having its downsides

The title of this thread is twin scroll "worth it" ..my response and OPINON was no.

That right there is why Subarus don't respond well to twin scroll. There is too much volume in the exhaust, and the exhaust pulses just kind of disappear, compared to a short runner style like most inline engines. The exhaust pulsing is what makes twin scroll efficient, pairing companion cylinders to even out the pulses and when they impart their energy on the exhaust turbine. And yes I am familiar with the Subaru world, had an 04 STi and 05 STi (blob eyes are my favorite other than a GC RSTi). With short runner systems, twin scroll makes an immidiate difference in not only initial spool up/thresh hold, but also in transient characteristics. My Evo X with a Full-Race twin scroll manifold and EFR 7670 has way better transient characteristics compared to my 04 STi with an 18g on it, and isn't far behind my old stock turbo'd 05 with full bolt on's, stock top mount, catless 3" turbo back. Short runner single scroll is even better than Subarus design on the EJ engines. I mean, Subaru has even switched to a shorter runner, twin scroll configuration on the new FA series engines.

Come on guys, the twin scroll is a "bit" more responsive. If you ask it to do its job on an unsuitable combination of pieces you will not be impressed.

There are a couple ts variations. Have any of you seen the tc layout that actually carried the separation all the way to the turbine blades? Or, almost all the way? The very first RX7 factory turbo used a variation of the gated housing, and it was less than impressive. The same turbo we used on the Mustang (a single guy) offered a better response than the Mazda gated feature. Mazda clearly had the wrong turbo.

A few moons ago Aerodyne asked me to make patterns for a one piece exhaust manifold/exh housing. It was a four syllable Mercedes Diesel, and the pulses arrived at the turbine in four separate paths, yet with enough force to begin cracking the turbine blades. Damn Aerodynes. Never saw cracked blades before or since. Responsive it was.

Sure, there are better turbo designs than the commie pinko things. For limited power applications and about 1/4th the cost, you can't raise too much of a fuss. It is cheaper and it works okay. If the size is appropiate, it too will work a tick better with the ts stuff.

Would I select a ts for my own turbo Miata? Probably not. My objectives are long black lines on the asphalt.

What are your's?

corky

see bold
That's cool. I acknowledge your OPINION. The other crap is stupid drivel.
We are not NABISCO. Check-book builders don't get to talk smack here. Only people that actually do things/ prove things do. No one cares what your tuner or his wife or their cousin or your homie or his dog said or did. Twin scroll is not pointless.
:party:

LOL
"last I saw you failed making big power, blew your crap, and parted it out, putting the car back to near stock. build a big power fast miata then talk.....mmmmmmmmmmmmkay?"

First off...the car is not going back to stock. It still has a built motor/heads cams e85 52mm bullseye turbo ect now i am in the process of assemballing in my little spare time i get so i can start tearing apart the miata for gasp that "higher" hp build you just called me out for not attempting to do. IF parted out means sold my 2000cc injectors i didnt need anymore, and my processwest intake manifold then sure i parted out my car. I only sold the things i did not need for the next setup i still even have the old turbo incase i ever decide to put it on either project car. Also if failed means many mid 10 second passes (still holding the MI subaru et and trap record) and daily driven for a couple months including winter before throwing a bigger turbo on and cranking it out on e98 till it bent some stuff sure i failed lol.


"here in the miata scene we don't all "talk to the tuner" like 99% of nabisco. We build and tune our own cars. almost all of us,"
Maybe because tuning a baby turbo run of the mill miata is a tiny bit easier then getting 2000cc injectors on speed density e85 ect to all work together start in negative degree michigan winters ect and to make a driveable car so you can actually drive it to work when youd like too. I leave that to the guy that knows what he is doing sorry that upsets you lol.


"gains on paper show gains in reality. shut your stupid troll mouth"

No you will NEVER Feel the difference of 300rpm in spool on the street day to day twin scroll will not whats so ever be some kind of saving grace and will only be an added expense to a group who you just admitted doesnt build with their checkbook. Get over your self :fawk:.

I like the turbomiata forums its like a bunch of little uncle scottys running around telling everyone how great they are lmao.

I will now retire back to lerking these forums as i have for many years :crx:.

I feel 300rpm in spool every single day, on the numerous cars I have the privilege of modding and tuning. You might want to look up transient response, I'm sure you don't even comprehend the concept with your ex-10 or 9 sec or whatever it is, subaru.

