OT: electric supercharging

supercharger:

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He's saying a supercharger can be driven thru a pulley/gear ratio such that you have - say - 8 psi at idle speed. Then, at higher speeds, you just wastegate/release pressure or otherwise limit boost. I suppose you could even have a cut-out clutch on the blower at some rpm where the turbo begins climbing.

*** That is precisely how most super/turbocharger combos work; the cut-out clutches disengage the supercharger at 3000-3300 RPM so there are no parasitic losses once the turbo is at full boost. Works very well as long as both forced induction systems use the same boost controller/wastegate set up.
Reply to
JD
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I'm with you. It doesn't add up; it makes no sense.

Reply to
JD

And a 1 liter vehicle is going to have a battery capable of repeatedly supplying close to a thousand amps of power? Or a charging system capable of replentishing said battery?

I'm still sceptical. At best.

Reply to
clare

Not to mention if you did not disable the alternator when boost was called for, it would draw so much power from the engine you would have a severe stumble just from the power consumption of the alternator.

I'm still not buying.

Reply to
clare

supercharger:

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With a positive displacement blower there is no such thing as a wastegate, and boost does not rise appreciably from idle to full RPM. Turbo compounded is a different story - that's using turbo along with PD supercharger.

A Paxon or McCullugh is not a PD unit. The supercharger on a 3.9 sss Poncho is - as is the supercharger on ther first generation MR2

Reply to
clare

But it doesn't seem like you would need the turbocharger (a gas-powered supercharger) to handle the "load" of providing the extra HP at the mid- to top-end of RPM if you already had a Whipple that can also handle that same range. Would you actually spend the money on an undersized Whipple to only handle the low-RPM range and not cover (provide enough flow) for the higher RPMs? Whipple is pricey so it seems you'd just go with that.

If in parallel, how to you prevent the leakage in the turbo (to slow its fan) if the Whipple is providing more pressure if no valving between to prevent backflow? The wastegate is upstream of the turbo fins to divert exhaust gases from over spinning the blades and creating too much pressure. But if in parallel with a Whipple, it seems the pressure from the Whipple (which comes up faster than the turbo) would back pedal into the turbo and slow its fins.

From

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justwhere is the output of the Whipple going to get connected? After theturbo? Then what prevents backpressure from the Whipple into the turbo? When inuse, I thought the VTES was in series with the turbo as shown at
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Got some diagrams on how toplumb superchargers that are in parallel to each other?

Reply to
VanguardLH

I doubt the consumers looking at getting turbos do so for fuel efficiency. The same logic applies to any supercharger whether electrical or mechanical.

I think you're stuck thinking of motors for your fridge or home heating furnace. Those aren't efficient motors. What you need is the torque to supply the air volume needed for the target pressure.

From the charts that I've seen for Whipple and turbos, boost doesn't start until after 1000 RPM.

But the electrically driven supercharger is NOT running at idle (unless tolerances for air flow were so tight that the fins have to spin in order to provide only the amount of air flow needed to run at idle but unboosted). It doesn't run constantly. It runs only on-demand and for a very short interval.

So far no one has even hinted at any physics involved. All claims have been "you can't do that" without any proof. For rational discussions on the progress and torque capacity of current electric motor design, I don't think this is the newsgroup for that. I doubt anyone here is up on that technology.

Also, there still seems to be confusion that the electric supercharger is the only supercharger. I never said (and neither did the company) that it replaces the turbocharger. The electrical system in the VTES augmented vehicle probably will need redesign but considering it is used on-demand for a very short interval at only the low-RPM range then it hardly seems an impossible task. It doesn't sound like something you just drop into your existing beater. This product is simply giving the initial push, not supplying all the supercharging needs.

Not really. That's only a cube of ~8-1/2 feet on each dimension and you've got a whole minute to move it. Doesn't seem a difficult task at all. Even a weak (that you can stop with your finger) 9-inch table fan can supply 900 CFM

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Yes, it has a largerdiameter than the intake for a supercharger but the supercharger isrunning at a huge difference in rotational speed for its fins but notjust for volumetric flow. The volume isn't what's difficult to achieve. It's pressurizing that volume. What does the turbocharger deliver when it kicks in? Up to to 14 PSI (I doubt consumer cars are going that high) but I thought the standard wastegate was calibrated for around 9 PSI for passenger cars. Does the VTES pre-boost unit have to supply 9 PSI? Hardly. It doesn't seem like the purpose of the VTES is to supplant the turbo but merely augment it during its lag period so just 3-5 PSI is more than enough.

