Undecided...What's the best SC kit for a '91GT?
12-05-2009, 01:20 PM
#32
Nordschleife Master
How about this one?
That is a CS style SC drag cars.
And I have seen tons of mustangs etc using these, and other type of CS style SC at the drag races.
That is a CS style SC drag cars.
And I have seen tons of mustangs etc using these, and other type of CS style SC at the drag races.
12-05-2009, 02:06 PM
#33
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This one runs a CS
http://www.audiracing.co.uk/
This one is Turbo'ed
http://www.redvictor1racing.co.uk/
12-05-2009, 02:43 PM
#35
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Canuck,
I think you need to do some more research.
Twin screw (TS) and roots are nearly the same but the twin screw has odd number vanes and they are twisted. They have a high efficency over the roots style because of this. The other main difference is that the roots provides the boost in pulses, where as the twin screw provides a more constant stream of boost. Both of these SC are great for low RPM power, In higher RPMs they fall off quickly compaired to a Centrifugal (CS) style SC.
A CS SC is basically the compressor side from a turbocharger which is being driven by the crank through gear changes to get the impellor speed fast enough to produce a charge. These tend to not create as much off the line power like the TS, but provide more power in the upper RPM ranges. If you want more HP a CS is more preferable over a TS.
If I were to boost an auto 928 that was to be driven every day, I would probably go the TS route myself.
For absolute power though, or a track car, I would never use anything but a Turbocharger.
I think you need to do some more research.
Twin screw (TS) and roots are nearly the same but the twin screw has odd number vanes and they are twisted. They have a high efficency over the roots style because of this. The other main difference is that the roots provides the boost in pulses, where as the twin screw provides a more constant stream of boost. Both of these SC are great for low RPM power, In higher RPMs they fall off quickly compaired to a Centrifugal (CS) style SC.
A CS SC is basically the compressor side from a turbocharger which is being driven by the crank through gear changes to get the impellor speed fast enough to produce a charge. These tend to not create as much off the line power like the TS, but provide more power in the upper RPM ranges. If you want more HP a CS is more preferable over a TS.
If I were to boost an auto 928 that was to be driven every day, I would probably go the TS route myself.
For absolute power though, or a track car, I would never use anything but a Turbocharger.
So now I am just a bit curious...
Is what you're saying that a TS prepared motor (any motor) cannot make as much power at higher RPM as a CS motor?
This is absolute lunacy.. How can you even state such stuff..?
The output of the motor (any motor) depends on how the motor is prepared, and compressor's abiity to move air (Mass air flow rate, Kg/hr or #/hr). If you needed more power at higher RPM from a TS, just get a bigger compressor, and change the pulley ratio so you don't over drive the compressor at your desired RPM, and problem solved..
What about this is so difficult to understand? The output is dependent on the RPM of the compressor, and its ability to move air mass. It is actually true for any compressor, yes, turbo, TS, CS, ROOTS, SCROLL, any...
I'm not trying to be an a$$ about this, nor am I trying to preach to any of you, but the truth is just that opinions and fact are really sometimes not on the same planet.
Guys, get real here..
12-05-2009, 02:53 PM
#36
Nordschleife Master
You are correct on the sizing of the units Richard. But each unit does have its own area that it works best. And for the "kits" that are out there for these cars, the TS tends to start falling off where the CS units start to take off.
but what I am saying is that taking a TS vs a CS style of SC the CS will (on average) produce greater peak HP numbers, where the TS will produce better peak TQ numbers.
but what I am saying is that taking a TS vs a CS style of SC the CS will (on average) produce greater peak HP numbers, where the TS will produce better peak TQ numbers.
12-05-2009, 04:08 PM
#37
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12-05-2009, 05:08 PM
#38
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You are correct on the sizing of the units Richard. But each unit does have its own area that it works best. And for the "kits" that are out there for these cars, the TS tends to start falling off where the CS units start to take off.
but what I am saying is that taking a TS vs a CS style of SC the CS will (on average) produce greater peak HP numbers, where the TS will produce better peak TQ numbers.
but what I am saying is that taking a TS vs a CS style of SC the CS will (on average) produce greater peak HP numbers, where the TS will produce better peak TQ numbers.
I understand what the point is that you're trying to make, in that based on the current offering of forced induction "kits" currently available for the 928, the CS kits show peakier data than the current TS "kit."
