Twin-Charging and Compound Turbo Charging
10-18-2009, 05:09 PM
#41
Got a link to that thread?
I think of it this way, since this is a difficult problem to solve, the best two solutions IMO are:
1. Wait for SP to apply their Supra magic to a sequential turbo setup for a VQ
2. Build VQ's made to rev to 9K, that way you can match turbo and still have a wide powerband, just higher up in the rev range
I think of it this way, since this is a difficult problem to solve, the best two solutions IMO are:
1. Wait for SP to apply their Supra magic to a sequential turbo setup for a VQ
2. Build VQ's made to rev to 9K, that way you can match turbo and still have a wide powerband, just higher up in the rev range
I just don't think sp is going to do any crazy sequential vq's, i wish though. Why? well lets look at the circumstance, to get noticed in the big power supra world they needed to do something crazy. They then put in the work to develop a sequential kit.
They are already basically at the top of the vq world (hp battle) so they really don't need to change anything.
I just don't see sequential kits for the Z because of the lack of space in our engine bays. I get the feeling the under hood temps would just skyrocket.
________
TTG35, the theory behind my twin charge idea is take the response of a good low down kit (like the jwt530) and add the s/c to give it tons of power higher in the band. Its like running nitrous in a way on an rb20 with an hks gt25. On the low end you get good turbo response and then when you need more power you just spray. So the engine feels larger than it really is. Does anyone understand the "logic" I am trying to explain?
Its like a second whim on the power-band.....
10-18-2009, 05:20 PM
#43
There is someone on G35Driver that is working on a Vortech blowing into a Stillen. The only big problem with using the Stillen is that it is not robust enough to handle the extra pressure according to the research provided in the thread. Something about the seals on the Stillen going bad.
I would do a twin turbo blowing into two twin centrifugals if you could. The piping would be feasible and it would make mad power.
I would do a twin turbo blowing into two twin centrifugals if you could. The piping would be feasible and it would make mad power.
Here's that G35 twin S/C just a quick search... don't know if he got it running because I haven't read it yet. Will read it later...
http://g35driver.com/forums/engine-d...arged-g35.html
_________
edit:
Bahahahaa that guy is crazy.
G35driver<My350z
Last edited by Resmarted; 10-18-2009 at 05:40 PM.
10-18-2009, 05:25 PM
#44
TTG35, the theory behind my twin charge idea is take the response of a good low down kit (like the jwt530) and add the s/c to give it tons of power higher in the band. Its like running nitrous in a way on an rb20 with an hks gt25. On the low end you get good turbo response and then when you need more power you just spray. So the engine feels larger than it really is. Does anyone understand the "logic" I am trying to explain?
Its like a second whim on the power-band.....
The idea of using a twin-charge system is to get the benefits of insta-spool with a supercharger in the low rpms, while still getting the benefits of a turbocharger in the high rpms. To use a supercharger for high rpm boost is very inefficent - it creates drag on the motor, which eats up hp.
Superchargers are nowhere near as efficient as turbochargers at producing boost in the high rpm ranges. If you are exlusively going with either a turbo or a supercharger, then using a supercharger makes sense in some cases, but not all. To use a supercharger that needs a turbocharger to suppliment it in the low rpms makes absolutely no sense at all. In my last post, I tried to elude to this, but you just did not get it.
In other words, turbo chargers are way, way more efficient than superchargers at producing boost at high rpms. The issue with turbochargers is the time it takes for them to spool. In twin-charged systems, superchargers are used to supplement the turbochargers in the low rpm range until the turbochargers spool up. If you choose a supercharger that spools up later than a turbo charger, there is absolutely no reason to use that supercharger. A turbo charger will generate more boost with less drag on the motor because it operates on energy contained in the exhaust gases, not energy derived directly from the crankshaft.
