vortech sc?
11-01-2001, 04:49 PM
#11
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Originally posted by RicePimp
The complicated part of a roots system vs. a centrifugal system in an s2000 is that you would need to machine a new intake manifold. An intercooler would also have to be built into the manifold, and would be much harder to just slap on, like you can do with a centrifugal blower or a turbo. This is no different than what jackson racing does for all of its existing systems. Once a system is actually engineered it would pretty much bolts on just like a centrifugal blower, except that it replaces your intake manifold, and you have to reinstall you fuel system/injectors. Quite a bit less complex than a turbo system, where you need to install headers and piping in addition to the turbo itself. I'm guessing that the biggest reason that Jackson Racing isn't doing an s2000 kit is lack of volume compared to things like civics and preludes, but that's just a guess.
Also, I'm sure that bgrubin was referring to the newer roots designs such as the eaton and whipple blowers, which use screw shaped designs for the pump itself. These are actually more efficient than a centrifugal SC or a turbo. In theory, the numbers look really good, so it would be cool to see what they are capable of in the real world on an s2000.
The complicated part of a roots system vs. a centrifugal system in an s2000 is that you would need to machine a new intake manifold. An intercooler would also have to be built into the manifold, and would be much harder to just slap on, like you can do with a centrifugal blower or a turbo. This is no different than what jackson racing does for all of its existing systems. Once a system is actually engineered it would pretty much bolts on just like a centrifugal blower, except that it replaces your intake manifold, and you have to reinstall you fuel system/injectors. Quite a bit less complex than a turbo system, where you need to install headers and piping in addition to the turbo itself. I'm guessing that the biggest reason that Jackson Racing isn't doing an s2000 kit is lack of volume compared to things like civics and preludes, but that's just a guess.
Also, I'm sure that bgrubin was referring to the newer roots designs such as the eaton and whipple blowers, which use screw shaped designs for the pump itself. These are actually more efficient than a centrifugal SC or a turbo. In theory, the numbers look really good, so it would be cool to see what they are capable of in the real world on an s2000.
Eaton blowers (which I refer to as roots-style) are more efficient than vortech or paxton centrifugal blowers. In heat and parasitic drag vs. pressure.
Whipple/Lysholm (twin screw) are more efficient than Eaton in both ways as well.
You guys honestly think JR isn't making an S2K eaton blower kit because it is somehow more complicated than any other kit they make? Bzzt. Sorry, try again. It's simply a question of volume. Not enough S2K's are made and modified yet. Jackson follows a supply/demand curve just like they should.
I'd also love to hear how you figure that the comptech "kit" is less complicated than any eaton-based JR "kit".
Talk about getting facts right.
Cheers,
Ben
11-02-2001, 01:54 AM
#15
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[sitting down in armchair}
I've always wondered why Comptech used a Paxton-based centrifugal SC unit for the S2000 when their NSX unit is Roots-type. I would have thought that the positive-displacement design would compliment the peaky nature of the F20C very nicely.
[standing up]
I guess whe'll have to wait until someone develops a Roots or Whipple/Lysholm style system for the comparison. I would hope that in a few more years there will be well developed turbo and positive displacement type SC systems in addition to the centrifugal SC designs on the table right now.
I've always wondered why Comptech used a Paxton-based centrifugal SC unit for the S2000 when their NSX unit is Roots-type. I would have thought that the positive-displacement design would compliment the peaky nature of the F20C very nicely.
[standing up]
I guess whe'll have to wait until someone develops a Roots or Whipple/Lysholm style system for the comparison. I would hope that in a few more years there will be well developed turbo and positive displacement type SC systems in addition to the centrifugal SC designs on the table right now.
11-02-2001, 02:25 AM
#16
Originally posted by CoralDoc
[sitting down in armchair}
I've always wondered why Comptech used a Paxton-based centrifugal SC unit for the S2000 when their NSX unit is Roots-type. I would have thought that the positive-displacement design would compliment the peaky nature of the F20C very nicely.
[standing up]
I guess we'll have to wait until someone develops a Roots or Whipple/Lysholm style system for the comparison. I would hope that in a few more years there will be well developed turbo and positive displacement type SC systems in addition to the centrifugal SC designs on the table right now.
[sitting down in armchair}
I've always wondered why Comptech used a Paxton-based centrifugal SC unit for the S2000 when their NSX unit is Roots-type. I would have thought that the positive-displacement design would compliment the peaky nature of the F20C very nicely.
