Close

Page 10 of 12 FirstFirst ... 89101112 LastLast
Results 226 to 250 of 277
  1. #226
    Join Date
    Jan 2012
    Posts
    5
    Rep Points
    10.3
    Mentioned
    0 Post(s)
    Rep Power
    0


    1 out of 1 members liked this post. Reputation: Yes | No
    Hey DFM, Ill do my best to expand on some topics. Much respect implied and thank you for your contribution.

    Click here to enlarge Originally Posted by DFM Click here to enlarge
    Turbo lag cannot be entirely eliminated without the use of additional anti lag technology. Regardless of how close time to full boost is for each platform, it will always be longer for the turbo (especially in lower RPM's). The computer needs to be able to progressively adjust the timing and fuel as the boost rises at an exponential rate. With a PD blower, boost is similar to an on/off switch, so the progressive adjustment of fuel and timing is more immediate. Where did the 2500rpm for the PD come from? pretty certain a PD blower hits max boost much sooner than 2500 rpm...
    In theory a PD pump / blower has a fixed displacement per revolution, in the same basic theory an engine is the same type of "pump". The TVS is a roots type supercharger with NO internal compression ( as opposed to a screw with an internal pressure ratio and work * back to this later ). The supercharger like an engine has its own volumetric efficiency curve.
    ref:


    Boost response is instant. Sometimes you control / adjust the bypass mechanism with a damper, restrictor orifice or ( digitally damped ) to bring boost on softly. Though this is over fractions of a second. Time-to-torque from driver request to torque at the tire is still instant, even compared to a small turbo setup its drastically noticeable. It's literally instant tire shread.

    Boost curve. Pressure is not necessarily constant over the power band. Refer back to the volumetric map.
    A small supercharger ( relative ) matched to a motor will have a very flat boost profile, for example from 2000-8500 RPM. While a larger supercharge matched to the same motor, with the same peak boost pressure request, will have a more ramped plateau. 60% of peak boost down low, to 100% of peak boost by redline. This is not lag, its just the result of the interplay of rotor speed, supercharger volumetric eff vs rpm, and the engines vol eff. With this charger I'm confident that this will be a complimentary component to the character of the car.

    In summary:
    Boost Threshold : is not a factor with the PD system. Its always able to make positive pressure. While a turbocharger there is only so much potential energy for a certain pressure ratio after a specific RPM point.
    Boost profile : PDs have flat to slightly ramped ( size dependent ) profiles. Superchargers since they are directly coupled to crank speed, have a FIXED boost profile.
    Lag or time to torque : Instant torque, reaches boost threshold immediately. as fast as the bypass valve is allowed to snap shut, Lag is non existent.



    As a function of RPM, because the turbo can probably push more air at the higher RPM's than a PD blower at the same boost level. You're right, it depends wholly on the turbo itself. Think of a jet engine. A jet engine is very efficient because the airflow is in one constant direction. Now with a car, we want to emulate this strait through flow as much as possible. A boost adder of any kind will greatly affect the flow of air from air filter to exhaust tips. The differences in the overall flow are extremely different for turbos vs PD blowers. How exactly does this affect the tuning? well, I would think it would only really affect the tuning if you are tuning the cam timing. Cam timing affects scavenging, and scavenging is affected by the airflow through the engine.
    Cam timing for a PD system, can be quite complex. There is tremendous gains to be realized if you get it right. Especially intake cam phase. You can control boost pressure with cam timing.