In a twin-charged system, we want a supercharger that starts producing boost early, before the turbo chargers would otherwise spool up. More specifically, we use the supercharger to get air flow volume at low rpms. This means the air flow volume is greater than it otherwise would be, wich means the exhaust gas flow is higher, which causes the turbos to spool up faster than they would if the supercharger were not there. Moreover, before the turbos spool up, the supercharger is providing boost. To use a supercharger that spools up after the turbochargers completely defeats the purpose of a twin-charge system, and actually unnecessarily bleads energy from the system.
Last edited by ttg35fort; 10-18-2009 at 05:52 PM.
10-18-2009, 05:49 PM
#45
I was trying to be very respectful because you have been so in your posts, and I greatly appreciate that. However, now I think we are going a little off course, so I'll be a little more straight forward.
The idea of using a twin-charge system is to get the benefits of insta-spool with a supercharger in the low rpms, while still getting the benefits of a turbocharger in the high rpms. To use a supercharger for high rpm boost is very inefficent - it creates drag on the motor, which eats up hp.
Superchargers are nowhere near as efficient as turbochargers at producing boost in the high rpm ranges. If you are exlusively going with either a turbo or a supercharger, then using a supercharger makes sense in some cases, but not all. To use a supercharger that needs a turbocharger to suppliment it in the low rpms makes absolutely no sense at all. In my last post, I tried to elude to this, but you just did not get it.
In other words, turbo chargers are way, way more efficient than superchargers at producing boost at high rpms. The issue with turbochargers is the time it takes for them to spool. In twin-charged systems, superchargers are used to supplement the turbochargers in the low rpm range until the turbochargers spool up. If you choose a supercharger that spools up later than a turbo charger, there is absolutely no reason to use that supercharger. A turbo charger will generate more boost with less drag on the motor because it operates on energy contained in the exhaust gases, not energy derived directly from the crankshaft.
The idea of using a twin-charge system is to get the benefits of insta-spool with a supercharger in the low rpms, while still getting the benefits of a turbocharger in the high rpms. To use a supercharger for high rpm boost is very inefficent - it creates drag on the motor, which eats up hp.
Superchargers are nowhere near as efficient as turbochargers at producing boost in the high rpm ranges. If you are exlusively going with either a turbo or a supercharger, then using a supercharger makes sense in some cases, but not all. To use a supercharger that needs a turbocharger to suppliment it in the low rpms makes absolutely no sense at all. In my last post, I tried to elude to this, but you just did not get it.
In other words, turbo chargers are way, way more efficient than superchargers at producing boost at high rpms. The issue with turbochargers is the time it takes for them to spool. In twin-charged systems, superchargers are used to supplement the turbochargers in the low rpm range until the turbochargers spool up. If you choose a supercharger that spools up later than a turbo charger, there is absolutely no reason to use that supercharger. A turbo charger will generate more boost with less drag on the motor because it operates on energy contained in the exhaust gases, not energy derived directly from the crankshaft.
See this is where we have different views. Yes s/c has less high rpm spooling capabilities but... the problem is (without being root style) no s/c can touch a twin gt25 setup for low end torque. So basically there are two ways for twin charging? Roots+big single, small tt + big centrifugal?
I just like the twin + centrifugal because i dislike roots
! Or what about middle of the road for both? greddy tt + vortech? haha compound boost is interesting.
10-18-2009, 06:01 PM
#46
Ahah!
See this is where we have different views. Yes s/c has less high rpm spooling capabilities but... the problem is (without being root style) no s/c can touch a twin gt25 setup for low end torque. So basically there are two ways for twin charging? Roots+big single, small tt + big centrifugal?
I just like the twin + centrifugal because i dislike roots! Or what about middle of the road for both? greddy tt + vortech? haha compound boost is interesting.
See this is where we have different views. Yes s/c has less high rpm spooling capabilities but... the problem is (without being root style) no s/c can touch a twin gt25 setup for low end torque. So basically there are two ways for twin charging? Roots+big single, small tt + big centrifugal?