So at, say, 4 PSI, how much volume at ambient pressure must be delivered to pressurize that 1.2 liter capacity? Isn't this a measure of pressure over ambient? That is, we're not measuring pounds-per-sq.inch-absolute but pounds-per-sq.inch-guage (which is relative to the surrounding atmospheric pressure). If we're talking absolute than 9 PSI would be a vacuum. Going from 14.7 PSI to 18.7 PSI absolute is the 4 PSI differential (guage). How much more air goes into the same 1.2 liter space (73 cubic inches) for a 29% increase in pressure?

For the same volume of 73 cubic inches, how much 1-atmosphere air needs to be delivered by the supercharger to produce 4 PSI (but without the restraint that the temperature remain constant since coolers are used in the turbo/supercharger setup)? Probably around 93 cu. in. I doubt that an electric motor cannot produce a 4 PSI differential and deliver a static volume replacement of 100 cubic inches. The VTES doesn't provide the HP of a supercharger (of which turbocharger is a variety). It doesn't need to provide the same higher PSI which incurs a much higher volume of air delivery. It operates at a much lower RPM (so less volume replacement rate) and under much less pressure.

I haven't found mention of how much PSI (over ambient) that the VTES supercharger will deliver but it doesn't have to come even close to what the typical supercharger delivers. Oops, I just reread the wardsautoworld.com article from my other post that mentions the PSI:

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They say about 5 PSI, so I wasn't far off on my guess of 4 PSI. Small volumetric displacement (1.2 liter, 73 cu. in.), low PSI, short boost interval. Sure seems doable to me.

"Controlled Power Technologies¢ VTES (Variable Torque Enhancement System) electric supercharger (earlier post) is being incorporated in a project by engine developer AVL and will also feature in the Ricardo-led £3 million (US$5-million) HyBoost program announced by the Technology Strategy Board on 9 September. Both projects are seeking to maximize powertrain efficiency at the lowest possible cost."

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The AVL List GmbH company
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and the $5M HyBoost program
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don'tseem to be rip-off programs. All-electric cars obviously cannot use thestandard electrical system found in typical gas-powered vehicles oftoday or yesteryear. Do hybrids not require a beefed up electricalsystem? In one of the other articles I mentioned in my other post, theVTES motor draws 220A steady state and 350A during acceleration so,yes, the electrical system will have to be beefed up.

Reply to
VanguardLH

Since what we want is a temporary influx of pressurized air, why not a system that charges a pressure vessel at cruise, then dumps the air through the intake when accelerating from a stop? Perhaps even recover some braking energy with an air pump?

OBTW - I kinda like the idea of the aircar anyway - but that's off the present topic;

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Reply to
1 Lucky Texan

Well, obviously a 1L engine would then need a full-sized lead-acid battery, just like you'd find on any larger engine. That would be the only concession to the electric supercharging. And of course, the supercharger doesn't even need to kick in if all you're doing is cruising along at low speeds, or you don't need to get away too quickly from the stoplight. The ECU can probably determine when to turn on the supercharger, depending on throttle position and RPM and other factors. Or at least the ECU can probably supply a separate computer over the CANBUS with all of this information so it can make the determination.

Yousuf Khan

Reply to
YKhan

You would definitely need a one-way valve because, as you say, the supercharger will build boost much faster. If all you are trying to do is avoid turbo lag, and a turbo will generally make more power than a supercharger because there are fewer parasitic losses, a supercharger for low RPM and a honkin' big turbo for higer RPM applications would give you good boost and good power through the entire rev range.

There was an article a couple of years back in one of the performance mags where somebody had done it to an STi.

Reply to
JD

Then why use electrical ones when direct-drive ones are proven technology and will be more efficient and effective?

A high-efficiency electric motor is still in the 90-95% range. The 5-10% represents losses. Electric motors get considerably heavie as they generate more power because of how they work; all electric motors work on the same basic principles.

You still need a huge motor with huge starting currents, which means huge cables and a massive alternator to be effective in even the very small window you are talking about.

They should hint at it. An electric motor is still just a method of converting electrical to mechanical energy and there are losses. A direct drive supercharge is basically using gearing and it is mechanical energy used directly. Herein lies the problem; to be effective, the electric motor needs to generate comparable energies to the mechanical supercharger; which, because of the physics of how electric motors work, is one big-assed motor.

