Anybody out there using a twin scroll setup?

[yellowfocus]

Just curious, since a few companies like ATP and Full Race are now offering Garrett GT3071R turbos in .78 A/R housing w/ V-Band outlet, which sounds like something more suited for track use, but you never know.

[chewbacca]

someone explain twin scroll technology to me. it just seems like an overly expensive technology...

[yellowfocus]

Copied form IWSTI.com:

A twin scroll turbocharger has two scrolls within one turbine wheel having different geometries from one another. In this case, the exhaust gases of the permanently enabled cylinders drive one scroll of the turbine and those of the cylinders which are selectively disabled drive the other scroll. The benefit of this arrangement is that when the engine is operating on a reduced number of cylinders connected to the appropriate turbine scroll, the turbocharger can still operate efficiently given the reduced gas flow through the turbine. When all the cylinders are enabled, an increased volume of exhaust gas drives the turbocharger through both turbine scrolls meaning that the turbocharger remains appropriately sized to supply air to all the cylinders."

The twin entry on the turbine side gives it away as being twin scroll. The benefits are much reduced lag on smaller displacement engines, such as 4-cylinder engines. The caveat is that to fully utilize the design, an equal pulse header is needed (aka equal length).

[yellowfocus]

I guess not. OK, I'll be the first then.....

[jdh0526]

It seems as though most twin scroll turbos are rather large for our engines. I see alot of honda guys using them, but alot of them rev to 8k+

[P-51]

I think the bit about displacement on demand or whatever (permanently enabled cylinders) is incorrect or not applicable in all cases.

I've never heard of a displacement on demand 4 cylinder, yet some 4 cylinders (Mitsu?) have twin scroll turbines.

The real short answer to why, is that the twin scrolls better utilize the power pulses coming out of the engine.

[yellowfocus]

Originally Posted by P-51

The real short answer to why, is that the twin scrolls better utilize the power pulses coming out of the engine.

In a nutshell, absolutely.

As far as larger displacement engines, you are correct, they don't make a GT28RS in twin scroll yet, but there might be a decent market for it. Essentially, if your maxing out the 28RS, but worry about the spool time on a GT30R, a twin scroll GT3071R might be the answer. Reading SR20DET forums, it sounds like 500-1000 RPM sooner boost is seen on the GT3017R twin scroll than the single scroll. So, its like having your cake (nice broad torque and HP numbers) and eating it too (less lag).

[jdh0526]

Originally Posted by yellowfocus

In a nutshell, absolutely.

As far as larger displacement engines, you are correct, they don't make a GT28RS in twin scroll yet, but there might be a decent market for it. Essentially, if your maxing out the 28RS, but worry about the spool time on a GT30R, a twin scroll GT3071R might be the answer. Reading SR20DET forums, it sounds like 500-1000 RPM sooner boost is seen on the GT3017R twin scroll than the single scroll. So, its like having your cake (nice broad torque and HP numbers) and eating it too (less lag).

1000 rpms sooner, going from identical 3071r, to 3071r with twin scroll? same size exhaust housings and compressors?? Do you have a link to this? Id love to read about it.... Im not saying its false, that just seems a bit dramatics as a 1000rpm spool increase is quite impressive

[guitarseth]

Another part of the benefit is from the fact that (from what I understand) they can use two separate vane geometries for each scroll. EDIT: Nevermind, I must have imagined that somewhere.

EDIT #2: I knew I had seen it somewhere, this isn't where, but its a little bit about the history of the twin scroll.

Originally Posted by http://www.mazda.com/mazdaspirit/rotary/story/p5.html

To improve the driving performance of the turbo rotary engine, the second generation Savanna RX-7 came with the Type 13B engine linked to a Twin-Scroll Turbo to minimize turbo lag. Exhaust gas supplied to the Twin-Scroll Turbo was divided in two, a large scroll and a small scroll, which allowed the turbine to be powered step-wise. With this configuration, the single turbocharger acted as a variable turbo and was sufficiently effective at both low and high rpm

[yellowfocus]

Originally Posted by jdh0526

1000 rpms sooner, going from identical 3071r, to 3071r with twin scroll? same size exhaust housings and compressors?? Do you have a link to this? Id love to read about it.... Im not saying its false, that just seems a bit dramatics as a 1000rpm spool increase is quite impressive

I've searched for about 30 mins on the DET forums and can't find the pic. To answer your question, no. To utilize the twin scroll turbo, you need a divided exhaust manifold. In the Zetec Focus case, our firing order is 1-3-4-2, so exhaust pulses from 1 and 4 go into one scroll and 2 and 3 go into the other, so that an exhaust pulse is hitting each scroll every 180 degrees of crank revolution.