    I disagree that its the same system theory. Turbo setups control boost by modifying the source of energy (exhaust gasses) and how that energy gets turned into boost. This PD blower controls boost by venting it. It has nothing to do with changing what is creating the boost in the first place, therefor the load the supercharger puts on the engine doesn't change, just the pressure in the manifold. Does this actualy affect the tuning? YES. Venting the exhaust gasses reduces the energy going into the turbo, which reduces the speed of the turbo, which modifies the flow volume/velocity of air at the compressor outlet, which lowers the boost in the manifold. Venting charge pressure (PD setup) does just that, vents the charge pressure and reduces boost very quickly. Now I can see how the E-BOV could be controlled similarly to a wastegate, but exactly how you control it is different because the wastegate is the start of a chain reaction in the piping, whereas the E-BOV is nothing of the sort.
    Correct:
    Turbo charges load the motor through pumping loses. Turbine inlet pressure which drives turbine shaft speed / boost, is back pressure. It is a very real pumping loss.

    The TVS / roots does no work internally. It does not compress the charge between the rotors. When it is in Bypass operation, it virtually has NO load, since no work is being done. Other PD blowers are always doing work always compressing, that is why some also have complex drive clutches ( Mercedes ). So if its not making boost, its not drawing power from the crank.


    confused on this statement, can you please explain a bit more thoroughly?

  2. #227
    Join Date
    Jun 2012
    Location
    NJ
    Posts
    4,198
    Rep Points
    1,800.2
    Mentioned
    102 Post(s)
    Rep Power
    19


    1 out of 2 members liked this post. Reputation: Yes | No
    Click here to enlarge Originally Posted by Sticky Click here to enlarge
    Guy is in over his head when he tries to discuss technical aspects it's been a repeat pattern for years. I do not believe he is very educated but it would be great if he did a little more reading and kept great threads like this on topic.
    So instead you ban him from the thread, preventing him from getting any additional information (or potential knowledge) of this setup on the S65 Click here to enlarge
    COBB AP ProTune by Bren of ///Bren Tuning
    Akrapovic DP | Helix FMIC | Alpina TCM Flash | Walbro 450LPH Fuel Pump


    "The moment money becomes your motivation, you are immediately not as good as someone who is motivated by passion and internal will." -A. Senna

  3. #228
    Join Date
    Jul 2011
    Location
    Jerzee
    Posts
    2,306
    Mentioned
    82 Post(s)
    Rep Power
    0


    2 out of 4 members liked this post. Reputation: Yes | No
    So we just banned one person for asking legit questions... DFM and Lost had some good stuff going here without a bunch of sarcasm or ego being involved. Good job on that
    We stay swingin...
    Click here to enlarge

  4. #229
    Join Date
    Mar 2012
    Posts
    515
    Rep Points
    621.9
    Mentioned
    4 Post(s)
    Rep Power
    7


    Reputation: Yes | No
    Click here to enlarge Originally Posted by Sledgehammer Click here to enlarge
    So we just banned one person for asking legit questions... DFM and Lost had some good stuff going here without a bunch of sarcasm or ego being involved. Good job on that
    Agreed.

  5. #230
    Join Date
    Mar 2012
    Posts
    515
    Rep Points
    621.9
    Mentioned
    4 Post(s)
    Rep Power
    7


    Reputation: Yes | No
    Thank you for taking the time to type this outClick here to enlarge

    Click here to enlarge Originally Posted by Jonathan@Aviva Click here to enlarge
    Hey DFM, Ill do my best to expand on some topics. Much respect implied and thank you for your contribution.



    In theory a PD pump / blower has a fixed displacement per revolution, in the same basic theory an engine is the same type of "pump". The TVS is a roots type supercharger with NO internal compression ( as opposed to a screw with an internal pressure ratio and work * back to this later ). The supercharger like an engine has its own volumetric efficiency curve.
    ref:


    Boost response is instant. Sometimes you control / adjust the bypass mechanism with a damper, restrictor orifice or ( digitally damped ) to bring boost on softly. Though this is over fractions of a second. Time-to-torque from driver request to torque at the tire is still instant, even compared to a small turbo setup its drastically noticeable. It's literally instant tire shread.

