Topic: Auto Tech: Boost - Supercharger vs Turbocharger

[Autos_Editor]

A closer look at the world of forced induction from both turbochargers and superchargers.
Read More...

[tpl]

 F1 cars already use a motor to keep the turbocharger speed up...the electricity for this gained from regeneration under braking with a battery in the way for storage.   I can see no reason apart from cost why this could not be put onto road  cars...certainly it would start on the more expensive cars as does every new technology.    But I can't see wht would be gained.  F1 do it for better performance when coming out of corners I suspect that doesn't matter to 90% of road car drivers. It probably means that one car get better performance, that is, a feeling  more like a bigger NA engine, out of a much smaller power-plant and that would be a matter for customer preference.   Lots of people on here who strongly prefer a NA V8 to a turbo 6 or 4 for all kinds of reasons.

[JacobBlack]

Using the electric motor to spool up the turbo on F1 cars is as much about delivering fuel economy as performance.
When an engine is making it's most possible power/torque it works less hard to achieve its speed.* Keeping the turbo in the sweetspot has a double benefit for both economy and power - it's one of the best things about turbos.
This is why a lot of people get better fuel results from a big six than a smaller four in the same car.




*Super rough and simple explanation has many factual and technical flaws that pedants will jump all over, but is largely true.

[bensonc]

IMHO, I think turbo small engine make no sense in fuel economy vs driving habit.
I am not engineer or physis guy but since the article already said fuel, air and horse power are closely related.  It sound like what  doing here is dump as much air as it can in a 2L engine so it gave the same power level to a 3L V6 used to.  And with all the hassle of extra lubrication, exhaust, intake and PCV system...
http://www.streetfire.net/video/143-top-gear-toyota-prius-bmw-m3-fuel_180378.htm

[mixmanmash]

In a lot of cases, the decision to go supercharger to turbocharger is less about performance and more about packaging and what will fit.

In most cases, a turbo sized properly will outperform a supercharger at the same boost level.  A good example of this is the Chevy Cobalt SS supercharged version.  I remember reading an article where the shop swapped out the supercharger and installed a turbocharger.  The dyno clearly showed no loss of lower RPM torque with lots gained at the mid to high RPMs.

As well, a supercharger is a constant parasitic drag on the engine, whether you're in boost or not, contributing to fuel consumption.

The article also really only described on type of supercharger - the screw style.  There is the centrifugal type which is similar to the compressor side of a turbo.   They offer a very different characteristic.  There is also the roots type.

[mixmanmash]

IMHO, I think turbo small engine make no sense in fuel economy vs driving habit.
I am not engineer or physis guy but since the article already said fuel, air and horse power are closely related.  It sound like what  doing here is dump as much air as it can in a 2L engine so it gave the same power level to a 3L V6 used to.  And with all the hassle of extra lubrication, exhaust, intake and PCV system...
http://www.streetfire.net/video/143-top-gear-toyota-prius-bmw-m3-fuel_180378.htm

I think the manufacturers have gone a little too small to gain any benefit.  Trying to take a 2 L turbo to power a Ford Explorer is silly.  The 2.7L Ecoboost would be better suited.  The off boost response and power would be enough for  moving the vehicle.  The 2.0L would probably require you to dip into boost, thereby circumventing and potential fuel economy gain.

[Sir Osis of Liver]

*Super rough and simple explanation has many factual and technical flaws that pedants will jump all over, but is largely true.

 

[Noto]

Neat article, Pritch!

I also would have mentioned the other types of superchargers (eaton's, roots), but it's somewhat irrelevant given the intention of the article.

What I would like to see better use of is the variable geometry turbocharger.  It seems far less complex than using an electric motor to 'pre-spool', and certainly there is no parasitic loss (vs a supercharger).

Personally, it's the feeling of a supercharger that I love...turbochargers are great once they kick in, but it's the turbolag that just kills it for me.  In the name of efficiency though, it's a no-brainer.

That's why I love twin-charged engines (super-and-turbo), and can't wait to take an S60 T6 Drive-E out one day.

I remember my buddy's dad's Olds LSS (3.8L V6 supercharged).  Made only something like 245hp, but man was the delivery delicious.  Drank fuel like an Irish fish though.

[Nuttygent]

  Turbo lag has all been eliminated with the added technology the engines now have. Some cars have it when they are trying to squeeze out too much power from a particular engine though. Pretty sure VW/Audi have tamed their 2 L of all the lag issues, they also had a super and turbocharged 1.4L in Europe that had good numbers.  Have to say it's come a long way, my 86 Dodge Colt turbo had a 1.6 with a storming 108 HP!!! My new 1.6 has 201 HP and is a far more refined engine.

[mixmanmash]

  Turbo lag has all been eliminated with the added technology the engines now have. Some cars have it when they are trying to squeeze out too much power from a particular engine though. Pretty sure VW/Audi have tamed their 2 L of all the lag issues, they also had a super and turbocharged 1.4L in Europe that had good numbers.  Have to say it's come a long way, my 86 Dodge Colt turbo had a 1.6 with a storming 108 HP!!! My new 1.6 has 201 HP and is a far more refined engine.

This.  As long as they haven't put a giant turbo on a small engine (looking at your CLA45 and GLA45).

