super charged vrs turbo charged

[Bernoulli]

What is the difference between an engine that is super charged and one that is turbo charged? Thanks in advance for all constructive comments.

 

[Dash8]

Supercharger
engine direct driven device to increase the fuel/air mixture in an engine

Turbocharger
same principle, but its driven by exhaust gas

there's pro's and cons to both, but imho, supercharging is better (and looks cooler )

 

[bigD]

Because the supercharger is being driven by the engine - there's a bit of power being used to drive it. Therefore, turbos typically provide more additional power than superchargers do.

The flip side of this is that because the supercharger is directly connected, it doesn't suffer from the lag that turbos do. On a turbo, the turbine needs to spool up, which results in a bit of lag before it begins providing boost.

 

[VNugget]

Also note that sometimes you'll see "supercharged" referring to either, especially in older writing.

 

[EagleRJ]

If you're talking about aircraft engines, turbocharging is more common than supercharging- probably because the supercharger's drive belt is one more thing to break in an airplane (there are gear-driven designs too, but it's still more complex). There are several types of adding power in an aircraft:

-Turbo-normalizing- Using a turbocharger to restore the induction charge to sea-level pressure as the aircraft climbs.

-Turbo-supercharging- Using a turbocharger to boost the induction charge above sea-level pressure.

-Turbo-compounding- Not really supercharging at all, but using an exhaust-driven turbine that is connected to the crankshaft by a gearbox. Used to recover lost energy in the exhaust and return it to the crankshaft as additional power.


As previously mentioned, turbochargers and superchargers each have their strengths and weaknesses. You should see some of the turbo/super throwdowns that get going on automotive message boards! They can be more spirited than the PFT/Mesa/Boeing/Airbus/religion discussions on here!

 

[crash-proof]

-Turbo-compounding- Not really supercharging at all, but using an exhaust-driven turbine that is connected to the crankshaft by a gearbox. Used to recover lost energy in the exhaust and return it to the crankshaft as additional power.

From my knowledgethe Wright 3350 was the only motor to use the turbocompund method, but were there others? Smaller GA engines? To me it makes sense, why throw away that exaust when you could use it to help regenerate power. I could see it being used in a smaller continental or lycoming type motor.

 

[bocefus]

"there are gear-driven designs too, but it's still more complex"

Perhaps, but gear driven superchargers on aircraft have proven to be much more reliable than exhaust driven turboshargers

 

[troy]

don't forget that when using an exhaust restricting device (turbo), the back pressure increases in the exhaust and combustion chamber resulting in a slight hp reduction. the turbo makes up for the difference. I've never heard of the turbo compund method, I wonder how much is recovered?

 

[FN FAL]

Also note that sometimes you'll see "supercharged" referring to either, especially in older writing.

You'll find that out if you ever have to get TSIO-470's worked on...they just about have to dig out some Egyptian stone tablets and dust them off, just to get a clue.

 

[wingnutt]

...superchargers are good, but turbos rock

 

[A1FlyBoy]

The flip side of this is that because the supercharger is directly connected, it doesn't suffer from the lag that turbos do. On a turbo, the turbine needs to spool up, which results in a bit of lag before it begins providing boost.

Sounds like you've driven a Saab...

 

[avbug]

If you're talking about aircraft engines, turbocharging is more common than supercharging- probably because the supercharger's drive belt is one more thing to break in an airplane (there are gear-driven designs too, but it's still more complex).

Most aircraft engine supercharging, virtually all of them, are engine driven at the back of the accessory case. Typically superchargers use a clutch to vary between high and low blower positions.

Turbo-compounding- Not really supercharging at all, but using an exhaust-driven turbine that is connected to the crankshaft by a gearbox. Used to recover lost energy in the exhaust and return it to the crankshaft as additional power.

The turbocompound R3350 utilized a supercharger as well as power recovery turbines, which provided drive back to the engine mechanically through a fluid coupling, so yes, it really is supercharged...the compound in turbocompound is supercharging plus the PRT's.

 

[crash-proof]

The turbocompound R3350 utilized a supercharger as well as power recovery turbines, which provided drive back to the engine mechanically through a fluid coupling, so yes, it really is supercharged...the compound in turbocompound is supercharging plus the PRT's.

Man those mofo's were complex weren't they? I'm suprised they didn't have 1 flight eng. for each motor. From what I understand pax in those days weren't phased at all when a shutdown occured. I also read that the exaust developed quite a bit of thrust.

