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Saving the world one leg at a time!
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Discussion Starter · #1 ·
I understand superchargers for the most part, but what would be the benefit of a turbo for the Mag instead? What are the pros and cons of each? Which would you rather have and why?
Thanks from those of us wanting to know more!
 

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LX Goo'Roo
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I thought this was an intelligent (albeit biased?) article regarding this subject. Source at the bottom of article. (I reformatted for readability purposes)

Forced Induction: The Eternal Struggle for Superiority
Between Supercharging and Turbocharging


Introduction

So, you just went out and bought the fastest car made by your favorite manufacturer. You paid a whole year's worth of your salary on this one car, so it must be the best car ever made. You pull out of the dealership and on to the street. You get up to a red traffic light and stop. Another "sports car" pulls up next to you. "Excellent," you think to yourself, "I'll show this guy what this car can do." You rev your engine and he returns the gesture. The light turns green, and in a near instant you are seeing nothing but the taillights of the car that you were supposed to be beating. How do you solve this dilemma? More horsepower. How do you get more horsepower you ask?

Forced induction.

The engine in your car, and every other gas-powered car is basically a big air pump. The intake sucks in air, fuel injectors add gas, your pistons compress that air/gas mixture, the spark plugs ignite the mixture, and the exhaust lets all of the pressure from the explosion out. The explosion in the cylinder is what causes the piston to be forced down and thus rotates the crankshaft, which basically makes your car go. In order to make more horsepower you need a bigger explosion.

The simplest way to get much larger explosions is to increase the amount of air and gas in the cylinder when the spark plug ignites the mixture. The extra fuel is easily added by using larger fuel injectors. The problem is getting more air into the engine. Enthusiasts use a system called forced induction to actually compress the air going into the engine, thus increasing the number of air molecules. There are two types of forced induction: supercharging and turbocharging. Turbocharging is a better method than supercharging for the automotive enthusiast to use as a form of forced induction on a daily driven street vehicle--based on cost, reliability, versatility, and efficiency.

Types of Forced Induction

All forms of forced induction work on one basic principal. A compressor unit, just a pump that pressurizes air, takes in a certain volume of air and compresses (or pressurizes) it into a smaller package, which can be crammed into a smaller space. This allows more air molecules into a given volume of space, such as a cylinder in an engine. The problem that presents itself is that it takes a very large amount of power to run these compressors due to the high volume of airflow they must produce. The question is how do we power them?

One method of powering the compressor is called supercharging. This method uses a pulley attached to the compressor and to a belt driven by the engine's crankshaft pulley to power the compressor unit. The crankshaft pulley on the engine spins and thus drives the compressor wheel and makes boost-pressure for an engine's intake (Francis, 2002, p. 2).

The other method of powering the compressor is called turbocharging. This method uses a turbine attached to the compressor and the air coming out of the engine to power the compressor unit. The exhaust gases flowing out of an engine are very hot and under extremely high pressure. Heat and pressure are two types of potential energy. We channel this readily available energy through the exhaust manifold and into a turbine housing, similar to a big pinwheel or watermill and allow them to spin the turbine and consequently the compressor wheel as well (Turbocharging, 2002, p. 1).

Turbocharger System--Versatility

In order to understand the claims of the superiority of the turbocharger system over the supercharger system one must also understand the basic parts of each system. The turbocharger system uses a turbocharger unit (which is the compressor), a special exhaust manifold, and wastegate.

The turbocharger itself is actually three parts. The first part is obviously the compressor section; which includes the compressor housing and compressor wheel. This section sucks in ambient air and blows it out as pressurized air-with a slightly higher temperature due to basic physics. "When you compress a gas, its temperature will increase…" (Turbocharging, 2002, p. 1). The second part is the turbine section; which in turn includes a turbine housing and turbine wheel. This section takes in high temperature-high pressure exhaust gases and spins the turbine wheel before letting all of the gases-minus heat and pressure-out of the outlet. The third section is the bearing and shaft section. This section houses a shaft, which connects the turbine wheel to the compressor wheel and also oiled bearings, which in turn keep the shaft spinning freely.