Currently, Garrett only offers the GT3071R/GT30R/GT3076R in a .76 A/R turbine housing, which is not available in single scroll setups. However, despite the larger A/R and in fact larger turbo over a GT28RS, spool time decreased dramatically and the turbo was able to flow more air in the higher RPM (like I said, have your cake, and eat it too).

The reason I ask first is I was torn between the GT28RS and the GT30R for my track/daily driver setup (RS for spool and driveability, 30R for more power, cooler air), and since I own an STi and a lot of guys rave about the JDM Spec C's twin scroll setup and calling it Insta-Boost on 400WHP, I began to study it and realize that having a GT3071R twin scroll might be exactly what I'm looking for. I am about 95% comitted to the twin scroll setup now, but I was just curious as to if I would be the first Foci to do so (barring the drag Foci out there).

[yellowfocus]

SR20DET twin scroll manifold from Full Race:

[yellowfocus]

Dyno plotting a (I believe) GT3076R twin scroll on an SR20DET:



I guess from reading the forum, they are talking about the head of this car (which is a red top DET) and that its head design is less desireable than a black top, so spool suffers a little. I remember reading the whole discussion on VE of our Zetec engines a bit ago and I never heard the whole story, but it would be interesting to see how this differs in the Zetec vs. DET vs. EVO and other 2.0s........

[yellowfocus]

Quotes of a guy who went from a GT3076R to a GT3076R twin scroll:

I had full boost of 1 bar by 3800 rpm's I would guess. I couldn't get any traction at all. I need to adjust the height of the car so I can go play more. Now I am really excited I got this stuff. It deffinatley felt a lot quicker spool than my old setup. No watching the boost build, it was all or nothing. Very fun.

Well I did some more driving today and its pretty nuts. It feels more like a GT28R spooling and the back end breaks lose everytime I get on it now. When I shift there is no loss in boost pressure and the tires spin like crazy. I got a bunch more pictures tonight so I will post them when I get back home. I have the boost set at 1.2 bar now like I ran before and it feels very fast. I still am adjusting the Duty cycle on the AVCR so its not a steedy 1.2 yet but it still feels nuts. I am very excited about this ner setup. I can't wait to get to the dyno and see what its like now and then do a 100 octane run. It sounds a lot different then it did before too. I think most of that is the 44mm vs the 35mm TiAl I had before.

I got the duty cycle setup and am now running 1.2 bar. It feels nuts. With my old setup at 1.35 bar my SAFC airflow % read 70% at the highest. And I only say it that high when it was really cold out. Last night evertime I got on it I saw 73-74% and that was reached in 2nd, 3rd or 4th gear. I also am able to reach higher percentages in the 4000-7000 rpm range. Where before I never saw over 60% until after 7000 rpm's for the most part.

I wish there was a way to show everyone how much fun this new setup is. It deffinately feels like a different car. Feels much faster and the spool is nuts. No watching the boost build on the boost gauge. The needle just flys to whatever I set it at. Sorry I keep posting but I can't express how happy I am with this new setup. Now I need to get to the track and see what I can do. I think this setup is the ultimate drag/drift/grip setup as it has power everywhere you need it for all kinds of racing.

Also found a GT3071R DET dyno (250 ft-lbs of torque by 3000 RPM is nuts):

[P-51]

From a 2.0L? Wow. It's not on boost yet at 3000, but it's pushing 340 ft-lbs at 3700! That is pretty impressive.

[Ted B]

Useful notes from a TS user:

- I'm presently using a T4 0.70 A/R TS PT67R on a 2.0L EVO. The previous configuration was a GT35R with 0.63 A/R open T3. Despite the larger turbo and the larger T4 TS hotside, there is no comparison in transient response. The open T3 feels dead as compared to the TS T4, despite the fact that the T4 makes the T3 look like a toy.

- If I were building a Duratec 2.3, I wouldn't bother going through the trouble and expense of TS unless I were using at least a GT 3076R. There's just not enough power in anything less to justify the expense (IMO). And where the GT 3076R is concerned, the 0.78 A/R TS T3 works very well. I might mention that there are two larger TS housings available in T3 configuration, including a 1.06 A/R monster that really wakes up a GT 3076R with minimum spool penalty. These are not off-the-shelf items, but are available.

