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to me, i think that a supercharger puts out more hp then a turbo can and it kicks in faster instead of lagging like a turbo.. my question to you guys are why everybody is fussing about a turbo and not a supercharger?? i emailed vortech like 4 times for them to produce or plan on doing one for a 2k1 civic but i had no replies yet..so my Q is Why Turbo and not supercharger???

 
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basically both a turbo and supercharger are Forced Induction meaning they force feed more air into your engine. But where a turbo runs on vaccum from your exhaust gasses, a supercharger is belt driven meaning that it robs your engine of power in order to produce more. Cars that are really torquey like alot of domestics benefit from superchargers, but most four cylinder engines can gain more power from a turbo. So basically, the main reason is that a 1.7 L d series motor does not have the power to make a supercharger work. So the question you should ask yourself is, what would be more power efficient for my particular motor? By the way, next time do a search.

 
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I'm not sure a SC would produce more HP than a Turbo. SC might be better in that they don't have lagging, but then again, you first loose some power on the drive belt. I personally would go for SC.
As for both systems on our 2k1. There's just not enough room for a SC in our cars. Technically everything's possible. Solving the fuel return issue for the Turbo is what's being done right now. But I don't think anyone is trying to fit a SC in there yet. I would think that's so much more complicated and would need some pretty heavy modifications. The scene is screaming for this, so perhaps. You never know.

 
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But you also have to remember that this is no ordinary drive belt. It takes ALOT to run a Forced Induction system. Its not like hooking up an accessory belt. A supercharger would drain so much from the motor, that the end benefit would not be worth it in the long run. If superchargers were always so much better on every application, then you wouldn't see turbos on supras, imprezas, and the like.

 
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Here, before we go any further read this:

The major difference is in the drive system of the 2 systems. A turbocharger's compressor section is connected directly by a shaft to the turbine housing. The turbine is the portion of the turbo that takes exhaust energy (heat and pressure) and converts it to motion. Since the turbine and the compressor are connected by a shaft, the compressor spins at the same rate as the turbine.

On a supercharger, the compressor section is connected to a step up mechanism (gears, belts, pulleys or whatever) and then to the engine drive belt. The step up mechanism is required to convert the 6000 (or so) engine rpm, to the 40,000+ rpm necessary to build boost.

Centrifugal compressors build boost as rpm increases in close to an exponential fashion. Turbo's come up to speed very quickly (almost instantly if properly sized), and once a desired boost level is reached, excess exhaust gas is bypassed around the turbine by a 'waste gate'. What this does is limit the speed of the compressor (and turbine) and therefore boost. The point where the waste gate opens can be set so as to produce a desired rpm and boost level. With a turbo then, as soon as there is sufficient exhaust flow, the turbine will come to speed, and you can have full boost within a fraction of a second. A properly sized turbo can achieve its maximum boost setting at almost any rpm you desire, on a 6000rpm motor, this can be as low as about 2500rpm.

A supercharger on the other hand relies on engine rpm to come up to speed, so maximum boost wont 'come on' until higher rpm. If you buy a supercharger marketed as an 8psi kit, that generally is the maximum boost on a stock engine. But due to it exponential nature, boost will quickly drop with rpm. If our kit makes 8 psi at 6000 rpm, it will generally make less than 2.5 psi at 3000rpm.

So far we have seen that due to the nature of the centrifugal compressor design, a turbo will reach its target boost level much quicker than a belt driven supercharger. Are there any other differences?

It takes power to pump (compress) a large volume of air (700+cfm). The supercharger's power is derived directly from the crank shaft, where as a turbo's power comes from energy contained in the exhaust gasses. On a typical 8 psi supercharger, the power used can be in the neighborhood of 40-60hp! On a 1500hp engine, the power used by the supercharger can be as much as 300hp! This would leave only 1200hp to accelerate the car.

A turbo is not entirely 'free' horsepower as some additional back pressure is created by the turbine, but a turbo derives a very large portion of its energy from heat. This is shown by the fact that exhaust gas temperature can drop by as much as 300 degrees Fahrenheit as it leaves the turbine housing. In essence the power 'robbed' by the extra back pressure is very small (also due to other more 'complicated' factors like critical exhaust flow, but we wont get into that here).