I just like the twin + centrifugal because i dislike roots
! Or what about middle of the road for both? greddy tt + vortech? haha compound boost is interesting.Last edited by ttg35fort; 10-19-2009 at 04:01 PM.
10-18-2009, 06:25 PM
#47
You are correct, it appears that the supercharger does need to be a root style supercharger for the twin-charged system to provide any significant benefits. Personally, I see absolutely no benefits in using a centrifugal type supercharger with our builds (other than cost, which is the "some cases" I elude to above).
Do you have legit plans for compound turbocharging? (like are you really going to do this?)
10-18-2009, 06:37 PM
#48
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Got a link to that thread?
I think of it this way, since this is a difficult problem to solve, the best two solutions IMO are:
1. Wait for SP to apply their Supra magic to a sequential turbo setup for a VQ
2. Build VQ's made to rev to 9K, that way you can match turbo and still have a wide powerband, just higher up in the rev range
I think of it this way, since this is a difficult problem to solve, the best two solutions IMO are:
1. Wait for SP to apply their Supra magic to a sequential turbo setup for a VQ
2. Build VQ's made to rev to 9K, that way you can match turbo and still have a wide powerband, just higher up in the rev range
i think sp already did that 2....reving to 9k...and that might be more than you need actually depending on how large turbo we talking about.....
10-18-2009, 06:45 PM
#49
What are your plans? What are you currenty running?
Last edited by ttg35fort; 10-18-2009 at 07:00 PM.
10-18-2009, 08:41 PM
#50
1. twin turbos and a single roots style [EDIT: or twin screw style] supercharger; or
2. twin turbos and twin roots style [EDIT: or twin screw style] superchargers - if somebody makes roots style [EDIT: or twin screw style] SC's that do not need to sit on top of the motor (I have never seen such SC's, but there is no reason they can't be made).
Last edited by ttg35fort; 10-19-2009 at 04:03 PM.
10-18-2009, 09:04 PM
#51
http://i137.photobucket.com/albums/q...E/S1030404.jpg
Last edited by BoostedProbe; 10-18-2009 at 09:08 PM.
10-18-2009, 09:36 PM
#52
Been saving up for a proper build, greddy twins, utec and rebuild the auto. Was supposed to be done up about a year ago, but financial crisis with the lack of dollars and the being expensive and the spending on stuff that needs to get fixed :/
Hoping to start the process late winter.... Until then I will just help buddies out with their builds (1.5jz + aem + blitz turbo kit = win)
Hoping to start the process late winter.... Until then I will just help buddies out with their builds (1.5jz + aem + blitz turbo kit = win)
10-18-2009, 09:40 PM
#53
See you would get the low down response with the twin charge kit you would not see in a regular turbo kit but have nearly the same, perhaps better mid range.
Edit:
Peak power at 4,000rpm 700hp... sounds monster to me...
Last edited by Resmarted; 10-18-2009 at 09:43 PM.
10-19-2009, 12:44 AM
#54
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Let's get some things straight here:
Roots-type (Stillen SC kit) are positive displacement superchargers.
Positive displacement = can move relatively more air and create boost at low RPM.
The supercharger on that ORC car looks like its a twin-screw (Lysholm-type) supercharger.
This supercharger is also positive displacement, but is a little more complex and a lot more efficient than a roots-type at high RPM/peak power.
The most widely known consumer company that sells these is Whipple superchargers.
The twin charging system on that VW is a sequential system,
the Supercharger is producing boost at low rpm, and then once the turbo is spooled up it takes over.
The bypass valve on the SC is opened, letting air flow directly to the turbo inlet without restriction, and the electromagnetic clutch gets rid of most of the parasitic drag from turning the lobes on the roots-supercharger (although if this is omitted, the efficiency loss isn't that high since the SC is just circulating air instead of compressing it)
To be honest, yes twin-charging systems are cool-**** and all, but in reality it doesn't make much financial or technical sense unless you are:
1. Trying to be unique for the sake of being unique.
2. Building a show/demo car and demonstrating your technical/engineering prowess (see #1)
3. Building some ungodly creation with massive boost in mind, and needs a somewhat more usable powerband rather than just 5500-7500 rpm.
