Tang divided turbo manifold

[uber95]

I was wondering if anyone makes/has made a tang divided header/manifold with the runners matched. The matching runners would help the exhaust pulses effect the turbine, and allow for faster spooling of a larger turbo. I didn't search as this may be an obscure prospect and I didn't think many folks really care, but I think it would really help. It has shown to make a real improvement on other engines.

[Yellow4g63]

you mean like the HKS mani?

[Sil240]

Isn't Tangential describe the exhaust housing?As opposed to on center exhaust housings?

[uber95]

Isn't Tangential describe the exhaust housing?As opposed to on center exhaust housings?

That is correct, but that is not what I asked.

There are basically two types of turbine housing configurations, tangential and on center. Tangential housings have the turbine inlet coming into the housing at a tangent to the turbine wheels. On center housings have the turbine inlet coming directly into the center of the turbine wheels axis. A tangential turbine housing is greatly more efficient as the gas path feeding the turbine has a straighter shot into the housing and a better impingement angle on the wheel. The gas entering an on center housing must go around a kink in the housing, which causes turbine efficiency to suffer by up to 10%. There are studies that show that a 2% gain in turbine efficiency can offset gains of up to 25% of the turbines inertia so a 10% loss in efficiency is quite significant. However the on center mounting can often give a bit of mounting flexibility to solve a difficult fit problem but because of the efficiency losses it is better to try to find almost any other solution to a packaging problem.

The above explains the differance between the two, the following describe what I want.

Another interesting aspect of turbine housing design is divided and undivided housings. A divided housing is exactly how it sounds, the scroll of the turbine housing is split in two. A savvy tuner can use a divided housing to his advantage on an engine with few numbers of cylinders. A divided housing works best on a 4-cylinder engine with some advantages on a 6 cylinder with a properly designed manifold. When a divided housing is used, usually cylinders 1 and 4 are fed into one side of the scroll and cylinders 2 and 3 are fed into the other side. The cylinders fed into each side of the scroll are as far apart in the firing order as possible. This allows the turbine to be hit with 4 distinct pulses as the engine goes through its firing order. This improves turbine efficiency, sometimes to the point where up to one size larger A/R housing with it’s attendant lower backpressure can be used, either that or less turbo lag can be enjoyed with the same size A/R housing. The divided housing can also improve volumetric efficiency by making reversion from adjacent in firing order cylinders much more difficult. This is because there is a great deal of separation in degrees of crankshaft rotation between the valve opening events of the adjacent cylinders. In order for a reversion pulse to contaminate an adjacent firing cylinder, it has to travel back through the spinning turbine blades and up the other side of the divided turbine-housing scroll to get to the adjacent cylinder. This is pretty difficult and the pulse will tend to take the path of least resistance, past the turbine to the area of lower pressure

I pirated the above from an online article as it is concise and I'm lazy!

Yellow4g63, is that manifold divided to pair cylinders, or just divided?

[jobestudios]

This stood out to me

Quote »However the on center mounting can often give a bit of mounting flexibility to solve a difficult fit problem but because of the efficiency losses it is better to try to find almost any other solution to a packaging problem. [/quote]Maybe in an R chassis, but S chassis is pretty tight no?

[uber95]

Turbo placement is almost always an issue in some form or other. I would opt for a smaller housing to aid in street driveability rather than big gains up top. That's just me.

[rbsileighty]

Turbo placement is almost always an issue in some form or other. I would opt for a smaller housing to aid in street driveability rather than big gains up top. That's just me.

It's all about area under the curve... which depending on your level of build and displacement can be done with smaller turbo or higher Redline (ie needing new manifolds, cams etc)

Packaging will be your biggest enemy for a manifold... which for an RB... were all designed to go in a Skyline that has no steering and brake master to deal with... so even if you find one... be careful... I'm making mine...

[uber95]

Lucky for me I have the ability and opportunity to experiment with some custom built turbos. My issue is finding a good header that will hopefully allow for the exhaust pulses to be optimized. Any "off the shelf" manifolds that can fit that bill? That HKS that's pictured above has the right style collector, looks like a T3 (maybe T4) flange. edited for spelling
Modified by uber95 at 12:04 PM 4/5/2007

[Darius]

I'm not understanding why the manifold you have pictured is any different than the stock manifold?

[Sil240]

Checkout this thread here:

http://forums2.nicoclub.com/sh...66545

Uber- if thats the HKS mani its a T4 Flange, I've heard that guys redrill the holes for a T3 or you can get and adapter too.

