Superchargers gain a gearbox
May 5, 2006 8:04 AM   Subscribe

The Supercharger was a fantastic innovation, but it has its downsides. Volkswagen tried solving them by adding both a Supercharger and a Turbocharger, in their TSI engines, but this solution is relatively expensive. Perhaps the new invention by Atonov has merit. Instead of using a standard Roots supercharger, it uses a more efficient centrifugal supercharger, and adding a small two-speed automatic transmission to the loop, ensuring that the engine operates on boost throughout the rev range.

It may not sound like much, but it may change the way superchargers are working forever, allowing smaller engines with higher performance, or adding obscene amounts of power to large engines
posted by SharQ (38 comments total)
Because better ways for people to speed and use more gas is what the world needs right now.
posted by jacquilynne at 8:13 AM on May 5, 2006

Alternatively: is this something I'd need to have a ghastly, environment-destroying internal combustion engine to know about?

Thanks for the post.
posted by yerfatma at 8:15 AM on May 5, 2006

jacquilynne, turbochargers and superchargers allow a much smaller engine to provide the power of a much larger engine, when necessary, which can lead to fuel savings. Diesels are also much more efficient when turbocharged.

Developments in this area will provide a benefit to the environment in one way or another.
posted by kableh at 8:20 AM on May 5, 2006

Multispeed superchargers aren't new -- they date back to WWII, used on piston powered aircraft. Supercharging is a huge win for aircraft -- air density drops with altitude, meaning less oxygen into the engine, thus, less power. Supercharging fixes that, meaning you get sea-level power, but high-altitude drag (this is why compressor engines, like piston+superchargers and jets, fly much faster at high altitude.) But at low level, you're wasting power spinning the supercharges. Multstage superchargers were the first answer, but you pay a weight penalty. Multispeed superchargers were the final answer (then the whole problem set changed with the turbine engine.)

better ways for people to speed and use more gas

Supercharges can save gas -- if you replace a 90hp, 1500 pound engine with a supercharged, 90hp, 900 pound engine, that's 600 pounds less weight you're hauling around, thus, you need less gas to move the vehicle.

It's true that most people think of sports cars when they hear about boost, but diesel trucks have used superchargers and turbo chargers for years to get more power out of smaller engine, reducing the dead weight, and increasing mileage.
posted by eriko at 8:23 AM on May 5, 2006

The use of turbochargers and superchargers is what permits many of the European auto makers to offer relatively higher performance engines with reduced emissions compared to their brawny American counterparts.

BMW announced a few weeks back that it is abandoning the 'horsepower race' to improve performance and instead is turning to technology to make its current motors more efficient and to provide greater output. American automakers tend to prefer to just beef-up the motor with greater displacement and more horsepower, whereas the Euros try to get more displacement out of the same sized engine using more technology and tricks.

Audi and Volkswagen have really been leading the charge on more efficient powerplants with reduced fuel consumption and emissions, their experiment with this combined super/turbo unit is pretty ingenius for mass production. VW/Audi's FSI (fuel stratefied injection) technology and diesel particular filter technology have really helped advance diesel technology along with the performance and consumption issues associated with regular gasoline motors.

I'm of the belief that these technologies are the ones that in the short to medium term, will provide the market with much better solutions than hybrid vehicles - especially for the US. If only Federal Regulations for diesel could be sped up so we wouldn't be losing VW diesels in 2007....(they will return, however)
posted by tgrundke at 8:28 AM on May 5, 2006

they make some claims in the first link about high output with greater efficiency, but I don't see any hard numbers and their swanky cg animation of a moving engine is no help. is it just the weight difference + the power output, or is there more to it?
posted by carsonb at 8:29 AM on May 5, 2006

Please stop pointing out actual benefits - it hinders my ability to vomit on the thread with self-righteous indignation.
posted by daveleck at 8:42 AM on May 5, 2006

Seriously, dudes, don't you fellas understand your place in Metafilter's political ecosystem? If you're going to bring up shockingly un-PC concepts such as horsepower, at least have the decency to leave such things undefended. What is this rational explanation bullshit?
posted by kalessin at 8:46 AM on May 5, 2006

On the VW site, anyone know what the units of power are? "PS"? I thought the SI units for power were kilowatts.
posted by notsnot at 8:48 AM on May 5, 2006

Pferdestärke = horsepower (literally)
posted by daveleck at 8:51 AM on May 5, 2006

PS = Pferdestärke = "Horsepower". In this case, it's the oddball "metric horsepower", defined as the power need to raise 75kg at 1m/s against standard gravity.
posted by eriko at 8:51 AM on May 5, 2006

I've got a degree in mechanical engineering, and I've never heard that. Ok, I learned something - I guess I can quit for the day.
posted by notsnot at 8:56 AM on May 5, 2006

Why is the two-speed supercharger better than sequential turbos?
posted by Kwantsar at 9:06 AM on May 5, 2006

"...better ways for people to speed and use more gas is what the world needs right now."