Anyway, talk is cheap.
For years I've been trying to talk myself into doing a twin-charging project, but to no avail.
Post when you actually have something to show!
Roots-type (Stillen SC kit) are positive displacement superchargers.
Positive displacement = can move relatively more air and create boost at low RPM.
The supercharger on that ORC car looks like its a twin-screw (Lysholm-type) supercharger.
This supercharger is also positive displacement, but is a little more complex and a lot more efficient than a roots-type at high RPM/peak power.
The most widely known consumer company that sells these is Whipple superchargers.
The twin charging system on that VW is a sequential system,
the Supercharger is producing boost at low rpm, and then once the turbo is spooled up it takes over.
The bypass valve on the SC is opened, letting air flow directly to the turbo inlet without restriction, and the electromagnetic clutch gets rid of most of the parasitic drag from turning the lobes on the roots-supercharger (although if this is omitted, the efficiency loss isn't that high since the SC is just circulating air instead of compressing it)
To be honest, yes twin-charging systems are cool-**** and all, but in reality it doesn't make much financial or technical sense unless you are:
1. Trying to be unique for the sake of being unique.
2. Building a show/demo car and demonstrating your technical/engineering prowess (see #1)
3. Building some ungodly creation with massive boost in mind, and needs a somewhat more usable powerband rather than just 5500-7500 rpm.
Anyway, talk is cheap.
For years I've been trying to talk myself into doing a twin-charging project, but to no avail.
Post when you actually have something to show!
Last edited by zads; 10-19-2009 at 12:49 AM.
10-19-2009, 02:11 AM
#55
Location does not matter, as long as you can get the engine crank to rotate it. This is what I build on my last car, I machined the transfer/jack shaft and fabricated all the brackets:
http://i137.photobucket.com/albums/q...E/S1030404.jpg
http://i137.photobucket.com/albums/q...E/S1030404.jpg
10-19-2009, 02:17 AM
#56
You really should take a look at that power enterprise gtr. The midrange is a straight whooping.
See you would get the low down response with the twin charge kit you would not see in a regular turbo kit but have nearly the same, perhaps better mid range.
Edit:
Peak power at 4,000rpm 700hp... sounds monster to me...
See you would get the low down response with the twin charge kit you would not see in a regular turbo kit but have nearly the same, perhaps better mid range.
Edit:
Peak power at 4,000rpm 700hp... sounds monster to me...
Last edited by ttg35fort; 10-19-2009 at 03:15 AM.
10-19-2009, 02:42 AM
#57
Let's get some things straight here:
Roots-type (Stillen SC kit) are positive displacement superchargers.
Positive displacement = can move relatively more air and create boost at low RPM.
The supercharger on that ORC car looks like its a twin-screw (Lysholm-type) supercharger.
This supercharger is also positive displacement, but is a little more complex and a lot more efficient than a roots-type at high RPM/peak power.
The most widely known consumer company that sells these is Whipple superchargers.
Roots-type (Stillen SC kit) are positive displacement superchargers.
Positive displacement = can move relatively more air and create boost at low RPM.
The supercharger on that ORC car looks like its a twin-screw (Lysholm-type) supercharger.
This supercharger is also positive displacement, but is a little more complex and a lot more efficient than a roots-type at high RPM/peak power.
The most widely known consumer company that sells these is Whipple superchargers.
EDIT: I looked up the Whipple superchargers, and they appear to provide quite a bit of low rpm boost. They don't provide a boost vs rpm plot, but by looking at the sample torque plots, it is apparent that they are moving massive amounts of air at low rpm. For the SC guys who don't mind a bulging hood, the Whipple superchargers are definitely worth looking into. The one issue is that SC's need some of the motor's hp to spin them. On the website, Whipple does not indicate how much hp that happens to be. I still can't find any information relating to boost vs rpm for the Stillen SC.