    Boost curve. Pressure is not necessarily constant over the power band. Refer back to the volumetric map.
    A small supercharger ( relative ) matched to a motor will have a very flat boost profile, for example from 2000-8500 RPM. While a larger supercharge matched to the same motor, with the same peak boost pressure request, will have a more ramped plateau. 60% of peak boost down low, to 100% of peak boost by redline. This is not lag, its just the result of the interplay of rotor speed, supercharger volumetric eff vs rpm, and the engines vol eff. With this charger I'm confident that this will be a complimentary component to the character of the car.

    In summary:
    Boost Threshold : is not a factor with the PD system. Its always able to make positive pressure. While a turbocharger there is only so much potential energy for a certain pressure ratio after a specific RPM point.
    Boost profile : PDs have flat to slightly ramped ( size dependent ) profiles. Superchargers since they are directly coupled to crank speed, have a FIXED boost profile.
    Lag or time to torque : Instant torque, reaches boost threshold immediately. as fast as the bypass valve is allowed to snap shut, Lag is non existent.
    This just confirms, to me at least, that tuning the two FI methods cant be compared with a number. the behavior of the boost curve for a turbo vs a PD blower (especially in the first few seconds after opening the throttle) isn't really comparable. The methods used to get the engine to run smoothly are different, since they depend on much different behaviors of the airflow through the engine. Excellent and easy to read explanation of PD boost response by the way, didn't leave me with many questions.





    Cam timing for a PD system, can be quite complex. There is tremendous gains to be realized if you get it right. Especially intake cam phase. You can control boost pressure with cam timing.
    I certainly don't know the specifics of cam timing for a PD system. Would be interested to know more about this. any good resources you know of?



    Correct:
    Turbo charges load the motor through pumping loses. Turbine inlet pressure which drives turbine shaft speed / boost, is back pressure. It is a very real pumping loss.

    The TVS / roots does no work internally. It does not compress the charge between the rotors. When it is in Bypass operation, it virtually has NO load, since no work is being done. Other PD blowers are always doing work always compressing, that is why some also have complex drive clutches ( Mercedes ). So if its not making boost, its not drawing power from the crank.
    Thank you for clarifying that for me. I should have known that because a friend of mine has a supercharged 4cyl Mercedes w/ a complicated drive clutch. Lets just say when you start changing the crank pulley to get more boost, the drive clutch is unhappy Click here to enlarge

    Since you have a good knowledge base on this subject, do you think you can just put a percentage number on how similar it is to tune a PD vs a Turbo on the S65?

  6. #231
    Join Date
    Jan 2013
    Location
    Netherlands
    Posts
    90
    Rep Points
    118.8
    Mentioned
    0 Post(s)
    Rep Power
    2


    1 out of 1 members liked this post. Reputation: Yes | No
    Click here to enlarge Originally Posted by Jonathan@Aviva Click here to enlarge
    The TVS / roots does no work internally. It does not compress the charge between the rotors. When it is in Bypass operation, it virtually has NO load, since no work is being done. Other PD blowers are always doing work always compressing, that is why some also have complex drive clutches ( Mercedes ). So if its not making boost, its not drawing power from the crank.
    This is imho not an accurate explanation. You make it beleve that other PD compressors (like the twinscrew) are compressing the air (internally) in a situation that it has nowhere to go (and thus costing a lot of energy and creating heat). That is not true. The air is 'squeezed' directly out the outlet (more like a peristaltic kind of way). It flows out immediately. It's compression with a hole (the outlet) at the end Click here to enlarge
    That is no different than taking a pocket of air and transporting it to the outlet (what a rootscompressor does). The efficiency of a bypassed twinscrew or roots/tvs is therefore about the same.
    Clutches are used because transferring air without building pressure also costs some energy as does the movement of the gears/lobes.
    E85 Z4 3.0i | ESS TS2+ | Quaife ATB LSD | Custom Brembo BBK front/rear | Schrick cams | Schmiedmann headers/cats | Powerflex/strongflex/PSB PU bushings | Vibra-technics engine mounts | H&R anti rollbars

  7. #232
    Join Date
    Jan 2010
    Location
    SoCal
    Posts
    117,708
    Rep Points
    31,535.2
    Mentioned
    2064 Post(s)
    Rep Power
    316


    Reputation: Yes | No
    Click here to enlarge Originally Posted by benzy89 Click here to enlarge
    So instead you ban him from the thread, preventing him from getting any additional information (or potential knowledge) of this setup on the S65 Click here to enlarge
    Sometimes it's necessary to keep a thread on course so EVERYONE ELSE can learn without distraction.

