OT: electric supercharging

[JD]

For clarification, you're saying the supercharger types you mentioned
provide pressurized air even at idle RPM? The Whipple is a mechanically
driven twin screw rotor supercharger. Well, if it is mechanically
driven then isn't its pressurization dependent on engine RPM? They do
seem to ramp up pretty quickly, though, yet they do have to ramp up (but
then the VTES seems to ramp up, too, from idle yet it seems to start
higher):

http://www.whipplesuperchargers.com/Images/productimages/DynoComparison.gif

But would you actually *combine* a Whipple with a turbocharger? The
VTES looks to augment the turbo, not replace it, hence its aftermarket
target. I would think if you went Whipple that you wouldn't bother with
a downstream gas-driven turbo. Since there exist mfr packages that
include a turbo, what would be the cost difference between adding the
augmenting VTES pre-boost electrically driver supercharger in an
existing turbo setup versus the labor and refit of removing the turbo
and adding just the Whipple? Can't tell yet because they're not into
production yet and no expected pricing for VTES was mentioned in the
articles. The articles just mention VTES is a reduced cost or low-cost
solution. I've seen Mustang GT kits for Whipple superchargers run $5700
to $6800.

Why wouldn't you combine them? As long as you are using the same wastegate
they can be run in parallel.

Because of the extremely tight specs required for the twin screws in a
Whipple running at high rotation speed, how is their reliability and
durability? Turbos are "loose" to eliminate having to repair them
(within the warranty period which is what interests the car mfr).

Some other articles I found on the VTES supercharger:
http://www.greencarcongress.com/2009/09/cpt-vtes-20090922.html
http://wardsautoworld.com/ar/auto_visteon_eyes_electric/
http://www.profeng.com/archive/2008/2104/21040058.htm
http://www.cpowert.com/products/vtes.htm

The last article finally gives some ratings on amp load.

"CPT¢s electric supercharger significantly increases an engine¢s air
charge density over the critical first 10 combustion cycles of a low
speed transient."

So it is over a very short burst or surge that the VTES gets used. At
1000 RPM, isn't that around 2.5 seconds? I also suspect that with the
0.3 second ramp up to 70K RPM that there isn't a huge air flow involved
so it's just for small engines, like 1.2 liter.

So... why would one use it since it reduces your lag by a few tenths of a
second assuming their calims are valid; which I don't believe. A 1.8KW
shaft pressure can't do what they claim.

 

[JD]

For clarification, you're saying the supercharger types you mentioned
provide pressurized air even at idle RPM? The Whipple is a mechanically
driven twin screw rotor supercharger. Well, if it is mechanically
driven then isn't its pressurization dependent on engine RPM? They do
seem to ramp up pretty quickly, though, yet they do have to ramp up (but
then the VTES seems to ramp up, too, from idle yet it seems to start
higher):

http://www.whipplesuperchargers.com/Images/productimages/DynoComparis...

But would you actually *combine* a Whipple with a turbocharger? The
VTES looks to augment the turbo, not replace it, hence its aftermarket
target. I would think if you went Whipple that you wouldn't bother with
a downstream gas-driven turbo. Since there exist mfr packages that
include a turbo, what would be the cost difference between adding the
augmenting VTES pre-boost electrically driver supercharger in an
existing turbo setup versus the labor and refit of removing the turbo
and adding just the Whipple? Can't tell yet because they're not into
production yet and no expected pricing for VTES was mentioned in the
articles. The articles just mention VTES is a reduced cost or low-cost
solution. I've seen Mustang GT kits for Whipple superchargers run $5700
to $6800.

Because of the extremely tight specs required for the twin screws in a
Whipple running at high rotation speed, how is their reliability and
durability? Turbos are "loose" to eliminate having to repair them
(within the warranty period which is what interests the car mfr).

Some other articles I found on the VTES
supercharger:http://www.greencarcongress.com/200...8.htmhttp://www.cpowert.com/products/vtes.htm

The last article finally gives some ratings on amp load.

"CPT¢s electric supercharger significantly increases an engine¢s air
charge density over the critical first 10 combustion cycles of a low
speed transient."

So it is over a very short burst or surge that the VTES gets used. At
1000 RPM, isn't that around 2.5 seconds? I also suspect that with the
0.3 second ramp up to 70K RPM that there isn't a huge air flow involved
so it's just for small engines, like 1.2 liter.