Darius- The manifold pictures is the HKS cast mani. (I think)Plus the manifold was divided unlike the stock mani where all the runners just go out through one hole.

[uber95]

Sil240, that link is busted.I'm not just interested in the tang division, I'm also shooting for paired cylinders for exhaust gas pulse "optimization"

[Sil240]

Ok for some reason everytime I try to post a link it changes to Nico.Go to Fresh alloy, in the GTR/GTS sectionThe title of the post is "Twin Scroll Turbo Setup Discussion"

How's that one.????

Tang Division???What is a Tang??I'm confused.

Do you want a Twin Scroll turbo setup?That's what it sounds like from your posts.Look at the pictures posted above.3 Cylinders goin into one outlet of the Exhaust mani and the other 3 go into the other. Each set of 3 runners has its own WG also.

The turbo has the divided exhaust housing in it.

[uber95]

Sorry for the confusion, tang division and tangential are essentially the same. The pairing of the cylinders needs to be done in such a way as to pair exhaust pulses. Firing order: 1-5-3-6-2-4, so when one cylinder is on the exhaust it's corresponding brethren is as well, enhancing the efficiency and making a little better use of the exhaust velocity.

What has been done with the header that you have pictured would be good if one was to have twin flanges with each having 3 cylinders mated to it and it's own turbo. What it looks like curently is a top mount design with twin wastegates.

[Darius]

The setup that Sil240 posted a pic of is exactly the way the stock manifold is designed except for the stocker is of a log design instead of the runners collecting at the turbo flange.

[Sil240]

Arggghhh!!!!!The two pictures above are a Twin Scroll setup. The turbine housing is Tangential and it is divided.

Take a look at this link here:http://www.turbobygarrett.com/....html

Figure that setup right there being a Twin Turbo setup but only ONE compressor.

It is setup EQUALLY 123 go to one side of the Turbine and 456 go to the other side.

I think what your trying to say is 153 to one side and 624 being on the other side of the turbine.That won't work.It'll spin one side of the turbine for the First half of the 720 (2 full revolutions) and then spin the other half of the turbine.

You don't want that.You want all the cylinders working together to spool the turbo quicker. Not taking turns at spooling the turbo.

Darius- the 1st manifold posted (not by me) is a HKS cast manifold.If you look closely then you will notice the manifold has a Divider in the middle.

[Darius]

Sorry man I thought that was your post for some reason

I totally see what you're saying now with the divided inlet to the turbo. I'm just a little slow some days.

Here's the stock manifold flange for the RB25.

[Sil240]

Its cool.I have my days and my Ex-gf blonde moments lol.

I never noticed that the RB25 manifold is divided. I assume the same for the 20.I haven't really looked at it.

[rbsileighty]

Arggghhh!!!!!The two pictures above are a Twin Scroll setup. The turbine housing is Tangential and it is divided.

Take a look at this link here:http://www.turbobygarrett.com/....html

It is setup EQUALLY 123 go to one side of the Turbine and 456 go to the other side.

I think what your trying to say is 153 to one side and 624 being on the other side of the turbine.That won't work.It'll spin one side of the turbine for the First half of the 720 (2 full revolutions) and then spin the other half of the turbine.

You don't want that.You want all the cylinders working together to spool the turbo quicker. Not taking turns at spooling the turbo.

I don't agree with your reason as to why that won't work. It would work ok except that it would cause unnessisary backpressure in each collector and most likely internal EGR

Arggghhh!!!!!The two pictures above are a Twin Scroll setup. The turbine housing is Tangential and it is divided.

Take a look at this link here:http://www.turbobygarrett.com/....html

Figure that setup right there being a Twin Turbo setup but only ONE compressor.

It is setup EQUALLY 123 go to one side of the Turbine and 456 go to the other side.

I think what your trying to say is 153 to one side and 624 being on the other side of the turbine.That won't work.It'll spin one side of the turbine for the First half of the 720 (2 full revolutions) and then spin the other half of the turbine.

You don't want that.You want all the cylinders working together to spool the turbo quicker. Not taking turns at spooling the turbo.

Darius- the 1st manifold posted (not by me) is a HKS cast manifold.If you look closely then you will notice the manifold has a Divider in the middle.

I don't fully agree with your logic. It would work in theory... and with very little difference I would think than the 123 456 setup, but the problem would be the potential of internal EGR caused by the higher backpressure caused in each collector since the cyls fire seq in each collector in the odd/even setup. The 123 456 setup is better due to alternating pulses in each collector... best of both... no internal EGR and better spool on a divided housing.