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    Thread: Holset user thread

    1. Member obdONE's Avatar
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      10-11-2010 11:47 AM #176
      i get mine back from being ported today. all ports and manifolds were gasket matched as well. can't wait!

    2. Member Dave926's Avatar
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      10-14-2010 10:02 PM #177
      something I found interesting today, apparently Chevrolet ran a holset at Indy http://books.google.com/books?id=y-M...%20gli&f=false

    3. Member Pat @ Pitt Soundworks's Avatar
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      10-15-2010 08:55 AM #178
      It also says the buick motors suffered from niggling problems. LOL

    4. Member Dave926's Avatar
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      10-16-2010 05:29 PM #179
      Quote Originally Posted by Pat @ Pitt Soundworks View Post
      It also says the buick motors suffered from niggling problems. LOL
      Was also the era of cocaine too so idk. Took the car out today to get some fuel, 8 psi feels great, definitely scoots. Kinda tough though watching the wideband, boost guage and road. Couldn't push it too hard though the aba injectors are still init. Tach isn't working either but it gets to 8psi pretty quick

    5. Member obdONE's Avatar
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      10-17-2010 10:48 PM #180
      Knife-edged twin scroll:


      Thanks Quntin for the idea.


      Installed:


      It's a big bastard! Super tight fight. Got it in there though


      Downpipe:




      Took almost an entire day to fab this thing (t-bolts are just to hold the titanium wrap on the pipe). Still have to do the exhaust and finish up a few other things, but it will take a while.
      Last edited by obdONE; 10-18-2010 at 12:01 PM.

    6. Former Advertiser Quintin@R.A.I.'s Avatar
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      10-17-2010 10:51 PM #181
      Quote Originally Posted by obdONE View Post
      Knife-edged twin scroll:


      Thanks Quntin for the idea
      sucks you installed it already....if you look at my pics i did more than just knife edge it ....the outer edges of the ports need to be widened to to actually match a t3 flange. regardless you'll love this turbo.

    7. Member obdONE's Avatar
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      10-17-2010 11:00 PM #182
      it was mildly ported, but we could have gone a bit further, honestly. The manifold was completely gasket matched though. This thing is going to rip, regardless. I'll post more when i have it.

    8. Member Daskoupe's Avatar
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      10-18-2010 10:14 AM #183
      what exhaust housing
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    9. Former Advertiser Quintin@R.A.I.'s Avatar
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      10-18-2010 10:46 AM #184
      Quote Originally Posted by Daskoupe View Post
      what exhaust housing
      thats OBVIOUSLY the 12cm housing newb!

    10. Member 95GOLFIIIJOSH's Avatar
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      10-19-2010 07:55 PM #185
      hey guys.. i got a holset h1c.. one of the older 8 blade twin scroll turbos.. its going to be on my vr6 this winter.. i have mild work.done to the motor.. when should i expect boost by?? anyone with experiance with a H1C and where can i find the propper fitting for the oil return

    11. Member Daskoupe's Avatar
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      10-19-2010 07:57 PM #186
      depends on your housing

      the smallest 9cm gives instant boost on vr6
      So if you have a 12cm think 3500rpm 14cm another 3800 rpm
      16cm probably around 4200k
      12.2@116mph-293whp305wtq 22psi stock aba-AC-DD My Jetta
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    12. Member 95GOLFIIIJOSH's Avatar
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      10-19-2010 08:07 PM #187


      Thats it. I'm not sure of specs how can I tell. ?

      Sent from my Eris using Tapatalk

    13. Member obdONE's Avatar
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      10-19-2010 09:56 PM #188
      I accidentally picked up an H1C that someone was selling under the guise of it being an HX35 I got rid of it as quick as I could. That compressor housing is just too damn small for a vr6. And the turbine is huge in comparison. I think it will be a laggy little bitch that will never flow enough air on the vr, but I could be wrong. I'm no expert...


      I haven't been able to stop thinking about my port job since Quintin called me out on it, so I took it off the manifold tonight to see just how bad it is:



      I'll be taking it back to get it properly ported, but it's really not that bad. I just figure I have the time, so may as well make it perfect.