 

[BD King]

In line with the subject matter, if you ever fly, especially a 400 Series Cessna that still has Turbo Charged on the side or on the cowls, watch the lineman very closely when refueling.

www.bdkingpress.com

 

[A Squared]

In line with the subject matter, if you ever fly, especially a 400 Series Cessna that still has Turbo Charged on the side or on the cowls, watch the lineman very closely when refueling.

Seems like I'd heard that the "turbo system" that Cessna put on the cowls was required to be covered or removed by an Airworthiness Directive. Anyone know if this was true?

 

[ackattacker]

The main difference is that supercharging is kind of 70's cool (think Road Warrior) while turbo-boost is definately 80's cool (think Michael Knight and K.I.T.T.)

 

[avbug]

Man those mofo's were complex weren't they? I'm suprised they didn't have 1 flight eng. for each motor. From what I understand pax in those days weren't phased at all when a shutdown occured. I also read that the exaust developed quite a bit of thrust.

No more complex than any other round engine. They were perhaps the highest evoloution of the radial engine. Operating the 3350 is no more complex than any other engine...certainly they don't demand the attention of a flight engineer of their own accord. I don't recall ever hearing that the exaust put out any significant amount of thrust, though I'm sure it may impart something. If that were the case, the exhaust would probably be angled back to take advantage of the "thrust."

If by passengers not being "phased" you mean that engine failures were common, that's partially true. Anybody who has flown round engines very much understands why I often say that an engine failure is not necessarily an emergency. It's a routine abnormal condition, and doesn't necessarily warrant much excitement.

 

[A Squared]

I don't recall ever hearing that the exaust put out any significant amount of thrust, though I'm sure it may impart something. If that were the case, the exhaust would probably be angled back to take advantage of the "thrust."

The exhaust stacks on the DC-6 point straight back, ostensibley to take advantage of exhaust thrust, according to one of my Douglas manuals. I don't have the book in front of me, but is seems like I recall they were claiming to recover several hundred horspower that way.

 

[TrafficInSight]

The exhaust stacks on the DC-6 point straight back, ostensibley to take advantage of exhaust thrust, according to one of my Douglas manuals. I don't have the book in front of me, but is seems like I recall they were claiming to recover several hundred horspower that way.

I'd love to see that part of the book. I remain fairly skeptical about that particular claim.

 

[TrafficInSight]

Seems like I'd heard that the "turbo system" that Cessna put on the cowls was required to be covered or removed by an Airworthiness Directive. Anyone know if this was true?

Don't know if it was required but the turbo Aztec at my school says "Charged" on the cowling.

No word on wether it's paid off or not yet

 

[erj-145mech]

The exhaust stacks on the DC-6 point straight back, ostensibley to take advantage of exhaust thrust, according to one of my Douglas manuals. I don't have the book in front of me, but is seems like I recall they were claiming to recover several hundred horspower that way.

The exhaust stack/s on B-17's, B-25's, F6F's, F4U's, AT-6's, BT-13's and my Skymaster all point aft, and they don't realize any "thrust" from the exhaust. They point aft to help in scavenge the exhaust gases from the pipe openings, reducing the back pressure on the engine.

 

[bocefus]

"In line with the subject matter, if you ever fly, especially a 400 Series Cessna that still has Turbo Charged on the side or on the cowls, watch the lineman very closely when refueling."

Can't happen if the AD's are complied with.

 

[gern_blanston]

The exhaust stack/s on B-17's, B-25's, F6F's, F4U's, AT-6's, BT-13's and my Skymaster all point aft, and they don't realize any "thrust" from the exhaust. They point aft to help in scavenge the exhaust gases from the pipe openings, reducing the back pressure on the engine.

Hawker's used to claim that a good bit of thrust was realized from the exhaust stacks on the Merlin.

 

[A Squared]

I'd love to see that part of the book. I remain fairly skeptical about that particular claim.

OK, I dug out the book. It's a study guide Douglas wrote for airline flight crews. It doesn't make a specific claim about the amount of power or thrust recovered. (I guess I remembered that detail incorrectly) it says: "The DC-6A uses a jet stack type exhaust arrangement that utilizes the exhaust velocity to augment the propulsive thrust"

 

[gern_blanston]

Found these 2 quotes googling 'Spitfire exhaust thrust'

"The '109 used exhaust thrust to gain more speed. Daimler-Benz charts show 120PS of exhaust power at 600 km/h at 4.5 km for the 109 Emil's engine. Another German paper shows 200-300hp produced by thrust alone at 600km/h at 10000m."

"In 1943 some spitfire Vbs also had their 'fishtail' type exhaust stubs replaced with multi-ejector stacks, the better aerodynamics and thrust generated by the new exhausts adding a further 5 mph down low."