That's one way to *brick* a turbocharger.
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I know! Everyone knows that:
hybrid and electric cars look bad
So much so that you do not even have to point it out. You need only say, "hybrid car" and everyone knows it is rubbish...
Filed under: That shit seemed a lot more clever until I typed it out. The hell with it, I am leaving it...
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no, merely anticipating someone elses argument. :-P
EDIT: and there it is... just not from the person i expected it from.
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deliberately arranged the test so that the M3 was in its element and the Prius wasn't.
I can assure you that an M3 is not "in its element" when puttering around behind a Prius. ;)
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the M3 was in its element
The M3's element is doing 85mph on the motorway being driven by a sales rep with a bad shirt and Bluetooth
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ok. fair enough. However, it was closer to its element than the prius!
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"The only problem with the M3 is that it is driven almost exclusively by cocks." - Jeremy Clarkson
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I feel like I am getting @lucas'd or @blakeyrat'd? Have you been drinking?
Jaime:
I am not interpreting the chart to say that. The chart specifically says that redline is where you get nearly the worst fuel economy....but you said earlier...
Jaime:
As a general rule, internal combustion engines are most fuel efficient at full throttle. Here is a chart:It's you that isn't reading carefully enough. Those two statements are only contradictory if redline is the same thing a full throttle. They are not.
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It's you that isn't reading carefully enough. Those two statements are only contradictory if redline is the same thing a full throttle. They are not.
Yeah -- you can get redline at full throttle or redline at part throttle, depending on what gear you're in and how much engine power you're drawing. Try driving around an oval at highway speed, but in a different gear for each lap, and noting down the RPMs for each gear...
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the M3 was in its element and the Prius wasn't.
What's this about a collision with a Honda?
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It's you that isn't reading carefully enough. Those two statements are only contradictory if redline is the same thing a full throttle. They are not.
I will give you that. You are correct. But that chart also really only applies to steady state usage, which is why I said it would apply to generators (and airplanes, since @tarunik sort of brought it up). When you have constantly varying throttle and acceleration in the mix, a larger engine can frequently do better on fuel economy. But you are correct that it is only when you push the smaller engine.
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(Sidenote: if you go "turbos are for ricers" and dismiss me that way, I'll have to drop a large pile of WWII era aircraft engines on your head.)
+1
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My friend's tongue-in-cheek fuel economy argument: if you accelerate to freeway speed in a V8, the engine only has to go full-bore for like 10 seconds. If you do it in a hybrid, you're engine's going full-bore for like 30-40 seconds. Therefore, the V8 will save gas over time.
I'd hope it'd be a lot less than 10 seconds.
Although it's funny to sit in one of my friends cars when they go WOT and count what seems like an eternity before they hit 60.
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This is actually a much bigger deal on forced-induction (turbocharged and/or supercharged) engines than it is on atmospheric-induction engines, but atmospheric-induction engines still benefit some from this technique -- low (to mid in your chart) RPMs at WOT give much better SFC than any RPM at almost no throttle.
I've read that forced induction systems help reduce pumping loss and can actually give a gain of 1-2MPG if you drive gently.
(Sidenote: if you go "turbos are for ricers" and dismiss me that way, I'll have to drop a large pile of WWII era aircraft engines on your head.)
http://www.promkings.net/RicerWorld/wp-content/uploads/2011/11/ricer-1.jpg
Ricers do like their turbos, though.
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I'm not saying that their result was wrong
Jeremy Clarkson was involved. Of course it was wrong.
https://www.youtube.com/watch?v=xgABbHPdwH4
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I've read that forced induction systems help reduce pumping loss and can actually give a gain of 1-2MPG if you drive gently.
Yeah -- low RPM and high MAP combine to yield minimal pumping losses in a turbocharged engine. Obviously, you are going to want a lean mixture for this, as well -- although that's for your mechanic to deal with ;)
(See the passage I quoted above for an explanation as to why)
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a larger engine can frequently do better on fuel economy
I'd say the most likely reason why the Prius did worse on the test is that it kept the engine at high rpm to get enough torque while the M3 had sufficient torque at more reasonable rpm and the inefficiency due to excessive rpm of the smaller engine beat the pumping losses of the larger engine (especially if the engine supports ultra-lean-burn, which eliminates the pumping losses in idle or little-above-idle crusie; I can't quickly find a reference, but it probably does). It seems to say something about the automatic shift of the Prius.
Note, that the chart posted by Jamie actually shows this, but one has to read it not in the obvious way of comparing points above each other.