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      10-19-2010 10:04 PM #189
      Since this is all about twin scroll... just have an honest question
      why do i see all these big turbo cars, whether vw, domestic, import (single turbo supras, turbo s2k etc) use open scroll instead of twin scroll setups? Is it really cost of turbo+manifold or is twin scroll not capable of making the same power figures as an open scroll setup? Thanks for any input

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      10-19-2010 11:22 PM #190
      Quote Originally Posted by Matt1023 View Post
      Since this is all about twin scroll... just have an honest question
      why do i see all these big turbo cars, whether vw, domestic, import (single turbo supras, turbo s2k etc) use open scroll instead of twin scroll setups? Is it really cost of turbo+manifold or is twin scroll not capable of making the same power figures as an open scroll setup? Thanks for any input
      really?

      i make a little bit of power, and i run a 4cyl 20v with a T4 1.00 A/R twin scroll Bullseye S366XL.

      my BASE HIT with 3rd gear and 7k rpm with only 23 psi just to baseline was over 500 AWHP, and it was rich as hell, too. (yeah its Quattro with locked diffs for 100% AWD). that was the first dyno pull on my new 2.0L stroker.



      the twin setup can bring the spool on much earlier....

      here ya go. this is a 1.9L 20v with that S366XL. 33 psi IIRC. and still, only 3rd gear pull. that dont look nice? this is 27 psi and 33 psi pulls, overlayed.


    16. Former Advertiser Quintin@R.A.I.'s Avatar
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      10-20-2010 12:11 AM #191
      Quote Originally Posted by Matt1023 View Post
      Since this is all about twin scroll... just have an honest question
      why do i see all these big turbo cars, whether vw, domestic, import (single turbo supras, turbo s2k etc) use open scroll instead of twin scroll setups? Is it really cost of turbo+manifold or is twin scroll not capable of making the same power figures as an open scroll setup? Thanks for any input
      twin-scrolls do suffer a little on the top-end compared to an equivalent open scroll. How much exactly i haven't found a true back to back dyno. Regardless...if you're a quarter mile guy/gal...twin-scroll = faster spool....and faster spool can win races. My reason for just going open scroll was i was too lazy to redesign my manifold.

    17. Member Pat @ Pitt Soundworks's Avatar
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      10-20-2010 08:16 AM #192
      Quote Originally Posted by Quintin@R.A.I. View Post
      twin-scrolls do suffer a little on the top-end compared to an equivalent open scroll.

      How do you figure? All things considered they should flow better on the top end as well. Your equivalent volute for estimating top end would be the same as the total housing AR, not half the housing ar. ex: a 1.0 ar twin scroll would have the equal or slightly better (due to runner separation) flow as compared to a 1.0 ar open scroll but should spool similarly to, but still slightly slower than, a .50 ar open scroll.

      At least that's the way it was always explained to me.

    18. Former Advertiser Quintin@R.A.I.'s Avatar
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      10-20-2010 09:46 AM #193
      Quote Originally Posted by Pat @ Pitt Soundworks View Post
      How do you figure? All things considered they should flow better on the top end as well. Your equivalent volute for estimating top end would be the same as the total housing AR, not half the housing ar. ex: a 1.0 ar twin scroll would have the equal or slightly better (due to runner separation) flow as compared to a 1.0 ar open scroll but should spool similarly to, but still slightly slower than, a .50 ar open scroll.

      At least that's the way it was always explained to me.
      it was explained to me another way that the lower volume collector and housing becomes a little more of a choke up top when velocities increase.

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      10-20-2010 10:11 AM #194
      Quote Originally Posted by Quintin@R.A.I. View Post
      it was explained to me another way that the lower volume collector and housing becomes a little more of a choke up top when velocities increase.

      i dont notice that effect.....