So what does this all mean? Basically an 8 psi turbo kit will produce more peak power due to the fact that a supercharger is using a fairly large amount of power just to get it spinning. What is more important for a street car is 'power under the curve' meaning the average horsepower produced. This is where the turbo really shines since you can have full boost at as little as 2500 rpm! This will make the turbo car feel like it has 50% more cubic inches (or more). The difference in torque at low rpm's can be as much as 100 lb ft in favor of the turbo due to the additional available boost....now that's performance!


So if you can read, turbo is more efficient, but it's also a touchier setup. That's why a supercharger is used a times, in order to avoid the use of wastegates, blowoff valves, intercoolers, turbo timers etc. etc.

One person to ask more about on this subject is Grey. Although I think I covered it...

 
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As a mechanical engineer I can assure you that turbos are a tad more efficient (around 72% vs. 55-65%).

I would like to state that turbo's still take a near equivalent whack of power to operate (both by driving up the temperature at the turbo inlet side (which affects the thermodynamic cycle of the engine) and by increasing backpressure) Turbos are NOT free, that is a misnomer and anyone who thinks so needs to take a thermodynamics course.

NOW....from an overall standpoint (excluding the physical workings of said devices) it is usually a matter of personal preference!

I think Car and Driver once did a survey on whether you were a supercharger or turbo fan.
They summed it up quite nicely........

Circle one:

a) I like sudden "rip your head off" acceleration with throtle tip in.
b) I prefer to wait several seconds before my head is ripped off.

Personally, I circle A.....every time.
I like big smokey burnouts and power curves that feel like the car has at least 2 cylinders more.

 
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There are advantages and disadvantages to both setups.

A supercharged D17 engine is still capable of gaining power from a header (for example). The air you force into the engine is also not as hot as that of a turbo's. You can still have an intercooler (aftercooler) in a supercharged engine. It's just that the intercooler would have to go after the supercharger. I don't think that I've seen a setup like this yet. The supercharger would have to be relocated to be farther away from the throttle body. Then you'de need to route the charge pipes through an intercooler and back into the throttle body. Since compressed air is automatically hotter than ambient an air-to-air intercooler will work nicely.

Of course, a turbocharged engine doesn't require any belts or gears. The turbine wheel spins due to a difference in temperatures betwean the exhaust gases and the ambient air (I think?). This in turn spins the compressor wheel and compresses the intake charge. Too much compression activates the BOV. Too much heat activates the wastegate (heat -> turbine -> compressor -> boost). All of the energy in the heat that would normally be wasted by being ejected out the tailpipe is converted into boost. A supercharged engine wastes this energy just like a NA engine.

I guess the ultimate boost solution would be something that had all of the advantages of both a turbocharger and a supercharger. Maybe an electric compressor driven by the energy that's wasted in the heat of the exhaust gases. Now that would be something!

 
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Grey..or like some crafty euro folks do..use a small eaton supercharger..which provides boost from idleto 3000Rpms..then Bypasses itself. And have a large turbo which doesn;t kick in untill 3000Rpms..

It's a cheat to bear turbo lag from large turrbo chargers.. Also some draggers with small displacement engines and high boost pressures come off the line firing a 50-100 Shot of nitrous to compensate for low compression and no boost at launch..

Cheers
Mohawk

 
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Re: I don't think that I've seen a setup like this yet

The ford thunderbird SC and XR7 used an supercharged and intercooled v6.

Thrasher also makes a liquid intercooler for the L67 i think it's www.tep.com

 
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jackson makes a water injection kit to cool their superchargers - it basically just sprays a light mist out.

 
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This is one of the questions for the ages .................

 
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vortech makes a supercharger with an aftercooler for the B series engines

 
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we are talking about the 7th gen civic

 
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we are talking about the 7th gen, but he was just pointing out that a low torque, but respectable motor such as the b series can run a supercharger. Just keep in mind though, that a turbo will be much more effective. At least from what I have seen and understand....