...when you can have VTES? ELECTRIC BOOST
French supplier Valeo just purchased a UK-based outfit that’s been developing electric superchargers. Called a variable torque enhancement system or VTES for short, it uses no rare-earth metals. Electric superchargers have less parasitic drag than mechanical ones making them more efficient. They’re also quicker to respond. This one can hit 70,000 RPM in about one-third of a second! The VTES system is designed to work on existing 12-volt electrical systems but the company is testing them with 48 volts, and that could give turbochargers some real competition.
'08 Jeep Liberty 6-Speed MT - "Last of the Mohicans"
I've read that BMW is supposed to use one of these on the new M3, along with a conventional turbo. Actually, there have been some reports that the new M3 will have 3 turbos, but my guess is that it will have one electric supercharger, and one twin-scroll turbocharger.
Anyway, the idea is to use the electric supercharger to provide low-rpm boost until the turbocharger can provide its own boost. I'm not sure if the electric blower is supposed to shut down at that point or it will continue to provide boost along with the turbo. Anyway, it should be interesting to learn exactly how this will all work.
In the meantime, maybe I'll rig an electric hairdryer in to my intake and see if I can make boost just off idle.
Rope-Pusher wrote:... Electric superchargers have less parasitic drag than mechanical ones making them more efficient...
I find that very interesting. I'm assuming they are talking about internal parasitic drag of the unit itself. But what about the fact that a turbo is driven by the exhaust flow, which means it is basically driven for "free" by wasted heat flow out of the engine. And of course an electric supercharger is driven by electricity, which does put additional load on the engine. Hmm....
Prolly trying to combine the benefits of both turbocharging and mechanically driven supercharging, while minimizing the negatives of each.
Sure, you have to put some juice back into the battery after you summon the DOG of boost, but that's better than spinning the thing with a belt all day long and twice on Sundays.
'08 Jeep Liberty 6-Speed MT - "Last of the Mohicans"
Rope-Pusher wrote:
Sure, you have to put some juice back into the battery after you summon the DOG of boost, but that's better than spinning the thing with a belt all day long and twice on Sundays.
Yeah, but you're only spinning a belt/pulley on a conventional supercharger. An electric supercharger may not spin a belt/pulley directly, but it kinda does in an indirect way because the electricity needed to drive an electric supercharger will cause the alternator to sap more power from the engine. So indirectly, the electric supercharger does have some parasitic loss. And of course a turbocharger doesn't spin a belt/pulley directly or indirectly. That's why I was wondering if the electric supercharger's advantage of less internal parasitic drag is offset at all by the possibility that it has more parasitic drag on the engine than a turbocharger. See what I'm saying?
Yeah, the turbo is using the "free" energy of exhaust expansion, but it's hell on emissions during a cold start and an electrically driven compressor could do it quicker and in a more controlled manner than even an electric wast-gate can do.
'08 Jeep Liberty 6-Speed MT - "Last of the Mohicans"
Rope-Pusher wrote:Yeah, the turbo is using the "free" energy of exhaust expansion, but it's hell on emissions during a cold start and an electrically driven compressor could do it quicker and in a more controlled manner than even an electric wast-gate can do.
Hmm....well, I was talking strictly about their claim that the electric supercharger has less internal parasitic drag, not really about emissions. And I have no doubt that an electric supercharger can provide virtually instant boost in an infinitely controllable way, so I'm sure it would be a big advantage there.
What makes you say that a turbo is "hell on emissions during a cold start"? How does the addition of a turbocharger change cold start emissions on a car? I'm just asking because I never thought about this and I'm not sure how a turbocharged engine would have a negative impact on cold start emissions. The exhaust flow basically goes through the turbine almost immediately after the exhaust header and then back into the rest of the exhaust system.
The turbo manifold/housing absorbs more heat energy from the exhaust, so the catalyst lights-off more slowly. They would do anything to get the catalytic converter closer to the combustion chamber these days. Didn't Chevy come out with new heads for their V-6, with the exhaust manifolds part of the heads instead of bolt-on? Seams tummy I read that onced or twiced.