      A twin scroll turbine housing uses dual side by side passages into the housing. When coupled with a pulse converter manifold that separates exhaust pulses as many crank degrees in the firing order as possible, a twin scroll or divided housing works to reduce lag, decrease exhaust manifold backpressure on the top end, reduce the potential for reversion, and increase fuel economy. The twin scroll is based off the same reasoning a tri-Y header uses: keep spent exhaust gases out of an adjacent cylinder drawing in fresh air. At high rpm on a turbo car, exhaust backpressure is usually significantly higher than atmospheric pressure, and often higher than intake manifold pressure as well. A divider between each of the two volutes allows the cylinders to expel the exhaust gases without it interfering with the fresh air for combustion. Since there are two openings, each a smaller overall volume than a single scroll design, the exhaust velocity of each pulse can be maintained. This also spins the impeller more easily because lag is a function of the scroll area. A single turbine housing opening isn't as efficient since cylinders on the exhaust stroke of the 4 stroke cycle contaminate the cylinders that are on overlap with exhaust gas. A conventional turbine housing is not as effective in using exhaust pulse energy to help spin the turbine up to speed as it does not exploit the energy contained in the pulses as well.
      and:

      A Look At Twin Scroll Turbo System Design - Divide And Conquer?

      From the May, 2009 issue of Modified Mag
      By David Pratte


      Back in the day, most aftermarket and factory turbocharger systems featured simple log-style exhaust manifolds. But just like on normally aspirated engines, where exhaust manifold design has become recognized as a critical element to maximizing horsepower and torque output, there has been increasing attention paid to turbocharger and turbo manifold design. Divided or "twin-scroll" turbos and manifolds have emerged as the preferred design of many of the top tuners and even OEMs, showing up on high-performance models like the Mitsubishi EVO, Pontiac Solstice GXP and JDM Impreza STI. But what exactly are the differences between single-scroll (or constant pressure) turbo systems and twin-scroll (or two-pulse) turbo systems and how do these design differences impact overall engine performance?

      Single-scroll systems have been in use for a long time, and for good reason. These systems are generally compact, inexpensive and extremely durable under the high heat they're exposed to. So from a simplicity of design, packaging and reliability standpoint, a single-scroll, constant-pressure turbo system is quite appealing-especially to the OEMs that must consider more than just power production. Although log-style or simple unequal-length turbo manifolds used by the OEMs can be tweaked for improved performance or replaced by a more sophisticated equal-length aftermarket manifold, this doesn't change the fact that there's a single exhaust gas inlet to the turbo's "hot side" turbine (which powers the "cold side" compressor, force feeding a denser and therefore more oxygen-rich air charge into the combustion chamber from the intake side). Because of this design limitation, single-scroll systems are not particularly efficient at low engine speeds or high loads. This decreased turbine efficiency contributes to turbo lag, something we've all probably experienced while driving a stock turbocharged vehicle.

      One of the biggest limitations of most factory single-scroll turbo system is the restrictive nature of its log or compact unequal-length exhaust manifold. Keep in mind, the purpose of this manifold isn't just to channel exhaust gases to the turbocharger's turbine wheel; the manifold must be designed to allow exhaust gases to exit the combustion chamber of each cylinder quickly and efficiently. Also keep in mind that these exhaust gases do not flow in a smooth stream because the gas exits each cylinder based on the engine's firing sequence, resulting in distinct exhaust gas pulses. Next time you fire up your car, place your hand lightly over the exhaust tip (before it gets hot!) and you will feel these pulses. With a log-style or compact OE-style, unequal-length runner exhaust manifold like you'll find on SR20DET or USDM STI engines, the pulse from one cylinder can interfere with subsequent exhaust gas pulses as they enter the manifold from the other cylinders, inhibiting scavenging (where the high-pressure pulse draws the lower pressure gases behind it out of the combustion chamber with it) and increasing reversion (where exhaust gas flow is disturbed so much that its direction of travel reverses and pollutes the combustion chambers with hot exhaust gases). The trapped and wasted kinetic exhaust gas energy from poor scavenging and too much reversion also means higher combustion and exhaust gas temperatures, necessitating less aggressive ignition timing and reduced valve overlap as well as richer air/fuel mixtures (and higher NOx emissions).

