super charger vs turbo?

[79rolla]

ok what exactly is the pros and cons of each?? my brother noes shit all aout cars but is a know it all and is good with maths and stuff and has convinced himself that supperchargers are the best and i dont know enough to fully inform him about each pro and con
what is the tru facts about each??

[Bling]

http://auto.howstuffworks.com/

[strap-on]

http://en.wikipedia.org/wiki/Supercharger#Supercharging_and_Turbocharging

Thats a good place to start, has a bit of info on there if you can get your head around it.

[d1 mule]

in short, s supecharger for initial power and torque in the low to mid rev range. Turbo tor torque & power mid to high. all about where ya want ya power, how big the turbo is and the sort of supercharger you are using also play a massive part in the power and torque charasteristics of each.

[matt dunn]

an engine at 12 psi makes a certain amount of HP,

the Turbo removes some of the HP due to the backpressure in the exhaut manifold, say 5-10% loss,

The supercharger takes power away from the engine via the drive belt,
and way more say 25-35% loss,

so psi for psi a Turbo makes more power.

Other than that it's just mounts and plumbing.

[sergei]

other thing about turbo that it is not mechanically connected - so the engine RPM change is not proportional to turbo RPM.

[Mr Revhead]

different horses for different courses.
and personal preferance.

i prefer a s/c over turbo in a road car.

[Stealer Of Souls]

I agree with revhead.
For a road car s/c. For a track type car a turbo.
As far as on road feel/performance.
S/C will effectively feel like a bigger engine the whole time. Plenty of low and mid range effect, tailing off at the high end. Good for highway cruising and lazy town driving. Really good if you've got an auto.
Turbo will give you the power rush when working the engine. "Sudden" overtaking is a good example of when a turbo shines on the road.

As mentioned. Turbos generally more efficient.
Pick the appilcation first. Then pick the method.

[darkwolf]

Slightly off topic maybe, but:

If a turbo spools off unburnt fuel, then would the fuel economy of a turbo would be less than that of a super charger despite the percentage of resistance?

Also, maybe I've heard the wrong end of a conversation but:
The percentage of loss in a supercharger seems extremely high. I assume that is based on a centrigufal super charger and not on a screw type which I have heard is more fuel friendly but provides a lower boost.

Please note anything in my post that is bollocks needs to be straightened out as I am looking at a similar road myself.

[Mr Revhead]

and way more say 25-35% loss,

yeah a little high for some applications....

[neo]

One goes whurrr the other goes phssst

[Crucible]

The percentage of loss in a supercharger seems extremely high. I assume that is based on a centrigufal super charger and not on a screw type which I have heard is more fuel friendly but provides a lower boost.

The big P.S.I screw blowers the V8 boys use, rob around 800 + hp just to drive the blower alone...60 psi anyone

the other disadvantage would be stress on the crank dampner/crank snout and keyway etc, quite a common problem on blown V8's.

[Stealer Of Souls]

Slightly off topic maybe, but:

If a turbo spools off unburnt fuel, then would the fuel economy of a turbo would be less than that of a super charger despite the percentage of resistance?

Also, maybe I've heard the wrong end of a conversation but:
The percentage of loss in a supercharger seems extremely high. I assume that is based on a centrigufal super charger and not on a screw type which I have heard is more fuel friendly but provides a lower boost.

There are three types of superchargers isn't there?
Roots
Screw
Centrifugal

Screw and centrifugal are the less power hungry, but both create boost proportional to the RPM.
Roots is the least efficient, but provides a relatively stable amount of boost.

The losses bit is a bit misleading I think. This was my understanding.
The power used to drive the s/c is proportional to it's rotating speed (therefore proportional to engine speed), and is fixed for a given rotational speed.
Therefore at peak power the power used to drive the charger is at it's lowest (as a percentage of engine output).

Not quite sure what you meant by the turbo spools of unburnt fuel. The turbo spools of the exhaust gases. More exhausts gases means more turbine speed, which equals more boost. (Some??) Antilag systems use unburnt fuel to produce more exhaust.

Turbocharging could result in relatively excellent fuel economy. All you need is a rather big turbo and drive off boost most of the time... Fuel economy that can rival an NA equivalent engine...

[evil_si]

it all depends what you want
i prefer a well suited turbo, get giood response with power right thru the range,

a s/c can be great for down low, but often results in a lot of unwanted wheel spin

14psi on a gze goes ok, but 11psi from a Ht18/t3 combo is awesome

[fivebob]

Fuel economy that can rival an NA equivalent engine...

Brake specific fuel consumption (the amount of fuel consumed per unit of power) of a turbo is far better than any NA engine, that's why they rule the LeMans 24hr

In other words Turbos have better fuel economy than NA engines that produce the same amount of power.

[pjay]

i heard a generalisation somewhere (dont remember where):

turbo = 200% efficiency
s/c = 90%

supercharger takes power to make power, but i prefer that whine anyday... instant boost ftw

[darkwolf]

What i mean by unburnt fuel is...

Fuel going through the turbo burning as it goes through providing faster spooling. Hence why turbos are run rich.

Again as I stated previously, this could easily have come from someones proverbial but seems somewhat logical.

[-Dan-Knee-]

Started a poll in polls see what peoples have to say!

[Adamal]

What i mean by unburnt fuel is...

Fuel going through the turbo burning as it goes through providing faster spooling. Hence why turbos are run rich.

I think you've got your wires crossed there!

Turbo's use the exhaust gasses. It doesn't ignite going through it.
I think you may be getting confused with Anti Lag, which is where the extractors have piping which injects air into them, which mixes with the unburnt fuel and ignites from the heat. This provides more exhaust gasses to keep the turbo spinning during gear changes.

Turbo's that run rich are probably not tuned properly. And with bigger turbos comes bigger injectors. Big injectors aren't very good at flowing small amounts. Now I'm not sure on this, but I would guess that as big injectors aren't good at small amounts, that they probably don't atomize the fuel very well either.

[Grrrrrrr!]

What i mean by unburnt fuel is...

Fuel going through the turbo burning as it goes through providing faster spooling. Hence why turbos are run rich.

Again as I stated previously, this could easily have come from someones proverbial but seems somewhat logical.

Turbos are often run rich to prevent detenation under high boost. The evaporation of the extra fuel keeps the temperature of the air/fuel mixture lower.

The turbos are spooled by the expansion of the exhaust gases in normal conditions. Running the mixture rich and pumping extra air into the exhaust to cause it to burn is one way of running anti-lag.