Then why would on use it at all? It would be parasitic at any rate and it kinda doesn't really solve any problem at all.

When you push more air through a smaller opening, you increase the pressure. A 9-inch fan would require less than 1/3 of the power of a 3-inch to generate the same volume assuming there is no more than ambient resistance. If you increase the resistance by 50% (typical in an engine inlet) you require a motor nearly 9 times the power of the 9-inch fan. Add to the fact that your table fan is an A/C motor and this application would be a DC motor requirement. If you want to boost the pressure to ambient because of the vacuum effect in an engine intake, and you are now doubling the requirement again. If you boost to seven PSI, you are now doubling it again; you now require 36 times the power of you tabletop fan.

Actually, many are going much higher. An STi, stock, deleivers 14.2 PSI. With some tuning, many people are running 21 to 25 PSI and even higher with meth injection.

A lot. Air compresses.

You are forgetting about the intake resistance of the engine; typically 1 atmosphere has an absolute pressure of 1006 mBar. In vacuum, MAP pressure is typically in the 400mBar range. You have to boost to ambient and then beyond to overcome the resistance.

I don't buy it. I know electric motors and none that I know of would be capable of doing what they claim on the power that they claim.

Beefed up? You would need a whole new generator system and a cable capable of delivering 350A, with a safety margin, would be huge unless you want to see the car burst into flames.

Seems to me that a conventional supercharger would be cost-effective and have way more benefits than this gizmo.

Reply to
JD

Since what we want is a temporary influx of pressurized air, why not a system that charges a pressure vessel at cruise, then dumps the air through the intake when accelerating from a stop? Perhaps even recover some braking energy with an air pump?

** Not a bad idea.

OBTW - I kinda like the idea of the aircar anyway - but that's off the present topic;

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I do too, but yes, it is a ways off yet.

Reply to
JD

Well, obviously a 1L engine would then need a full-sized lead-acid battery, just like you'd find on any larger engine. That would be the only concession to the electric supercharging. And of course, the supercharger doesn't even need to kick in if all you're doing is cruising along at low speeds, or you don't need to get away too quickly from the stoplight. The ECU can probably determine when to turn on the supercharger, depending on throttle position and RPM and other factors. Or at least the ECU can probably supply a separate computer over the CANBUS with all of this information so it can make the determination.

Yousuf Khan

Why not just use a smaller turbo? It would have the same effect.

Reply to
JD

Why not a little turbo for low RPM and a bigger one for the higher stuff.

Hang on.........that's what I've got !!

Seriously, and without going into the numbers, when you look at when this device might be used, I would think that you're only going to get about half-a-car-length advantage over the guy next to you when you get to the next set of lights.

I like the idea but the practicality/benefits don't add up. Much like designing a chocolate teapot.

Reply to
bugalugs

I think the gimmick is to have more horsepower at the low RPM end of the range instead of linearly (or even non-linearly) increasing along with RPM. You start with more HP at the start of the curve instead of having to building it up.

I've since talked with a buddy that is far more into cars than I am. He goes to all the car shows, even the buff shows, and custom shows. His son is going through tech school to be a car mechanic and he has lots of contacts that have customized their cars (like father, like son). From their experience with other jobbers, pre-boost units that just deliver 1 or 2 PSI to help at low RPM are often used by trucks that need low-speed horsepower for towing. Because they are looking at getting horsepower up immediately at the bottom end of the RPM range, superchargers don't work for them. That's why I think the VTES is going to convince buyers that often look at horsepower and off-the-mark takeoffs without having to first rev their engines while holding down on the brakes.

Not if you're talking about electric motors that only have to provide a peak load and don't run constantly at that load. Consider a 2-watt resistor. Will it blow because you momentarily make it dissipate 4W? Nope, but it better be a short interval.

For a constant or sustained HP rating, yes. Doesn't appear to be the situation here. I think at this point that we can only agree to disagree. It will interesting to see how fruitful is the HyBoost project and what car mfrs pickup on the VTES supercharger to include it as an add-on option to their turbo package.

I don't think the VTES is even targeting that after-market. It looks like they want to provide a car mfr production solution for typical passenger cars but let them go to smaller displacement engines to improve (reduce) emissions.