[standing up]
I guess we'll have to wait until someone develops a Roots or Whipple/Lysholm style system for the comparison. I would hope that in a few more years there will be well developed turbo and positive displacement type SC systems in addition to the centrifugal SC designs on the table right now.
Yes, the fact that Comptech had the "right" stuff in their toolbox and at their disposal, but went out of their way to procure the "wrong" stuff has got to be a clue that shouldn't be ignored.
We can sit around (in our arm-chairs) all day long bench racing compressor efficiencies while ignoring real issues like air metering technique (before or after the compressor) ........ plumbing issues (you ever thought about intercooling a Roots Type, what a pain)...........cantilevered drive loads........ availability .......durability ........lalala.... the entire package.
If the selection is made purely on compressor pumping efficiencies then the arm-chair tuner just demonstrated his true ignorance.
11-02-2001, 03:53 AM
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>>The biggest (only?) advantage over a turbo would that there is no lag. <<
Sometimes turbo lag is more of a subjective problem than a get the car moving issue. It's possible to have a "low-lag" device like a centrifugal SC feel better yet be slower than turbo. Suppose at some lower RPMs the SC guy can get 1-2 psi at will. Just floor it. Suppose an 8 psi turbo can essentially instantly provide about 3-4 psi and then quickly but noticeably build to 8 psi. At all times it would be faster, yet the thottle response issue could bother some. It is certainly possible to design very low lag turbo rigs these days. Some folks feel that S2K has built in lag cuz you gotta build revs or downshift to get the most oompth. To me, from looking at the turbo S2Ks torque curve, it seems like it would be very nice to drive, even up a gear or two from optimum.
Stan
Sometimes turbo lag is more of a subjective problem than a get the car moving issue. It's possible to have a "low-lag" device like a centrifugal SC feel better yet be slower than turbo. Suppose at some lower RPMs the SC guy can get 1-2 psi at will. Just floor it. Suppose an 8 psi turbo can essentially instantly provide about 3-4 psi and then quickly but noticeably build to 8 psi. At all times it would be faster, yet the thottle response issue could bother some. It is certainly possible to design very low lag turbo rigs these days. Some folks feel that S2K has built in lag cuz you gotta build revs or downshift to get the most oompth. To me, from looking at the turbo S2Ks torque curve, it seems like it would be very nice to drive, even up a gear or two from optimum.
Stan
11-02-2001, 04:00 AM
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>>Someone remind me why companies produce systems around these units? Oh yeah.. they're cheap. <<
They are also an excellent match for old tech motors. Those that are very strong in the low to mid range and then fade when revved. Cuz the limitations of the motor are covered up by the centrifugal sc and vice versa. Such cars wind up with a MUCH flatter torque curve over an extended RPM range when cent. SCed.. A peakier car might be best served by a different approach.
Or to put it another way... An sc car would need very high peak HP numbers to accelerate as well as a turbo or non centrif SC car with significantly lower numbers. Huh? It's called area under the curve folks.
Stan
They are also an excellent match for old tech motors. Those that are very strong in the low to mid range and then fade when revved. Cuz the limitations of the motor are covered up by the centrifugal sc and vice versa. Such cars wind up with a MUCH flatter torque curve over an extended RPM range when cent. SCed.. A peakier car might be best served by a different approach.
Or to put it another way... An sc car would need very high peak HP numbers to accelerate as well as a turbo or non centrif SC car with significantly lower numbers. Huh? It's called area under the curve folks.
Stan
11-02-2001, 07:41 AM
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My theory on why we keep getting centrifugal SC instead of something better: Centrifugal SC build boost in a highly nonlinear manner, yielding big boost near redline, but no boost at low rpms and very little boost at midrange. This makes it easier for companies to throw together a kit which works with our ECU...they only have to worry about making it work in a small range of rpms.
Note that Comptech threw in the towel on trying to use more boost because they didn't want to deal with fuel management issues.
If someone made a positive displacement SC, they would have to make it work at all rpms, VTEC and non-VTEC, 1500rpms and 9000rpms. If existing SC go for $4500 and Derryck's turbo goes for $6500, there isn't much pricing room to earn back the engineering costs to make it work.
My opinion.
Tanq
Note that Comptech threw in the towel on trying to use more boost because they didn't want to deal with fuel management issues.
If someone made a positive displacement SC, they would have to make it work at all rpms, VTEC and non-VTEC, 1500rpms and 9000rpms. If existing SC go for $4500 and Derryck's turbo goes for $6500, there isn't much pricing room to earn back the engineering costs to make it work.
My opinion.
Tanq