The twin charging system on that VW is a sequential system,
the Supercharger is producing boost at low rpm, and then once the turbo is spooled up it takes over.
The bypass valve on the SC is opened, letting air flow directly to the turbo inlet without restriction, and the electromagnetic clutch gets rid of most of the parasitic drag from turning the lobes on the roots-supercharger (although if this is omitted, the efficiency loss isn't that high since the SC is just circulating air instead of compressing it)
the Supercharger is producing boost at low rpm, and then once the turbo is spooled up it takes over.
The bypass valve on the SC is opened, letting air flow directly to the turbo inlet without restriction, and the electromagnetic clutch gets rid of most of the parasitic drag from turning the lobes on the roots-supercharger (although if this is omitted, the efficiency loss isn't that high since the SC is just circulating air instead of compressing it)
https://my350z.com/forum/forced-indu...under-way.html
https://my350z.com/forum/forced-indu...rev-2-0-a.html
Here are the reasons why I started this thread:
1. To get an exchange of ideas. As I indicated in the first post, I am really leaning toward a compound turbo system if I can get turbos with the correct compressor design. A sequential turbo system also is in the back of my head. I'm not sure about the twin-charged route, but if I were going in that direction, there is a lot information provided herein that would be helpful for planning such a build. A supercharger that produces the type of boost I am looking for below 3k rpm is likely going to be too large to fit in my engine bay (and I don't want a supercharger sticking out through my hood, nor do I want a big hood scoop).
2. I have spent a lot of time researching the turbos offered by Garrett, and I cannot find any turbos with the proper compressor designs to make a compound turbo worthwhile. The Garrett compressors reach peak efficiency for the required MAF at too high of a pressure ratio to make a compound turbo system beneficial for our cars. I was hoping somebody would chime in with information on other BB/water-cooled turbos that would work (not "hey, go look at those turbos," rather something like "this particular turbo moves xx lb/min of air at a 1.8 pressure ratio with 77% efficiency").
3. I already have the new turbo kit, but to add a set of small turbos to make a compound or sequential turbo setup should be do-able. At this point, I am VERY interested in SP's sequential turbo valving Tom indicated. I'm going to look into that. Had I not started this thread, I would never had known that SP had such components available.
First I am going to get the 4.0L motor installed with the GT3071 - 0.64 A/R turbos and see how the torque curve looks. If I am getting over 300 ft-lbs of torque at 3000 rpm, and 750 whp by 7500 rpm, I may just leave that setup alone. I chose the 0.64 A/R to try to get the turbos to spool up as quickly as possible. I am somewhat concerned that with these turbine housings reversion will become an issue at high rpms. I won't know until we get it on the dyno. If my concern plays out and the small turbine inlet is holding me back at high rpms, then I am going to implement a compound, sequential or twin-charged build. My preference is a compound turbo system, but again, if I can find the right turbos. I want to make sure I have all of my ducks in a row so that the car is not sitting around more time while I get things figured out. It has already been down nearly a year waiting for the new motor and I don't want any more down time that otherwise can be avoided. I am building my car to drive, not sit.
Last edited by ttg35fort; 10-19-2009 at 06:39 AM.
10-19-2009, 04:36 PM
#59
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Thank you for the clarifications. What is the pressure ratio of these superchargers in the 2k - 3k rpm range?
EDIT: I looked up the Whipple superchargers, and they appear to provide quite a bit of low rpm boost. They don't provide a boost vs rpm plot, but by looking at the sample torque plots, it is apparent that they are moving massive amounts of air at low rpm. For the SC guys who don't mind a bulging hood, the Whipple superchargers are definitely worth looking into. The one issue is that SC's need some of the motor's hp to spin them. On the website, Whipple does not indicate how much hp that happens to be. I still can't find any information relating to boost vs rpm for the Stillen SC.