You will swing e-wang when you achieve something with a miata. You have no idea how ignorant you sound with the "little baby 300hp miata tuning" statement. Everyone that comes from other platforms always acts the fool and a complete douchebag like you, cause they think they're just SOOOo much better than us. Then they fail miserably or pay someone to do everything for them, cause all they know is how to write a check and swing peen on the interwebz. It's just a dinky miata, how hard could it possibly be to tune, right?

I've tuned ID2000's on speed density. Have you? Personally? Come at me bro.

Uncle Scotty wouldn't last in here for more than 5 minutes. Go ahead and tell him to join. I dare you.

One last post actually

"Everyone that comes from other platforms always acts the fool and a complete douchebag like you, cause they think they're just SOOOo much better than us."

from other platforms?
I have had modified miatas (supercharged 02 se turtle) long before joining team broken ringland. Actually my first car was a miata. So no i dont really "come from another platform" I have just spent time in both. Like i said i have lerked here for years before i made a account because of the fighting pit that is this forum and now i will go back to lerking again.
Uncle Scotty would be a good fit for this forum i dont care what you think :rofl:.

Oh yeah? Well my turbo spools faster than all of yalls!!!

300rpm worth of spool
http://accessecu.com/dyno/graph.php?...rgb2=204000000

your butt dyno would have to be demolished by a football team to not feel that

Wow look at that torque fall from the peak, almost 100tq in 3k rpm. The boost falls off pretty rapidly, maybe the exhaust?

Tiny turbo.

at first i thought "Dang that's not a bad little turbo motor", then i saw the STI label. :giggle:

lol it's a bone stock sti, if you think that's bad don't look at any other oem turbocharged cars, it's pretty bad
https://www.miataturbo.net/attachmen...ine=1436216936

It is more than 300rpm of spool in most cases if done right. The problem is most manifold designers for Miatas aren't interested in every little bit of extra performance, but rather packaging in a tight area and keeping the costs down for marketability. It has been done a couple of times with good success, however. This is a dyno of a built 1.9 liter Miata with VVT and a forged bottom end using a twin scroll GT3071R turbo and a 1&4 and 2&3 separated tubular manifold.

Attachment 183887
As you can see, the spool characteristics are pretty amazing for a turbo that size.

:laugh: I actually thought of posting that up earlier but was on my phone


But really: you're right. I even posted something along those lines in the very 1st handful of posts.
The only reason I even argued with that shortpenisbk guy is because he was using the stupidest arguments known to mankind.

Did someone say torque drop off?

Attachment 183886

Twinscroll worth it?
 

So that was my thread on rx7club from a while ago.

The key with an even fire piston engine (I6, I4) is keeping the pulses separated, as has been mentioned already. This can be done with valve events or manifold and turbine housing design. On odd fire engines like normal cross plane v8's for example, a quick spool valve has more relative advantage because you can't get pulse separation without even firing order or unusual exhaust manifolds.

Evos were among the first piston gasoline vehicles to use twin scroll single turbos. The stronger pulses create more turbine power and allow more boost at low speed full load. This increases the torque you get when you are lugging at higher gears. So if you're in 5th gear at 1800rpm on the street you can actually make boost if it's sized right.

The twin scroll housings are more restrictive though and they increase turbine inlet pressure and residual gases at high speeds. This increases pumping work and knock sensitivity.

The thing people forget about are valve events. So on the newest Audi engines for example they run divided manifolds with undivided turbine housings, and then switch to late opening short duration exhaust cams to get a twin scroll pulsation effect. Then at higher speed they move to conventional valve events, and you don't have the normal high speed penalty you get from small exhaust cams or twin scroll manifolds.

See this thread for details (scroll down) http://www.thewolfweb.com/message_to...=617123&page=7

at least they can spool.

subaru turbos spool slow and drop off.

everytimes I see an ST plot it makes me consider trading in the WRX for one more and more. But yeah, they have no guts up top, I'm sure if you raised the boost it would do nothing about 5K, and at least with a subby you can still push the top end a bit.

I currently rocking a TD04L. 212whp and 302wtq

Journal bearing:noob:


Needs a lot more timing after 5000rpm, but i need to make new detcans for listening to knock. Also needs to be a little more rich.

https://www.miataturbo.net/attachmen...ine=1436285941