- 90% of the difference TS makes is readily apparent in normal driving, and isn't something that can be measured by a dyno. Never again will I use an open housing, only TS for me from this point forward. But then again, I don't fiddle with small turbos any longer, and large turbos are where TS really shines.

I hope you all find this useful.

[d.bluefocus21]

all of that is really tempting, but how much would a setup like this cost on a Foci? zetec or duratec? would the cost for the power be worth it to convert from a normal turbo to a t.s.?

and if nobody does make a manifold for us, who would we have to go through to get this done? I do know the saying ya pay to play, but how much are we payin lol?

[yellowfocus]

Originally Posted by d.bluefocus21

all of that is really tempting, but how much would a setup like this cost on a Foci? zetec or duratec? would the cost for the power be worth it to convert from a normal turbo to a t.s.?

and if nobody does make a manifold for us, who would we have to go through to get this done? I do know the saying ya pay to play, but how much are we payin lol?

Well, from scratch, maybe just nominally more, since TS turbos are a tad more expensive than single scroll turbos. Also, an equal pulse header will need to be designed with a divided housing, which I plan to fabricate. To mate to the V-Band turbine housing, a new/modified downpipe will need to be fitted. Finally, an external wastegate is needed since very few twin scroll turbos use internal wastegates except for OEM (i.e. JDM STis and USDM EVOs). So not too much more. If this goes well for me, I will plan on offering TS manifolds to Zetec Foci people, so stay tuned in the coming months.....

[d.bluefocus21]

Originally Posted by yellowfocus

Well, from scratch, maybe just nominally more, since TS turbos are a tad more expensive than single scroll turbos. Also, an equal pulse header will need to be designed with a divided housing, which I plan to fabricate. To mate to the V-Band turbine housing, a new/modified downpipe will need to be fitted. Finally, an external wastegate is needed since very few twin scroll turbos use internal wastegates except for OEM (i.e. JDM STis and USDM EVOs). So not too much more. If this goes well for me, I will plan on offering TS manifolds to Zetec Foci people, so stay tuned in the coming months.....

well, depending on cost of it all, i'll be all for that once I get a built bottom end. As of right now my t3 super 60 does my stock svt bottom fine lol

BUT upgrades are always needed in the future, so yes, please keep us informed : )

[Ted B]

Originally Posted by d.bluefocus21

. . . would the cost for the power be worth it to convert from a normal turbo to a t.s.?

It is, especially when the turbo becomes large enough such that spool characteristics become an issue. 4-cyl engines benefit greatly from TS because there is so much time between exhaust pulses. One drive in a TS equipped setup, and you'd want to throw rocks at the old open T3.

In short, TS takes a turbo that's been demonstrated to deliver 500whp on 93 octane (PT67R) for a 2.0L EVO, and makes it nicely streetable. I see no reason why this should not translate comparably to a 2.3L Duratec. Or, for those who are intimidated by those numbers, a GT3071R with TS will knock your socks off where quick spool and midrange punch are concerned.

Originally Posted by yellowfocus

Finally, an external wastegate is needed...

Actually, two WG would normally be required for a TS setup. A single WG can be engineered into it, but it's a tricky proposition.

[d.bluefocus21]

Quote:
Originally Posted by
Ted B

"I see no reason why this should not translate comparably to a 2.3L Duratec"

what about the zetec? ; )

[yellowfocus]

The two wastegate idea is true: one for each collection of tubes, but as long as you have a 2-1 tube that has a divider in the middle to prevent the exhaust pulses from exiting into the other set of tubes before it gets to the wastegate. I'll try and find a pic of what I'm talking about....

[Ted B]

Originally Posted by d.bluefocus21

Quote:
Originally Posted by
Ted B

"I see no reason why this should not translate comparably to a 2.3L Duratec"

what about the zetec? ; )

I don't know the particulars of the 2.0L Zetec (bore/stroke/rod length/port flow data), but I can vouch with reasonable certainty that a G3076R with divided .78 A/R T3 hotside will make a properly equipped and tuned Zetec feel like a V8.

[Ted B]

Originally Posted by yellowfocus

The two wastegate idea is true: one for each collection of tubes, but as long as you have a 2-1 tube that has a divider in the middle to prevent the exhaust pulses from exiting into the other set of tubes before it gets to the wastegate. I'll try and find a pic of what I'm talking about....

No need to go searching for pics, the arrangement of which you speak is presently on my car (and works very well).

[d.bluefocus21]

that is a nice looking piece you have there : D

[yellowfocus]

Wow, that's a great piece! Is this on your EVO?