Which is better? Supercharger or turbo?

[Kiamo]

Ok, I've wondered this for a while. I know turbos have "turbo" lag and superchargers don't, but that's about the only rock solid reasoning I can see between the two. Why do most people going for more power get a turbo? Exactally what makes them the more popular choice? And don't they cost a lot more?

Thanks for any help!

[BLOWN3]

Turbos will only experience lag if the turbo is too big for the displacement of your engine. BUt you have to put up with it if you want to make a lot of peak power.

Turbos cost more mainly because of the plumbing (e.e. exhaust manifold) that's necessary but a good turbo system won't cost much more than a good supercharger system.

[RobE46RX7]

turbo is generally used for more boost and more power at the expense of a more complex system and paying more.

A properly sized turbo can work with almost no lag, especially a dual ball bearing design, you have a lot more flexibility with a turbo settup (IMHO) Supercharger is a lot simpler, less expensive and takes up less space.

-Rob

[Midnight Shark]

Originally posted by Kiamo
Ok, I've wondered this for a while. I know turbos have "turbo" lag and superchargers don't, but that's about the only rock solid reasoning I can see between the two. Why do most people going for more power get a turbo? Exactally what makes them the more popular choice? And don't they cost a lot more?

Thanks for any help!

Well, you must understand how both work to get a clear picture.
The Turbocharger is "exhaust driven" and the supercharger is "belt driven". The TC has a more complex system coz you have to reroute the "wasted exhaust" into the TC assembly. The general rule is that a turbocharger maximizes the power band at a higher rpm, because it is powered by the amount of exhaust being forced through it.

It takes a second for the turbine to get up to speed, before boost is produced. This results in a feeling of lag when you step on the gas, and then the car lunges ahead when the turbo gets moving.

So at low RPM's you will not be able to feel any effect. Some cars (Twin-turbos) have 2 different size turbos. One that handles the low RPM and a larger turbo that takes over at higher RPM's thus minimizing "lag".

On the other hand, a supercharger has a better low-end torque, since a belt directly connected to the crankshaft controls it. A supercharger is already injecting air into the system, even at extremely low rpm. It is a self-contained unit, while the turbocharger relies on the engine’s exhaust system, and often, an intercooler system, to function. Generally, superchargers cost a little more than turbo kits, but a turbo kit is tougher to install. You must typically route your exhaust system through the turbocharger, as well as add an intercooler.

Thus a turbo is usually more power efficient than a supercharger since the turbo uses the ambient air from the exhaust to increase power.

the supercharger relies more on the spinning of the crankshaft belt attached to it and the engine can only spin as fast up to a point, also increasing engine workload.

Just my .02

[Sean M3]

I always had the impression that turbos cost more than blowers. Anyways, I think for a LOT of power, turbos are the way to go.

[///95M3-R1]

Superchargers put a lot more stress on the engine because it's always on. Whereas the turbo puts stress on the engine if you're on it and high RPM.

The only thing you have to realize is, even though the Supercharger is constantly putting pressure on the engine and the turbo is only when you're spooling, when the turbo is full boost, the stress it puts on the engine is about 10x more powerful than the supercharger.

For power=turbo.
For money- S/C
Reliability=turbo or s/c....depends on tuning and how you drive it.

Either way, BOTH are FI, the reliability isn't gonna be there like an N/A......you're literally forcing the car to produce a shit load more power than it can.

[Guido]

active autowerke is the supreme bimmer place for forced induction

[dusty89325i]

turbo set up in my eyes is more effective since first of all its running off watsed exhaust, second you can make a lot more power with one, third it can run at diffrent speeds then your engine. A supercharger puts more strain on your engine at lower rpms, and it robs engine power. Take a supercharged top fuel car it takes a thousand horse power to run the supercharger, but the pay off is still good. A supercharger is like an engine with one gear, and a turbo is like a continuiously variable transmission if that makes sense.

[PrinceE30]

supercharger is like an engine with one gear, and a turbo is like a continuiously variable transmission if that makes sense.

That's a grossly innaccurate was of looking at it.

The supercharger produces the same power boost throughout the speed of the engine and of the car. The turbocharger gives more power the faster the engine is going.

Safety Note : The sudden rush of power from the turbo can be dangerous if you don't know how to control the power. Sure, the engine is all calm and quiet up to 5000rpms. Then *pow*...huge power rush. Takes skill to know when and how to use the power.

-Prince

[BLOWN_M_COMPACT]

Originally posted by Midnight 97M3


a supercharger has a better low-end torque,

Since when !!!! It is known that a BMW SC'd engine lose's power at first . I had both and spent over $12K with each and I would never go with a SC'd BMW again

[Duncan G.]

