Has anyone done a direct divided versus undivided manifold comparison on a 13B?
Thread Starter
Senior Member
Joined: Jul 2009
Posts: 377
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From: England
I still cant see from those 2 pics how the gasses can be even close to be completely blocked from going in to one of the two scrolls.
Is there a third bit we cant see in the pics?
And do you know the specs of the S4 vs S5 hot sides?
Is there a third bit we cant see in the pics?
And do you know the specs of the S4 vs S5 hot sides?
I don't have an s4 turbo manifold in my possession. But from the classifieds section:
The twin scroll valve is normally open. You can see the flapper open here. When the engine is on, manifold vacuum is applied through the twin scroll solenoid and check valve to close the flapper. In terms of the control system, this is very similar to the way the charge control valve and solenoid work on the FD. At 2800 rpm the solenoid turns off, vacuum releases and the door opens to allow exhaust into both the small and large passageways.
s4 on the right
According Bryan of BNR, the specs on the HT18S-2S s4 and s5 wheels:
Turbine major: 2.51" 63.75 mm
Turbine exducer: 2.15" 54.61 mm
Compressor inducer: 1.72" 43.68 mm
Compressor exducer: 2.48" 63 mm (48 trim)
On the compressor side, the closest size wheels would be like a GT22 or a T3 50 trim. This engine made 182bhp at 5.5psi (s4) and 200bhp at 8psi (s5).
As for the turbine housing A/R, well it depends who you ask and how they are doing the measurement. One school of thought says that the s4 turbine housing has the small passageway with a .4 A/R scroll and a .6 A/R scroll, while the s5 turbine housing has two passages with .5 A/R . But remember that A/R is a ratio and you can't really compare that directly to A/R on a T4 frame turbo.
The twin scroll valve is normally open. You can see the flapper open here. When the engine is on, manifold vacuum is applied through the twin scroll solenoid and check valve to close the flapper. In terms of the control system, this is very similar to the way the charge control valve and solenoid work on the FD. At 2800 rpm the solenoid turns off, vacuum releases and the door opens to allow exhaust into both the small and large passageways.
s4 on the rightAccording Bryan of BNR, the specs on the HT18S-2S s4 and s5 wheels:
Turbine major: 2.51" 63.75 mm
Turbine exducer: 2.15" 54.61 mm
Compressor inducer: 1.72" 43.68 mm
Compressor exducer: 2.48" 63 mm (48 trim)
On the compressor side, the closest size wheels would be like a GT22 or a T3 50 trim. This engine made 182bhp at 5.5psi (s4) and 200bhp at 8psi (s5).
As for the turbine housing A/R, well it depends who you ask and how they are doing the measurement. One school of thought says that the s4 turbine housing has the small passageway with a .4 A/R scroll and a .6 A/R scroll, while the s5 turbine housing has two passages with .5 A/R . But remember that A/R is a ratio and you can't really compare that directly to A/R on a T4 frame turbo.
Thread Starter
Senior Member
Joined: Jul 2009
Posts: 377
Likes: 2
From: England
Maybe (ok, highly likely) I'm being a retard, but looking at the manifold pic, I cant see how that totally blocks off one of the two scrolls on that S4 setup?
It would need some kind of large throttle style flap to close the scroll off from both exhaust ports, but it doesnt seem to have anything at all there?
It would need some kind of large throttle style flap to close the scroll off from both exhaust ports, but it doesnt seem to have anything at all there?
Joined: May 2005
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From: North Bay, Ontario
If you look at the first picture Arghx posted, you'll see inside the flange, manifold side, an actuator with a flapper. This is used to close off the smaller runner on the turbine housing, as shown on the right housing of the last picture.
