There should be no positive or negative effects of running the divided housing on a non-divided manifold. The center divided should not cause any major issues or degradation in turbine efficiency.

 

I have found the exact opposite. I build turbo manifolds for a living, and have seen as much as 76rwhp and 1000rpm faster spool from a turbo 6 cylinder running mid 9's(i'm in australia, not US) and the car picked up 7mph and 6/10's at the track by changing nothing on the car ther than a split housing on an open manifold to a open housing.

I have also just finished building a manifold for a local drag car(RB30-3litre nissan single cam) that picked yp 6-800rpm of spool, and they have a turbo tach(sensor to measure shaft RPM) and with there open manifold and split housing they were seeing turbo shaft speed of 2000-2500rpm at 1200rpm idle, which has now increased to 5500-6000rpm at 1200rpm idle. I'd stay right the hell away from a split turbine on an open manifold!!!


Cheers..................................6BOOST

 

6boost. Well, I ask this as I cannot find a open housing for a GT4276R turbo on the 1.01 A/R.

 

6Boost ......Can you Post a pic of one of your manifolds...?

 

if divided flange is so bad, then why are FR mani's divided?

 

I'd like to see proof of 6-800rpm better spool and big power gains from switching to divided mani's and turbos....

 

This is a test Full-Race did. It was on an SR20DET

The solid line is with the twinscroll 3071R, the dotted line is with the singlescroll 3076R. There is about a 20whp/wtq gain by 2000rpm, a 30whp/wtq gain by 3000rpm, and a 100whp/wtq gain by 4000rpm. It makes 200 ft lbs @ 3600 rpm, 200hp at 4100 rpm, 400ftlbs at 4600 rpm and 400hp at 5400rpm

Even with the Honda's. With a good design divided collector exhaust manifold (Full-Race, Neukin) they're making full boost quicker than similar open collector exhaust manifold setups. GT42R's making full boost by 5800RPM when other's are making it at 6500RPM. I personally have no back to back data

 

That looks like more of a power band shift instead of gains. I wonder how a divided manifold would perform with larger turbos with larger turbine housings and how it affects the top end.

 

when you pair a properly designed twinscroll manifold with an optimized twinscroll turbo, you can run huge turbine housings and still have great spool. If you ran an A/R that was this big on a undivided setup it would laggggg.

Sertan gets 30 psi by 5000 rpm on an 80mm turbo and he is using a 1.28 A/R.

If you are planning on using that 1.01 on your turbo, it wont allow you to get the spool you want (becuase the housing is too big for low rpm) and it is too small of a turbine housing to get the top end power you want (because the housing is too small for high rpm).

 

We've all seen the FR stuff and 4 cylinder claims. I'd like to see something on a 6 cylinder car mainly a SUPRA since this discussion pertains to Toyota Supras.

 

I agree. I was just posting the only public comparison I have seen

 

ask supraforums user 'Furi' what he thinks of our twinscroll turbo setups. He sees 30 psi by 5000rpm on a 3.0L with a gt4508R on our manifold. Thats probably the reason he sent me an email asking for two more twinscroll setups this morning

 

imo, they are the most beautiful and best designed single scroll turbine housings most anyone has ever seen (including competing turbo mfgers). Unfortunatley, they are single scroll so other than the convenience of a vband, eliminating the possibility of nuts/bolts loosening and providing slight performance increases, they still wont be able to touch the potential of a twinscroll single turbo (unless you go twins with 2 tial turbos..)

 

I will add to my previous comment and clarify that I have no problems with wither split or single entry manifolds as such, or turbochargers for that matter. The simple fact is that you should not run a split turbine on an open manifold. You can run open/open, split/split, or even a split manifold with an open housing is fine. When you run a split turbine on an open collector, gas flow, especially when hot and turbulent doesn't divide evenly, or calmly into the split housing when its swirling around in an open collector, and we have done some testing with a fog machine on the flow bench and perspex on the side of the collector to watch through, put simply, your loosing power, and spool.


For the whole split V single manifold debate, I personally have found little difference on anything up to a GT42R turbocharger. Wehave a few customers with stock internal 2J's that make full boost at 4800-4900rpm with a GT4276 and are using the T6 footprint 1.01 rear housing. With the smaller T4 footprint housing this would probably drop another 100rpm. I haven't done any back to back testing with an open manifold on this big a turbocharger, but with smaller T66 style turbo's and my 6 into 1 merge collector, we have seen the same spool rpm and more top end power from using a single entry design over a split pulse setup.

I will say however that Geoff at full race builds both types of manifolds, single and split, and has nothing to gain it telling you that one works better than the other, so if his testing has led to those findings, rather than question it, possibly ask yourself why he would make that statement when he could easily suppy you with either.........

Cheers..............................6BOOST

 

the question that needs to be asked is WHY did Full-race use a divided setup instead of an open. What are the dynamics behind it.

 

As far as I am aware, and judging by looking at their website, they make single entry and divided yeah?? So where is the question as to why they use divided?? They use both???

6BOOST

 

we make both, and split are a hell of a lot more work!!!

 

My Holset HX35 had a split scroll housing, and it was going on my 2.3 turbo Mustang and if you didnt cut out the divider you wold have serious boost control issues

 

i dont think cutting out the divider was the right solution. you are just changing turbine efficiency to get the boost you want..the best way is to increase the amount of gasses that can bypass the turbine. a bigger wastegate (or 2 small ones) would work

 

for our 2.3 engines it causes serious boost problems so you have to cut it out, it has to do with motor size tho

 

I am just wondering when will there be a twin scroll T6 Exhaust Housing available to take advantage of this great technology???

 

they are out there... sort of

 

i agree backpressure is important!

 

In australia T6 split housings if anything are common place, although over here, we don't have many companies like precision and turbonetics, 85% of our aftermarket performance turbochargers are from garrett. We have most of the turbo's that you guys have in terms of the garrett range, right up to the GT4788, and while I've noticed that the big trend in the use is T67 style turbo's over here the biggest selling turbo all round would have to be the garrett 3582R, or often known as the GT35.

After my long ramble, my point I was getting to was that all turbo's from GT40 upwards have split rear housings, I've never even seen a single entry rear housing on a GT42, 45, 47 and so forth. If you wanted one, it wouldn't be hard to get hold of, just contact someone like MTQ engine systems or GCG turbochargers and buy one brand spankers off the shelf, with the exchange rate it would cost you about $350. There are definately T6 split housings, I have used several.

Do you mean you find back pressure important Geoff or lack of back pressure important?? As I have found, depending on engine size and hp output, that you can expect anywhere from 3-6hp gain per psi of back pressure dropped in the exhaust manifold pre turbo.

6BOOST