  8. #233
    Join Date
    Jan 2010
    Location
    SoCal
    Posts
    117,708
    Rep Points
    31,535.2
    Mentioned
    2064 Post(s)
    Rep Power
    316


    Reputation: Yes | No
    Click here to enlarge Originally Posted by Sledgehammer Click here to enlarge
    So we just banned one person for asking legit questions... DFM and Lost had some good stuff going here without a bunch of sarcasm or ego being involved. Good job on that
    Thread viewing can be lifted it's quite simple I think it's best to let this thread stay on course with the great posts we are getting for now so it does not continue towards OT posts. Thanks for your concern.

  9. #234
    Join Date
    Jan 2010
    Location
    SoCal
    Posts
    117,708
    Rep Points
    31,535.2
    Mentioned
    2064 Post(s)
    Rep Power
    316


    Reputation: Yes | No
    Click here to enlarge Originally Posted by DFM Click here to enlarge
    he behavior of the boost curve for a turbo vs a PD blower (especially in the first few seconds after opening the throttle) isn't really comparable.
    And hence leading to difficulty for the tune.. and the stock rods of course. So this setup is definitely quite different and requires different approaches/tuning.

  10. #235
    Join Date
    Jan 2010
    Location
    SoCal
    Posts
    117,708
    Rep Points
    31,535.2
    Mentioned
    2064 Post(s)
    Rep Power
    316


    Reputation: Yes | No
    Click here to enlarge Originally Posted by Jonathan@Aviva Click here to enlarge
    Cam timing for a PD system, can be quite complex. There is tremendous gains to be realized if you get it right. Especially intake cam phase. You can control boost pressure with cam timing.
    So essentially somebody is doing some heavy VANOS work?

  11. #236
    Join Date
    Jan 2010
    Location
    SoCal
    Posts
    117,708
    Rep Points
    31,535.2
    Mentioned
    2064 Post(s)
    Rep Power
    316


    Reputation: Yes | No
    Click here to enlarge Originally Posted by GuidoK Click here to enlarge
    The efficiency of a bypassed twinscrew or roots/tvs is therefore about the same.
    Based on...? The efficiency of a twin screw over a roots has been shown at high rpm or with high volumetric efficiency whereas a roots tends to have better efficiency at lower boost from every comparison I have seen.

  12. #237
    Join Date
    Jan 2013
    Location
    Netherlands
    Posts
    90
    Rep Points
    118.8
    Mentioned
    0 Post(s)
    Rep Power
    2


    Reputation: Yes | No
    Click here to enlarge Originally Posted by Sticky Click here to enlarge
    Based on...? The efficiency of a twin screw over a roots has been shown at high rpm or with high volumetric efficiency whereas a roots tends to have better efficiency at lower boost from every comparison I have seen.
    There is no buildup of boost in the set example. Basically it's just the moving of the parts (and there's about the same amount in the same configuration).
    So there's no 'internal compression of air' of some sort like what Jonathan@Aviva was making believe (or at least that how I interpreted his post) and that was my point.
    E85 Z4 3.0i | ESS TS2+ | Quaife ATB LSD | Custom Brembo BBK front/rear | Schrick cams | Schmiedmann headers/cats | Powerflex/strongflex/PSB PU bushings | Vibra-technics engine mounts | H&R anti rollbars

