[DMCForum] Re: Why Dave thinks it won't work (was Livin' the dream in 11
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[DMCForum] Re: Why Dave thinks it won't work (was Livin' the dream in 11472)
- From: "twinenginedmc12" <twinenginedmc12@xxxxxxxxxxxxxxxxx>
- Date: Wed, 24 Sep 2003 10:12:23 -0500
Hi Dave.
Whoa, hold the firehose. You may be right on all counts. Perhaps
it's impossible. I like doing things that are impossible. It's fun.
Rick.
--- In DMCForum@xxxxxxxxxxxxxxx, "Dave Stragand" <dave.stragand@xxxx>
wrote:
> Yes, but how in the heck are you ever going to synchronize them?
Due to the
> different power curves and gearing ratios, it's simply not
mechanically
> possible to get the output-at-the-wheels curves to match. Even with
> automatics, you're still going to have a lot of issues.
>
> If one is assembly is ever moving faster than the other, it's going
to push
> or drag the second (and this will almost always be this case) --
yes, even
> with automatics. This very effect is going to cause the powerband
on both
> engines to alter their power and load, cause the trans's to up and
downshift
> erratically, and wreak havoc on the frame as it is accordianed back
and
> forth -- stresses neither the original nor your front sub were
designed or
> suited for.
>
> Even if you had two identically matched engines and transmissions,
you'd
> have a hard time ever getting them synced. As far as I know, the
only beast
> to successfully accomplish this multiple engine feat was WWI-era
Sherman
> tanks, which had four straight-six Chrysler engines running
together.
> However, they shared a -common- crankshaft and drivetrain. The old
> Cartercar of the 19-teens had a dual engine setup, but again --
they were
> mechanically synchronized via gears.
>
> You say that due to having two auto trans's, therefore you won't
have these
> issues, but you will, as well as torque converter chatter and
foaming. And
> unless you have positraction-type differentials in each trans, it's
not
> going to want to go in a straight line either.
>
> You're going to run into these issues if you have both engines on.
But if
> you run on a single engine at a time, you're still going to have
some bad
> issues. The oil pump on an auto trans runs off of power from the
engine, not
> off of the wheels. So with the car rolling on one engine, the
other's
> transmission is going to be running without lubrication. That's why
> manufacturers tell you that you should not tow an automatic on the
drive
> wheels for more than 25 miles or so tops, unless the engine is
running or
> you disconnect the driveshaft. The inside of the trans WILL fry
after about
> 50 - 100 miles. You're going to be running metal-on-metal inside
the case.
>
> It may work Jim, but I'd venture to bet that due to these
engineering
> limitations, you're going to run into:
>
> 1) lots of blown transmissions
> 2) unstable steering, especially under load
> 3) 'bouncy' braking as the trans's will downshift at different times
> 4) unstable, chirpy, jerky, crooked acceleration
>
> Walt is right. Older four-wheel drives shared these same handling
issues,
> and they even used the SAME engine and transmission. The effects
are going
> to be greatly magnified in your configuration.
>
> Your car will certainly be unique, and a great novelty, but I
wouldn't plan
> on trying to run both engines together on any regular basis.
Another way to
> look at it -- in 100 years of folks trying to make cars faster, why
hasn't
> anyone (including the world's best engineers) ever come up with a
functional
> dual-engine auto?
>
> I commend your efforts, but unless you have some seriously complex
and well
> thought out designs to counter these and other issues, I'm betting
that your
> car under dual power will actually run -slower- than stock, with
dangerously
> unstable handling to boot. I really hope you can prove me wrong,
but these
> are some serious engineering feats to surmount -- that have never
> successfully been surmounted before. What are your thoughts on
overcoming
> these challenges?
>
> -Dave
>
>
> ----- Original Message -----
> From: "Jim Strickland" <ihaveanaccount@xxxx>
> To: <DMCForum@xxxxxxxxxxxxxxx>
> Sent: Tuesday, September 23, 2003 10:12 PM
> Subject: Re: [DMCForum] Livin' the dream in 11472
>
>
> > C'mon Walt, think harder.
> >
> > The engines, and therefore wheels, are not connected, so there
will be no
> > drag or slip. Consider that there are two engines, and also two
> > transmissions. The engines will run at different RPMs, as will
the
> > transmissions. Both the transmissions are automatic, and will
shift when
> > they need to.
> >
> > Like stacking batteries, the energy will add, not subtract.
> >
> > Jim
> >
> >
> > On Tue, 23 Sep 2003 20:46:00 -0400 "Walter Coe" <Whalt@xxxx>
writes:
> > > Hi Rick,
> > >
> > > You're a maniac, what else is there to say? (Sorry, couldn't
help
> > > saying
> > > that.)
> > >
> > > So my question to you is: Isn't there going to be a problem with
> > > traction?
> > > I mean like consider what happens when you run a 4-wheel drive
truck
> > > on a
> > > paved road. People say not to do this because one set of wheels
> > > will tend
> > > to spin at a different rate than the other causing a set to
drag or
> > > slip.
> > >
> > > Walt
> > >
> > > P.S. I want a ride too, provided that Greg goes first and
survives.
> > > ;-)
> > >
> > >
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