Which Twin Scroll Turbo for a 930

[b930]

I use a GT35 with a 1.06 twin scroll hot side on a T4 flange, fits the bill for me with full boost a 3000rpm, zero boost creeps or spikes with the twin gated headers and a screaming top end. Need to get it to a dyno to see what its doing but it feels extremely strong.

Twin Scroll 1.06 A/R GT35 and dual gated Rarlyl8 headers

[WERK I]

Sorry to be a skeptic here guys, but some of these numbers are blowing me away. I think I'm missing part of the story. Will you report what work has been done to the heads as part of your signatures? Are you using 3.2 heads, SC heads, ported the 930 heads to SC or 3.2 specs?

Thanks

[1979-930]

Brian,

What was the outcome of this search? Was the Garrett GT3582R the answer?

Originally Posted by RarlyL8

Thank you for you inputs.
This is a specifc application and the build parameters are set in stone:
> CIS
> Oil only cooling - no water
> 400WHP max at 1.0bar, 6500rpm redline.
> T3 or T4
> Twin Scoll devided housing turbo
Goal is to find the widest powerband twin scroll turbo that will support 400WHP.
I took a look at the CompTurbo website but see no information on sizing for application or any specific range of operation data. May have missed that page.

[David]

What's the latest on twin scroll?

I'm thinking of replacing my B&B turbo headers with something new and changing my GT3582R turbo housing to a twin scroll and having the exhaust built to match.

[TurboKraft]

Do you need/want heat exchangers?

[RarlyL8]

Old thread, much has evolved sense that time!
The split plenum design was incorporate into our headers back then and is still present today. T3, T4, V-band inlets available. Heat exchangers are optional as are T3, T4 or v-band flanges and twin waste gates.
There are a dizzying amount of turbo options on the market now-days. You can have a twin volute turbo built to your specifications and our headers designed to match.

[David]

I'd like heat exchangers and be able to reuse my GT3582R turbo and Tial 46mm wastegate.

I was figuring I'd call Brian about his headers but wanted to post here for more ideas.

[Beetspeed]

Originally Posted by RarlyL8

The header design of this is awesome!, but that wastegate design destroys the effect of twinscoll.

You can use a single wastegate but only if you run a divider wall all the way up to the wastegate valve head. That doesn't seem to be the case here.

Much and much better is just using two smaller wastegates for each scroll. Then the scrolls stay seperate as intended by the concept of twin scroll.

[RarlyL8]

The wasted flow has no affect on the flow of each bank to the turbo. When the waste gate is closed each bank feeds one side of the inlet housing while the waste gate circuit remains pressurized. When the waste gate opens the excess flow mixes during exit but the main flow still feeds each side of the inlet housing.
Dual waste gates offer a quicker theoretical response due to a shorter path. Feedback from track car owners is that this allows a touch better control in the corners.

[Beetspeed]

. When the waste gate is closed each bank feeds one side of the inlet housing while the waste gate circuit remains pressurized.

No, when the gate is closed, you have created a pressure path from one scroll to another with the Y-part. The twinscroll effect is thereby gone and that costs spool and thus some power down low.

If you really want one gate with a twinscroll turbine, just keep a divider wall all the way to the gate head, so scrolls can’t mix.
I am sure you know this 😉

Feedback from track car owners is that this allows a touch better control in the corners.

Thats probably because they now have less power/torque in the corner because RPM is usually lower there.

[/QUOTE]
See, thats the way to keep the scolls seperated. 👍👍

[RarlyL8]

In theory yes in practical application it's difficult to tell.
It's tough to tell a difference on the street or see any significant difference on a dyno. The racer feedback is that the twins open a touch more crisply which allows them better control exiting corners. There is no data indicating reduced or increased power due to waste gate configuration on stockish engines. Heavily modified is a different story with many variables. The tuned primaries and equal length secondaries produce more torque at lower RPM and off boost than non-tuned systems which may be why we don't see the marked difference that might exist in non-tuned systems. Packaging with one waste gate allows the stock location to be retained while being able to take advantage of the other aspects of the system. If that is not an issue then twin wastegates are an option.