However if both of the kits are examined in detail, and the components analyzed, there are several things that become quite apparent. The list is extremely long, and this is why i have designed, and am currently building my own setup.
Anyway, back to comparing apples to apples.. For any of the current kits, look at the dynamometer charts, and cross correlate the compressor wheel speed, and the mass air flow it is producing, and you will see that there will be in fact a linear relationship between engine speed and compressor flow rate based on the output flow map of the compressor. Excluding turbos, as the rate will not be linear to engine speed. However, there will still be a direct relationship on the speed of the compressor wheel to the amount of air the compressor is moving. (Any compressor flow chart/map will give this information.)
Therefore, if may be fair to say that some ROOTS applications (such as the Eaton 112) will encounter boost (pressure) drop off at certain compressor speed, but that will not give you meaningful data unless you are abe to determine air flow rate. Pressure is resistance to flow, and unless MORE air is supplied by the compressor, more power will not be made in an equally prepared motor.
The Autorotors/Lysholm TS units do not suffer this problem. There are several reasons why is may be happening on the the current "kits," and that has to do with the design of the kit, and not the compressor. Most of the TS kits are using the Autorotor MX422 (2.2L)compressor, and DR told me his setup was using the MX417 (1.7L). I have seen Louie's friend's car (the red SC'd GT)with an MX424 (2.4L). All these Autorotors have internal pressure ratios of 1.1 to 1.2, and this also affects the compressor's ability to move air. Further, the max recommended compressor speed is 15,000 RPM with no reduction in flow.
If you have a pulley ratio of 2:1 SC:Crank, then it means the motor could spin to 7,500 RPM, and the compressor will flow air all the way to the 7,500 RPM engine/ 15,000 RPM TS compressor limit and not lose any flow.. Granted, most 928's are at 6500 RPM, and not 7,500 RPM.
With the CS kits, IIRC the compressor is a Vortech V1/T1, and looking at that flow map will againtell you how much air it can move and at what compressor RPM. If you go through the calculation, you can again find the flow rate and engine speed based on pulley ratio as I did above.
So, my point is that even for the current "kits" although the dynamometer charts show peakier numbers for CS kits VS TS kits, it may not be the compressor that is causing this. I am not going to give the thing away, but I am absolutely sure it has more to do with "kit" design than anything else. There is no reason why a 928 TS setup with an Autorotor MX422 should not be able to make the same peak number as a CS V1/T1 compressor, and have a wider torque curve which actually means the motor will be producing more power across the entire powerband, and not just at the peak. The devil of course is in the details, and the design of the setup.
All the compressor is doing is pumping air, if the same amount of air is being moved by both a TS and CS compressor, then the same motor should produce the same power at the corresponding mass airflow point.. The engine has no idea what kind of compressor is pushing air into the ports, just how much....!
Enough with my rambling...!
Have a great day!
12-05-2009, 05:38 PM
#39
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You hit that nail square on the head, that's for sure.
Any "kit" is going to be a compromise in some way. That is why we have guys like Louie, Greg, Todd etc... pushing the envelope further than any bolt on kit could realistically do.
Todd's car is making over 700rwhp with a relatively stock motor and a centrifugal supercharger. Problem is to reach the state of perfection in the tune he has, requires some extensive data logging and more hours on the dyno than most people spend driving their cars. His setup is repeatable (there are 2-3 in the works) it's not a "bolt on" like the Murf928 setup.
And a nice rant it was
Speaking of "fastest cars" with a centrifugal supercharger, here are a few.
Words Fastest pump gas car - Nova with a Procharger 8.18ET @ 170MPH:
http://www.procharger.com/chevy_nova.shtml
Well, not fastest anymore, recently beat by a T-Bird with a Procharger 7.957 @ 182mph
http://www.procharger.com/supercharger/blog/?p=88
Worlds fastest Mustang.....with a Procharger: "Sonic Blue SVT Cobra is equipped with a 32 valve DOHC V-8 Iron 5.0 Boss from Ford Racing, and although heavily modified, remains legally licensed and inspected for highway driving."
http://landspeedmustang.com
It's holds more than a few records
Worlds fastest Camaro:
http://www.procharger.com/supercharger/blog/?p=49
Drag Radial Record:
http://www.procharger.com/supercharger/blog/?p=62
2,000hp on Pump Gas? Hey check that out, Centrifugal Supercharger:
http://www.procharger.com/supercharger/blog/?p=50
Yup, nobody builds drag cars with Centrifugal Superchargers.....except these guys
http://www.smreperformance.com/
Yes I realize not all of these are drag cars. I thought I would post them all before someone says: "Yea, but what about top speed....." So I covered that too.
