I want to add; I will be dividing the header even if I use the old (undivided) Turbonetics. My plan was to use the flange I have now but fabbing up a divider piece and then notching between the secondaries and welding in. Finish up by milling flat the mating surface and call it done.

That's pretty much what we do on our split plenum headers. The only remaining area of concern is your waste gate pipes. Using smoother WG pipe transitions and completely divided banks as shown below should correct your overboost issues.

http://forums.pelicanparts.com/uploa...1293166598.jpg

Yep, your the one I got the idea from. I remember you mentioning dividing the headers even if you use an undivided scroll. Made sense to me so that will be the minimum.

Brian,

Wow, I sure like that header set. Best of the best.

And what a clean work bench.


Wondering if that turbo that was so jumpy in traffic you described above was still using the stock compressor bypass valve?

Thx.

Keith,
I use cardboard to cover my work bench so I can just throw it away when it gets dirty, ha!

The above headers were built for a 550+WHP engine. Primaries are 1.625" with the gasket protectors deleted so the flanges could be port-matched.

The "jumpy" 930 used a K27HFS turbo and 965BOV. It went from just spooling quick to jumpy after the fuel and ignition curves were customized and dialed in perfect.

IMO forget ball bearing as anything much else than a sales argument. 100rpm at it max on a 3.3L and short life time (see why does honeywell/Garrett have the same programe with 360 trust bearings..). And billet or cast is not related to spoolup time. It is has to do with reliability (cast, forced, machined). When talking about the wheels vs. spoolup it is mostly a matter of effencency (wheel pattern/flow pr. rotation)...and weight.

Look instead on puls physics....THINK and if not -> look at what the industry with same issues (diesel industry, early formula 1, etc) has done....

NO 6 cylinder engine fires ALL 6 cylinders or even two cylinder at the same time = try to think what happens with each puls ...

Why is it TWIN SCROLL gives up to 1500-1700rpm earlier spoolup than compaired to a single scroll.....on a 3.3L..??

Ballbearing vs. Twin Scroll (BLING BLING vs. physics)

1) PULS ENERGY - Look at your 4 stroke 3.3L engine. Each cylinder fires individual after each other. Start and look at cylinder #1 - What do you think happens when this puls is correct paired with two "neighbor" cylinders closest on 360 degree apart compression stroke (cam/door clost) AND entering a "half size width" turbine wheel and half sized A/R on a Twin Scroll turbine??

Now take the same scenario on single scroll turbine ... why do you then think the puls energy and thereby the ROTATION DIES completely when sharing volume of 5 header pipings, many of them with "cam-leaks" (see stroke/cam overlab) before entering the turbine wheel - wich again is twize as big on width size and A/R surrounding volume???

Which application do you think have +1500rpm earlier spoolup....Single scroll + bling bling Ballbearing < OR > any other Twin Scroll 360 degree trust bearing turbo.....!?!

On top of that - Try to think what backpressure on cam overlab dos to ignition timing ..... not only in regards to spoolup but also tourge.... Why is it race cars now days on single turbo setup use twin scroll applications and have NO CONCERNS on cam overlab and use high revs NA cams...how can they do that and what is ment by..."forced induction is only NA engine on a different atmospheric pressure" how can that be approached and what advantages dos that have in regards to spoolup...??

2) No "ketchup effekt"....again think why...

3) High backpressure on low revs when you want it (it spoolups turbo) AND LOW backpressure in high revs when you least want it (flow stop) - what benefits dos that have to spoolup and tourge and how do you fit Bling bling ballbearings into this...!?!

4) Twin scroll = Possibility to run higher CR = quicker spoolup + more power + much better fuel economy "off-boost".