There are different advantages to each system. Superchargers provide instantanious boost at any rpm because they are belt driven, and much larger than most turbos. This allows superchargers to produce more low end torque than a turbo because the impeller is much larger and they are not relying on exhaust pressure in order to spin the impeller. Turbos are exhaust driven and therefore the impeller speed is not limited by engine speed thus allowing them to produce more peak boost at high rpms, but at low rpms there is usually not enough exhaust pressure to spool the turbo up, and therefore most TC cars experience turbo lag in between gears, and right after you hit the throttle. SC's do not cause you to loose power at low rpms because thay can provide positive manifold pressure(pmp) at almost any rpm. PMP means more air and more fuel which in turn creates more power. SC's do produce boost at any rpm, and so do turbos. Both systems have ways to release this pressure or else it would be extremely hard on the engine. A turbo has a blowoff valve which is usually vacuum controled, and a SC has a bypass valve which is also vacuum controled. Niether system provides boost to the engine until the throttle is opened. Bost systems put extra drag on the engine due to the way they work. A turbo restricts the exhaust flow in order to create back pressure and spool up, and a SC requires the engine to turn another pulley to produce boost. Since turbos use hot exhaust gases to turn there impeller, they introduce lots of heat into the intake charge, and require an intercooler to cool the air and function efficiently. In either case the extra power produced easily cancels the extra drag on the engine. IMO a SC is the more efficient system because you can still get good gains from running headers and the right set of cams with the SC, and SC are much easier to plumb because the air charge is not being heated by the exhaust as its forced in to the engine. This means that you dont have to run intercoolers/aftercoolers unless you are running a ton of boost(compressing air creates heat). Also for you boost crazy people out there, most new centrifugal SC's can produce more than 20 psi of boost with the right set of pulleys. Remember, a centrifugal SC is just like a big belt driven turbo, and they dont produce full boost until high rpm, but response is instantanious and predictable unlike a turbo which come on with a big rush when exhaust pressure climbs. A roots type blower produces full boost at very low rpms, but they usually can't provide more than 10 psi max pressure. Roots blowers are good when you need tons of torque. Extra strain on the engine is dependant on how much peak boost you choose to run, and since SC usually run less peak boost than turbos and only produce big boost at higher rpms, I think that they are probably easier on your engine.

[///95M3-R1]

Duncan G., nicely done.

However, take a SC'd car at 4Krpm against a turbo car at 4Krpm....who's gonna take it? Mash the throttle of a SC engine at lower RPM and you will no way out take a turbo car that's at full boost at 3,5rpm. Think about it. That's the only problem I see with SC.....you can't really get full boost at lower rpm whereas the turbo, some cars can be full boost at 3K.

[klasic]

Which is better?

Well that is not really a fair question, it depends on a lot of factors and what the goals are. Do you want instant throttle responce? Do you want something that gets good gas mileage? Do you want the power to come on in the top end? What size motor are you working with in the first place? Is the motor built to withstand the added boost and temps?

If one was "better" than the other you would only see it used, but the fact is you have turbo and superchargers being used by companies today. Ford and MB are using a quite few turbos in their cars, and Porsche, Subaru, Nissan, and others are using turbos.

If you want to talk plain efficency the turbo is normally regarded as the better option because it is not in use when off boost, but MB has added an electronic clutch to its supercharges so it is only in use when required as well.

there are many setups for both superchargers and turbochargers, and really what ever is best depends on the application.

For me the turbo is the better option because normally you can tune more hp out of them, and they offer more flexibility, than and I know a whole hell of a lot more about them.

[stimpee]

Originally posted by BLOWN_M_COMPACT



Since when !!!! It is known that a BMW SC'd engine lose's power at first . I had both and spent over $12K with each and I would never go with a SC'd BMW again

I'll agree with Blown If, and only if, you are constrained to a centrifugal supercharger. A centrifugal in NO WAY will compete with the low end torque of a turbo. But, I will also say, that even a properly sized turbo will always have a "boost threshold", and hence non-linear power delivery that is harder to handle (buy WAY fun).

Problem is these days, everybody talks about superchargers relative to the old roots blowers on V-8's that did make great low-end torque, but all the existing SC kits use centrifugals that have essentially NO boost below 3.5-4k rpm.

The "middle ground" is the positive displacement supercharger, which is why I am working on it! Great low end and midrange power, good top end power, no lag, completely predictable, and a bit cheaper and simpler than a turbo.

The turbo will still always be the best for absolute outright CRAZY high hp numbers, as it doesn't "steal" crank power to drive it, and can be selected to be efficient at any power level...

Steve

[M10-Power]

Reading SCC just now and had such a laugh I put OJ out my nose, there is an ad in the back that simply must be seen. Absolutely the most pathetic thing I've ever seen, and to think its "Rated #1 new product by auto enthusiasts!"

http://www.sunamiturbo.com/products.htm