  13. #238
    Join Date
    Jan 2013
    Location
    Netherlands
    Posts
    90
    Rep Points
    118.8
    Mentioned
    0 Post(s)
    Rep Power
    2


    Reputation: Yes | No
    Click here to enlarge Originally Posted by Sticky Click here to enlarge
    Based on...?
    Also if you look at performance maps of a lysholm 1600ax vs an eaton m62 (they're the most similar in the lineup in application) the low efficiency regions (you know, pressure ratio's of about 1.1 or 1.2) are about the same. (30 or 40% or so). But still that is not relevant because that is way way more boost than a bypassed compressor. At that point the efficiency would be more like 0% Click here to enlarge
    You absolutely cannot view/read the efficiency or dissipated energy from a compression map for a bypassed compressor, as it would not register (by definition that is)
    E85 Z4 3.0i | ESS TS2+ | Quaife ATB LSD | Custom Brembo BBK front/rear | Schrick cams | Schmiedmann headers/cats | Powerflex/strongflex/PSB PU bushings | Vibra-technics engine mounts | H&R anti rollbars

  14. #239
    Join Date
    Jan 2010
    Location
    SoCal
    Posts
    117,708
    Rep Points
    31,535.2
    Mentioned
    2064 Post(s)
    Rep Power
    316


    Reputation: Yes | No
    Click here to enlarge Originally Posted by GuidoK Click here to enlarge
    Also if you look at performance maps of a lysholm 1600ax vs an eaton m62 (they're the most similar in the lineup in application) the low efficiency regions (you know, pressure ratio's of about 1.1 or 1.2) are about the same. (30 or 40% or so). But still that is not relevant because that is way way more boost than a bypassed compressor. At that point the efficiency would be more like 0% Click here to enlarge
    You absolutely cannot view/read the efficiency or dissipated energy from a compression map for a bypassed compressor, as it would not register (by definition that is)
    I think we may be discussing two different things.

  15. #240
    Join Date
    Jan 2010
    Location
    SoCal
    Posts
    117,708
    Rep Points
    31,535.2
    Mentioned
    2064 Post(s)
    Rep Power
    316


    1 out of 1 members liked this post. Reputation: Yes | No
    Now that we have some real tech discussion going @LostMarine may participate again as I think it would help him to read it.

  16. #241
    Join Date
    Mar 2012
    Posts
    515
    Rep Points
    621.9
    Mentioned
    4 Post(s)
    Rep Power
    7


    Reputation: Yes | No
    Click here to enlarge Originally Posted by Sticky Click here to enlarge
    And hence leading to difficulty for the tune.. and the stock rods of course. So this setup is definitely quite different and requires different approaches/tuning.

    Exactly.

  17. #242
    Join Date
    Jan 2012
    Posts
    5
    Rep Points
    10.3
    Mentioned
    0 Post(s)
    Rep Power
    0


    Reputation: Yes | No
    Click here to enlarge Originally Posted by DFM Click here to enlarge
    Thank you for taking the time to type this outClick here to enlarge
    Always a good time.


    ...Excellent and easy to read explanation of PD boost response by the way, didn't leave me with many questions.

    I certainly don't know the specifics of cam timing for a PD system. Would be interested to know more about this. any good resources you know of?
    I don't know of particular outside sources you can reference. Click here to enlarge


    Thank you for clarifying that for me. I should have known that because a friend of mine has a supercharged 4cyl Mercedes w/ a complicated drive clutch. Lets just say when you start changing the crank pulley to get more boost, the drive clutch is unhappy Click here to enlarge

    Since you have a good knowledge base on this subject, do you think you can just put a percentage number on how similar it is to tune a PD vs a Turbo on the S65?
    I don't think they are remotely similar. From direct experience: it takes less intake manifold pressure to get the same cylinder filling with turbochargers than it does with superchargers. Partly due to preserving the stock intake, and tuned intake manifold. It helps.. a ton. But if you change that advantage ( i don't see anyone boosting the stock m3 plastic plenum chamber ) then I'm not sure. In summary: It is not something similar to compare.

