Sorry, kind of outside-of-topic to Subarus (unless Subaru is thinking of
using such a system, but I have no direct knowledge of that). Looks like
an interesting way to boost low-speed performance. Wonder why no one had
thought of it before? Unless it was simply a matter of computer
technology catching up to allow it to happen now. Looks like you can use
it in conjunction with turbochargers. The electric supercharger will
operate at lower speeds, thus not having to worry about turbo lag. The
turbo will operate at the higher speeds, of course.

Yousuf Khan

CPT’s VTES electric supercharger shows impressive results in a
Volkswagen Passat!
"A company called Controlled Power Technologies is offering something
new called a VTES, or Variable Torque Enhancement System. It’s basically
an electric supercharger. There are alot of people who try to install
fans in the middle of the car’s intake tract and try to call it a
supercharger, but this is a proper compressor that can spin
independently of crank speed at rotational speeds of up to 70,000rpm.

CPT has installed it on various test systems including a 1.2 liter
turbocharged engine. The VTES electric supercharger is meant to
complement the existing turbo. CPT reported an increase of over 50% in
torque at engine speeds below 3,000rpm. I guess what it does is
compensate for any turbo lag there is at low engine RPMs, allowing the
turbocharger to be larger than it normally would have needed to be to
spool up that quickly."
http://paultan.org/2009/09/23/vtes-electric-supercharger-shows-impressive-results/

On Wed, 23 Sep 2009 03:14:33 -0400, Yousuf Khan <bbbl67 (AT) yahoo (DOT) com>
wrote:

Hi Yousuf!

Consider that it takes a fair bit of power from the crank to spin a
conventional supercharger. This, indeed, is one of the principal
arguments in favor of the turbocharger systems. It takes a pretty
stout electric motor, and lots of current to generate this kind of
power (several horsepower at least), _way_ more than will be generated
by the device shown in the link you posted, I can assure you. Also
consider that if the supercharger _isn't_ making boost, it is simply a
restriction in the inlet tract, which will tend to reduce the power
output, especially at higher crank speeds.
Without independent testing on a real dyno, I'd be very suspicious . .
..

ByeBye! S.

Steve Jernigan KG0MB
Laboratory Manager
Microelectronics Research
University of Colorado
(719) 262-3101

On Sep 23, 12:09*pm, S <jerni... (AT) chester (DOT) uccs.edu> wrote:
I understand what you mean, but this device seems to be a very
temporary boosting system, used only when needed to pass at lower
speeds. Once the power is delivered at lower speeds, the engine will
then enter a higher speed range, where the turbocharger can take over
the boosting duties. They said that the standard 12V battery and
alternator combo is enough to power this for that short amount of
time. It's not likely to even come on in normal acceleration or
cruising situations.

As for being a restriction in the inlet when it's not used, you can
say that about a turbocharger too.

Yousuf Khan

About a decade ago a common ebay scam was teo sell marine bilge fans
as electric superchargers. Unforunately they were of such low quality
that the blades sometimes broke off and got sucked into the engines.
Oops. I did a little research on how much power one of thse would take
to do any good, and althoug I forget the numbers, my 2.2 liter needed
far more than my electrical system could muster. I guess that is why
they make all thsoe qualifications like tested on a 1.2 liter engine
(which would suck down less air than a 2.2 liter engine.) and that it
is for low engine speeds. At higher engine speeds it simply could not
feed air fast enough. So you need to have this thing cut in when you
need power at low revs, but shut off when you exceed a certain engine
speed that would be determined by the flow rate that this thing is
capable of. Sounds like a lot of extra controls. How often are you
actually in a low RPM situation where you need extra power? Unless you
get surprised, you should be able to get engine speeds up by either
downshifting or slipping the clutch on launch.

As you said, a turbocharger is a restriction. And it causes parasitic
losses. Owning one means that you accept those losses for the gains
the turbo gives you. This also provides parasitic losses. Whether or
not it is worth it depends on the gains it provides. I think that the
gains are not worth the added complexity of the system and the
controls involved. there are other ways to fight turbolag like twin
turbos.

Bill

Yousuf Khan wrote:

The only way this device would "complement" the existing turbocharger is
if adds further compression than the turbocharger can perform alone.
Well, turbochargers (and wastegates) are configured to prevent over
highly pressures which would blow the gaskets or past the rings.
Something that goes beyond the safe pressure range of the turbocharger
means you put your engine at higher risk. Also, this added compression
would have to be past the wastegate; else, the over pressure would open
the wastegate and you lose energy (that you put into the ancilliary
turbocharger unit; i.e., this VTES thing). From further reading (and
noted below), this unit does not increase boost so it can easily be
installed upstream of the turbocharger.

By electrically controlling the ancilliary turbocharger, it can be made
neutral when needed or to accurately gauge how much more pressure it
will add rather than rely on the exhaust flow rate as feedback. Also,
because it is electric, it can immediately begin pressurizing the inflow
when you hit the accelerator pedal rather than wait for the exhaust flow
rate to come up (hence eliminate the turbo lag). Of course, this also
means less fuel efficiency with you peeling off more quickly from a
stop.