'08 Jeep Liberty 6-Speed MT - "Last of the Mohicans"
Rope-Pusher wrote:The turbo manifold/housing absorbs more heat energy from the exhaust, so the catalyst lights-off more slowly.
Hmm...never thought about that. But they did come out with heated O2 sensors and pre-heated catalysts a while back to help with that particular problem.
They would do anything to get the catalytic converter closer to the combustion chamber these days. Didn't Chevy come out with new heads for their V-6, with the exhaust manifolds part of the heads instead of bolt-on? Seams tummy I read that onced or twiced.
Yeah, I think you're correct about that. And it's not just Chevy. If I remember correctly, someone else had a similar set-up.
I believe BMW's system in integrated into one turbo... Basically adding an electric motor between hot and cold sides and helping to remove lag.
Companies have been testing for a while with diesel motors, since temps are lower. Most materials lose their magnetism around 300 degrees F; tough conditions for something right beside the hot side of a turbo.
Not only does the system provide a couple of psi when it is most needed, also works (as stated in all the BMW press) as a built-in wastegate and recovers a bit of energy in the process. Curious how that will sound/work without strangling the engine at high RPM.
-Standardshifter
Shifting the Standard of Automotive Websites
Standardshifter wrote:I believe BMW's system in integrated into one turbo... Basically adding an electric motor between hot and cold sides and helping to remove lag.
Companies have been testing for a while with diesel motors, since temps are lower. Most materials lose their magnetism around 300 degrees F; tough conditions for something right beside the hot side of a turbo.
Not only does the system provide a couple of psi when it is most needed, also works (as stated in all the BMW press) as a built-in wastegate and recovers a bit of energy in the process. Curious how that will sound/work without strangling the engine at high RPM.
Do you have a link? I'm only asking because I've read that there will be a separate electrically powered "supercharger" that works in conjunction with a twin-scroll turbocharger. There's a lot of confusion though....I've also read reports that the new M3 will have three turbos.
Also, how would it be possible to add an electric motor to assist the turbo? I mean, if the motor somehow spins the turbine/compressor wheels, wouldn't that cause havoc with the exhaust? I would think if the turbine is spun up faster than it would have been by the exhaust flow, it could create a vacuum on the exhaust. I dunno...it just seems that they wouldn't integrate an electric supercharger and a turbocharger into one unit, but I guess anything is possible.
There's a paper on the basics on what folks have been working on, sans using it as a wastegate replacement. There are prototypes out there for at least five years now for diesels.
This case, the motor is on the other side of the compressor, which helps with the heat issue.
Only able to produce a couple of psi...which is all that is needed to boost response time before the exhaust takes over. Great for scavenging exhaust out cylinder (and maybe will make two-stroke turbodiesels viable again combined with direct injection)
As far as the BMW goes specifically:
"When maximum boost is reached, the electric motor switches to an alternator mode, generates power for the battery, and avoids the turbine exceeding a certain speed. This renders a wastegate needless and ensures sure no energy from the turbine is wasted."
Hmm...interesting. I can't wait to see what they come up with and how the finalize the design. It seems like a good evolution of the turbocharger. People have been trying to come up with a solution for the whole "small turbo- spools fast, but runs out of breath at high rpm, big turbo - lots of lag, but boosts great at high rpm" issues for years now. Personally, I love the idea of a sequential twin-turbo set up that was common on most of the Japanese sports cars of the 90's. A small turbo that boosts up quickly with minimal lag, followed by a larger turbo that provides a hard kick at higher rpm.
Then I also remember variable vane turbos that were developed to provide minimal lag and still provide good higher rpm power, all in a single turbo. This idea never really seemed to catch on, although Chrysler did give it a good shot. I remember hearing that there were a lot of issues with the vanes not moving as intended after a while.
Around the same time, someone came up with the idea to create ball bearing hybrid turbos, which is exactly what I put in my old Eagle Talon Tsi. It had a larger compressor wheel, but still used the stock turbine wheel, with the idea being to push more air without creating additional lag.
Today we have twin-scroll turbo designs. Again, to help minimize lag while still providing decent boost at high rpm.
And now we're looking at electrically-assisted turbochargers, once again to solve the same age-old problem of lag and high rpm boost.
