expensive, but sweet....

[lucamabob]

Take a look at this, this is a supercharging system from vortech. It adds 117 horsepower to your engine and is for the 1999-2000 civic Si.

I was wondering if this is a good system, i like turbos. but i prefer the imediate response of superchargers and people say thier easier to maintain.

Heres a link: Click here

[eckoman_pdx]

Originally Posted by lucamabob

Take a look at this, this is a supercharging system from vortech. It adds 117 horsepower to your engine and is for the 1999-2000 civic Si.

I was wondering if this is a good system, i like turbos. but i prefer the imediate response of superchargers and people say thier easier to maintain.

Heres a link: Click here

As has been explained to you in 3 other threads now, the vortec supercharger is a cyntrifigal supercharger. This means you DO NOT GET IMMEDIATE RESPONSE. This system bascially functions like a big turbocharger, expect belt driven. It has a very high rpm power output but produced no power down low. This means, this supercharger effectively has what you know better as TURBO LAG.

The saying superchargers give you immidiate response and turbos produce lag is a board generalization and a commen misconception.

That supercharger may make a lot of power, but you must look at the power curve. It's all up high, much of it a good deal post-vtec crossover. This means, like a big turbo, you have o power increase until you get high in the rpm band when the power kicks in. As I said, this suercharger, and all cyntrifigal superchargers, basically have what you would call "turbo lag."

[got v-tec?]

take a look at this, this is a nitrous system from zex. It
adds 65whp&75wtq@2000rpm's for 99-00civ si
works wonders for low end hp&tq.

[Auto_newb]

Originally Posted by eckoman_pdx

As has been explained to you in 3 other threads now, the vortec supercharger is a cyntrifigal supercharger. This means you DO NOT GET IMMEDIATE RESPONSE. This system bascially functions like a big turbocharger, expect belt driven. It has a very high rpm power output but produced no power down low. This means, this supercharger effectively has what you know better as TURBO LAG.

The saying superchargers give you immidiate response and turbos produce lag is a board generalization and a commen misconception.

That supercharger may make a lot of power, but you must look at the power curve. It's all up high, much of it a good deal post-vtec crossover. This means, like a big turbo, you have o power increase until you get high in the rpm band when the power kicks in. As I said, this suercharger, and all cyntrifigal superchargers, basically have what you would call "turbo lag."

Actually, a centrifugal supercharger has SOME lag, but it's really nothing compared to standard turbos. What the S/c does is that is requires you to be above a certain rpm so the compressor wheel is spinning so fast that no air can escape, much like a fan. You will NOT get full boost until you hit the redline because that is where the engine RPMs spins the fastest, the faster the compressor wheel spins, the more air goes in and the more compressed the air will be (due to the centrifugal force)

When your engine is at low RPMs, the centrifugal will actually steal horsepower because it is a driven accessory and it isn't creating much boost to make up for it.

BTW, power DOES NOT "kick in" AT high rpms, the boost reaches it's maximum at redline.

Anyway, just keep the engine revved above the point where it STARTS giving in boost.

[Auto_newb]

Originally Posted by got v-tec?

take a look at this, this is a nitrous system from zex. It
adds 65whp&75wtq@2000rpm's for 99-00civ si
works wonders for low end hp&tq.

That is crazy, what shot of N2O is it?

[eckoman_pdx]

Originally Posted by Auto_newb

Actually, a centrifugal supercharger has SOME lag, but it's really nothing compared to standard turbos. What the S/c does is that is requires you to be above a certain rpm so the compressor wheel is spinning so fast that no air can escape, much like a fan. You will NOT get full boost until you hit the redline because that is where the engine RPMs spins the fastest, the faster the compressor wheel spins, the more air goes in and the more compressed the air will be (due to the centrifugal force)

When your engine is at low RPMs, the centrifugal will actually steal horsepower because it is a driven accessory and it isn't creating much boost to make up for it.

BTW, power DOES NOT "kick in" AT high rpms, the boost reaches it's maximum at redline.

Anyway, just keep the engine revved above the point where it STARTS giving in boost.

I am well aware of how a cynfriugal supercharger (s/c) works. I tried to explain it shot and in lames terms before. In order for a cytrifugal s/c to create much boost, it must be spun to a critcial speed. Typically, the compressor section much spin in excess of 30,00-60,000 rpms. One of the reasons the power is peaks at the high end andthe boost really doesn't start to be felt until the middle rpm range (near the vtec crossover point on hondas) is due to the nature of how a cyntrifugal s/c works. To prevent overspeeding of the compressor @ high rpms, you must select a step-up gear ratio that won't spin the compressor too fast at the engines max rpm. This is needed since care much be taken to not overdrive the compressor into surge at high engine rpm (where air backs up in the compressor and oscillates violently back and forth in the compressor wheel). This occurs when the engines "swollowig capacity" is exceeded by the compressors output, resulting in air backing up in the intake tract. Because of this, the step-up gear ratio must be used so that the compessor is not spinning so fast as to drive the comperssor into surge @ high engine rpms (as I said above). Due to this, the compressor is spinning nowhere near it's optimal boost producing level in low rpms, though it is at a safe level at the high rpms when the motor peaks (preventing the occurance of surge). This is what cases the resulting "lack of a low end" that cyntrifugal s/c's are known for, and the high peak hp at redline they are also know for.