The exhaust manifold for a turbocharger is simply a modified manifold that collects all of the hot -pressurized gases out of the engine and directs them into the turbine housing of the turbocharger. All engines have an exhaust manifold to collect the exhaust and send it out the tailpipe. The turbocharger system simply uses a slightly modified one that allows the gases to go through the turbocharger before going out the tailpipe (Francis, 2002, p. 1).

The wastegate is the last but not the least part of a turbocharger system. The wastegate serves as a bypass for exhaust gases. It allows the pressure to bypass the turbine housing and go directly to the tailpipe. The wastegate therefore determines the speed with which the turbine spins and thusly controls the level of boost being made by the compressor. By adjusting the amount of exhaust bypassed, one can also adjust the boost level (Bell, 1997, p. 142).

Supercharger System-Lack of Versatility

The opponent of the turbocharger system is the supercharger system. It includes three major components as well. It uses a supercharger (the compressor), a belt and pulley, and brackets (CamdenSupercharger, 2001, pp. 1-2).

The supercharger itself is a fairly simple unit compared to the turbocharger. It has only one major section, the compressor. The compressor section of a supercharger is identical to that of a turbocharger. It uses a compressor wheel and compressor housing to suck in ambient air and blow out pressurized air-which also has a higher temperature. Keep in mind that higher temperature air isn't a good thing, but it is a necessary evil shared by both superchargers and turbochargers because "when you compress a gas, its temperature will increase…" (Turbocharging, 2002, p. 1). Many people think that only turbochargers increase the intake temperature, because they are connected to the exhaust manifold. That is not true. Both systems increase the intake air temperature.

The belt and pulley system on a supercharger are connected to the compressor wheel in lieu of the turbine section found on a turbocharger. This belt and pulley vary in power directly to the speed at which the engine turns. This directly influences boost pressure. The only way to get more boost is to either rev up the engine or increase the ratio of the pulleys on the crankshaft and supercharger by taking off one pulley and putting on another pulley that costs around $165 each time you want a different boost level (Francis, 2002, p. 2).

The third component of a supercharger system, which you cannot do without, is brackets. You must have some form of bracket to mount the supercharger to the engine and additional brackets for belt tensioners for the drive belt and pulley system. Turbos use the manifold itself as the mounting bracket.

Costs

The first and perhaps most obvious benefit of turbocharging, only to an accountant, is the difference in cost between a supercharger and turbocharger system. One basic comparison in cost comes from an anonymous article on turbocharging a Ford Mustang versus supercharging a Ford Mustang. In this comparison and many other similar ones the turbocharger system is less expensive but only to the trained eye. Superchargers appear to be cheaper because the basic kit only costs $3000 whereas the turbocharger basic kit costs $4000. However the supercharger companies are very good at concealing the truth about costs (Turbocharging, 2002, p. 3).

The basic kit for a supercharger does not include the following required items for forced induction. Fuel injectors, priced at $210, are required to increase the amount of fuel in the air/fuel mixture; after all we need more fuel too not just more air. Headers, another name for the previously mentioned exhaust manifolds, are also needed and they cost around $159. The problem with putting more air into an engine is that you also have to allow more air out of an engine; these do just that. The mass air meter is a meter that is found inline between the compressor unit and the intake of the engine. It can be a major restriction if it is too small. It must be upgraded to an 80mm unit which costs $400. Spark plug wires, another $50, give you increased spark power to ignite the additional air and fuel in the cylinders. Cold air induction, which is generally priced around $250, gives you a colder initial intake air temperature, which in turn, lowers the final air intake temperature-i.e. cooler air = more power. Total price of supercharger system basic kit plus all of the additional required parts is $4070 (Turbocharging, 2002, p. 3).

Now the two systems seem to have very similar costs: turbocharger $4000, and supercharger $4070. But there is also one other thing that the turbo kit includes that the supercharger kit doesn't: an intercooler. Intercoolers cost around $1400 for a sufficient unit. Although intercoolers aren't required, they do add a considerable amount of horsepower to an engine and value to a kit. When you take all of this into account-as only a very keen eye would-you can see that a turbocharger system is actually cheaper than a supercharger system (Turbocharging, 2002, p. 3).