[bensonc]

I think the manufacturers have gone a little too small gain any benefit.  Trying to take a 2 L turbo to power a Ford Explorer is silly.  The 2.7L Ecoboost would be better suited.  The off boost response and power would be enough for  moving the vehicle.  The 2.0L would probably require you to dip into boost, thereby circumventing and potential fuel economy gain.

I understand this part, many countries yearly registration fee increase with engine size.  When I was in HK, they have M.Benz E180,S280, BMW 728, Audi A6 1.8T, A8 2.8...(10 yrs old model I am referring)....But those make no sense to me as it most of time use more gas then the main steam model with the right size engine.
I don't have much experience with turbo car, only owned 94 Toyota Aristo and 08 Passat wagon and both does need more attention in maintenance with very little fuel economy advantage only if you drive like an old man to stay off boost

[Sir Osis of Liver]

  Turbo lag has all been eliminated with the added technology the engines now have. Some cars have it when they are trying to squeeze out too much power from a particular engine though. Pretty sure VW/Audi have tamed their 2 L of all the lag issues, they also had a super and turbocharged 1.4L in Europe that had good numbers.  Have to say it's come a long way, my 86 Dodge Colt turbo had a 1.6 with a storming 108 HP!!! My new 1.6 has 201 HP and is a far more refined engine.

This.  As long as they haven't put a giant turbo on a small engine (looking at your CLA45 and GLA45).

That's how they minimize lag, tiny turbos with low inertia, but that comes at the expense of top end power. Not that that is the wrong way to do it for street cars, but there's no free lunch.

[Silverbird]

I think the electric supercharger is finally coming into play.

I know these used to be a joke, but with the brushless tech, they are feasible.
I know there is a Miata kit that uses one, giving a few seconds of boost running of a light 24V battery and then recharging via the alternator.

Audi had a prototype system as well, where it was filling in at the low RPM until the turbo boost hit.  No parasitic drag, and only the weight penalty.

Really only useful for intermittent use, but a good idea still.

[mixmanmash]

  Turbo lag has all been eliminated with the added technology the engines now have. Some cars have it when they are trying to squeeze out too much power from a particular engine though. Pretty sure VW/Audi have tamed their 2 L of all the lag issues, they also had a super and turbocharged 1.4L in Europe that had good numbers.  Have to say it's come a long way, my 86 Dodge Colt turbo had a 1.6 with a storming 108 HP!!! My new 1.6 has 201 HP and is a far more refined engine.

This.  As long as they haven't put a giant turbo on a small engine (looking at your CLA45 and GLA45).

That's how they minimize lag, tiny turbos with low inertia, but that comes at the expense of top end power. Not that that is the wrong way to do it for street cars, but there's no free lunch.

Yep, along with VTG turbos and other tricks like variable valve timing to get better breathing at low RPMs.

In my 300zx, I have opened up the breathing to the point where going with a larger turbo does not impact low RPM torque at all while gaining a ton of power at the top.

[hemusbull]

Making smaller engine more powerful by any type of boost makes it less reliable. Adding the complexity of the electronic control worsens the reliability even more...The pure designs like non boosted engines like Mazda's SkyActiv, Honda's VTEC and technologies like DI or keeping the six cylinders is still better choice in that regard.  Even the fuel efficiency in new Ford eco boosts or Fiat multi air are no better than the natural aspirated predecessors. Don't mind a F150 V6 eco boost for example is at least 5 grand more expensive...

[rrocket]

That's how they minimize lag, tiny turbos with low inertia, but that comes at the expense of top end power. Not that that is the wrong way to do it for street cars, but there's no free lunch.

Well there is...but no OEM is using it yet (as far as I know).  A "Quick Spool Valve" is used with a divided turbine housing and a non-divided manifold. This creates the effect of a multiple sized turbine A/R housing.  So it can behave like a small turbo at low RPM and a big one at high RPM.  It increases velocity at lower rpms while being wide open up top.  With this simple gadget, big turbos make small turbo low end power and spool without sacrificing any top end.

Here's a graph with some otherwise laggy turbo.  But having the valve activated by ECU, the turbo spools significantly faster and picks up 150 RWHP down low. You can see on the overlay, the top end is identical.

There's your free lunch. 

[redman]

Nice article in light of trend for Turbo engines.

Electric turbocharger and supercharger could be powered or assisted by capacitors.

Found this article titled "How electric superchargers went from fantasy to feasibility" Short Read with some interesting points.
http://www.roadandtrack.com/car-culture/a8965/why-electric-superchargers-make-sense-now/

[mixmanmash]

Making smaller engine more powerful by any type of boost makes it less reliable. Adding the complexity of the electronic control worsens the reliability even more...The pure designs like non boosted engines like Mazda's SkyActiv, Honda's VTEC and technologies like DI or keeping the six cylinders is still better choice in that regard.  Even the fuel efficiency in new Ford eco boosts or Fiat multi air are no better than the natural aspirated predecessors. Don't mind a F150 V6 eco boost for example is at least 5 grand more expensive...

Lol.  I disagree.  I have seen factory stock 300ZX twin turbos go 400k miles (640k kms).  Just regular oil changes.

[tpl]

^^ I disagree as well.   yes, you can make an unreliable boosted engine with the help of bean counters and when I had my first boosted engine ( SAAB Turbo) in 1982 they were less reliable...but those good engineers and chemists do seem to have fixed all that now.