"turbos are for ricers"
If you care about fuel economy, you have diesel and diesels are almost always turbo (surprises me Prius is not diesel).
I've read that forced induction systems help reduce pumping loss and can actually give a gain of 1-2MPG if you drive gently.
Turbocharged systems have relatively significant lag in throttle response, because the turbine has to spool up and this takes a bit of time. So when you add power too fast, they are running too rich and loose efficiency—and produce a puff of smoke.
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@tarunik said:
"turbos are for ricers"
If you care about fuel economy, you have diesel and diesels are almost always turbo (surprises me Prius is not diesel).
And more and more often, petrol engines are being shrunk and turbocharged too; the M5 went from a natural V10 to a twin-turbo V8, for instance. And you can get a Mustang with a 2.0 turbo instead of the V8 (though why would you?).
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If you care about fuel economy, you have diesel and diesels are almost always turbo (surprises me Prius is not diesel).
Agreed -- forced-draft diesels do a fantastic job on fuel economy. Now, it's just a matter of perfecting the technology to the point where 40 gallons of Jet-A gets you several hours of flight time, without the need for MX to go swap the engine every thousand Hobbs hours... ;)
Turbocharged systems have relatively significant lag in throttle response, because the turbine has to spool up and this takes a bit of time. So when you add power too fast, they are running too rich and loose efficiency—and produce a puff of smoke.
Exactly -- I'm almost wondering why they don't schedule the fuel so that you don't wind up with that efficiency loss...
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@Bulb said:
Turbocharged systems have relatively significant lag in throttle response, because the turbine has to spool up and this takes a bit of time. So when you add power too fast, they are running too rich and loose efficiency—and produce a puff of smoke.
Exactly -- I'm almost wondering why they don't schedule the fuel so that you don't wind up with that efficiency loss...
Probably because you need that fuel to produce enough power to spool the turbo up ;)What should be done really is have two turbos; a small one that spools very quickly and works at low revs, and a bigger one that gives more power at higher revs. That way the lag from the big unit is covered by the small unit.
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Which is what the Supra did, and it was rubbish.
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I once read an article on the variable transmission of a prius, probably linked from here. It actually keeps the (gas) engine at a fixed ideal RPM except at max throttle.
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What should be done really is have two turbos; a small one that spools very quickly and works at low revs, and a bigger one that gives more power at higher revs. That way the lag from the big unit is covered by the small unit.
You might try using an electrically-powered small turbo so that it can be spun up very quickly by the ECU when it detects a requested rapid increase in acceleration.
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You might try using an electrically-powered small turbo so that it can be spun up very quickly by the ECU when it detects a requested rapid increase in acceleration.
A sort of anti-lag? That could work
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electrically-powered small turbo
Yeah...that's not going to work...
Dump some raw fuel in the exhaust though...that would work.
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Yeah...that's not going to work...
I'm not arguing for it to be a replacement for the main turbo. Just something to get the system pressurising sooner.
Mind you, I'd also be interested in looking at electric transmissions instead of mechanical ones; I suspect they're getting light enough and efficient enough that it is worth doing. Essentially making a hybrid with a V8 engine providing the power.
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Essentially making a hybrid with a V8 engine providing the power
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Turbocharged systems have relatively significant lag in throttle response, because the turbine has to spool up and this takes a bit of time. So when you add power too fast, they are running too rich and loose efficiency—and produce a puff of smoke.
My Duramax has a second or two of turbo lag, noticeable but not really an issue IMO. Even before the turbo spins up, it's a hell of a lot quicker than my old gasser. Then again, I don't race it. It also only smokes during turbo lag if it's very cold out and the engine isn't warmed up yet and I stomp on the throttle, my guess is it sometimes misses ignition under those conditions.
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Twin turbos are a popular mod in the diesel world, you replace the stock single large turbo with two much smaller ones in series. Since they're smaller, they have less rotating mass and a smaller moment of inertia so they spin up much more quickly.
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I'm not arguing for it to be a replacement for the main turbo. Just something to get the system pressurising sooner.
But, it just won't be possible. The amount of energy you would have to put in to something like that does not work in car scenarios. The sheer amount of wattage it would take, on a 12V system would make for a massive amount of amperage.
But, in WRC they dump raw fuel in to the turbo to keep turbo lag down to zero. Not exactly great for fuel economy, or service life, but it works. ;)
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Variable geometry turbos also help to reduce lag. They're pretty common in modern diesel cars. Certainly those in Europe anyway.
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But, it just won't be possible. The amount of energy you would have to put in to something like that does not work in car scenarios. The sheer amount of wattage it would take, on a 12V system would make for a massive amount of amperage.