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.

 

[JD]

The tradeoff is large current spikes being drawn from the battery -
and the emission hit would be very short too - like the current draw.

The electrical efficiency will be quite low - convert engine power to
electrical using innefficient automotive alternator, store generated
power in lead acid battery, then pull it out and run a low-efficiency
high power electric motor..

I don't buy it.

I'm with you. It doesn't add up; it makes no sense.

 

[clare]

I'd say they're mainly aiming it at the daily driver. If you've got
something like a 1L engine, then turbocharging takes care of the high-
end power problem, but low-end power would require a supercharger.
Once the turbocharger takes over, then the supercharger is no longer
needed, so an electric supercharger can be shutoff completely.

Yousuf Khan

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.

 

[clare]

It doesn't matter. There are electrical losses no matter how you size it up
and the reason they don't generally build electric superchargers is for that
very reason. Power is not free; to make it, requires gas.


If you do a bit of math, to get even 10 PSI (to overcome just the vacuum of
the engine) takes a BIG electric motor.



An engine idling at 600 RPM will generate far more boost than a small
electric motor. In addition, the electric supercharger would draw enough
power that even at idle, the car would be a considerable gas hog just to get
to ambient pressure. You would be better to size a direct-drive
supercharger and a wastegate for the application.

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.

 

[clare]

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.

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

 

[VanguardLH]

Why wouldn't you combine them? As long as you are using the same wastegate
they can be run in parallel.

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 http://www.mazdarotary.net/images/tech_pics/turbodiagram.jpg, just
where is the output of the Whipple going to get connected? After the
turbo? 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
http://www.cpowert.com/products/vtes.htm. Got some diagrams on how to
plumb superchargers that are in parallel to each other?

 

[VanguardLH]

There are electrical losses no matter how you size it up and the
reason they don't generally build electric superchargers is for that
very reason. Power is not free; to make it, requires gas.

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

If you do a bit of math, to get even 10 PSI (to overcome just the
vacuum of the engine) takes a BIG electric motor.

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.

An engine idling at 600 RPM will generate far more boost than a small
electric motor.

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

In addition, the electric supercharger would draw enough power that
even at idle, the car would be a considerable gas hog just to get to
ambient pressure.

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.

That is assuming it has the power to do that; which it won't. A
typical electric motor would lose 10% over direct-drive drive and the
size of the motor would be a limiting factor. A direct-drive
supercharger requires a belt or chain. An electric supercharger of
that size would require a huge motor and monstrous cables to conduct
the electricity. Its all about conservation of energy and you can't
beat the physics yet.

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.

Gor how many cubic feet of air per minute? To charge a 2.5 lire
engine just to ambient, would require a fan to move more than 600
cubic feet per minute of air. That is a lot of air.

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 (http://tinyurl.com/yby6q3g). Yes, it has a larger
diameter than the intake for a supercharger but the supercharger is
running at a huge difference in rotational speed for its fins but not
just 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:

http://wardsautoworld.com/ar/auto_visteon_eyes_electric/

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."
(http://www.greencarcongress.com/2009/09/cpt-vtes-20090922.html)

The AVL List GmbH company (www.avl.com) and the $5M HyBoost program
(http://www.greencarcongress.com/2009/09/tsb-10mil-20090910.html) don't
seem to be rip-off programs. All-electric cars obviously cannot use the
standard electrical system found in typical gas-powered vehicles of
today or yesteryear. Do hybrids not require a beefed up electrical
system? In one of the other articles I mentioned in my other post, the
VTES motor draws 220A steady state and 350A during acceleration so,
yes, the electrical system will have to be beefed up.

 

[1 Lucky Texan]

It doesn't matter.  There are electrical losses no matter how you size it up
and the reason they don't generally build electric superchargers is for that
very reason.  Power is not free; to make it, requires gas.



If you do a bit of math, to get even 10 PSI (to overcome just the vacuum of
the engine) takes a BIG electric motor.



An engine idling at 600 RPM will generate far more boost than a small
electric motor.  In addition, the electric supercharger would draw enough
power that even at idle, the car would be a considerable gas hog just to get
to ambient pressure.  You would be better to size a direct-drive
supercharger and a wastegate for the application.


