DON BOYD, JOAN IKOMA wrote:
>
> You guys should go back and check out that turbodyne web site again.
Well, this doesn't sound like a supercharger in any normal sense of the
word--it seems to be something which is quite expensive and is designed
to overcome turbo lag.
> The
> units they picture appear to have a motor considerably smaller than the
> compressor housing. They also have two 12 v units, one sized for 1500cc
> engines, and one sized for motorcycles . 95 and 75 amps respectivly.
If that motor only has to run 4 seconds at a crack, the manufacturer can
probably increase the size of the windings so that 95 amps is possible
for a small unit. Increase the time running, or the duty cycle, and it
turns itself into copper jelly.... There's simple physics involved here.
Pushing current through windings causes heat, and heat melts things,
including wiring. <smile>
> Mind you, I still dont think they are practical on LBC because of thier
> short duty cycle.(they are meant only to give instant boost to eliminate
> pollution during the "rich" phase of initial acceleration , or to give
> instant boost until the main turbo system catches up.Also, it's only 4 psi.
> Bah humbug,that aint enough. Just keep your nitrous systems guys. Kudos to
> Dan the man for finding that website though.When the original question was
> asked, my little enginering brain said "nope , no way could you build a
> system that would be usable. Too many amps", but the Turbodyne folks
> ,within thier design envelope, did it in a clever way. Too bad the fun only
> lasts 4 seconds.
Their design envelope seems geared to streetlight-to-streetlight racers
with turbos installed. 14v @ 95 amps is 1330 watts. Include the losses
to run the electrical system with that drain, and the effective load is
about 2200-2500 watts. And, it produces 4 psi boost with a motor which
likely won't last more than 4 seconds. Even if it were capable of
continuous duty, which it can't, this would require roughly two to
two-and-a-half more 80A alternators to keep the thing going.
With losses, that translates to about 5-7 bhp to keep the thing going,
even if it could last on a continuous basis, and at only 4 psi boost.
For the purpose for which this item is specifically designed, it
probably does well. But for continuous duty (even prolonged intermittent
duty), it is useless. It's simple physics--every time there is a
conversion step, there is a loss by some sort of lost heat or energy.
With the same supercharger installed on the same engine, driven by a
belt, with an electric clutch, the losses will have to be smaller than
that supercharger driven by an electric motor, because the alternators
to drive will have belt losses, and mechanical losses and electrical
losses, as will the motor driving that compressor.
Would the unit described be suitable as a small supercharger for LBCs if
driven from the crankshaft? Possibly. But the supercharger (ignoring the
motor driving it for the moment) might not be up to continuous duty any
more than the motor is.
I think this installation is mostly for the turbo-equipped crowd who
simply have no pulley available to drive the supercharger, or who might
think this to be another trick item. With a small motor of severely
limited duty, the unit can be placed almost anywhere convenient in a
tight engine compartment. That's probably the principal attraction.
The original estimates still apply. A motor with a 100% duty cycle of
5-8 hp would be far larger than the one described, and would not fit
well at all in an LBC. <smile>
Cheers.
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