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Old 11-17-2014, 02:11 PM
 
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What are the pros and cons of a turbo and a supercharger? It seems like there are a lot more cars built with turbos than superchargers. Ford, Kia, Hyundai, Cadillac, Volvo, Audi, Mercedes, Porsche, BMW, Lexus and many other makes go with turbos while Jaguar, Land Rover, and Chrysler go with superchargers. Why is that?
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Old 11-17-2014, 02:21 PM
 
Location: San Jose, CA
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The idea in both is the same; they increase the density of the air being supplied to the combustion chamber in order to fuel a more powerful explosion in the chamber, producing more power. In general, a supercharger will give you immediate throttle response, because it's being driven mechanically, and a turbo will have some lag, because its compressor is being driven by the exhaust. On the other hand, a turbo is more efficient since it doesn't cause a constant load on the motor. A wastegate is used to allow excess exhaust gases to flow through the compressor to the tailpipe to prevent energy-robbing spikes in backpressure. There are some exceptions; the Mazda Millenia had an electrically driven "supercharger" which doesn't really fall into either category, and was prone to frequent failure.
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Old 11-17-2014, 02:25 PM
 
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That is what I though. Why don't more manufactures go with superchargers to avoid the lag associated with turbos.
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Old 11-17-2014, 02:51 PM
 
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Quote:
Originally Posted by straight shooter View Post
That is what I though. Why don't more manufactures go with superchargers to avoid the lag associated with turbos.
I would say because most cars that are adding a turbo are adding such a small turbo that there is very little lag.
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Old 11-17-2014, 03:06 PM
 
Location: Phoenix metro
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I prefer superchargers, and Im glad to see them making a comeback. Pros? Instant boost. Cons? Expensive. Turbo pros: generally cheaper than superchargers, more adjustability. Cons: boost lag, more destructible.
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Old 11-17-2014, 03:28 PM
 
Location: Prosper
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Quote:
Originally Posted by straight shooter View Post
That is what I though. Why don't more manufactures go with superchargers to avoid the lag associated with turbos.
Because turbos are more efficient than superchargers.

Both force pressurized air into the engine. However, a supercharger relies on engine RPM spinning a belt driven supercharger to achieve this. This costs horsepower, the same way running the air conditioner costs horsepower. Obviously, a supercharger adds more horsepower than what it saps in drivetrain loss.

A turbocharger on the other hand, is far more efficient. It's not gear or belt driven, so there is no parasitic loss on the engine. Instead, it's powered by the wasted energy from the exhaust, so instead of all that hot air just leaving the car out of the exhaust pipe, some of it is converted to kinetic energy by spinning the turbine wheels which then spin the compressor wheels to pressurize air to increase the amount of air flow.

The supercharger on the other hand, the exhaust gases are just wasted, along with causing engine drag.

The only place superchargers really have an advantage over a turbo is on a drag strip, and even then, it's mainly confined to Top Fuel type cars.

A well designed turbo system will have virtually no lag, because the turbos are sized appropriately for the engine size and air flow. My old Stealth twin turbo had the smallest turbos of any of the Japanese super cars in the 90's... the result was that it made 320 ft/lb of torque at only 2,500 rpm, besting all the others and trouncing the horsepower/torque figures of all it's competitors at the time. The trade off? You could only increase the maximum horsepower by so much, eventually you needed to upgrade the turbos to something larger.
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Old 11-17-2014, 03:28 PM
 
Location: SF Bay Area
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Quote:
Originally Posted by straight shooter View Post
That is what I though. Why don't more manufactures go with superchargers to avoid the lag associated with turbos.
Turbo design today is quite good with even larger Garrett's exhibiting significantly less lag compared to equal sized turbos a decade or more ago. With most manufacturers utilizing smaller turbochargers relative to engine size (a larger displacement motor can better utilize a larger turbocharger compared to a smaller displacement motor with a larger turbocharger as the volume of exhaust gas available to spin the turbine is greater) turbo lag is fairly minimal with any properly matched and tuned engine combination. The latest supercars (McLaren P1, LaFerrari, etc) actually utilize large turbos in combination with a hybrid electric drivetrain so that the electric motors get the car moving before the turbos are fully spooled to eliminate the perception of lag.

Superchargers on their own are horribly inefficient compared to turbochargers so the move towards turbocharged hybrid electric setups make the most sense given the general direction the automotive market is headed in.
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Old 11-17-2014, 04:05 PM
 
Location: Texas
3,253 posts, read 1,551,954 times
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Quote:
Originally Posted by headingtoDenver View Post
I would say because most cars that are adding a turbo are adding such a small turbo that there is very little lag.
Exactly. They're adding small turbos, or compound turbo setups (where one smaller feeds a larger) to eliminate this lag.