Disatvantages when applying Twin Scroll physics to your application:

1) KNOW-HOW ->> You need to identify the firing order to determinate the cylinders that needs to be paired (2 x3) with the closest 360 stroke apart. NOT necessarely JUST the 3 easiest paired on a row!!! Could be, but not necessarely...depends on the firing/stroke order

2) EXTRA WORK - Two seperated WG or ONE BIG wg with DIVIDED wall all the way up under the WG-valve (very important)

3) TIME/WORK = money

IMO Choose GT3582R if you want BLING BLING and a label saying BALLBEARING (juhuu). HOWEVER ANY same sized turbo as a GT3582R with TWIN SCROLL will beat a GT3582R with +1500rpm in spool up and top end power if headers and WG setup are divided correctly. It is pure physics.

Put your money on puls efficiency and correct manifold setup (with "application-tuned" tube primary and secoundary diameters -> secoundary not necessarely bigger than the 3 primary unless very high rpm -> again engine only fires ONE puls at the time). Hereafter choose your correct wheel (and A/R) sized twin scroll turbo for your application.

You go Jakob.


We are lucky with the flat 6 set up. The phasing of each bank is equal with an exhaust event every 240 deg's on each side. Most domestic V8's do not have equal events side to side.

Without a divided exhaust, a stock cam has overlapping exhaust events about 72% of the time and 964's about 92% of the time making for significant exhaust reversion potential.

Split the exhaust and that goes to zero overlap with most the cams we run.

I suspect, go over 240 deg's exhaust duration on a 6 and you start to get back into a potential reversion situation.

On a race motor with a radical cam, twin scroll is probably not as much of an advantage over a single scroll turbo. on a 6. On a 4 it is a different story.

For example, a stock 930 cam has 206 deg's, a 964 has 230 and the 935's had a crazy 324 deg's of duration. Thus, even with twin scroll, go much past about 964 specs and we may start to loose some of the reduction in reversion advantage of twin scroll.


Fun stuff.

911st - interesting stuff you are mentioning with the exhaust duration from 930, 964 and 935...thanks for sharing.

IMO exhaust reversion is only an issue when we are running boost below backpressure...

Duration and overlab...depending on the application...say racing then one of the BIG advantages of Twin Scroll is the possiblity to build low topend backpressure without hurting the spoolup time. Low top end backpressure gives us much more posibility to keep the "balance score-card" still equal (boost vs. backpressure) 1:1 or best 1:0.8 (example) THEN we are still running a "NA engine" and we are much more free to pick the most suitable cam without the normal concerns on backpressure. A "turbo" cam is then "almost" non-existing and we can now have the discussion on "blow through" in regards to valve cooling, cylinder filling etc...

Mount a "10mm brake nipple" just before the turbine inlet and fit a 30cm copper piping in a spiral with say 10 turns. Then fit a silicone vacuum hose to it and place a boost gauge on the other end and place it just near the inlet boost gauge. That will give some fun stuff/thinking in regards to A/R turbine-, exd/ind turbine wheel-, AND cam selection. Or even better log all data within your ecu log file.

Keeping boost over, or equal, to backpressure on high revs and we are in for high effiency build applications. Twin Scroll will do that when build correct AND with not much lost on spoolup (still race application with BIG turbines to hold 1:1 all the way up to say 8.000 rpm). On single scroll setup you would need to run a turbine as big you could stick your arm through it. Seen it. Early cars running 402m did first huge bling bling turbos and had full boost as late as 6.000 rpm running up to 10.000rpm (and empty pockets) and then afterwards building twin scroll (using truck twin scroll turbos) and now having same size turbo (now twin scroll) and now full boost from 4000 rpm and same high end power and rev pattern. Such cases mostly 4 cyl (not porsche) with boost vs. backpressure about 1:0.5-1 at full boost/power and CR 10.5:1 on race fuel (or 9-9.5:1 on normal fuel). In comparison the 993 air cooled, ecu driven, twin turbo runs CR 9:1.