      Twin-scroll turbo system design addresses many of the shortcomings of single-scroll turbo systems by separating those cylinders whose exhaust gas pulses interfere with each other. Similar in concept to pairing cylinders on race headers for normally aspirated engines, twin-scroll design pairs cylinders to one side of the turbine inlet such that the kinetic energy from the exhaust gases is recovered more efficiently by the turbine. For example, if a four-cylinder engine's firing sequence is 1-3-4-2, cylinder 1 is ending its expansion stroke and opening its exhaust valves while cylinder 2 still has its exhaust valves open (while in its overlap period, where both the intake and exhaust valves are partially open at the same time). In a single-scroll or undivided manifold, the exhaust gas pressure pulse from cylinder 1 is therefore going to interfere with cylinder 2's ability to expel its exhaust gases, rather than delivering it undisturbed to the turbo's turbine the way a twin-scroll system allows.

      The result of the superior scavenging effect from a twin-scroll design is better pressure distribution in the exhaust ports and more efficient delivery of exhaust gas energy to the turbocharger's turbine. This in turn allows greater valve overlap, resulting in an improved quality and quantity of the air charge entering each cylinder. In fact, with more valve overlap, the scavenging effect of the exhaust flow can literally draw more air in on the intake side while drawing out the last of the low-pressure exhaust gases, helping pack each cylinder with a denser and purer air charge. And as we all know, a denser and purer air charge means stronger combustion and more power, and more power is good!

      But the benefits of twin-scroll design don't end there. With its greater volumetric efficiency and stronger scavenging effect, higher ignition delay can be used, which helps keep peak temperature in the cylinders down. Since cooler cylinder temperatures and lower exhaust gas temperatures allows for a leaner air/fuel ratio, twin-scroll turbo design has been shown to increase turbine efficiency by 7-8 percent and result in fuel efficiency improvements as high as 5 percent.

      Combine these benefits with a well-engineered tubular equal-length manifold and the design strengths of a twin-scroll approach can pay even bigger dividends. "Equal length" simply refers to the length of the primary exhaust manifold tubes or runners that the cylinder head exhaust ports breath out into, which should ideally be of equal length before merging at a narrow angle at the collector so that the gases flow smoothly together into the turbine inlet. This helps maintain exhaust gas pulse energy, resulting in better boost response and overall higher turbo efficiency.

      Designing a high-performance twin-scroll tubular manifold like those available from top tuners like Full-Race is no simple task. Fitting equal-length primaries into the tight confines of a turbocharged car's engine bay while maintaining proper radius bends and strong exhaust gas flow characteristics is a serious design challenge. Determining the best length and diameter of the primaries and angle of the merge collector also requires a lot of R&D, as does choosing the best wall thickness and material for the tubing itself. That's where Full-Race's team of highly educated mechanical engineers and years of constant refinement of their designs comes into play. According to Geoff at Full-Race, "Because of the increased turbine efficiency found in twin-scroll systems, twin-scroll manifolds can often use a smaller runner than a single-scroll design. However, due to the complex shape of the runners and the requirement for a second wastegate and dumptube (one for each side of the divided turbine) there's more mass and more parts which adds expense and complexity. Plus, twin-scroll turbos are physically larger than their single-scroll equivalents, so it's more difficult to make them fit our cramped engine bays." Overcoming these challenges means developing extremely robust manifolds that make smart use of the available space, something Full-Race does with the help of computer programs like SolidWorks and other proprietary processes.