I used Boyle's law to determine how much ambient air would have to be supplied to compress to 4 PSI and came up with the 74 cu. in displacement in the engine would need 93 cu. in. That's for an ideal gas with no temperature change due to pressure change. Maybe it would be 100 cu. in. in reality for this pre-boot and turbo setup. The intake volume went up 29%, the same as the pressure change, according to Boyle's law (as I understood when I read it when replying here). I didn't see a 29% (34% for the 5 PSI the article mentioned) as being "a lot" but I guess you do.

Well, since 1-2 PSI pre-boost superchargers have apparently existed previously for use with low-RPM power improvement for truck towing, it seems they're just trying to incrementally up the pressure. With a smaller engine in the same car, they probably may have the extra room for the pre-boost supercharger and its electric motor (or it might get so tight that they'll have to remove the front grill and fenders to get at anything).

I'd suspect they wouldn't be using round stranded cables anymore but instead bus bars. Or they could go with 0000 guage (0.46" diameter) solid wire (not stranded) which means it would have to be pre-moulded to the car and model since you couldn't bend it or do so as well to route it through the confined constrains of a packed engine compartment.

That's why I mentioned the really high cost of adding a Whipple supercharger, like six grand. The VTES would probably be offered as an option to their turbo package (i.e., the consumer would first have to choose to pay more to get the turbo and then decide if they also want the VTES). It's hard to say what the production cost would be to add the VTES supercharger to a turbocharged model (and then how much markup the car mfr will charge for the luxury package). I don't want to even hazard a guess as how much less the VTES option would be (in addition to the turbo option) versus a Whipple supercharger alone option (which appears very, very pricey).

It will be interesting to watch this project to see if it actually provides a usable and far cheaper solution than the others presented here. I remember the naysayers that claimed you couldn't achieve zero resistance at room temperature but now we're experimenting with carbon nanotubes. I'm hoping you'll be surprised. Alas, it's doubtful that any of my future passenger work-a-day cars will have this stuff. I'm more into practical cars these days than ego-puffing monster fun cars (and which got me lots of tickets).

Reply to
VanguardLH

A two-watt resistor is resistive. A motor is inductive. Because it is inductive, it doesn't matter how much power you try to deliver to the motor; it won't get there without heavy enough cabling, and it won't generator the power without a stator of sufficient size, and windings of sufficient gauge because wire becomes resistive when you put enough current through it. Its basic physics; it how electric motors work.

No. Even for the short intervals you are talking about.

Except it won't and there are other options that are cheaper, lighter, and more flexible.

I do. Because air compresses and you need a near instantaneous increase in pressure (which this thing claims to do by running up to 70K RMP in 0.3 sec) to get the air into the engine in a short time, it is still a massive amount of energy in comparison to what a 1.0 L engine could deliver in its electrical system.

I would imagine that 100 HP would be considered a pretty high output for a small engine like that. 25KW is a little over 33 HP; approx 1/3 of the engine's total power out, ignoring losses and ignoring the added weight, would be required to spool the thing up.

I would expect with the required additions to the electrical system, the required safety additions for high currents, the additional batteries since car batteries could never discharge at that speed and would not have the capacity required, probably about the same

I highly doubt it. There have been lots of scams on the internet about electric forced induction, brown's gas makers that allow you to run your car on water; you name it. This looks like just another in a long list.

Reply to
JD

What a great idea!

Figured somebody probably would.

Assuming it worked; which it probably wouldn't.

There is a cost to everything; power is never free.

Reply to
JD

What do you drive, a JDM TT Legacy by any chance? Martin

Reply to
Martin Whybrow

What was the incrementap price difference from a Bonneville 3.8 to a Bonneville SSE supercharged, or from a Grab Prix to a GTP? How about drom an MR2 to a MR2 Sopercharged?

The Supercharged Tundra in 2002 was a $3500 option - for 90 extra ponies. Upgrading the complete exhaust for an extra $1000 gained an extra roughly 25HP. Thats available across the band horsepower for about $35 per horsepower, a 0ne percent horsepower increase per hundred dollars.

I'm betting this is a better cost-benefit ratio than the referenced electric turbo.

And for a good debunking go to:

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The Thomas Knight electric supercharger is a different animal. He is running an electric powered Roots type blower which is analogous to a bottle of nitrous - requiring recharging of the high capacity battery system after every couple runs.

Reply to
clare

Better to just couple the big series wound motor directly to the driveshaft and use the INSTANTANEOUS torque of the series motor to provide the extra accelleration torque.

Reply to
clare

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