[DeTomaso] NPC- Definition of acceleration

Dave McManus dave at damardirect.com
Tue Oct 13 13:58:40 EDT 2009


Ok, I sent the thread to my engineer super son-in-law for his 2 cents. He
says he likes ACME rockets!

IndyDave

Here are his thoughts:

His thought process is wrong as far as how he is looking at the volume of
the engine.  500 cubic inches is not the volume of the cylinder, it is the
displacement.  You would have to figure out how many cc the heads are.  You
would then add that to the gap caused by the head gaskets times the diameter
of the piston.  He may know this but he did not include it in his
calculation.
 
Hydraulic lock also references that the mixture is incompressible.  So
basically you are taking 3 Liter of nitro / air (1L/cylinder compressed at 3
bars) and jam it a 1L cylinder. The cylinder goes through its combustion
cycle and further compresses the mixture.  At TDC the volume of the cylinder
is only the volume calculated above.  At some pressure point its easier for
the rod to set sail than continue on the compression path.  The compression
ratio is 6.5:1.  The pressure inside the cylinder is much higher than the 3
bars.  I believe you can use pV=nRT from Thermodynamics here.  Thus,
p1V1=p2V2.  That would mean the cylinder is at 19.5 bars or 280psi.  I am
sure they are minimizing the cc's of the head to maximize power and the
hydraulic lock would be the limiting factor.
 
http://www.motortrend.com/features/112_0502_top_fuel_numbers/index.html
Brandin Ray 
Forming & Shoring Design Engineer
-----Original Message-----
From: Göran Malmberg [mailto:hemipanter at hemipanter.se] 
Sent: Tuesday, October 13, 2009 3:35 AM
To: michael at michaelshortt.com; 'Thomas Tornblom'
Cc: 'List Pantera'
Subject: Re: [DeTomaso] NPC- Definition of acceleration

I believe we could say that the air is very much only a media for the
supercharger to transport fuel in to the combustion chamber and not
really for burning. At idle it is very rich and does literally shower
out the exhaust. Another thing is that by using smaller diameter  and
longer stroke we can make the engine act as a bigger than 8 litre. By
using larger combustion chamber we can stuff more fuel in to it as well
as if the diameter was larger.
Goran

-----Ursprungligt meddelande-----
Från: detomaso-bounces at realbig.com [mailto:detomaso-bounces at realbig.com]
För michael at michaelshortt.com
Skickat: den 12 oktober 2009 23:07
Till: Thomas Tornblom
Kopia: List Pantera
Ämne: Re: [DeTomaso] NPC- Definition of acceleration

I don't know anything about all that math stuff, but I do know that a
great
deal of the air used in the "explosion" is contained in the fuel mixture
itself ( like rocket fuel )

And from having seen lots of them "blow up", they certainly do come
apart
with great explosive force, often removing the blower and scoop, heads
and
headers ( although nowadays they are held down by straps ) or they lose
fire
and dump loads of raw fuel out of the header pipe of the offending
cylinder
( which you see on TV all of the time ). and sometimes the bottom end
also
comes apart ( and that's when all the action stops and the track has to
be
cleaned up ).


Nothing else smells like Burnout tire smoke and Nitro methane, it smells
like.............Victory!


Michael Shortt





On Mon, Oct 12, 2009 at 4:52 PM, Thomas Tornblom
<Thomas.Tornblom at hax.se>wrote:

