discussion: divided housing turbine housings.

[euroford]

As I understand it, twin scroll turbine housings are designed to pair exhaust gas pulses to make the most effective use of the exhaust energy and eliminate lag. This requires header design to properly pair cylinders to each side of the divided housing and can be extremely effective, especially on smaller four cylinder motors spooling large chargers.

Our engines in factory configuration and most aftermarket setups use divided turbine housings. However they are fed by log type manifolds or aftermarket headers that do not time exhaust pulses and are then routed through up pipes that feed the turbine from each half of the motor.

This doesn't utilize the advantages of a divided housing in any way whatsoever. given the packaging challenges of a properly timed and paired twin scroll system, i'm not surprised that this would be value engineered out, but it still baffles me that we utilize a twin scroll housing in the first place.

heck, i'd almost reckon that you'd see a minor performance increase by porting out the divided portion of the uppipe collector and removing some of the divider from a stock housing, or going with a non-divided aftermarket housing. at the very least this might help create more equal backpressure between each side of the motor and make the factory wastegate more effective.

i'm just curious about our forums thoughts. maybe all i said above is correct, but it just doesn't matter when you have 7.3 liter's spooling yer stuff up.

here's a pretty good post from the lsx forums regarding twin scroll:

https://ls1tech.com/forums/forced-induction/1461494-lsx-twinscroll-turbo-design-analysis.html

 

[Swaan]

You are correct ........ too a point.
The only engine you can do what your saying is a 4 cylinder. As you only have 2 cilinders that the exaust header pipes weld into a divided t4 or t3 flange.
And this does help tremendously for response over a open housing. But as you get into 6 and 8 cylinder applications you simply can't merge every single pipe at the collector flange. The only way you can do it with a 6 or 8 cylinder is run 2 turbos. One one each bank with 3 or 4 individual pipes feeding them.

Having said all that , diesels being inline 6 or v8 will have a log style manifold. They still benefit from a divided housing more then you think. Your still getting 4 seperate exaust pulses feeding half your turbine housing. Still better then all 8 feeding the whole open turbine housing.

Ive tested both types ex housings on big cats and detroit diesels and the divided housing still makes a huge diffrence on response and spool up over the open type.
Even get more boost at lower rpm on the jake brake.

 

[Garbage_Mechanic]

"Ive tested both types ex housings on big cats and detroit diesels and the divided housing still makes a huge diffrence on response and spool up over the open type.Even get more boost at lower rpm on the jake brake."

I remember when the pulse manifolds and divided housing higher performance turbos first came out for the Cummins Big Cam 855 cu in engine. Huge difference over the ancient t-50 style turbos. But i also recall having to made mods to the Jake's so they wouldn't over boost on Jake...

Yep divided housing is the way to go if you are looking for driveability.

I've often wondered why the valve system that directs all flow through one side of the scroll isn't more popular. It way even made for the 7.3 for a while.

 

[euroford]

So what i'm gathering here is that even when an exhaust system is not optimized (pretty much impossible on a v8!) to take full advantage of a twin scroll housing, it tends be beneficial anyways and provide quicker spool vs. non-divided housings.

I'm surprised i haven't seen one for the cummins guys. obviously it can be done on an inline six, below is a twin scroll header for a 2jz.

 

[johnp115]

I'm surprised i haven't seen one for the cummins guys. obviously it can be done on an inline six, below is a twin scroll header for a 2jz

I agree.

 

[gnxtc2]

Whoever designed this header doesn't know anything about wastegate plumbing.

Billy T.
[email protected]

 

[Jonnydime]

I'm surprised i haven't seen one for the cummins guys. obviously it can be done on an inline six, below is a twin scroll header for a 2jz.

There are a ton of manifolds like that out there for a Cummings.