  18. #243
    Join Date
    Jan 2012
    Posts
    5
    Rep Points
    10.3
    Mentioned
    0 Post(s)
    Rep Power
    0


    Reputation: Yes | No
    Click here to enlarge Originally Posted by GuidoK Click here to enlarge
    This is imho not an accurate explanation. You make it beleve that other PD compressors (like the twinscrew) are compressing the air (internally) in a situation that it has nowhere to go (and thus costing a lot of energy and creating heat). That is not true. The air is 'squeezed' directly out the outlet (more like a peristaltic kind of way). It flows out immediately. It's compression with a hole (the outlet) at the end Click here to enlarge
    That is no different than taking a pocket of air and transporting it to the outlet (what a rootscompressor does). The efficiency of a bypassed twinscrew or roots/tvs is therefore about the same.
    Clutches are used because transferring air without building pressure also costs some energy as does the movement of the gears/lobes.
    Sir GuidoK,
    I try to be as accurate in my explanation. I don't mistake my self for any authority.
    Roots type positive displacement superchargers do not internally compress the charge. This is directly opposite of how a twin screw supercharger works. Twin screw SCs have an internal pressure ratio they create as they operate. The charge ( captured ) volume changes between intake and discharge. This internal ratio is a function of the drive ratio and size pair of the mating screws, ONTOP of the external pressure created by the restriction point at the motor.

    The work performed by a bypassed roots and a bypassed twin screw are very different. To eliminate parasitic losses of a twin screw during cursing OEM designers use electronic clutch systems.

    There is more information to be found at EATON.com and other published whitepapers.

  19. #244
    Join Date
    Jan 2012
    Posts
    5
    Rep Points
    10.3
    Mentioned
    0 Post(s)
    Rep Power
    0


    2 out of 2 members liked this post. Reputation: Yes | No
    Q: What’s a Twin-Screw supercharger and how is it different from an Eaton roots type supercharger?
    A: All Eaton superchargers use the roots type supercharging principle. The roots supercharger is a positive displacement pump that moves air in pockets from the inlet to the outlet of the supercharger with no internal compression. The supercharger creates “boost” by moving more air into the intake manifold than the engine is utilizing, thus creating higher than atmospheric pressures in the intake manifold. When boost is not desired on an Eaton roots supercharger, the bypass valve allows the supercharger to spin with negligible parasitic loss as there is no internal compression. The Eaton roots supercharger uses 3 lobe (“M”) or 4 lobe (“TVS-R”) meshing rotors that are similar (but reversed) in geometry. The rotors operate at a 1:1 speed ratio. The Twin-Screw type supercharger is also a positive displacement pump in that it moves a fixed amount of air per revolution. The Twin-Screw uses 2 non-similar screw type rotors that mesh together to compress and move the air pocket axially along the rotors. This internal compression ratio will lead to greater parasitic losses when boost is not required as you cannot turn this compression “off” by simply using a bypass valve. These rotors will have different rates of rotation due to their non-similar geometry and lobe quantity. The rotors of a Twin-Screw will commonly operate at 3:5 and 4:6 speed ratios. This means as the drive rotor spins at 15,000 rpm, the driven rotor will rotate at 25,000 rpm with a ratio of 3:5. This limits the Twin-Screw to lower rpm limits than the roots due to bearing life concerns.

  20. #245
    Join Date
    Feb 2010
    Location
    NJ
    Posts
    13,460
    Rep Points
    58.0
    Mentioned
    318 Post(s)
    Rep Power
    0


    0 out of 2 members liked this post. Reputation: Yes | No
    Click here to enlarge Originally Posted by Sticky Click here to enlarge
    Guy is in over his head when he tries to discuss technical aspects it's been a repeat pattern for years. I do not believe he is very educated but it would be great if he did a little more reading and kept great threads like this on topic.
    lol, your gonna make this fun for me arent ya. ok, challenge accepted, we shall see who the educated one is..