If we don't use it all up, we'll never get our atomic-powered flying cars.
posted by mr_crash_davis at 9:07 AM on May 5, 2006

"Why is the two-speed supercharger better than sequential turbos?"

Turbo lag. Superchargers, being crank-driven, provide boost at all engine speeds.
posted by mr_crash_davis at 9:09 AM on May 5, 2006

The practice of combining a supercharger and a turbocharger is called twincharging. i know this because i asked mefi a while back.
posted by quin at 9:17 AM on May 5, 2006

"obscene amounts of power"

You mean obscene amounts of power in an engine?

I don't even think that's possible.
posted by Relay at 9:20 AM on May 5, 2006

Turbo lag.

Also, quite often, mass. Turbos require exhaust piping and intercooling, multiple turbos require more of the same. If you can replace a twin turbo with a multispeed supercharger that provides and identical boost profile, you'd gain simply on the mass loss. The fact that it takes up much less space is a big win in other ways -- never mind the fact that the supercharger will have a better boost profile.

The one problem with superchargers is parasitic power loss. It is trivial to install a wastegate onto a turbo and shut it down when you simply don't need the boost. A multispeed supercharger with a clutch could do the same thing, provided that there's enough airflow through the idle supercharger to feed the engine. Being able to turn the supercharger off when you don't need much power (such as highway cruise) and then back on instantly when you do (such as a highway pass) would really help with the overall efficency, and would mean the super/turbocharger wars would be over, and superchargers would win.

What I've always wondered is why not power them electrically? You'd need to add another alternator, because a supercharger can take a bunch of power, but then throttling the unit becomes easy.
posted by eriko at 9:25 AM on May 5, 2006

There have been some attempts at cheesy, low-output, electric forced-induction solutions. Here's one.
posted by daveleck at 9:30 AM on May 5, 2006

Oh, and speaking of cars that are both turbo and supercharged:

The Lancia Delta S4. And that car is 20 years old.

posted by Relay at 9:32 AM on May 5, 2006

Yeah, but dude, it's a *Lancia*....

posted by tgrundke at 9:41 AM on May 5, 2006

jacquilynne, turbochargers and superchargers allow a much smaller engine to provide the power of a much larger engine, when necessary, which can lead to fuel savings. Diesels are also much more efficient when turbocharged.

Exactly. Americans keep using these innovations to make the cars BIGGER.

We just got the new Jetta TDI and it is amazing. Even with Biodielsel the power that thing has! AND gets almost 50mpg.

BTW: Where are the hybrid diesel electric engines? Seems to me that is where to go.
posted by tkchrist at 9:46 AM on May 5, 2006

Hey, the Lancia Stratos was a beautiful piece of work.

The link to the S4 appears to be dead, btw.
posted by Swervo at 9:51 AM on May 5, 2006

Interesting concept, thanks for the post, sharq. While the addition of a transmission seems to help matters, it also adds to the complexity of the works. In my opinion, that is one of the huge downsides about adding bits and bobs to the internal combustion engine. I think it's best to keep the moving parts to a minimum. And with that attitude, you're either talking about something like a rotary engine or a more favorable power to weight ratio with a standard IC engine. If you look at some of the '60s muscle cars, you won't find a fairly simple machine without heavy things like the gobs of insulation and power accessories (like power windows and AC). Of course the downside is they didn't have the safety features of modern cars, which also adds to weight.
posted by SteveInMaine at 10:05 AM on May 5, 2006

Very cool topic. It's strange being a gearhead on MeFi -- the "you should feel dirty for enjoying this stuff" brigade never seems to miss an opportunity to be self-righteous.

Centrifugal superchargers are very cool -- significantly more effecient than a Roots-style SC. I run a Roots-style SC on my 4Runner, and have a turbo on my other vehicle (both 4 cylinder motors), and can vouch for the benefits of arftifically increasing displacement via forced induction. When driven modestly, my fuel economy is on par with the normally aspirated versions of my motors; however, when needed, the extra power is right there, ready to use. A two-speed centrifigual SC would be fantastic, as the SC is ineffecient above a a certain RPM (supercharger RPM, not necessarily engine RPM).

Thanks for posting this.
posted by mosk at 10:15 AM on May 5, 2006

BTW: Where are the hybrid diesel electric engines? Seems to me that is where to go.

The auto industry isn't the computer industry. The Prius and Insight have been around for over five years and the competition is just getting around to introducing competition of their own. Give it a decade or three before hybrid powertrains to be common across product lines.
posted by b1tr0t at 10:15 AM on May 5, 2006

I got your Diesel Electric Hybrid right here...
posted by zeoslap at 10:22 AM on May 5, 2006

Where are the hybrid diesel electric engines?

Okay. Yes, diesel gets better mileage. It should -- it has a higher energy density than gasoline -- 32MJ/l, as opposed to 29MJ/l. So, a gallon of diesel holds almost 20MJ more energy.