Efficiency--Reliability

Another fundamental advantage of turbochargers over superchargers is efficiency. The turbocharger system steals almost no power from the engine itself to make boost. Supercharger systems on the other hand can take as much as 20% of the engines power to make boost. It seems almost comical to think that someone would design a unit to increase power on an engine that initially takes away 20% of its power (Francis, 2002, p. 1).

Turbochargers use the exhaust gas heat and pressure from an engine to generate power for the compressor and make boost. "A turbo captures some of the energy in hot gas that normally is wasted out the tailpipe" (Robinson, 1999, p. 1). This heat and pressure would otherwise be wasted out the tailpipe and in to the atmosphere. This is "free" energy that we are harnessing here (Francis, 2002, p. 1).

On the other hand, superchargers use valuable power from the crankshaft of the engine itself to power the compressor and make boost. This power is not free and thus is a loss in horsepower that must be subtracted from the net gain in power caused by the system (Francis, 2002, p. 1).

If both systems are making 10 lbs of boost and thus generating a 40% increase in engine output on the same base 200hp engine, then the turbocharged setup would be producing 280HP and the supercharged setup would be producing 240HP. Which system would you want? The supercharger would have to increase boost pressure in order to make the same amount of power as the turbocharger. This extra boost pressure obviously will cause greater wear on the engine itself thus resulting in shorter engine life and less reliability (Francis, 2002, p. 1).
Another factor which causes superchargers to have less reliability than turbochargers is the fact that the supercharger system puts increase stress on the front half of the crankshaft due to the tension placed on it by the pulleys and belt that drive the supercharger.

Conclusion

When comparing supercharging and turbocharging systems and weighing out one's options on what to buy to make one's high-performance street machine faster, one must take into account the efficiency, reliability, versatility, and cost of his options. If you choose to do so, you will undoubtedly see the overwhelming superiority of turbocharging to supercharging. Many arguments have been raised at cruise-ins, dinner tables, performance shops, internet forums, and even grocery stores. But the only way to solve this argument is at the track. Time and time again, turbocharged cars have given out beatings to supercharged cars, and until the majority of racers start seeing through the facade created by supercharger companies to cover up their shortcomings, I will be included in the few that are proud to hand out those beatings-with my turbocharged racecar.

See the original here:
http://www.hotrodders.com/forum/turbo-vs-supercharger-write-up-29060.html
 

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2 Fast, not that Furious
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2,586 Posts
I've always understood it to be like this:
SC for off the line
TC for top speed

Given the massive combination of cars and uses for cars, I'm not sure you can pick the right or wrong induction system.
 

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I'm tryin' to think but nuttin' happens
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5,151 Posts
Ozzie said:
Note the question mark, Bob. I was merely suggesting that maybe there was some advantages to the S/C not covered. I, for one, agree totally with the article's conclusions.
Hey Oz you know how hard it is to broadcast sarcasm on a keyboard. Do they have a smilie for that?
 

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LX Goo'Roo
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3,537 Posts
bobf said:
Hey Oz you know how hard it is to broadcast sarcasm on a keyboard. Do they have a smilie for that?
HaaaHA! Yeah I was thinking that maybe you were being a wee bit droll as soon as I posted. I think the one that could work is :roll:

:doh:
 

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LX Padiwan
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392 Posts
Superchargers are better for throttle response off the line, which is why all Top Fuel Dragsters, Fuel Funny Cars, Alcohol Dragsters, and Alcohol Funny Cars use them, despite the hugh power it takes to drive them. They simply provide more bottom end power and better throttle response. Turbochargers provide more top end power because they take a lot less power to drive than a Supercharger does, which is why Indy cars, Champ cars and road racing cars use them.
In the past turbo's have been notorious for throttle lag, but they are much improved today. Often cars with dual turbos will have a smaller one to improve bottom end performance and a larger one for top end. This is done in an effort to improve power across the power band instead of just having big power the top end. Turbochargers typically get better mileage that a supercharger will.
I am not sure I agree with the articles conclusion that turbochargers are more reliable than superchargers. Turbochargers have tremendous heat to deal with that superchargers do not. They are more complicated as well. There are several type of superchargers, some of which are turbine design, similar to turbochargers, except thay are driven by a belt on the crankshaft instead of a turbine in the exhaust.
Finally, he says that turbo charging wins at the track, but does not specify what track. At the dragstrip, this is not the case, on a road or oval that is most likely the case. My 2 cents.


