As title really, ie using the same turbo and ideally a virtually identical manifold.

Doesnt have to be "perfectly" divided (ie inc wastegate take-off), but still.

I just wondered what the difference in spool REALLY is? Theory and reality can be very different

My current setup is T4 divided (but with a single wastegate split between the two pipes) but really wondered (out of interest for the future really) what difference it would be if it was an undivided manifold or turbo.

If any direct comparison testing has been done, please show me a link as TBH ive never seen any

Thanks

 

An undivided manifold and divided turbine housing is not a good match. I would like to see someone test a divided manifold/turbine vs the same turbine and undivided setup.

Sean, can you make it happen??

 

Yeah thats what id like to see. I can deffo see the divided manifold helping, of course, but how much is what ive always wondered.

TBH id love to see someone test a divided manifold versus a non divided using one of those (overpriced!) SP quickspool valves too. That's probably the ultimate test with regard to spoolup.

 

I think the general question is excellent. Divided vs undivided on a 13b in reality.

I too have read the exhaust pulse science and am fascinated.

FYI my stuff is all aspec divided mani and exhaust housing on stock ports. I'll limp the car to aspec for tuning soon. I would love to compare. Even on my car.

That would require oil return line removal... On second thought. Maybe not. hahah

 

Wow you guys read my mind, today I was just thinking I seriously need to do a comparison of different housings and different wheels all on the same car so nothing else changes. Time is the biggest issue. I have too much on my plate already.

~S~

 

I've done it--maybe not scientifically, but I've done it and I can speak about it anecdotally.

Started out with an FC HKS cast log manifold, undivided. P trim .96 hotside, 60-1 compressor.

Switched to a Feed divided stainless manifold. P trim 1.00 hotside, T04R compressor.

Spool was still better even though it was a bigger turbo. Flooring it from 2500rpm (something you would do on a dyno) wasn't that much different. Where I really noticed it was in 5th gear, where I could build boost more easily. In between shifts was better as well. Or if I have it tached up to 5k on some back road, the boost will hit quicker. It's a noticeable improvement but you still have to match the turbo to the engine properly. A dyno or some datalog doesn't really show it well. You have to drive the car to feel the difference.

There's a reason why Mitsubishi switched to a divided housing and manifold on the Evo IV. There's a reason why Subaru uses a divided housing and manifold on the EJ207 JDM STi engines. There's a reason why Mazda switched to a divided housing and manifold from the Turbo I (12a T) to the Turbo II (13B T, series 4 and series 5). Subaru is now using twin scroll setups on the 2010 Legacy GT. BMW has switched from twin turbos in the N54 engine (335 etc) to a single twin scroll turbo in the upcoming N55 engine. It's a proven design.

 

but, to be fair, the HKS log isn't the best of manifolds, and even a properly built tubular un-divided manifold may have performed better. I have a divided manifold and undivided housing ATM, and plan on running it and switching out to a divided housing shortly after to see if there is any noticeable difference in spool.

 

no it's not the best of manifolds. in fact, it sucks considering the other stuff out there. But many people running undivided setups have FC Greddy or HKS log manifolds, so it's still a valid comparison. Or they have tial vband setups, which is a little different.

another thing I noticed when I had the HKS undivided setup... say I wanted to floor it on the highway from 70mph. with the undivided setup, putting it in 3rd was a bad call because by the time it got near peak boost I was getting close to redline and would have to shift again. So I would put it in 4th. It would still lug for a bit but once it got into boost I didn't have to worry about the shifting problem.

When I switched to divided, I can put it in 3rd and drop the hammer and the boost will hit pretty quick. It's not instant top end power like my old nonturbo setup, but it's far more useable.

 

The point of this thread is all things equal though, and that's what I'm hoping to test using the same manifold, but different turbine housings. I'd love to run a TiAl setup at some point, but I'm also stuck on the train of thought that the divided exhaust pulses are better for spool, etc. Hopefully someone can do some real-world testing on say a 35R, completely undivided, divided T4, then V-Band TiAl style.