> Göran Malmberg skrev:
> > Problem arises if there is missfiering, the hydrolock is a result.
>
> Is this really true btw?
>
> I just did a quick calculation and I don't see how there could be
hydro
> lock, even if it doesn't ignite.
>
> Assume a 500 cui engine, or 8 liter.
> Air mass is ~9500l/kg at atmospheric pressure.
> Density of nitro is 1.13 kg/l.
> Lambda 1 AFR for nitro is 1.7:1 (by weight)
> Assume 3 bar boost
>
> So each cylinder gets 1 liter of air at 3 bar boost per cycle, or
3/9500kg.
>
> The amount of fuel (by weight) is 1/1.7 of the amount of air,
3/(9500x1.7).
>
> The amount of fuel by volume is 1.13 x the amount by weight.
>
> So the volume of fuel per cycle is:
>
> 3/(9500x1.7x1.13), which if I have calculated everything correctly
> amounts to 0.16cc.
>
> I don't see how this would result in a hydro lock, unless the
combustion
> chambers would have zero size.
>
> It appears that many of the items on this list are myths.
>
> Another list can be found here:
>
http://www.motortrend.com/features/112_0502_top_fuel_numbers/index.html
>
> What I find interesting is that the crank only turns 569 turns over
the
> quarter mile, and the intake valves open just 284 times :-)
>
> Thomas
>
>
> > Dual sparkpluggs is a good idea then.
> > Goran
> >
> > -----Ursprungligt meddelande-----
> > Från: detomaso-bounces at realbig.com
[mailto:detomaso-bounces at realbig.com]
> > För Sean Korb
> > Skickat: den 12 oktober 2009 20:57
> > Till: List Pantera
> > Ämne: Re: [DeTomaso] NPC- Definition of acceleration
> >
> > 58-65 degrees spark advance.  By the time the piston is at TDC, much
> > of the charge has already burned.
> >
> > sean
> >
> > On Mon, Oct 12, 2009 at 2:28 PM,  <adin at frontier.net> wrote:
> >> An old, old email.
> >>
> >> But, if one thinks a moment . . . .(whew) running a 1.7 to 1 fuel
mix
> >> means that over 1/3 of the charge is "liquid" ??????  At that
> >> compresion ratio, isn't that true hydro-lock????
> >>
> >> How does that work?
> >>
> >>
> >>
> >>
> >> Quoting "michael at michaelshortt.com" <michaelsavga at gmail.com>:
> >>
> >>> A friend sent this to me, fun read.
> >>>
> >>>
> >>>
> >>> For all of you old drag racers
> >>>
> >>>
> >>>
> >>> THE DEFINITION OF ACCELERATION!!
> >>>
> >>>  One top fuel dragster 500 cubic inch Hemi engine makes more
> > horsepower
> >>> than the first 4 rows of stock cars at the Daytona 500.
> >>>
> >>>  It takes just 15/100ths of a second for all 6,000+ horsepower of
an
> > NHRA
> >>> Top Fuel dragster engine to reach the rear wheels.
> >>>
> >>>  Under full throttle, a dragster engine consumes 1-1/2 gallons of
> > nitro
> >>> methane per second.  A fully loaded 747 consumes jet fuel at the
same
> > rate
> >>> but with 25% less energy being produced.
> >>>
> >>>  A stock Dodge Hemi V8 engine cannot produce enough power to drive
> > the
> >>> dragster's supercharger.
> >>>
> >>>  With 3,000 CFM of air being rammed in by the supercharger on
> > overdrive,
> >>> the fuel mixture is compressed into a near-solid form before
> > ignition.
> >>>  Cylinders run on the verge of hydraulic lock at full throttle.
> >>>
> >>>  At the stoichiometric (stoichiometry: methodology and technology
by
> >>> which quantities of reactants and products in chemical reactions
are
> >>> determined) 1.7:1 air/fuel mixture of nitro methane, the flame
front
> >>> temperature measures 7,050 deg F.
> >>>
> >>>  Nitro methane burns yellow.  The spectacular white flame seen
above
> > the
> >>> stacks at night is raw burning hydrogen, dissociated from
atmospheric
> > water
> >>> vapor by the searing heat of the exhaust gases.
> >>>
> >>>  Dual magnetos supply 44 amps to each spark plug. This is the
output
> > of
> >>> an arc welder in each cylinder.
> >>>
> >>>  Spark plug electrodes are totally consumed during a pass. After
