[JamesNoBrakes]

Yep, I agree that this acticle/text is pretty slanted. Maybe it's from the 1970s too

Originally Posted by rez333

I found this information on the net which answers all my questions (finally!):

Lag
This is perhaps the biggest advantage that the supercharger enjoys over the tubo. Because a turbocharger is driven by exhaust gasses, the turbocharger's turbine must first spool up before it even begins to turn the compressor's impeller. This results in lag time which is the time needed for the turbine to reach its full throttle from an intermediate rotational speed state. During this lag time, the turbocharger is creating little to no boost, which means little to no power gains during this time. Smaller turbos spool up quicker, which eliminates some of this lag. Turbochargers thus utilize a wastegate, which allows the use of a smaller turbocharger to reduce lag while preventing it from spinning too quickly at high engine speeds. The wastegate is a valve that allows the exhaust to bypass the turbine blades. The wastegate senses boost pressure, and if it gets too high, it could be an indicator that the turbine is spinning too quickly, so the wastegate bypasses some of the exhaust around the turbine blades, allowing the blades to slow down..
A Supercharger, on the other hand, is connected directly to the crank, so there is no "lag". Superchargers are able to produce boost at a very low rpm, especially screw-type and roots type blowers.

Kind of, but not really. Lag is not really much of an issue anymore, with twin-scroll turbos, variable vanes, big displacement engines with two smaller turbos (rather than one) and the acceleration/spool up is so fast as to be instantaneous. As a comparission, my SS takes a LOT longer to make decent power and it's "sweet spot" is up very high, but a turbo can hit a lot of torque early. I'd again go to "cost" for the real reason, more expensive to design the turbo, protect it from heat, make sure all the components interact properly, etc.

Efficiency
This is the turbo's biggest advantage. The turbocharger is generally more economical to operate as it as it is driven primarily by potential energy in the exhaust gasses that would otherwise be lost out the exhaust, whereas a supercharger draws power from the crank, which can be used to turn the wheels. The turbocharger's impeller is also powered only under boost conditions, so there is less parasitic drag while the impeller is not spinning. The turbocharger, however, is not free of inefficiency as it does create additional exhaust backpressure and exhaust flow interruption.

It's not just more economical in terms of gas, it will make more power at the same boost levels (internal pressures in the engine), that's a benefit of the efficiency.

Heat
Because the turbocharger is mounted to the exhaust manifold (which is very hot), turbocharger boost is subject to additional heating via the turbo's hot casing. Because hot air expands (the opposite goal of a turbo or supercharger), an intercooler becomes necessary on almost all turbocharged applications to cool the air charge before it is released into the engine. This increases the complexity of the installation. A centrifugal supercharger on the other hand creates a cooler air discharge, so an intercooler is often not necessary at boost levels below 10psi. That said, some superchargers (especially roots-type superchargers) create hotter discharge temperatures, which also make an intecooler necessary even on fairly low-boost applications.

This isn't quite true, that supercharger STILL heats air and puts it into the engine, maybe not as bad as a turbo without an intercooler, but it's also not good for the engine and not near normall-aspirated temps(when air is actually being compressed). I've dealt with a few turbo engines without intercoolers, OMG those things get hot, but still, SC without is also hot. There's also the issue of downstream, the more the turbo is working, the cooler the exhaust is going to the other parts like cats and so on, the intercooler will have a higher chance of melting the cats at the same WHP.

Surge
Because a turbocharger first spools up before the boost is delivered to the engine, there is a surge of power that is delivered immediately when the wastegate opens (around 3000 rpm). This surge can be damaging to the engine and drivetrain, and can make the vehicle difficult to drive or lose traction.

Um, not really, BOV valves and proper tuning/installation mean this isn't an issue. This seems like hyperbole from someone with a poorly tuned blown civic or something.

Back Pressure
Because the supercharger eliminates the need to deal with the exhaust gas interruption created by inserting a turbocharger turbine into the exhaust flow, the supercharger creates no additional exhaust backpressure. The amount of power that is lost by a turbo's turbine reduces it's overall efficiency.

Hmm, I'd assume this is more of a wash if even true, the turbine is harnessing hot exhaust gases, that means you are getting something (compression of air). Hot air comming out the exhaust manifold of the SC engine is not going to cool as it passes a turbine, nor is it going to benefit you in any way once it's left the cylinders.

Noise
The turbocharger is generally quiter than the supercharger. Because the turbo's turbine is in the exhaust, the turbo can substantially reduce exhaust noise, making the engine run quieter. Some centrifugal superchargers are known to be noisy and whistley which, annoys some drivers or makes some very happy!

Hmm, it's maybe a different kind of noise, many turbo systems incorperate "silencers" in the induction to mask the noise, with it removed it's definitely more noisy, then there's the blow-offs and everything. I'd say a little quieter, but when we're really comparing to compressors that can build up to the same boost (usually this is not the case because the SC needs MORE boost to make the same power) they can both be pretty loud.

Reliability
In general, superchargers enjoy a substantial reliability advantage over the turbocharger. When a a turbo is shut off (i.e. when the engine is turned off), residual oil inside the turbo's bearings can be baked by stored engine heat. This, combined with the turbo's extremely high rpms (up to 150,000rpm) can cause problems with the turbo's internal bearings and can shorten the life of the turbocharger. In addition, many turbos require aftermarket exhaust manifolds, which are often far less reliable than stock manifolds.

Kind of, but it's like the top issue: These have been designed arond in most cars, with coolant systems that continue to circulate after shutdown. This is a very strange paragraph anyways, because its not comparing apples to apples, it sounds like comparing a OEM SC to an aftermarket TC, and even if not, it's not like you bolt on the SC and drive away, there's more involved in the install.

Ease of Installation
Superchargers are substantially easier to install than a turbos because they have far fewer components and simpler devices. Turbos are complex and require manifold and exhaust modifications, intercoolers, extra oil lines, etc. - most of which is not needed with most superchargers. A novice home mechanic can easily install most supercharger systems, while a turbo installation should be left to a turbo expert.

Agree

Maximum Power Output
Turbos are known for their unique ability to spin to incredibly high rpms and make outrages peak boost figures (25psi+). While operating a turbocharger at very high levels of boost requires major modifications to the rest of the engine, the turbo is capable of producing more peak power than superchargers.

Not only that, but at the same PSI, you're getting significantly more power output from your engine with a turbo!

Tunability
Turbochargers, because they are so complex and rely on exhaust pressure, are notoriously difficult to tune. Superchargers, on the other hand, require few fuel and ignition upgrades and normally require little or no engine tuning.

I've never agreed with this in the contex of "harder to tune", but this IS the reason they are a bit more expensive. You have to have all the required supporting components (just as you have to for a SC, in fact some of the same components are usually necessary, like intercooler, bigger injectors, higher pressure fuel pump, etc). This gives a tuner what they need to be able to make the system work, and if it's an OEM system, this stuff is usually figured out easily at the factory and designed with safety margins for every possible situation that could be encountered. The reason I disagree with it is that I DID turbo-tuning and I ran just fine with my modificaitons, but I knew my limits.

The end reason is most likely cost and simplicity (which is also cost essentially).