What will flow more in a twin setup?

[Extended Power]

Using a 68mm exhaust wheel on the secondary:

First housing is a .70 T3 tall port with internal wastegate ports.
Second housing is a .83 T4 non gated housing.

Using a 40mm external gate in the exhaust manifold headers off the engine...dumping to atmosphere on both set ups.

Only difference is the secondary exhaust housings.

Looking for a more powerful setup...

 

[Headcase98002]

If I remember right, a non-gated housing will flow more than a gated housing of the same size. Since you have external gates, I'd throw the .83 on.

 

[Big Blue24]

If the internal gates are functional/functioning/open, the .70 housing will flow more.

 

[Extended Power]

If I remember right, a non-gated housing will flow more than a gated housing of the same size. Since you have external gates, I'd throw the .83 on.

I am currently running the T4 x .83 housing. It "feels" stronger than the T3 x .70 gated housing, as it breaks the tires loose at 50 mph now instead of 40.

If the internal gates are functional/functioning/open, the .70 housing will flow more.

This is way I'm going to throw it back on and see.
As of right now, the external gate dumps to the atmosphere at anything about 70psi drive pressure in the manifolds.
I think that by using the smaller housing with the internal gates working at a set pressure of about 30psi, the internal gates will help spool the primary harder, and the external gate will still dump anything above 70psi. (Or whatever I set it to.)

Some things I have noticed:
-with the .70 housing, if drive pressure was a 10psi, then the primary had 5 psi drive to it.
-now with the .83 T4 housing...with 10 psi drive, there is only about 2, maybe 3psi drive to the primary.

Maybe I should tie the external 40mm gate back into the feed to the primary, to help drive it harder.

Thoughts?

 

[Extended Power]

Actually...I think I will throw the T3 x .70 back on...use it's internal gates to help drive the primary harder, and still use the external 40mm dumping to the atmosphere...should get even quicker spool up, better midrange/cruising boost, and drive the primary a little bit harder too.
It just looks so nice right now...no leaks...and I really don't wanna try welding the external gate into the hotpipe just yet!

 

[cummins939]

Do you think it's breaking loose later because its spooling slower? And power should more linear with a smaller housing?

 

[NickTF]

There are .83 a/r internally gated t4 housings as well. They only gate one volute but I'm fairly confident the gating provides a worthy additional source of flow.

 

[Extended Power]

Do you think it's breaking loose later because its spooling slower? And power should more linear with a smaller housing?

It may be.
I'm not getting as much pressure out of the primary now, but it's compounding more now.
For examples with the T3 x .70 housing, internal gates disabled:
Before, drive to secondary was over 100psi
Before, drive to primary was about 50psi
Before, boost from primary was about 30-33psi
Before, overall boost to manifold was 60-65psi.
Before, external gate was plumbed into hot pipe, in front of primary. Set at 65psi from a spring combination.

Now with the T4 x .83 non-gated housing:
Now, drive to secondary is over 100psi
Now, drive to primary is about 30psi
Now, boost from primary is about 20-22psi
Now, overall boost to manifold is 60-65psi
Now, external gate is plumbed to atmosphere, set at 65psi with boost controller. Also, tied into both up pipes for excellent priority.

I'd like to try the .70 housing again, and use the internal gates to help drive the primary harder. The boost controller should still easily control the drive pressure to whatever it's set at.

To throw another curve into the mix...the "before" examples were done with a 63mm over a 80mm turbo configuration.
The "Now" examples were done with a 66mm over a 84mm.

 

[Extended Power]

There are .83 a/r internally gated t4 housings as well. They only gate one volute but I'm fairly confident the gating provides a worthy additional source of flow.

Are these the ones people talk about "cross-drilling" them?

Do you have a link?

 

[Lostnwalmart]

Good luck ballancing an internal and external gate to work together. ...

 

[cummins939]

I know of someone running an he351 and s480 combo, he was seeing low overall numbers and only got a little better 55psi or so with enough fuel for 700 but I really think the little guy is choking it out. Makes me think you might be at your potential with the 68 turbine.. Have you dynoed your truck?
Sounds like the setup is a little more on point with the t4 housing

 

[Extended Power]

I know of someone running an he351 and s480 combo, he was seeing low overall numbers and only got a little better 55psi or so with enough fuel for 700 but I really think the little guy is choking it out. Makes me think you might be at your potential with the 68 turbine.. Have you dynoed your truck?
Sounds like the setup is a little more on point with the t4 housing

Dynoed the truck last year with the 63/70 over 480: 793rwhp, back up with a 12.2@113.06mph 1/4 mile @ 7850 Lbs

Dynoed the 66/.83 over 84mm, but they could not load the truck past 35psi boost. Did 677rwhp @ 35psi total boost. Could not back it up, as the track was rained out on Friday night, Saturday was the dyno and racing, I chose to dyno it, as I don't have one close by where I live, but do have a track that is open when I'm always at work. (So it seems.)

 

[Extended Power]

Good luck ballancing an internal and external gate to work together. ...

I dont think it will be a problem.
I still have too much drive pressure with the 40mm gate dumping to the atmosphere. (Which is controlled by a AMS-1000) If the internal gates can help relieve some more, then maybe it can start to actually control the drive pressure. Right now...a single 40mm gate isn't big enough.

 

[cummins939]

I was just reading another guy made 877 with a 60/68/.91 and cast 480/96/1.32 you should have some room to grow. Are you running dual cp3s? Cummins swap correct?

 

[Extended Power]

I was just reading another guy made 877 with a 60/68/.91 and cast 480/96/1.32 you should have some room to grow. Are you running dual cp3s? Cummins swap correct?

Negative Ghostrider......just a 'lil 'ol 6.0LLOL

I really think by swapping out the .83 housing to the .70, it will drive the primary harder...it has some small cracks starting on the inside, but I was told that the T4 .83 would flow about 20% more, and to dump to the atmosphere instead of the hotpipe.

 

[Extended Power]

Sent a PM to T$ asking for a price on a couple of new housings/turbos.
Sent an email to HHT for a price on one of their stainless steel 13 housings.

 

[BIGRPOWR]

you wanna drive the atmosphere hard. you wanna loosen the hp exhaust side to the edge of what you feel is still driveable to your needs. externally gate in between stages and gate overall .

 

[Extended Power]

you wanna drive the atmosphere hard. you wanna loosen the hp exhaust side to the edge of what you feel is still driveable to your needs. externally gate in between stages and gate overall .

Yeah that would be the ticket for sure.
Only right now, I need a bigger gate anyways, but theres not enough room for it...so just trying to cheat it as much as I can before having to cut everything up again.
Thats why I may have to step back to the T3 housing, and use it's internal gates to help drop the drive pressure more, and drive the primary harder than it is now.

The warm season is just too damn short.

 

[Extended Power]

Is there any truth to what I was told about the 68mm turbine wheel flowing more than the 71mm wheel?
The 68mm being the "J" cup style.
Looking at a 64/71/13 with a stainless steel housing...

I have already tried a 66/73/80, and it was a slug.

 

[NickTF]

Are these the ones people talk about "cross-drilling" them?

Do you have a link?

No clue about cross drilling.

If you do a search under my name and fmw 62 dt466 etc. you should be able to turn up a link to the factory replacement turbo which is my secondary and is equipped with this housing.