This is the one good thing about american cars!

junglestylz

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#1
Here's some fun water cooler trivia for all my automotive/engineering/science/techno-nerd friends/family...


* One Top Fuel dragster 500 cubic inch Hemi engine makes more horsepower than the first 4 rows at the Daytona 500.

* Under full throttle, a dragster engine consumes 1-1/2 gallons of nitromethane per second; a fully loaded 747 consumes jet fuel at the same rate with 25% less energy being produced.

* A stock Dodge Hemi V8 engine cannot produce enough power to drive the dragster's supercharger.

* With 3000 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 for nitromethane the flame front temperature measures 7050 degrees F.

* Nitromethane burns yellow. The spectacular white flame seen above the stacks at night is raw burning hydrogen, dissociated from atmospheric water vapor by the searing 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 ½ way, the engine is dieseling from compression plus the glow of exhaust valves at 1400 degrees F. The engine can only be shut down by cutting the fuel flow.

* If spark momentarily fails early in the run, unburned nitro builds up in the affected cylinders 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 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 redline is actually quite high at 9500rpm.

* The Bottom Line; Assuming all the equipment is paid off, the crew worked for free, and for once NOTHING BLOWS UP, each run costs an estimated $1,000.00 per second.

The current Top Fuel dragster elapsed time record is 4.441 seconds for the quarter mile (10/05/03, Tony Schumacher). The top speed record is 333.00 mph. (533 km/h) as measured over the last 66' of the run (09/28/03 Doug Kalitta).

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 past 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 1320 foot long race course.

That folks, is acceleration.
 
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I would have to doubt the one regarding the power of a 747 vs the dragster. A 747 at takoff power produces in the range of 200,000 lbs of thrust. Depending on how you convert the numbers I think the 747 has the dragster beat by several times in useable power. I recall a conversion of thrust to hp from when I was a kid of something like this: at 30,000 feet 1 lb of thrust = 1 hp. I doubt the dragster is producing anything near that. I would venture a guess that most of the power in the dragster is going out the exahust pipes in heat--not power!

Steve
 

junglestylz

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Actually the 747's Rolls Royce RB211 engine produces a maximum of 59,500 lbs of thrust. The General Electric versions of the same engine produe 62,100 lbs.. While the most powerful engine, the Pratt and W#hitney puts out 63,300 lbs.

Since thrust is a measure of force, and horsepower is a measure of work, comparing the two is like comparing apples and oranges. The crazy thing is that a honking great jet engine generating 1,000lbs of thrust is producing ZERO horsepower if it's not moving (ie: attached to a static test stand). However, if we add another factor, "velocity", we can come up with some rough guides for converting thrust to HP. Given the conversion that 1 lb.= 1hp at 330knots, and that 1knot = 1.155077945 mph. then 330 knots = 381 mph. The top speed of the 747 is 567mph. So if the engine is producing 63,300 lbs. at 567 mph (491 knots). At 381 mph, it is about .67195 it's possible speed. Take 63,300 and multiply it by .67195, and you get 42,990 lbs. of thrust. That would be at roughly 330 knots. Meaning that it would be 1 lb. thrust for every hp. This still could not be used as you would have to convert the hp into thrust by judging the amount of hp, and it direct relation to the speed that the car was moving after exactly 1.5 seconds of running, and the amount of torque that it produced getting there. As you can see, it is a little harder than just adding some and multiplying some number. There is also the total amount of energy used and laden weight of the dragster, as well as unladened weight having to be considered given that they don't state that in the question. It also has a lot to do with drag. To calculate this, you would need to know the amount of frictionand drag force being created by the tires on the ground, the wheel bearings, and the actual air friction enforced drag of the dragsters aerodynamic shape (or lack there of).
 
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junglestylz said:

Since thrust is a measure of force, and horsepower is a measure of work, comparing the two is like comparing apples and oranges. The crazy thing is that a honking great jet engine generating 1,000lbs of thrust is producing ZERO horsepower if it's not moving (ie: attached to a static test stand). However, if we add another factor, "velocity", we can come up with some rough guides for converting thrust to HP. Given the conversion that 1 lb.= 1hp at 330knots, and that 1knot = 1.155077945 mph. then 330 knots = 381 mph.
Lets make it easier--The RB211 engine when used as a core for power generation produces about 26,500 kW--or in excess of 35,000hp/engine. A dragster at 5000hp does not even come close to a single aircraft turbine in the horse power race.

Some of the larger gas turbines produce in excess of 300,000hp.

Steve
 

junglestylz

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Would that be kWh¿ What is the time basis for that equation¿ Not saying that you are wrong, Just want to try and figure this out. If that is speaking as a basis for a genset of some sort, what else is the engine running¿ Some gogen's can create power from what can be called almost a perpetual motion, but actually lack power which is what makes then extremely effecient.
 
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junglestylz said:
Would that be kWh¿ What is the time basis for that equation¿ Not saying that you are wrong, Just want to try and figure this out. If that is speaking as a basis for a genset of some sort, what else is the engine running¿ Some gogen's can create power from what can be called almost a perpetual motion, but actually lack power which is what makes then extremely effecient.
The ratings are for continuous duty operation. The hp rating is at the output shaft with no additional heat/power recovery from the exhaust.

Steve
 
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#10
junglestylz said:

Under full throttle, a dragster engine consumes 1-1/2 gallons of nitromethane per second; a fully loaded 747 consumes jet fuel at the same rate with 25% less energy being produced.

One way to simplify this problem is to just compare the potential energy in the fuel, and for comparision assume that both engines burn 100% of the fuel.

Nitro provides about 5,000 btu per pound; kerosene (which is basically what jet fuel is) provides abot 18,600 btu per pound. The air to fuel ratios are different, but that doesn't matter since we are talking about energy produced per equal units of fuel consumed in a second. So looking at it this way, it would seem that the above statement is incorrect since jet fuel contains almost 4 times as much potential energy as nitro.

I guess it could be true if the jet engine were grossly inefficient and only extracting 4,000 btu from the jet fuel, but I know they are not that inefficient.

I have seen this post elsewhere, I don't think Jungle is the original author, nor does he claim to be, so I don't take him to task to defend the statement.
 

junglestylz

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I wasn't defending it anyway, I was just trying to make some sense out of it and figure out how the original author came about with that statement. Especially the fully ladened statement about the 747. The engines would create the same amount of power regardless of weight. They would just need to create more because of the greater amount of drag. I'm an engineer so things like this have a tendency to really bother me.
 
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#12
junglestylz said:
Putting all of this into perspective:

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 1320 foot long race course.

That folks, is acceleration.
Yeah, now you got me analyzing the other statements too. The above statement is stretching the truth. According to my calcs (200 mi/h * 5280 ft/mi * 1h/3600s), 200 mph = 293 ft/sec, so the 'vette will do the quarter mile in 4.5 secs. The record was 4.44 seconds for a top fueler. So the TF beat the vette JUST at the finish line, certainly not 3 seconds into his run.

Still, it's darn impressive acceleration.
 


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