Phil
 

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LX Padiwan
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762 Posts
I wonder where he got those cost numbers from? TC price sounds like a turbine an IC upgrade kit not a full conversion.

The article forgot to mention that the hidden cost associated with the SC are the same for the TC plus a few plus a BOV, BPV, oil line and timer(optional)
The most important cost was left out also. Installation cost is probably double for a TC.

Short answer:
SC = leave you at the line
TC = blow by you later

Drag racing :
TC = small engines SC = big engines

Road course:
TC all the way
 

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Mr. White Chocolate P. Rock
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1,458 Posts
Great article. Listen to an 18 wheeler as it gets on the gas ( diesel) and listen to the turbo spool up, takes a few seconds. All our fire trucks are diesel turbos and a blast to drive in a "hurry"..
 

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LX Guru
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14,153 Posts
Great article, but modern superchargers are very reliable.The Eaton superchargers used by GM and Toyota, Ford. Mercedes etc are as durable as the motors they are bolted to. The Eaton supercharger requires periodic oil changes, not all manufactures tell you that! I had one on a Toyota and Toyota has no mention or even a oil available. Had to go to a GM dealer. I ran an overdrive pully 10-12 psi boost, a seventh injector and water methanol. That 4WD Tacoma would launch like a SRT8 Jeep, maybe better. Traded it for my Ram with 150,000 miles.
 

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rest in peace dad
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great article!!! i wanna get my supercharger for my car... ohhh when my waranty is up..
 

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Premium Member
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Dang Ozzie, you sure can sweet talk!! HAHAHAHa!

I like the super for simplicity but the turbo for overal power and useabilty.
 

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Builders of the 500rwhp 426's
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5,341 Posts
I TOTALLY disagree that a bower (SC) works better at the line compared to a turbo.........

A SC is linear to engine RPM...........the only way it works at the line better is if you leave the line @ an RPM close to full spool.

A turbo, if small, will work better at the line than a LARGE blower.........

And BTW..........what style of blower are we talking about anyways?

Roots? Centrifical? Twin Screw?

I mean, all of these act different.................

I can't fathom too many centrifical blowers(used on our cars) beating a properly sized turbo from 2K - 5K RPM...........

A Vortec or Paxton won't usually come to full boost till 5-grand or higher while most turbos are at full spool around 2,500 RPM..........

All of this said...........size of the blower or turbo REALLY REALLY matters!

The blowers on drag (top fuel) cars run what they run because I don't feel enough R&D has been done with turbos in this class..........I don't know if these guys are even ALLOWED to run turbos.......

When blowers and turbos are put head to head (like in many street classes) they usually limit turbo inlet size, add weight to them, and liet the blowers guys run as big as they want.........

In most EVERY case, a turbo will full spool sooner while a blower takes longer to reach full potential......

BOTH have the same hidden costs...........

Both can have coolers............

SC takes more power to spin..........

Turbos make more heat...........

If having to pick between the two.......its turbo hands down.........but for the street..........I prefer the bottle! :friday:
 

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GHTOSLD: short for Ghetto-Sled
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177 Posts
lets not forget the battle of the cool sounds people

SC----whistlin dixie

TC----niffty blow off valve

either one would go well with the sound of the rumblin hemi :p
 

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Builders of the 500rwhp 426's
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5,341 Posts
ehattey said:
lets not forget the battle of the cool sounds people

SC----whistlin dixie

TC----niffty blow off valve

either one would go well with the sound of the rumblin hemi :p
Even that is argueable................

There are silent blowers..........a Kenne Bell and Whipple make no noise.

Gear driven centrificals are way loud while a belt driven centrifical is quiet.

A large, sucking turbo can scream just a loud as a SC.............

And both can have whooooooooooshing BOV's.................but recirculation most find more efficient.
 
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