With a cyntrifugal s/c, like Vortecs B16A kit, it DOES suffer lag comparable to a turbo. In Vortecs B16A kit, the fat part of the boost curve (when you actaully begin to feel the power finally) hits right at the Vtec crossover, which is around 4500-5000rpm. That type of lag IS COMPARABLE to turbo. A smaller ball bearing turbo made for quick spool, like a T3 w/ a 60-62 compressor trim and a .60 housing, using a T25 6-79 turbine and an exhaust housing of T25 .86, has a strong boost onset of around 2000-3000RPM. This turbo can typically produce power numbers in the 200-300HP range on a 1800cc-2200cc motor, like honda B18's and H22's (for a B16A, slightly smallr a/r housings around will result in simlier strong boost onset points). This is BUY FAR much lower rpm for strong boost onset than the centrifugal s/c has, where the strong boost onset typicaly hits around what we know as the vtec crossover point (as I said above), which is abut 4500-5000rpm.

Now turbos with a strong boost onset comparable to the centrifugal s/c like vortecs would be a T04E, 46 trim .50 comprssor housing w/ a T31 76 trim turbine and a T3 .48-.63 exhuast housing a/r will have a strong boost onset of around 4500-5000 rpm, very similer to the Vortec s/c's "strong boost onset and lag. A turbo like this should be able to produce 220-350 hp (I could have found a turbo combo with a little less spool time and a higher approx HP potential than this one, but chose to use on where the range was right near the cyntrifugal s/c like votrecs for comparitive purposes).

Now, if you want a turbo with a slightly high boost onset than an typical s/c (like vortec's, which has a strong boost onset of around 4500-5000rpm), a turbo with a T04E, 60 trim .60 compressor housing, a T350 76 trim turbine and T3 .82 exhuast housing a/r, will have a strong boost onset of around 4500-6000 rpm. Now the low and middle end of this range is still within the cyntrifugal s/c like vortecs strong bost onset range, but the higher part of the range is indeed higher. However, a turbo combo like this has an approx power potential of 400-500 rpm, which is a full race combination type of turbo with a much higher potentail for power then the vortec cyntrifual s/c.

[Auto_newb]

Hmm I didn't really know that a centrifugal s/c could have the same lag comparable to a turbo, but it can't really be compared to turbo lag, because turbo lag is load dependant or dependant on the amount of heat/exhaust being pushed out the engine, the S/C is RPM dependant, it really depends how fast you reach the 5000 RPMS or whatever.

BTW, if it takes that much RPMs maybe it's because it sucks?

[eckoman_pdx]

Originally Posted by Auto_newb

Hmm I didn't really know that a centrifugal s/c could have the same lag comparable to a turbo, but it can't really be compared to turbo lag, because turbo lag is load dependant or dependant on the amount of heat/exhaust being pushed out the engine, the S/C is RPM dependant, it really depends how fast you reach the 5000 RPMS or whatever.

BTW, if it takes that much RPMs maybe it's because it sucks?

No, turbo lag IS ALSO RPM DEPENDANT!!! I really shouldn't be called turbo lag, it should be called boost lag, since that's really what it is, it's the lag until the onset of boost occurs.

First off, just cuz it takes longer "doesn't mean it sucks." Not all turbos are the same size. Bigger turbos like a full on race one can create much more power because they are bigger, allowing them to flow much more air. This bigger physical size, amoung other things, means it takes longer for the pressure (boost) to built up so that the extra power is felt.

It takes until a certain rpm for the exhaust gases to exit the motor and spin the compressor of the turbo fast enough towards the critical speed of the turbo that a strong boost onset occurs. The rpm this occurs at is dependant on many factors, compressor and exhuast housing size, the turbine size and design, etc. For example, in the smaller turbo in my first example above, the rpm at which the exhaust exiting the motor begins to spin the compressor fast enough that a strong boost onset occurs at around 2000-3000rpm. This is dependant on the RPM, not the heat of the exhaust. The rpm of the motor must be enough that the air exiting the motor spins the turbine fast enough that an onset of boost occurs.

This is same reason lag occurs in the cyntrifugal s/c, except with a cyntrifugal s/c the engine rpm must be fast enough that it spins the shaft fast enough so that the compressor can compressor enough air to cause a "strong onset of boost."

With a turbo, the engine rpm must be fast enough so that the exhaust exits the motor fast enough to spin the turbines fast enough so that the compressor can compressor enough air to cause a "strong onset of boost."

With both, the both a s/c and a turbo, this "boost lag" is rpm dependant. With a turbo, the lag depends on the turbos design. Turbos designed to produce 500HP will flow a lot more air than one than is designed to produce 300HP. Thisextra size and airflow required to make extra power also results in more boost lag however. It doesn't suck. It's just a trade off. That's why when you ask "what turbo should I get," people will always want to know what you are playing to use the car for after the turbo is installed, and what your power goal is.