Why either Supercharging or Turbocharing?

[Josh48065]

Something I've never really understood is why do some car manufactures use a turbo charger and some use a supercharger?

For instance - the GTR uses the 3.8 v6 twin turbo, and the ZR1 or the GT500 is supercharged?
I'd don't understand why certain engineers choose one over the other?
Cost? Avoiding the turbo lag? Superchargers hurt MPG specs?
~Thanks!

 

[sasilverbullet]

Superchargers are more expensive and use more gas - but are more powerful.

 

[beast3300]

Turbos are far more efficient than roots style superchargers (like my car.) The reason one is picked over another is just what they want the car to do. Corvette you want instant power at any rpm and throttle (supercharger). A GTR you want it to scream at higher rpms (which turbo use best) that DOHC V6 do easily up to 200mph.

 

[Drew99GT]

Originally Posted By: sasilverbullet
Superchargers are more expensive and use more gas - but are more powerful.


I don't know about that, at least in absolute terms. Aside from nitrous oxide and nitromethane, the most powerful and the fastest drag racing cars running gasoline (and boats for that matter) use turbochargers.

Look at Nelson Racing engines website; they make some of the worlds most powerful engines used for motorsports. By far their most powerful (2,500+ horsepower) are twin turbocharged.

Turbos are much more efficient than superchargers, but they require more plumbing and more engine tuning. As to the original question, I think that's one reason why engineers would go with a supercharger. On a vehicle like the Corvette ZR-1, it would probably cost a lot more to factor in the plumbing required for a twin turbo setup vs a positive displacement supercharger. There is just no room under the hood. If you look at the aftermarket kits for Corvettes, they stick the turbos either where the mufflers would go or in the front fenders!

Turbocharging went out of fashion for a decade or so because people wouldn't maintain their turbocharged cars like they needed to, resulting in blown out turbos after less than 100K miles. However, recent advancements in both lubrication technology (better API motor oils) and turbo technology (water and oil cooled heavy duty bearing assemblies) have turbocharged engines making somewhat of a comeback in the market.

 

[45ACP]

Please note that single turbo is more efficient than twin turbo. Even Bentley went to it in their car, i recall reading about it in the more powerful Bentley. This one seems to describe thw twin-turbo. Perhaps the turbps of the 2000s were single Garrett T56s? http://en.wikipedia.org/wiki/Bentley_Turbo_RT

Still, general rule is single turbo is more "efficient" than twib-turbo. Big power on TT, though.

 

[mpvue]

both methods have their respective pros and cons. from the factory, smaller engines do better w/ turbos, larger engines do better w/ superchargers.
it makes sense, because smaller engines spin faster, and turbos are spun by fast moving exhaust, while larger engines have the low end torque to spin a supercharger.
aftermarket, all bets are off; for the aforementioned corvette, they have kits to go wither way, but the supercharger is lots simpler.

 

[d00df00d]

Roots-type superchargers build power more gradually and allow engine output to follow throttle input more cleanly (although still not as cleanly as a naturally aspirated engine). This makes superchargers better for traction and throttle adjustment during cornering.

Turbochargers, on the other hand, are lighter and make it easier to produce a lot of power. So, when you're starting with a small engine and want to crank out big power, you use turbocharging.

I'm sure there's a LOT more to it than that, but there's my $0.02.

 

[BillyTheKid]

One thing to not forget is a supercharger uses power to make power where a turbo does not. A supercharger is spun by the crank, hence using some power to make power. The turbo uses the exhaust flow to spin its wheel to make the power. Both are forced induction systems and do well making the extra power.

I am no guru of either, but I think the turbo would be more friendly to make the needed adjustments of power on the go. I do believe making a decent amount more power on the supercharger would need pulley changes, etc. That is from what I can tell from my experiences.

 

[45ACP]

Honest question.. how many Super AND Turbocharger setups? I heard of maybe two card that had this.. aftermarket Ford GT and perhaps a Lotis Esprit S4S

 

[SteveSRT8]

Not many, the only ones I've ever seen were at the Florida Mile and were Ford GT's. Another guy here in Sarasota FL does them on Lambos.

BTW guys, they are BOTH superchargers. One driven by exhaust and one driven directly (usually by a belt).

And there's no free lunch. BOTH cause parasitic power loss.

 

[silverrat]

I think VW had something called Twin Charging?

 

[Quattro Pete]

Originally Posted By: 45ACP
Honest question.. how many Super AND Turbocharger setups? I heard of maybe two card that had this.. aftermarket Ford GT and perhaps a Lotis Esprit S4S

BMW has a tri-turbo diesel engine in the works... two of them are exhaust-driven and the third one is electric. Does that qualify?

http://www.autoweek.com/article/20111123/CARNEWS/111129965

 

[sciphi]

There are fuel economy benefits to turbocharging. It makes a little engine have the same power of a bigger engine while sipping fuel like a little engine when the power's not needed. The engine also does not work as hard drawing in air, so pumping losses are reduced a little bit.

 

[PeteTheFarmer]

Originally Posted By: silverrat
I think VW had something called Twin Charging?


Yes, The VW Golf Mk5 GT offered a four cylinder gas engine with both a turbocharger and supercharger.

