[DeTomaso] NPC- Definition of acceleration

Thomas Tornblom Thomas.Tornblom at hax.se
Mon Oct 12 16:52:28 EDT 2009


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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