      All this hard work does translate to serious performance gains in the power-delivery department, particularly at spool-up and peak torque where sophisticated tubular twin-scroll manifolds properly matched to a twin-scroll turbo deliver superior airflow to single-scroll or OE twin-scroll designs. According to Geoff, "Our twin-scroll turbo kits have a higher average cylinder pressure and turbine efficiency, while single-scroll systems tend to have a higher peak cylinder pressure and exhaust backpressure. We have found the twin-scroll systems have higher backpressure at low rpm (which is good for turbo spool-up) and lower backpressure at high rpm (which is good for top-end performance). On the other hand, single-scroll systems have lower backpressure at low rpm (bad for spool-up) and higher backpressure at high rpm (which hurts top-end performance)." In order to realize the full benefit of a top-shelf twin-scroll system like one of Full-Race's, the manifold design and A/R ratio of the turbo must be spot-on, so it's best to get the help of a professional when choosing a turbo for this type of system.

      It's certainly possible to generate huge power and great high-rpm performance with a single-scroll turbo system. There are plenty of examples of very high-horsepower, single-scroll turbocharged engines out there, but with single-scroll systems spool-up and response are much slower than with a twin-scroll design, yet twin-scroll systems still provide excellent top end performance. Although switching from single-scroll to twin-scroll can be expensive, for hard-core boost junkies who want much faster throttle response without giving up any top end, there is no better solution. With the added benefits of higher turbine efficiency, lower cylinder temps and EGTs which allow more aggressive timing and fuel mapping, and the freedom to run more overlap, twin-scroll turbo system design is really a perfect match for the high specific output engines featured in many of our favorite sport compact machines.
      http://www.modified.com/tech/modp-09...ign/index.html


    20. 10-23-2010 10:47 AM #196
      hi guys do you rate these holset turbos , i thought id try some
      12cm hx35 8blade 20psi on my vr6 , evern thow it pulls its nothing exciting
      14cm hx40 7blade thow it to back of garge spooled too late on my 12v vr6
      engine spec slighty modified vr6 manifold
      640cc tunie
      46mm wastgate
      3inch straight thew pipe
      tubiler twin scroll manifold
      100mm intake
      8.5 .1 compression
      02m gearbox
      4wd added

    21. Member Pat @ Pitt Soundworks's Avatar
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      10-23-2010 11:03 AM #197
      They show very good results in a LOT of applications. And for the purchase price, they're hard to beat.

      A more fair comparison is how do YOU rate it compared to OTHER TURBOS you have used? You say it spooled late?

      an 8blade hx35 flows 52 lb/min = 3071R
      a 7 blade hx40 flows 69lb/min = gt35R

      housings:
      12 cm2 = 0.89 A/R
      14 cm2 = 0.97 A/R

      Take the 7-blade hx40 compressor wheel and compressor housing, and put it on the hx35 turbine wheel/housing/cartridge. Then you'll have a .89a/r 69lb/min turbo and should be happy. Or just send both to me and I'll recycle them for you. I'll pay shipping too

    22. 10-23-2010 11:48 AM #198
      double posted

    23. 10-23-2010 11:52 AM #199
      Quote Originally Posted by Pat @ Pitt Soundworks View Post
      They show very good results in a LOT of applications. And for the purchase price, they're hard to beat.

      A more fair comparison is how do YOU rate it compared to OTHER TURBOS you have used? You say it spooled late?

      an 8blade hx35 flows 52 lb/min = 3071R
      a 7 blade hx40 flows 69lb/min = gt35R

      housings:
      12 cm2 = 0.89 A/R
      14 cm2 = 0.97 A/R

      Take the 7-blade hx40 compressor wheel and compressor housing, and put it on the hx35 turbine wheel/housing/cartridge. Then you'll have a .89a/r 69lb/min turbo and should be happy. Or just send both to me and I'll recycle them for you. I'll pay shipping too

      i was just going to ask u reckon there will be any differnce in spool power by changeing the cold side to a 7blade hx40 on the 12cm t3 twinscroll , as i thought it only has 7blades so maybe worse
      Last edited by adaptorman; 10-23-2010 at 12:14 PM.

    24. Member Pat @ Pitt Soundworks's Avatar
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      10-23-2010 12:16 PM #200
      Definitely.

      the 7-blade compressor blades more more air than their 8-blade companions. The swap of the hx40 cold side to the hx35 hot side is called the hx35/40. It's popular among the DSM guys.

      Or like I said, pack it up and send it all to me

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