Next message: Mark Mowery AA8TC: "lv-ab: Foam Online - unbelievable"
It is not actually a supercharger, more like a charger. It does not give
the engine "extra" power, the engine cannot get any air at all without it.
When the pistons are at their lowest position they uncover holes in the
cyclinder and exhaust valves open in the cyclinder head. At this time air
is blown in through the holes and push the smoke out through the valves.
Then the piston rises and compresses the air.
Norm
S/V Bandersnatch
Lying Norfolk VA
> [Original Message]
> From: Letsgosailing <>
> To: A LiveAboardList <>
> Date: 6/15/2007 10:26:16 PM
> Subject: Re: lv-ab: ER Casualty Two Follow-up
>
> "For those unfamiliar with Detroit Diesels, they require a blower to blow
> combustion air into the cylinders, they don't suck it in like other
> diesels. This blower is a Roots blower consisting of two lobed
> counter-rotating rotors in a housing, somewhat like a gear pump, which is
> driven by a shaft connecting from the gear train that drives the cam
> shafts. This is the shaft that shattered into two main pieces and two
> other bits."
>
> Norm,
> This is actually a supercharger, that Detroit diesels get the extra power.
> It is like a turbocharger but mechanically driven not by exhaust gases.
> The power is at all range of RPM unlike turbochargers that need to rev-up
> for the turbo to kick in and create about 7 psi boost.
>
> Yanni Marinated
> S/V Princess Thalia
> Hamilton-Fifty Point @H3
> www.yannismarine.ca
> ----- Original Message -----
> From: "Norm of Bandersnatch" <>
> To: "A LiveAboardList" <>
> Sent: Friday, June 15, 2007 9:31 AM
> Subject: lv-ab: ER Casualty Two Follow-up
>
>
> >
> > All,
> >
> > The new blower shaft did arrive the next day ($89 + $20 Fedex overnight
> > COD), we installed it and the engine was back up and running fine in
> > minutes. An interesting point was that the new shaft is significantly
> > thicker.
> >
> > For those unfamiliar with Detroit Diesels, they require a blower to blow
> > combustion air into the cylinders, they don't suck it in like other
> > diesels. This blower is a Roots blower consisting of two lobed
> > counter-rotating rotors in a housing, somewhat like a gear pump, which
is
> > driven by a shaft connecting from the gear train that drives the cam
> > shafts. This is the shaft that shattered into two main pieces and two
> > other bits.
> >
> > After we were underway again I began seriously thinking about what I
would
> > have done if it had happened offshore. Towing with the dinghy would be
> > almost impossible in the seaway, and at one mile per gallon we would not
> > have enough fuel to get to port. (Although I have it on good authority
> > that gas engines can be run on diesel fuel once started on gas!)
Calling
> > the CG to send a towboat would be very expensive, and there was always
the
> > probability the towing people would claim salvage and gouge me for a
huge
> > bill. Then I considered the possibility of repairing the shaft.
> >
> > The old shaft consists of a piece of hardened steel 6 1/2" long. The
> > splined (48 splines) ends are 3/4" diameter, while the shaft itself is
> > 7/16" diameter.
> >
> > I have TIG welding gear aboard and with the 8 KW genset can get about
120
> > amps of welding power, not enough for my stock 1/4" aluminum, (because
it
> > soaks up heat so fast) but perhaps enough for a bit of steel. I would
cut
> > out the bad part, about two inches, and cut a high grade bolt (I have
> > several for coupling bolts) to fit with tapered ends (I have lots of
> > grinders), clamp the three pieces in a piece of angle with hose clamps
and
> > shims and have at it with the TIG welding just a bit at a time rotating
> > the
> > piece and welding more. It would be difficult rolling in the trough of
a
> > four to six foot seas, but given time and energy I think it would be
> > do-able and the shaft might hold if I kept the rpm's down to idle, 750
> > rpm,
> > which in flat water gives us 3.5 mph.
> >
> >
> > I cannot say too much positive about the River Forest Manor marina, the
> > owner Axson Smith, and his staff.
> >
> > As he does to all visitors apparently, he loaned us a golf cart to go to
> > the marine supply store where we got two bilge pump switches and a pump
to
> > complete a
> > project, then cruised the half mile or so the center of town to visit
the
> > Wachovia bank and Ace hardware store while our laundry was in the dryer.
> >
> > We had given his front desk clerk cash for the Fedex COD, but cash is
> > unacceptable to Fedex (probably to avoid being robbery targets), they
only
> > accept checks or money orders, but the staff covered it by cutting a
check
> > in lieu of my cash.
> >
> > We did have a memorable ($120, including $50 bar bill!) anniversary
> > dinner,
> > but we did not rent a room, nor did we rent dock space, yet the entire
> > facilities were open to us and everyone was so hospitable. We were
> > impressed!
> >
> > Another interesting point I missed in my first message is that the Manor
> > House is actually a Sears kit house! The Magnolia model. Shipped in
> > large
> > crates, Sears kit houses were conventional, fully-found, houses. The
> > crates contained everything required to build a house, doors and
windows,
> > all lumber, siding, shingles, electrical and plumbing, even the nails!
> > The
> > basic building was elaborately enhanced and added to over the years and
is
> > a wonder to tour.
> >
> > All in all it was a prime example of one of our basic principles: we
> > cruise
> > to allow serendipity a chance to happen!
> >
> >
> >
> >
> > Norm
> > S/V Bandersnatch
> > Lying Norfolk VA
> >
> >
> >
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