> >>> halfway, the engine is dieseling from compression, plus the glow
of
> > exhaust
> >>> valves at 1,400 deg F. The engine can only be shut down by cutting
> > the fuel
> >>> flow.
> >>>
> >>>  If spark momentarily fails early in the run, unburned nitro
> > immediately
> >>> builds up in
> >>> the affected cylinder and then explodes with sufficient force to
blow
> >>> cylinder heads off the block in pieces or split the block in half.
> >>>
> >>>  In order to exceed 300 mph in 4.. 5 seconds, dragsters must
> > accelerate an
> >>> average of over 4G's. In order to reach 200 mph (well before
> > half-track),
> >>> the launch acceleration approaches 8G's.
> >>>
> >>>  Dragsters reach over 300 miles per hour before you have completed
> >>> reading this one sentence.
> >>>
> >>>  Top fuel engines turn approximately 540 revolutions from light to
> > light!
> >>> Including the burnout, the engine must only survive 900
revolutions
> > under
> >>> load.
> >>>
> >>>  The red line is actually quite high at 9,500 rpm.
> >>>
> >>>  Assuming all the equipment is paid off, the crew worked for free,
> > and
> >>> for once NOTHING BLOWS UP, each run costs an estimate $1,000.00
per
> > second.
> >>>  The current top fuel dragster elapsed time record is 4.428
seconds
> > for
> >>> the quarter mile (11/12/06, Tony Schumacher, at Pomona , CA ). The
> > top speed
> >>> record is 336.15 mph as measured over the last 66' of the run
> > (05/25/05 Tony
> >>> Schumacher, at Hebron , OH ).
> >>>
> >>>  Putting all of this into perspective:
> >>>
> >>>  You are driving the average $140,000 Lingenfelter 'twin-turbo'
> > powered
> >>> Corvette Z06. Over a mile up the road, a top fuel dragster is
staged
> > and
> >>> ready to launch down a quarter mile strip as you pass. You have
the
> >>> advantage of a flying start. You run the 'Vette hard up through
the
> > gears
> >>> and blast across the starting line and pass the dragster at an
honest
> > 200
> >>> mph. The 'tree' goes green for both of you at that moment..
> >>>
> >>>  The dragster launches and starts after you. You keep your foot
down
> >>> hard, but you hear an incredibly brutal whine that sears your
> > eardrums and
> >>> within 3 seconds, the dragster catches and passes you. He beats
you
> > to the
> >>> finish line, a quarter mile away from where you just passed him.
> >>>
> >>>  Think about it, from a standing start, the dragster had spotted
you
> > 200
> >>> mph and not only caught, but nearly blasted you off the road when
he
> > passed
> >>> you within a mere 1,320 foot long race course.
> >>>
> >>>  ... and that my friend, is ACCELERATION!
> >>>
> >>> --
> >>>
> >>>
> >>>
> >>>
> >>>
> >>>
> >>>
> >>> Michael L. Shortt
> >>> Savannah, Georgia
> >>> www.michaelshortt.com
> >>> michael at michaelshortt.com
> >>> 912-232-9390
> >>>
> >>>
> >>> This email is protected by the Electronic Communications Privacy
> >>> Act, 18 U.S.C. Sec. 2510-2521, is confidential and may be legally
> >>> privileged.  If you are not the intended recipient, you are hereby
> > notified
> >>> that any retention, dissemination, distribution or copying of this
> >>> communication is strictly prohibited.  Please reply to the sender
> > that you
> >>> have received this message in error, then delete it.  Thank you
> >>> _______________________________________________
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>
> --
> Real life:   Thomas Törnblom             Email:
Thomas.Tornblom at Hax.SE
> Snail mail:  Banvallsvägen 14            Phone:    +46 18 444 33 21
>              S - 754 40 Uppsala, Sweden  Cellular: +46 70 261 1372
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Michael L. Shortt
Savannah, Georgia
www.michaelshortt.com
michael at michaelshortt.com
912-232-9390


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