[DMCForum] Re: Why Dave thinks it won't work (was Livin' the dream in 11472)

["twinenginedmc12" <twinenginedmc12@xxxxxxxxxxxxxxxxx>]

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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