 

Yeah, what has been brought up is the problem, there are plenty of undivided log to divided tubular comparisons, and thats certainly better, but is the effect biggest due to the divided, or the general design? Too many variables to be sure.

I've no doubt in my mind a divided one is best, and the exact reason people (OEM or tuners) run divided housings, but just wondered, compared to an otherwise equally well designed undivided one, how much of a difference it actually is.

 

Overpriced? and your from england? um yeah there's this thing called exchange rate...($250) or 167 pounds for this one.http://performancemetalwerkz.com/Sales.html

 

From what I understand, Performance Metal Werks have gone out of business and took some peoples money with them

Shame as their quickspools are well made and work well.

Dont know anyone but SP selling them at moment, and they crazy money really.

 

What!! when did this happen and why is their website still in operation?

Is this true or hearsay?

 

Have a hunt around on LS1Tech, various mentions there on a couple of threads.
Hope im wrong, but thats what it seems like from reading there.

 

I was just about to mention the quick spool valve that SP makes. Apparently the supra boys are starting to get into that...you know since they love using ridiculously laggy turbos to get the ultimate HP numbers. Here is a vid of it http://www.youtube.com/watch?v=I6ZCOTFET6s. It makes a huge difference, makes me wonder how much of a difference it would have on a rotary setup.

 

damn! Interesting

 

It was the main reason for this thread TBH.

Whats the most effective, twin scroll, or that.

On a piston engine I always say the quick spool from what ive seen.

But on twin rotors, well im not sure, does each rotor having its very own exhaust path make a massive difference in comparison to a good twin scroll setup on a piston engine? Ive no idea.

 

The Quickspool valves work well, thats for sure. The one thing that has never been tested has me concerned, the heat buildup on the turbine housing/manifold when driving for extended periods of time(road racing, for example).

 

I've swapped a .96 undivided to a 1.00 divided housing on a 57 trim to4E. Boost response was a little crisper, target boost pressure ( 15psi) was reached 300 rpms faster...

 

were do you buy one of these things from?

 

On what manifold?

Only person that seems to sell them at the moment (as PerformanceMetalWerkz seems to have gone down the *******) is Sound Performance, and they are not cheap from them...
http://www.spracingonline.com/store/...ool_Valve/3659

 

"Quick Spool Valve." Interesting invention! Too bad Mazda used it 25 years ago on the series 4 Turbo II.



And they used a special exhaust housing along with it, because it was actually engineered as a complete system.



And you know what Mazda did? They canned the design after two model years and went to a fully divided manifold with two equally sized passages in the exhaust housing. I love when the aftermarket recycles old OEM designs and claim some kind of innovation. You'll see this in the marketing of EFI conversions for small block chevy's, using batch fired technology from the late 70s.

 

Everyone knows its not new technology.

But on the other hand that 'old' technology is still used on some brand new engines, as it works.

Am I right in saying it was only on S4 FCs and not S5s? Did S4s and S5s have the same size exhaust housing/wheel? I presume they wouldve had similar spool, so that might tell us something.

Im confused what im seeing in that pic of the manifold though, I dont see anything that would shut off completely one of the scrolls?

 

spracingonline.com I believe.

 

in the upper left corner of the manifold you can see the flapper. it's controlled by the twin scroll actuator, which was the predecessor to the FD's turbo control valve. It operates by vacuum only.



The s5 has a normal divided inlet with a fully divided manifold. The s4 had a smaller passageway in the turbine housing for low rpm, to which all exhaust gases are directed. Then at higher rpm the larger passage is opened and exhaust flows to both. It's actually a much better design than the aftermarket imitation here. The manifold and turbo are engineered as a system, instead of throwing a universal part at any old turbo with a matching inlet flange. The s5 also had a better internal wastegate design. Exhaust was bled from both passageways, whereas the s4 only bled from one.