Based on that comment alone, their test isn't valid. You don't run the same AR between a Vband and twinscroll housing. On a 6466 for example, you would run a .82 Vband housing, or a 1.15 twin scroll.

I'm not saying twin scroll isn't better, but modern Vband turbine housings are very good. And again, smaller turbos aren't even offered in twin scroll. And, even boost threshold may be close on say a twin scroll gen2 6266 vs a Vband gen2 5558, the smaller turbo will have better transient response above the boost threshold rpm.

The turbo should be seized for the power goals based on the fuel your going to run, and then an appropriate turbine housing for that turbo should be selected.

Side note, ATP makes a twins scroll turbine housing for the Garrett 30r.

 

@spdracerut do you recall a discussion on sizing the ts housings and whether the corrected math used volute area instead of using the total area including divider? I cant find that thread.

@letsgetthisdone the new improved ni-resist, geometry ts housings are really nice too..

I cant see invalidating results because of a "rule of thumb". Infact taking the test results as they appear is probably the best course.

 

But the test isn't properly done. Sooo.... the results suck.

 

You're canning a test that illustrates the differences. You yourself even know that the difference is there. I know the fudge factor exists but I'm not going to can a test that makes a direct comparison. Scaled up the TS stil makes better power left of peak with a larger ar than ss.

The test clearly demonstrates that twin scroll makes better response and equivalent power. Where did they not show this? They compared it to a same size ss housing.

To me this is relative to the OP because it can help a max effort pump gas car not be on the edge to make the target power and or response.

Does the OP even have reliable e85 pumps?

We are losing 93 to 90.

 

OP didn't specify available fuel. I would not try to make more than 480, 500 at MOST on a stock motor on pump gas. Your just asking for it at that point.

And yes, in the same turbo, twin scroll is better; If there's an available twin scroll housing with a useable AR. But not very turbo has an available twin scroll housing.

 

The Garrett v-band single scroll and T3/v-band twin-scroll housings have the same A/Rs, but the twin-scroll housings have more cross-sectional area at a larger radius. So bigger A over larger R, hence same A/R but different cross-sectional flow areas.

The interesting bit is comparing the old T3 flanged single scroll 0.82 with the v-band 0.83 A/R. They have basically the same corrected turbine flow and curves, but the v-band housing has a significantly larger flow cross-sectional area IIRC. It's been a while... like 10 years.

Picture of cross sections of the v-band and T3 twin-scroll:


Old T3 flanged

 

RS Motors has the worst customer service ever. I'd stay away.