Probably correct, IIRC a turbo can spin at 100,000+ RPM. Going from near zero to that in less than a second would require a heck of a motor.
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You could always just not let up off the throttle. That keeps turbo lag to a minimum also. ;)
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Makes slowing down more tricky though ;)
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Why would you want to slow down? Slowing down hurts fuel economy. You put all of that energy in to the car, no sense burning it off as heat in the brakes. ;)
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IIRC a turbo can spin at 100,000+ RPM. Going from near zero to that in less than a second would require a heck of a motor.
Also, energy out = energy in - efficiency losses. Unless you change the laws of thermodynamics you are going to have a hell of a time getting enough energy in to the turbo to make it worthwhile to have it spun up electrically. Turbos and superchargers take quite a bit of horsepower to run. More than you could ever get out of a cars electrical system.
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Someone who's interested in "fixing" the throttle response may not be interested in efficiency at all.
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Hmmmmm, I phrased that poorly. As I do very frequently.
Did you ever see one of those ads for "electric superchargers"? They promise 2-3 lbs of boost with an easy install. Everyone who has tried one has shown zero boost, even on small engines. I have seen where people have done the calculations and shown that even at 100% efficiency there is no possibility of it ever working. If you have a 12V circuit, and even if you pumped 100A in to it at 100% transfer efficiency to moving air, you would get less than 1HP of work being done to pump air in to the engine.
Considering that even small turbos or superchargers use a lot more than that, even a massive electrical circuit would do jack shit towards moving air and creating pressure. It is just not possible. Efficiency would have to be > 100%.
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http://www.superstreetonline.com/how-to/engine/0406tur-knight-turbo-electric-supercharger/
There is an article that kind of shows what I am talking about. In order to get any sort of positive boost, the amount of energy put in to the system gets pretty staggering.
Electric might get you close to atmospheric pressure fairly easily, but that is trivial really. That is not where the lag is.
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Getting back on topic, it would have been possible to salvage the server if you had a bag of sugar (or even just a cup) in the house: sugar prevents concrete setting.
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Yeah, I wouldn't use it after that anyway. Also, you would have to thoroughly mix the sugar in to the concrete, in all of the DIMM slots, and the CPU socket, etc.
It was trash the moment concrete started pouring in to it. Not worth the trouble.
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surprises me Prius is not diesel
I heard they tried it, but they got better performance and fuel efficiency from the motor by leaving out the hybrid drive train and the batteries, so a product development VP made them quietly bury it.
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the turbine has to spool up and this takes a bit of time
Does anybody make a turbocharger with a computer-controlled electric boost motor on it?
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Does anybody make a turbocharger with a computer-controlled electric boost motor on it?
Hanzo'd by a couple of hours. See above for reasons this won't work.
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electric transmissions
In my ideal-car fantasy world, pancake electric motors have become lightweight enough that you can just use them as wheels and you don't need gears or even driveshafts any more.
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The sheer amount of wattage it would take, on a 12V system would make for a massive amount of amperage.
I can't imagine you'd need more power to spin up a little turbopump than it takes to cold-crank an engine, and you wouldn't need it for as long. More often, though. Still should be doable.
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What should be done really is have two turbos; a small one that spools very quickly and works at low revs, and a bigger one that gives more power at higher revs. That way the lag from the big unit is covered by the small unit.
Yup.
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I can't imagine you'd need more power to spin up a little turbopump than it takes to cold-crank an engine, and you wouldn't need it for as long. More often, though. Still should be doable.
Well, you are forgetting that you are trying to pump air, at an incredible rate. See the above article for an explanation.
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There is an article that kind of shows what I am talking about.
...except that it's an article about a successful electric supercharger design, so it's kind of the opposite of what you're talking about?
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...except that it's an article about a successful electric supercharger design, so it's kind of the opposite of what you're talking about?
Where the guy uses multiple batteries in order to get voltages much higher than a normal car is capable of producing, and there are a shitload of problems that constantly come up, and it constantly breaks.
Must be the Aussie version of "successful"?
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there are a shitload of problems that constantly come up, and it constantly breaks.
@the article that Polygeekery linked said:
Two years of constant use on the Avenger test mule has proven the
Eaton/electric to be indestructible. The Eaton lasts 158K as a
belt-driven supercharger. As an ESC they should last 4 million miles.
The electric motors have a 1000-hour life expectancy; at 400 seconds per
day that's 24 years.One of these things is not like the other one
Toyota TS040 Hybrid - Wikipedia