  21. #246
    Join Date
    Feb 2010
    Location
    NJ
    Posts
    13,460
    Rep Points
    58.0
    Mentioned
    318 Post(s)
    Rep Power
    0


    0 out of 6 members liked this post. Reputation: Yes | No

    This post by LostMarine is hidden due to excessive negative ratings. Click expand to view the post.



  22. #247
    Join Date
    Jan 2010
    Location
    SoCal
    Posts
    117,708
    Rep Points
    31,535.2
    Mentioned
    2064 Post(s)
    Rep Power
    316


    Reputation: Yes | No
    Not sure if you guys saw this:

    Click here to enlarge

  23. #248
    Join Date
    Mar 2012
    Posts
    515
    Rep Points
    621.9
    Mentioned
    4 Post(s)
    Rep Power
    7


    Reputation: Yes | No
    wow, no cutting required either. This seems to be a very well engineered product. Looking forward to the results.

  24. #249
    Join Date
    Jan 2010
    Location
    SoCal
    Posts
    117,708
    Rep Points
    31,535.2
    Mentioned
    2064 Post(s)
    Rep Power
    316


    Reputation: Yes | No
    Click here to enlarge Originally Posted by Jonathan@Aviva Click here to enlarge
    Q: What’s a Twin-Screw supercharger and how is it different from an Eaton roots type supercharger?
    A: All Eaton superchargers use the roots type supercharging principle. The roots supercharger is a positive displacement pump that moves air in pockets from the inlet to the outlet of the supercharger with no internal compression. The supercharger creates “boost” by moving more air into the intake manifold than the engine is utilizing, thus creating higher than atmospheric pressures in the intake manifold. When boost is not desired on an Eaton roots supercharger, the bypass valve allows the supercharger to spin with negligible parasitic loss as there is no internal compression. The Eaton roots supercharger uses 3 lobe (“M”) or 4 lobe (“TVS-R”) meshing rotors that are similar (but reversed) in geometry. The rotors operate at a 1:1 speed ratio. The Twin-Screw type supercharger is also a positive displacement pump in that it moves a fixed amount of air per revolution. The Twin-Screw uses 2 non-similar screw type rotors that mesh together to compress and move the air pocket axially along the rotors. This internal compression ratio will lead to greater parasitic losses when boost is not required as you cannot turn this compression “off” by simply using a bypass valve. These rotors will have different rates of rotation due to their non-similar geometry and lobe quantity. The rotors of a Twin-Screw will commonly operate at 3:5 and 4:6 speed ratios. This means as the drive rotor spins at 15,000 rpm, the driven rotor will rotate at 25,000 rpm with a ratio of 3:5. This limits the Twin-Screw to lower rpm limits than the roots due to bearing life concerns.
    Great simple overview here.

  25. #250
    Join Date
    Feb 2011
    Posts
    1,584
    Rep Points
    2,017.3
    Mentioned
    10 Post(s)
    Rep Power
    21


    2 out of 2 members liked this post. Reputation: Yes | No
    All: I just received the latest European Car magazine, and there is an article on the Harrop-charged M3. I guess a guy named Matthew was the first in the US to get the kit installed, so they did an article on it. I can scan the article and throw it up if it's okay with Sticky - not sure if that's "legal". Click here to enlarge

    Nothing much of value in the article that we don't already know though - however, it's still cool to read about. No dyno numbers or anything of this nature - the car is still in a tuning/test stage - however, the way it's worded makes it sound like it's very close to done.

    Very similar horsepower numbers to the other supercharger players in the game, but more torque down low in the range is how the power is rated.

    Cheers.

Page 10 of 12 FirstFirst ... 89101112 LastLast

Tags for this Thread

Bookmarks

Posting Permissions

  • You may not post new threads
  • You may post replies
  • You may not post attachments
  • You may not edit your posts
  •