The problems with diesel. 1) It's rather dirty, esp. in particulates. 2) It needs a heavier engine. 3) US Diesel, in particular, is crap -- it's loaded with sulfur, which makes controlling emission very hard, since the sulfur ruins most catalysts. The US is trying to go to Ultra Low Sulfur Diesel (ULSD), but the problem with this is that sulfur is a natural lubricant, and taking it out means it needs to be replaced, or the engine wear increases dramatically. This is one area where biodiesel helps -- a ULSD/Biodiesel mix can replace conventional diesel.

And, in the end, the carbon emissions are about the same, when compared to the energy consumed. So, while you might save a few dollars, it really doesn't win you much, and when ULSD happens, the cost will probably balance it against gas, mpg/dollar.
posted by eriko at 10:48 AM on May 5, 2006

Interesting. All I could see from the links was that this was a way to get more gas in the engines and make them go faster. Woo! That this actually leads to greater efficiency would not have been what I expected.

Any concrete numbers on how much efficient they are?
posted by jacquilynne at 11:22 AM on May 5, 2006


1. Biodiesel.
2. about 2x the weight of a gas engine, so assuming a car is 2700 lb., a 300lb. diesel compared to a 150lb. gas engine means a weight difference of around 5% while still getting at least twice the mileage (imagine if it were of equal weight)
3. Biodiesel.
posted by linux at 11:27 AM on May 5, 2006

To add to linux's comments, low-volume soy-biodiesel is already reaching parity with petro-diesel. When algae production comes online, biodiesel will have significant price advantages.
posted by b1tr0t at 11:38 AM on May 5, 2006


Not there yet. We can't go biodiesel completey using known techniques -- there isn't enough surface area in the country to grow the plantstocks we'd need. Algae based biodiesel would change that equation, but that's new tech, and it has no effect on the fuel economy right now. Today, the best use of biodiesel is in B5 ULSD, restoring the lubricity of ultra-low sulfur deisel.

There's also that nasty issue of carbon emmision, though biodiesel is better, since making it extracts carbon from the atmosphere, so the net add is much lower than with petro fuels. But it's still an add. However, unlike Hydrogen, biodiesel, once made, is trivial to work with. Most anything capable of working with petrodiesel either can, or can be made, to work with biodiesel.

But, as of today, and for at least a few years, there's just not enough feedstocks to convert a significant fraction of the transport base to biodiesel.
posted by eriko at 12:20 PM on May 5, 2006

Ok. So Bio-diesel electric hybrid is the way to go.

We curently run the Jetta on Biodiesel at about 49MPG. I feel pretty good about that.
posted by tkchrist at 1:14 PM on May 5, 2006

"The Prius and Insight have been around for over five years"


One of the points of the VW TSI engine is to keep an element of fun.

Not all drivers are staid, boring, old farts who think boring cars for people who are "grown up" and self rightous are good cars.

Some of us actually enjoy driving.

And before you get on your high horses about how wrong I am to enjoy driving and start bumming the Prius some more. The mpg saved with a Prius compared to the engergy used to make the car and the extra energy used to make the car, which is more complex that an regular car - the savings are nothing - its academic.

If you buy a Prius your still a tosser. You should be using public transport or walking to work or summin.

For those of us who actually like and enjoy driving (and those like me who will intentionally go out and rev my car to piss enviromentalists off) - this supercharger stuff sounds interesting.
posted by 13twelve at 1:57 PM on May 5, 2006

Well, aren't you just a smart little fella.
posted by Jimbob at 2:13 PM on May 5, 2006

zeoslap writes "I got your Diesel Electric Hybrid right here..."

Beat me to it....
posted by mr_roboto at 2:17 PM on May 5, 2006

Jimbob - nah, that probably came accross more tetchy that it needed.

And I spelt "energy": engergy lol
posted by 13twelve at 2:25 PM on May 5, 2006

tkchrist: Where are the hybrid diesel electric engines? Seems to me that is where to go.

The Green Goat is a diesel hybrid. Unfortunately it's not street-legal.

The case for diesel hybrids is not as compelling as one might think. The gasoline engines used in cars like the Prius aren't straight-up Otto-cycle engines like in other cars; there are some tricks that make a Prius engine (for example) more efficient (and in some ways more diesel-like) than standard gasoline engines. For one, the control computer tries to keep the transmission in a tall ratio with the throttle wide open, "lugging" the engine to minimize pumping losses. For another, the Prius uses a modified Otto cycle (the Atkinson Cycle) that offers better thermal efficiency than the standard Otto cycle.

I don't know if these measures completely close the efficiency gap between diesel and gas engines. But the gas engines currently used in hybrids run very clean, and start and stop very readily. With a reduced (or eliminated) efficiency lead, diesels would have to offer some other compelling advantage to be chosen for use in hybrid passenger cars.
posted by Western Infidels at 2:47 PM on May 5, 2006

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