Originally Posted by ctdrftna (Post 449530)

im kinda pissed i didnt look into twin scrolls, when i bought my turbo(3071r), they just wernt as popular with the tunner scene 2 years ago, now twin scroll housings are everywhere. i woulda had my manifold built for twin scroll and had a sick setup

Originally Posted by sixshooter (Post 449645)

Twin scrolls do it sooner. Spool that is. And you should look into the new hot thing -quick spool valves for twin scrolls- if you've got money and really hate to wait for spool.

http://www.spracingonline.com/images/products/3659.jpg

Originally Posted by Midtenn (Post 449303)

There was a huge post over on MR2OC a few months ago about the benefits of twin scroll on a 4 cylinder. The general consensus was that there is very little to be gained because the exhaust pulses are just to far apart.

Originally Posted by Sam Amporful (Post 449734)

why do people think a small single turbo would have much lag. If you're worried about spool and lag just run a gt2554. Its not like its a vette and you cruise at like 1500-2000rpms. most likely you will already be in your "good spool" range while just driving around

Originally Posted by TurboTim (Post 449647)

Hmm that actually makes a lot of fun sense. Closing off one "scroll" effectively makes the turbine much smaller, greatly helping spool. You'd need a non-twin-scroll manifold however, but that's easy & more common anyway.

What's the smallest twin scroll turbo?

Originally Posted by Jike Spingleton (Post 449724)

Subaru, Mitsubishi, and Porsche must not read MR2OC.

Originally Posted by ATS Scott

Bruce, I now have an answer for you. But first a quick summary of set-up…
Oh and for those folks that have not read the whole thread:
SS=Single scroll
TS=Twin scroll

Both set-ups are re-routed, with 3" DP's. The SS was a .63 A/R exhaust housing, and a SS ATS adapter, and the TS was the .78 A/R with Divided adapter. Everything else remained the same. I used my EVC5 Boost controller, and used the peak hold feature for consistancy. I was shooting for 17 psi on all runs, as that is what I run on the street with 93 octane. All runs were done on 93 octane. One thing I noticed immediately, was the SS required lower settings on the BC to make 17.3 psi, where the TS needed higher settings to make 17.2 psi. That was the first clue. I got it tuned for just under 12.0:1 A/F and managed a 395 rwhp run. Dangerously Lean made more power (413 rwhp)

Next up was swapping back to my TS set-up and attempting to duplicate the results. This is as close as I could get. TS is run 58, SS is run 19:

http://www.atsracing.net//dyno%20run...01.2%20bar.jpg

I wanted to see if dangerously lean would pick up the power of the TS, it did, but nothing like the SS. TS is run 54, SS is run 16.

http://www.atsracing.net//dyno%20run...bar%20LEAN.jpg

From my datalogs, the SS consistantly hit 1.0bar boost at 3900 RPM, and the TS at 4000 RPM, even though the TS was beating the SS to 200 ft/lb by 100 RPM. (3400 vs 3500 RPM) at the 3400 RPM mark the SS was consistently ahead at .6 bar vs the TS at .5 bar. So the SS was building boost faster than the TS, but the TS was still spooling slightly faster. After 4400 RPM the TS just falls behind.

So Bruce, I say TS advantages are a myth on a GT30 turbo. This makes me want to ditch my TS set-up...