IMO the 935 could run crazy 324degr. exhaust duration only due to a "correct balanced" boost vs. backpressure all the way up the revs. I have had a 935 twin scroll turbo in my hand and the turbine wheel exducer is huge. I will measure that turbo (ind/exd) next time.

I havent had my first porsche yet, but I hope it (930) will come soon. At that time I will build it as a "NA" and choose the turbo with an exducer wheel in a A/R 1.0 hous that will tip the "balance" 1:1 on full boost rpm/power @ 8.00rpm and select a "NA" 8.000rpm read line cam and run TB + ECU. CR 9:1.
Luckely I stock/sell full range of turbos and housings (and ecu's) so I will have fun testing to get the 930 to a "NA" Twin Scroll setup.

Wow, you guys...

I am gone think about this for a while. Then I'll go back and read it again.
Thanks for sharing. Very educational.
Jesper

My 964 Turbo has almost no lag in comparison to my previous 930 (both 3.3) I don't know what the factory did but it worked.
All I've done to it is a 1 bar spring and no muffler or cat.

I have to read this a few times......

Holy crap Jakob, you're giving me a headache! Too much information for my feeble mind to contend with. I would need to be an automotive engineer to digest all this on one sitting.

My advice to you: Get yourself a 930 as soon as possible, and proceed to put your knowledge where it counts....and then share success with us!!!

What you propose for min spool time is to build a N/A engine and turbocharge it. Very effective for that goal but no longer a turbo engine. A true turbo engine must use all the tricks to reduce spool time as that is not the build parameter, but rather top end power through increased boost levels.
Electronics have blurred these lines. Not part of the equasion for the CIS 930.

Ok Jakob, I have read your words twice and I want to summarize.

What I interpret:

1. Ball bearings do nothing for quicker spooling and are also less reliable.
2. Billet wheels do nothing for quicker spooling but usually have more efficient maps.

Correct?

I have two questions then:

1. Why did, say Garrett go to ball bearing if it did nothing for spool time and is less reliable (not to mention cost a lot more to produce than journal bearings/center sections)?
2. If a billet wheel is lighter, wouldn't that translate to quicker spool time (not to mention cost a lot more to produce than cast wheels)?

Jus' trying to understand if this really is marketing BS.....SmileWavy

IMO lighter wheels and BB work better in light load situations like when running in lower gears. When having a lot of load they get balanced out.

Good reading.

That is my goal; get the most boost I can in first gear. I don't have a 930, I have a C3.2 with the G-50 so first is pretty low. If the BB works, I would love to get it.

It will make more power to a point as I said. But the engine makes peak torque at the same RPM regardless of when it makes boost (except if it makes peak boost after torque peak). My comment was more about diminishing returns on your investment to make peak boost come in under peak torque RPM. I would strive to have spool up come as quickly as possible for a street driven car, in fact I run a turbo on my car based on that more than top end power so I'm not against your goal. I would not trade boost at 2500rpm for power at 6000rpm for my street car but I wouldn't spend too much more money trying to get 2000rpm spool up.

did I make any sense? it's still early

There are a lot of varables that effect when, where, and how fast boost comes on.

AR and turbine sizing. Turbine wheel relitive to compressor wheel sizing. Clearances, rotating mass, friction. Exhaust system design, intake system design. Ignition, air fuel optmization...

The best info I have seen of a comparison between normal and ball bearing center section was in there TurboTec section.

From their site:

http://forums.pelicanparts.com/uploa...1293554921.jpg

Tippy, I see full boost by 3800rpm in 1st gear with my little $500 Master Power 60mm. So while 1st gear in a 4 speed is longer you will still notice a huge difference when 1st becomes a usable gear. Compare that to my K27 that didn't reach full boost at all in 1st.

I don't want too much boost in first gear as it only ends up spinning the tires. My current low power turbo spins my 315 tires on first gear and I don't like it as it eats the tires pretty soon.

Maybe with an avcr or similar ebc ot would make sense when you can dial it so its just right in every gear.