I love these threads!!!!
I'll give the turbo guys some press. Worlds fastest Viper (on pump gas) has two huge exhaust driven hair dryers up front.
7.993 @ 183.10 - .......slower than the T-Bird posted above
http://www.dpccars.com/car-videos-08...n-Pump-Gas.htm
Any "kit" is going to be a compromise in some way. That is why we have guys like Louie, Greg, Todd etc... pushing the envelope further than any bolt on kit could realistically do.
Todd's car is making over 700rwhp with a relatively stock motor and a centrifugal supercharger. Problem is to reach the state of perfection in the tune he has, requires some extensive data logging and more hours on the dyno than most people spend driving their cars. His setup is repeatable (there are 2-3 in the works) it's not a "bolt on" like the Murf928 setup.
And a nice rant it was
Nothing to support my info? Go to any dragstrip on any weekend and see how many guys are running Centrifugal....if you can find any!
Two of the fastest genuine street cars in the world. Both run 7's at 180mph+ . No engine rules,free choice of TS,CS or turbo or anything else.
This one runs a CS
http://www.audiracing.co.uk/
This one runs a CS
http://www.audiracing.co.uk/
Words Fastest pump gas car - Nova with a Procharger 8.18ET @ 170MPH:
http://www.procharger.com/chevy_nova.shtml
Well, not fastest anymore, recently beat by a T-Bird with a Procharger 7.957 @ 182mph
http://www.procharger.com/supercharger/blog/?p=88
Worlds fastest Mustang.....with a Procharger: "Sonic Blue SVT Cobra is equipped with a 32 valve DOHC V-8 Iron 5.0 Boss from Ford Racing, and although heavily modified, remains legally licensed and inspected for highway driving."
http://landspeedmustang.com
It's holds more than a few records
Worlds fastest Camaro:
http://www.procharger.com/supercharger/blog/?p=49
Drag Radial Record:
http://www.procharger.com/supercharger/blog/?p=62
2,000hp on Pump Gas? Hey check that out, Centrifugal Supercharger:
http://www.procharger.com/supercharger/blog/?p=50
Yup, nobody builds drag cars with Centrifugal Superchargers.....except these guys
http://www.smreperformance.com/
Yes I realize not all of these are drag cars. I thought I would post them all before someone says: "Yea, but what about top speed....." So I covered that too.
I love these threads!!!!
I'll give the turbo guys some press. Worlds fastest Viper (on pump gas) has two huge exhaust driven hair dryers up front.
7.993 @ 183.10 - .......slower than the T-Bird posted above
http://www.dpccars.com/car-videos-08...n-Pump-Gas.htm
12-05-2009, 06:03 PM
#40
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Stop putting a "c" in my name, your upsetting the Norwegian Gods.
12-05-2009, 07:31 PM
#41
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Here is the more important question:
If he wanted to order one of these "kits" for his 928, which one would ship out the same week, and he could be installing it the next weekend?
You could say that any one of these systems is better for any number of reasons. Top horsepower, top torque, best price, worst price, etc... But it seems like only the MURPH systems are ready to ship when you place an order...
If he wanted to order one of these "kits" for his 928, which one would ship out the same week, and he could be installing it the next weekend?
You could say that any one of these systems is better for any number of reasons. Top horsepower, top torque, best price, worst price, etc... But it seems like only the MURPH systems are ready to ship when you place an order...
12-05-2009, 10:55 PM
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I will put in my two cents when it comes to blowers. Not saying one is better than the other as my experiance is w/ roots style and TS. I modified Thunderbird supercoupes for years. The TS out performeded the roots style blower which is no surprise. The point I am trying to make is that the TS never even comes alive until 17lbs and ran best at around 19 to 20lbs.
Running a TS between 5 and 9lbs is fun but you are leaving so much on the table. Build a proper shortblock and turn the boost up and then you will see what a twinscrew can do. The hp will not drop off!
Stephen
Running a TS between 5 and 9lbs is fun but you are leaving so much on the table. Build a proper shortblock and turn the boost up and then you will see what a twinscrew can do. The hp will not drop off!
Stephen