For smaller displacement engines they're using small turbos to give you that extra torque to help you accelerate from slower speeds, but they quickly run out of breath up top, where most people don't really need it.

Smaller turbos, faster response, more torque in the lower RPM's, great for daily driving.

Bigger turbos, generally slower spool, more torque in the medium to upper RPM range, great for racing.
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Old 11-17-2014, 04:12 PM
 
30,877 posts, read 24,200,485 times
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Quote:
Originally Posted by sonarrat View Post
The idea in both is the same; they increase the density of the air being supplied to the combustion chamber in order to fuel a more powerful explosion in the chamber, producing more power. In general, a supercharger will give you immediate throttle response, because it's being driven mechanically, and a turbo will have some lag, because its compressor is being driven by the exhaust. On the other hand, a turbo is more efficient since it doesn't cause a constant load on the motor. A wastegate is used to allow excess exhaust gases to flow through the compressor to the tailpipe to prevent energy-robbing spikes in backpressure. There are some exceptions; the Mazda Millenia had an electrically driven "supercharger" which doesn't really fall into either category, and was prone to frequent failure.
Quote:
Originally Posted by MckinneyOwnr View Post
Because turbos are more efficient than superchargers.

Both force pressurized air into the engine. However, a supercharger relies on engine RPM spinning a belt driven supercharger to achieve this. This costs horsepower, the same way running the air conditioner costs horsepower. Obviously, a supercharger adds more horsepower than what it saps in drivetrain loss.

A turbocharger on the other hand, is far more efficient. It's not gear or belt driven, so there is no parasitic loss on the engine. Instead, it's powered by the wasted energy from the exhaust, so instead of all that hot air just leaving the car out of the exhaust pipe, some of it is converted to kinetic energy by spinning the turbine wheels which then spin the compressor wheels to pressurize air to increase the amount of air flow.

The supercharger on the other hand, the exhaust gases are just wasted, along with causing engine drag.

The only place superchargers really have an advantage over a turbo is on a drag strip, and even then, it's mainly confined to Top Fuel type cars.

A well designed turbo system will have virtually no lag, because the turbos are sized appropriately for the engine size and air flow. My old Stealth twin turbo had the smallest turbos of any of the Japanese super cars in the 90's... the result was that it made 320 ft/lb of torque at only 2,500 rpm, besting all the others and trouncing the horsepower/torque figures of all it's competitors at the time. The trade off? You could only increase the maximum horsepower by so much, eventually you needed to upgrade the turbos to something larger.
Quote:
Originally Posted by iTsLiKeAnEgG View Post
Turbo design today is quite good with even larger Garrett's exhibiting significantly less lag compared to equal sized turbos a decade or more ago. With most manufacturers utilizing smaller turbochargers relative to engine size (a larger displacement motor can better utilize a larger turbocharger compared to a smaller displacement motor with a larger turbocharger as the volume of exhaust gas available to spin the turbine is greater) turbo lag is fairly minimal with any properly matched and tuned engine combination. The latest supercars (McLaren P1, LaFerrari, etc) actually utilize large turbos in combination with a hybrid electric drivetrain so that the electric motors get the car moving before the turbos are fully spooled to eliminate the perception of lag.

Superchargers on their own are horribly inefficient compared to turbochargers so the move towards turbocharged hybrid electric setups make the most sense given the general direction the automotive market is headed in.
good information in these posts.

as noted superchargers have instant boost from idle to redline because they are driven directly from the engine. turbos tend to have a bit of lag until the compressor wheel spins up and starts producing boost.

superchargers are heavier, and require power to run them. turbos dont require engine power, but they are not free horsepower either as the turbine does create extra back pressure that does rob the engine of a bit of efficiency.

superchargers have to be mounted on the engine since they are engine driven, turbos can be mounted just about anywhere, since they are exhaust driven.

superchargers produce boost on a linear curve, for the most part, centrifugal superchargers dont, but they are limited in the maximum boost pressure just like a roots type blower is. a turbo builds boost exponentially. at 1000rpm a supercharger might be making 1psi, at 2000 rpm it might be making 2 psi, etc. where as a turbo might be making 1/2psi at 1000 rpm, but at 2000 rpm it might be making more like 3.5psi.

when the systems are well engineered, either one does very well, and makes the engine they are installed on feel like it has gained 100 cubic inches or more at full boost.

i prefer turbos over superchargers, mostly because at freeway speeds, a turbo generally wont be producing any boost at part throttle, but it does help take the load off the engine by moving more air through the system.

in the end which one you choose depends on what you are wanting from the engine.
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Old 11-17-2014, 04:52 PM
 
799 posts, read 556,643 times
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There is no replacement for displacement!
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