EDIT: I looked up the Whipple superchargers, and they appear to provide quite a bit of low rpm boost. They don't provide a boost vs rpm plot, but by looking at the sample torque plots, it is apparent that they are moving massive amounts of air at low rpm. For the SC guys who don't mind a bulging hood, the Whipple superchargers are definitely worth looking into. The one issue is that SC's need some of the motor's hp to spin them. On the website, Whipple does not indicate how much hp that happens to be. I still can't find any information relating to boost vs rpm for the Stillen SC.
Negating some minor effects of the SC volumetric efficiency and adiabatic efficiency, its constant boost from the moment you open the throttle.
While the SC (all types) drive belts typically aren't toothed (except in some extreme applications), the SC is still more or less rotating at a fixed ratio to the RPM of the crankshaft (depending on the pulley ratio).
On positive displacement SC, these displace a fixed amount of air per revolution from the SC intake to the SC exhaust, and since the engine is displacing a fixed volume of air on each revolution, the pressure ratio is fixed (constant boost pressure).
Many positive displacement superchargers are named using this convention.
Eaton/roots-type: M45, M62, M90, M112, etc (number = CI displaced per SC revolution)
Whipple/twin-screw: W100 to W510 (CI displaced per SC revolution)
Also think- if you get your crank to SC RPM ratio completely wrong for a given SC (hard to do), you will actually have a constant vacuum in your intake instead of boost!
The centrifugal SC and turbo compressor airflow (boost) follows a curve, making the RPM to boost also non-linear.
I'm not sure who that comment was directed to, but I already have something to show. Here are my build threads:
https://my350z.com/forum/forced-indu...under-way.html
https://my350z.com/forum/forced-indu...rev-2-0-a.html
https://my350z.com/forum/forced-indu...under-way.html
https://my350z.com/forum/forced-indu...rev-2-0-a.html
I was referring to having "something to show" as far as a twincharged setup.
Well, you definitely look like you're willing to drop plenty of money on your car.
When doing a twincharging project, compound or sequential.. that will come in handy!
Here are the reasons why I started this thread:
1. To get an exchange of ideas. As I indicated in the first post, I am really leaning toward a compound turbo system if I can get turbos with the correct compressor design. A sequential turbo system also is in the back of my head. I'm not sure about the twin-charged route, but if I were going in that direction, there is a lot information provided herein that would be helpful for planning such a build. A supercharger that produces the type of boost I am looking for below 3k rpm is likely going to be too large to fit in my engine bay (and I don't want a supercharger sticking out through my hood, nor do I want a big hood scoop).
1. To get an exchange of ideas. As I indicated in the first post, I am really leaning toward a compound turbo system if I can get turbos with the correct compressor design. A sequential turbo system also is in the back of my head. I'm not sure about the twin-charged route, but if I were going in that direction, there is a lot information provided herein that would be helpful for planning such a build. A supercharger that produces the type of boost I am looking for below 3k rpm is likely going to be too large to fit in my engine bay (and I don't want a supercharger sticking out through my hood, nor do I want a big hood scoop).
-Replace AC compressor with Whipple SC, but may not have enough longitudinal depth without a crankshaft pulley extension, or it may have clearance issues to the wheel well or crossmember
-Use Kinetix SSV style offset manifold and see if you can squeeze the SC under the hood, upside-down basically sitting on top of the driver's side valve cover.
Anyway I'll finish the rest later.
Last edited by zads; 10-19-2009 at 04:38 PM.
10-19-2009, 04:43 PM
#60
^^^^^
Cool.
You obviously know what you are talking about, but you have posted only 43 times in nearly 4 years. Why not post more often to share your knowledge? In my humble opinion, this forum certainly could benefit from people who have signiificant knowledge, such as yourself, posting more frequently...
Cool.
You obviously know what you are talking about, but you have posted only 43 times in nearly 4 years. Why not post more often to share your knowledge? In my humble opinion, this forum certainly could benefit from people who have signiificant knowledge, such as yourself, posting more frequently...
Last edited by ttg35fort; 10-19-2009 at 04:52 PM.