With statements like "50% in torque at engine speeds below 3,000rpm", I
suspect this is an electrically controlled pre-boost unit. The turbo
lag is eliminated with some partial boost afforded by the electrically
driven fan rather than waiting for the turbo fan to get up to speed
after the exhaust flow rate has come up. If you look at their own
chart, they are NOT increasing the overall horsepower afforded by the
turbocharger. They are merely trying to eliminate the initial turbo lag
typical of fans that are dependent on the exhaust air flow rate. You
get quicker boost. You don't get more boost.

If you look at their own charts but then create your own that shows the
*differential* in boost then you see they only add some boost (not
nearly as much as can the turbocharger) to give you some small boost
earlier until the turbocharger catches up.

On Wed, 23 Sep 2009 10:22:58 -0700 (PDT), YKhan <yjkhan (AT) gmail (DOT) com>
wrote:

simpler - but does play havoc with emission controls. (it consists
primarily of a small injector feeding fuel into the exhaust ahead of
the turbo)
NO turbo lag.

"VanguardLH" <V (AT) nguard (DOT) LH> wrote

It would still take WAY more electricity than the car's electrical system
can deliver. Even if it could, the electrical losses would limit how much
boost could be provided at any range. A direct-drive supercharger would be
FAR more efficient in combination with the turbo.

JD wrote:

Guess that depends on how many amps your alternator can put out, how
much is consumed during driving (after startup), and the difference left
over for reserve (usable to other devices). I doubt that the load by
this pre-booster is large or sustained. Just a short burst (surge) of
boost is all that is needed to compensate for turbo lag.

All the blower has to do is pressurize the exhaust from the fan.
Doesn't take much horsepower to run an electrical motor even at 70K RPM.
I do doubt that it provides as much boost as the turbocharger. It just
provides SOME boost before the turbo kicks in (i.e., to eliminate the
turbo lag). That's why I said you need to look at their chart and then
create a NEW chart that shows the *differential* between the boost
afforded from the start of the curve to when the turbo takes over. That
differential shows the pre-boost isn't that high. If you look at their
chart, their pre-boost unit only provides half the boost and only over a
small 500 RPM range (between 1000 to 1500 RPM).

But is still dependent on engine RPM whereas there is no RPM dependency
for an electrically controlled supercharger.

Turbochargers have a definite lag before there is enough exhaust flow to
spin its fan fast enough to pressurize its output. Supercharger boost
(for dynamic compressor types) are dependent on the engine RPM. This
VTES pre-boost supercharger isn't to add more horsepower but simply move
the curve of when it is available.

I don't think the point of the experiment was to create a monster
horsepower car but to eliminate the turbo lag. Nowadays the throttle
response for turbochargers is nearly the same to mechanically powered
superchargers. Both still have lag. The VTES description says it is a
compressor type supercharger so there would also be lag if it were
dependent on the engine RPM; however, since it is electrically
controlled, it can be made to provide boost faster than for the increase
in engine RPM. Having this pre-booster handle the low RPM range also
means a larger turbocharger (with more lag) could be put into the car to
provide even more horsepower.

"The supercharger¢s speed can increase from zero up to 70,000rpm in less
than 1/3 of a second.

So how much lag is there with a compression-type supercharger? How much
does the RPM have to come up before there is effectual pressurization?
An electrical supercharger doesn't have lag but might not be able to
handle as large a load for sustained periods - but then it doesn't look
like this was a standalone solution, either. With your turbocharged car
and mashing down on the accelerator, how long before you feel that rush
of power kicks in? With your supercharged car, how long after mashing
the accelerator before you get a significant increase in horsepower?
Does a mechanically-driven supercharger based on the engine's RPM not
have any lag?

The article says they are using a 25kW electrical motor at 12V. There's
no way they're going to get over 2000 amps from the alternator. I
doubt their motor is consuming 25kW but is instead simply designed to
operate at that current load for a sustained period because it makes for
a motor that can handle a large surge current. It's a peak (or spike)
rating, not a sustained rating. It might be that, yes, this motor can
take a high surge current for quick spin-up but it cannot be sustained.
Maybe it's only designed to handle the pre-boost load for a couple of
seconds (until when the turbo is expected to kick in).

With that short blurb of a "news" article, there are just too many
variables in implementation that are unknown. More info is definitely
needed.

On Sep 23, 1:53*pm, weelliott <weelli... (AT) gmail (DOT) com> wrote:
Well, in my case, I'm in low RPMs almost all of the time, since I'm
mostly doing city driving. I rarely get above 3000 RPM until I'm on
the highway.

I can see a temporary boost being useful when getting away at
stoplights, especially for a small engine. I don't mean for stoplight
racing, just for not being a hinderance to traffic.

Well, they did mention that if this is used in conjunction with a
turbo, you can make the turbo much larger, and thus less restrictive.
And I'm sure the little supercharger itself can be easily bypassed
when not being used with a simple vane the directs the airflow around
it through a different pipe, if they deem the restrictions too
severe.

Yousuf Khan

On Sep 24, 9:57*am, VanguardLH <V... (AT) nguard (DOT) LH> wrote:
Yeah, that's my understanding too. It's not intended to be a sustained
booster of power, just a transient booster.

There was a longer article that I had read about it, here:

Electric Supercharging - Controlled Power Technologies - European Car
Magazine
http://www.europeancarweb.com/news/epcp_0909_electric_supercharging_low_carbon_vehicl es/index.html

Yousuf Khan