[DeTomaso] NPC- Definition of acceleration

Thomas Tornblom Thomas.Tornblom at hax.se
Mon Oct 12 17:22:13 EDT 2009 

Thomas Tornblom skrev:
> There must be some gross error in my calculation. I don't see how they 
> can spend "22.75 gallons of fuel during warmup, burnout, staging, and 
> the quarter-mile run." otherwise.

The air mass was wrong. 1m³ or air weighs 1.293kg, or 773l/kg, at normal 
atmospheric pressure, so the formula becomes:

3/(773x1.7x1.13) or 2 cc per cycle.

They are not likely running at stoich, so it will be more, but how much 
more?

With dragsters nothing is normal...

> 
> 
> 
> Thomas Tornblom skrev:
>> 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
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> 
> 


-- 
Real life:   Thomas Törnblom             Email:  Thomas.Tornblom at Hax.SE
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