 

[45ACP]

Originally Posted By: SteveSRT8
Not many, the only ones I've ever seen were at the Florida Mile and were Ford GT's. Another guy here in Sarasota FL does them on Lambos.

BTW guys, they are BOTH superchargers. One driven by exhaust and one driven directly (usually by a belt).

And there's no free lunch. BOTH cause parasitic power loss.


True. Question is, HOW?

Quote:
Danny's Supercharged 1000 hp (850 wheel hp) 402ci forged motor mallett c6 corvette ran into a twin turbo ford gt that was still feeding through the supercharger. Ford GT was about 1500 hp @ the crank, guestimate would be 1200 whp on race gas (which i think it was running).




Quote:
Yes, The VW Golf Mk5 GT offered a four cylinder gas engine with both a turbocharger and supercharger.


What year(s) what model (was it GTI?) and was it available in the US? The R32 wasnt that... was it? And its called "Twin charging?"

 

[mahansm]

Both are means of getting more air into the engine. Both require power to perform their function. The Roots type supercharger (and variants such as Lysholm) uses a belt to tap power from the crankshaft while the turbocharger uses a turbine to recover energy from the exhaust stream.

Positive displacement (roots type) advantages:
boost available at idle and above
no lag
fixed maximum boost

disadvantages:
takes substantial HP from crankshaft
Always takes power from crank unless clutched with air intake bypass
Can be damaged by backfire
Higher intake charge temperature for same boost as turbocharger.

Turbocharger:
advantages:
Highest HP output; uses blowdown energy from cylinders for power.
Lower intake charge temperature.
More freedom in positioning (doesn't need pulley aligned with crankshaft)
Not damaged by backfire
In some applications may raise intake manifold pressure above exhaust manifold pressure so that engine shows larger than expected power gain (only at full throttle)

Disadvantages:
No boost at low RPM
Lag between throttle application and boost
Overboost when engine RPM slows rapidly
Needs careful matching with engine, as increased exhaust volume leads to increased boost, which causes increased exhaust volume.
May require wastegate (lower efficiency) to overcome lag and provide boost at lower RPM while preventing overboost.
Requires uninterrupted flow of oil for cooling/lubrication; is hard on oil (shear, temperature loading)
Requires operator consideration (cooldown after hard use).

The two can be staged; I've seen pictures of rail dragsters with turbochargers feeding a supercharger. I've also seen marine installations with a turbo feeding the Roots blower on a Detroit Diesel.

Tractor pull guys have run three turbos in series, with manifold pressures on the order of 150 psi. Block strength becomes an issue...

 

[Quattro Pete]

Originally Posted By: 45ACP
What year(s) what model (was it GTI?) and was it available in the US? The R32 wasnt that... was it? And its called "Twin charging?"

It was an MkV Golf GT with a 1.4 liter TSI engine, not sold in the US.

http://en.wikipedia.org/wiki/List_of_Volkswagen_Group_petrol_engines#1.4_R4_16v_TSI.2FTFSI_90-133kW

 

[PeteTheFarmer]

Quote:

What year(s) what model (was it GTI?) and was it available in the US? The R32 wasnt that... was it? And its called "Twin charging?"


It never made it to the US.

http://www.leftlanenews.com/report-vw-to-kill-1-4l-twincharger-engine.html

 

[beast3300]

Originally Posted By: mahansm
Both are means of getting more air into the engine. Both require power to perform their function. The Roots type supercharger (and variants such as Lysholm) uses a belt to tap power from the crankshaft while the turbocharger uses a turbine to recover energy from the exhaust stream.

Positive displacement (roots type) advantages:
boost available at idle and above
no lag
fixed maximum boost

disadvantages:
takes substantial HP from crankshaft
Always takes power from crank unless clutched with air intake bypass
Can be damaged by backfire
Higher intake charge temperature for same boost as turbocharger.

Turbocharger:
advantages:
Highest HP output; uses blowdown energy from cylinders for power.
Lower intake charge temperature.
More freedom in positioning (doesn't need pulley aligned with crankshaft)
Not damaged by backfire
In some applications may raise intake manifold pressure above exhaust manifold pressure so that engine shows larger than expected power gain (only at full throttle)

Disadvantages:
No boost at low RPM
Lag between throttle application and boost
Overboost when engine RPM slows rapidly
Needs careful matching with engine, as increased exhaust volume leads to increased boost, which causes increased exhaust volume.
May require wastegate (lower efficiency) to overcome lag and provide boost at lower RPM while preventing overboost.
Requires uninterrupted flow of oil for cooling/lubrication; is hard on oil (shear, temperature loading)
Requires operator consideration (cooldown after hard use).

The two can be staged; I've seen pictures of rail dragsters with turbochargers feeding a supercharger. I've also seen marine installations with a turbo feeding the Roots blower on a Detroit Diesel.

Tractor pull guys have run three turbos in series, with manifold pressures on the order of 150 psi. Block strength becomes an issue...



Roots type superchargers' boost changes with ambient temp and humidity unless there is a cooler under the supercharger (aftercooler) with a heat exchanger mounted up front of the radiator.

 

[mechtech2]

New superchargers are more efficient than the old types.
And turbos are much better than before, also.

It's a toss up for me nowadays. Turbos are probably easier to integrate into an existing car design, for Mfrs.