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Discussion Starter · #1 ·
Hey guys,
I just wanna know the difference between a turbo and a supercharger. I know that turbo's give more of a top end boost, and that a supercharger gives more of an all around boost that isn't as big. I was just wondering what the difference was on the actual inside of the turbo compared to that of a supercharger. By the way I love all the boosted cars out there. Keep 'em coming. :D

Thanks alot,

Jay
 

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I guess technically, they are both superchargers. The major difference between the two is how the compressor is driven. On a turbo, it is driven by the exhaust gasses (free power) and with a supercharger it is beltdriven (requires power from the engine to turn it). A turbo isn't 100% free because it isn't 100% efficient. A supercharger isn't 100% efficient either. Turbo's give you near stock power at low throttle (until the turbo spins up) and the supercharger gives you power on demand (no spin up time).
 

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Discussion Starter · #3 ·
DarkStorm said:
I guess technically, they are both superchargers. The major difference between the two is how the compressor is driven. On a turbo, it is driven by the exhaust gasses (free power) and with a supercharger it is beltdriven (requires power from the engine to turn it). A turbo isn't 100% free because it isn't 100% efficient. A supercharger isn't 100% efficient either. Turbo's give you near stock power at low throttle (until the turbo spins up) and the supercharger gives you power on demand (no spin up time).
Thanks alot man. I actually noticed on a pic of a supercharger the belt and I was kinda confused. Thanks alot for the information.

Thanks,

Jay
 

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the link was a big help but i got some questions after reading it....so if i understand it correctly, superchargers have NO lag? and how much horsepower can you add off of a turbocharger...i see all the turbo IS's have got lyke 500 rwhp but what about the superchargers how much horsepower are they getting?? thanx
 

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Superchargers have no lag(the time it takes for the snail to spool up). However, it does have annoying supercharger wine. Turbos give up to 1000 or more RWHP but engine modifications have to be mad in order to support so, keep in mind that turbos come in different sizes. and in general, it is cheaper to upgrade turobs since the turbo is made bu different companys and come seperated from the manifolds.
superchargers give plenty of power also but im not a SC person. maybe someone else will help you on that.

azndragon808 said:
the link was a big help but i got some questions after reading it....so if i understand it correctly, superchargers have NO lag? and how much horsepower can you add off of a turbocharger...i see all the turbo IS's have got lyke 500 rwhp but what about the superchargers how much horsepower are they getting?? thanx
 

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You also have to remember that both systems have a very specific efficiency range. There are superchargers that will deliver 40psi too, but they suffer from low end lag much like a turbo. Both can give huge top end or good all around power.

The amount of power you add by either system depends on the size of the compressor wheel used (intake side). Many of the large horsepower cars you see are very peaky in the power delivery. Meaning only a small amount of the rpm band is good for power. This is a very important aspect of deciding which turbo/supercharger to use on your setup. If you use a smaller turbo it will spool (full boost) faster but will most likely not be able to maintain full boost all the way to redline (it gets out of it's efficiency range and ends up pushing more hot air than anything). If you use a larger turbo it will take longer to spool, but you will beable to run a higher boost level for longer.

Also with a supercharger there is some parasitic loss between the belt driving the compressor and the actual compressing of the air. There are clutch assemblies on S/C though so when your cruising the loss is minimal. As already mentioned turbo use free power because you've already used the air but they are not 100% efficient so you will not regain all of your spent energy.

I know I got a little off track, but I felt like typing extra this morning.

Here is a link that might explain some other things. http://auto.howstuffworks.com/turbo.htm
 

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So here's a question I've always had... is the accessory belt always spinning at the same speed, regardless of engine RPM?

That would explian how s/c's don't have to spool up and are able to drive a constant boost, but that would mean there'd have to be some sort of reverse gearing mechanism to gear the acc belt speed to stay constant and independant of engine rpm...

How's this work?
 

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dasgalloway said:
So here's a question I've always had... is the accessory belt always spinning at the same speed, regardless of engine RPM?

That would explian how s/c's don't have to spool up and are able to drive a constant boost, but that would mean there'd have to be some sort of reverse gearing mechanism to gear the acc belt speed to stay constant and independant of engine rpm...

How's this work?
The supercharger speed varies with engine speed. It's just belt driven, so it speeds up and slows down with the engine.
 

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bartkat said:
dasgalloway said:
So here's a question I've always had... is the accessory belt always spinning at the same speed, regardless of engine RPM?

That would explian how s/c's don't have to spool up and are able to drive a constant boost, but that would mean there'd have to be some sort of reverse gearing mechanism to gear the acc belt speed to stay constant and independant of engine rpm...

How's this work?
The supercharger speed varies with engine speed. It's just belt driven, so it speeds up and slows down with the engine.
If the s/c spins at varying speeds... how is it able to provide a constant level of boost? Also, why is there no lag time with the s/c... you'd think if the s/c was spinning slower at idle it would have to spool up just like a turbo as the engine rpm increased...

Hrmm... something's not connecting here... :-?
 

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superchargers are constantly compressing air, and if sized correctly, flowing as much or more air than the engine can ingest at that rpm

when they engine rotates, so does the charger, and it compresses more and more air, the faster it spins

there is no "lag" because as soon as you crack open the throttle plate, there is more compressed air to ingest, than the engine could flow in a n/a state. with turbochargers, a certain amount of exhaust energy has to be created before this is the case

its all about energy, the belt driven charger takes kinetic energy and can instantly produce potential energy, which can be turned back into more kinetic energy. the turbocharger takes potential energy and recreates kinetic energy, but there is a lull while the threshold is reached, that where more kinetic energy is produced, than potential energy is wasted.

lag is the time it takes potential energy to turn into positive kinetic energy and create positive pressure
a supercharger doesn't have that, because it does not use potential energy, it uses kinetic energy to create more kinetic energy, but that is also why it is less efficient

did any of that make sense?

-gte




dasgalloway said:
bartkat said:
dasgalloway said:
So here's a question I've always had... is the accessory belt always spinning at the same speed, regardless of engine RPM?

That would explian how s/c's don't have to spool up and are able to drive a constant boost, but that would mean there'd have to be some sort of reverse gearing mechanism to gear the acc belt speed to stay constant and independant of engine rpm...

How's this work?
The supercharger speed varies with engine speed. It's just belt driven, so it speeds up and slows down with the engine.
If the s/c spins at varying speeds... how is it able to provide a constant level of boost? Also, why is there no lag time with the s/c... you'd think if the s/c was spinning slower at idle it would have to spool up just like a turbo as the engine rpm increased...

Hrmm... something's not connecting here... :-?
 

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It spins with the engines RPM. So at say 2-3K RPM, the S/C is pushing 2-3 PSI through the engine. At 4-5K it pushes 4-5 PSI. At 6-7K it pushes 7PSI and max boost. Thats why when you look at a dyno of a S/C it is a very linear powerband. As the RPM's rise the motor gets more boost.
 

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dasgalloway said:
Yup, thx GTE.
BTW it was the scale on the s/c dyno charts that threw me off... the scale is so fine (-150 to 350) IT looks like the line is completely flat when in fact its increasing about 30-40 hp through a range of rpms. Looking at the "flat" line I couldn't figure out how that could happen if psi increase with RPMs...

I got it now. :)
 
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