>* One Top Fuel dragster 500 cubic inch Hemi engine makes more horsepower >than the first 4 rows at the Daytona 500.
The usual figures given for digger output are between 7000 and 8000 Hp, and the latter sounds high to me. The figures for NASCAR run up to 780 Hp. I asked around web and got figures of 8 and 12 cars in front four rows and I don't know myself. If 8 cars, total Hp is 6240, and hence above is true. If 12, total Hp is 9360 and above is not true. Anyone can juggle figures to get results he likes, so no hard and fast truth is available. >* A stock Dodge 426 Hemi V8 engine cannot produce enough power to drive the >dragster's supercharger. A quick intuitive feeling for this can be had in looking at the timing belt that drives the blower. It may be three inches wide ... anyone think it could safely transmit 350 Hp at the pully radius of a digger crank? IOW, most probably yer 426 could easily run the blower. >* 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 9500 RPM the above 500 CID motor passes only 1375 CFM. That means given the 3000CFM above the blower supplies boost of roughly 2.2 atmospheres. Given 10:1 CR, that means 470 PSI in cyls at room temp. Since the mix is also heated, I would give the max compression about 525-550 PSI. That is hardly enough make the mix turn solid. Some Diesels in fact have almost that much max pressure; my VW Rabbit had 450 PSI spec'd. It is impossible to even liquify air by pressure alone and I don't think it can be made solid at temps much over AZ. >* Nitromethane burns yellow. Nitro and alky, both used in model airplane fuel, both burn blue. >The spectacular white flame seen above the >stacks at night is raw burning hydrogen, dissociated from atmospheric water >vapor by the searing exhaust gases. Water vapor constitutes way too small a fraction of air to do that, and it doesn't disassociate at those temps anyhow. Water is generated by combustion, but it's just that: water. >* Dual magnetos supply 44 amps to each spark plug. This is the output of an >arc welder in each cylinder. If you assume 30,000 average volts at the plug, that would be an instantaneous 1,320,000 watts each. Typical spark duration is about .025 sec and a Joule is one watt-sec, so the energy in that spark is 33,000 Joules. The digger motor makes let's say 1000 Hp per cyl per spark. One Hp is 746 watts, so the motor makes 746,000 watts per power stroke. If the power stroke is 120 deg long, it takes about .019 sec at 9500 RPM. Hence the energy is 14175 joules. IOW, at the figures given above, it takes 2.3 times as much energy to make the spark as the motor produces. That is singularly absurd!! Most maggies and indeed most iggies have primary currents of about 3 amps and primary voltages of 350-400. The actual wattage then is at best about 1200 watts. The efficiency is probably 85-90%, so actual output in the spark is in range of 1000 Watts or 25 Joules. Even if your primary current in racing maggies is twice as high, the energy is still only 50 Joules. >* Spark plug electrodes are totally consumed during a pass. After 1/2 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. No doubt plugs do erode but I doubt they go completely away each pass. These engines are shut down by cutting off fuel, indeed, to prevent Dieseling. I wouldn't concede that the ignition is by hot valve heads though, it's still spark-controlled. >* 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. The usual result is a blower explosion; blower has a lot more internal volume and is nowhere near as stoutly constructed as the motor asm itself. Never heard of heads coming off. >* Including the burnout the engine must only survive 900 revolutions under >load. Real close. Now as for that 200 MPH motorcycle getting beat by the digger ... it's true. It takes 4.5 sec for a 1/4 mile at 200 MPH. The digger record is 4.41 sec. The dragster crosses the finish line while the biker is still 26 feet away. That's acceleration fersure. I wondered where the material in original post came from ... am always suspicious of un-ref'd text. This is the cross I bear from having been scientifically trained. For other interesting facts, and those a bit more reasonable, see: http://www.nhra.com/streetlegal/funfacts.html