I doubt it works.  There are serious limitations to electric motors forsuch
applications.


That is assuming it has the power to do that; which it won't.  A typical
electric motor would lose 10% over direct-drive drive and the size of the
motor would be a limiting factor.  A direct-drive supercharger requiresa
belt or chain. An electric supercharger of that size would require a huge
motor and monstrous cables to conduct the electricity.  Its all about
conservation of energy and you can't beat the physics yet.


That's great.  Gor how many cubic feet of air per minute?  To charge a 2.5
lire engine just to ambient, would require a fan to move more than 600 cubic
feet per minute of air.  That is a lot of air.






There is no way that any cable in any car (except hybrids and electric cars)
can handle 25KW, and most 25 KW motors are several hundred pounds.

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;
http://www.mdi.lu/english/index.php

 

[YKhan]

 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?

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

 

[JD]

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 http://www.mazdarotary.net/images/tech_pics/turbodiagram.jpg, just
where is the output of the Whipple going to get connected? After the
turbo? 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
http://www.cpowert.com/products/vtes.htm. Got some diagrams on how to
plumb superchargers that are in parallel to each other?

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.

 

[JD]

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

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

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.

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.

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.

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.

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.

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.

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.

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.

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 (http://tinyurl.com/yby6q3g). Yes, it has a larger
diameter than the intake for a supercharger but the supercharger is
running at a huge difference in rotational speed for its fins but not
just for volumetric flow.

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.

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.

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.

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?

A lot. Air compresses.

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.

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 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:

http://wardsautoworld.com/ar/auto_visteon_eyes_electric/

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.

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.

"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."
(http://www.greencarcongress.com/2009/09/cpt-vtes-20090922.html)

The AVL List GmbH company (www.avl.com) and the $5M HyBoost program
(http://www.greencarcongress.com/2009/09/tsb-10mil-20090910.html) don't
seem to be rip-off programs. All-electric cars obviously cannot use the
standard electrical system found in typical gas-powered vehicles of
today or yesteryear. Do hybrids not require a beefed up electrical
system? In one of the other articles I mentioned in my other post, the
VTES motor draws 220A steady state and 350A during acceleration so,
yes, the electrical system will have to be beefed up.

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.

 

[JD]

It doesn't matter. There are electrical losses no matter how you size it
up
and the reason they don't generally build electric superchargers is for
that
very reason. Power is not free; to make it, requires gas.



If you do a bit of math, to get even 10 PSI (to overcome just the vacuum
of
the engine) takes a BIG electric motor.



An engine idling at 600 RPM will generate far more boost than a small
electric motor. In addition, the electric supercharger would draw enough
power that even at idle, the car would be a considerable gas hog just to
get
to ambient pressure. You would be better to size a direct-drive
supercharger and a wastegate for the application.


I doubt it works. There are serious limitations to electric motors for
such
applications.


That is assuming it has the power to do that; which it won't. A typical
electric motor would lose 10% over direct-drive drive and the size of the
motor would be a limiting factor. A direct-drive supercharger requires a
belt or chain. An electric supercharger of that size would require a huge
motor and monstrous cables to conduct the electricity. Its all about
conservation of energy and you can't beat the physics yet.


That's great. Gor how many cubic feet of air per minute? To charge a 2.5
lire engine just to ambient, would require a fan to move more than 600
cubic
feet per minute of air. That is a lot of air.






There is no way that any cable in any car (except hybrids and electric
cars)
can handle 25KW, and most 25 KW motors are several hundred pounds.

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;
http://www.mdi.lu/english/index.php

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

 

[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?

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.

 

[bugalugs]

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.

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.

 

[VanguardLH]

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

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.

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.

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.

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.

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.

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.

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.

A lot. Air compresses.

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.

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.

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).

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.

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.

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

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).

 

[JD]

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.

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.

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.

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

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.

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

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.

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.

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).

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

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).

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.

 

[JD]

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

What a great idea!

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

Figured somebody probably would.

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.

Assuming it worked; which it probably wouldn't.

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

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

 

[Martin Whybrow]

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

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

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

 

[clare]

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).

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:
http://www.wildweasel.ca/HowTo/Auto/eTurbo.aspx

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.