Top Fuel "Facts"pedal-force8/09/14 10:36pmFiled to: antiviral273EditPromoteShare to KinjaGo to permalinkAlright, so these "facts" (I use quotes because I'm not so sure on some of them) have been going around the internet for at least 10 years. The first source is possibly this page, but it is just a paste of an e-mail chain the author got. It lists some stuff from the 2003 season though, so it can't be much earlier than that. Someone copy-pasted them into the comments section of the Sploid post about Top Fuel Funny Car engines exploding and how cool it looked (it does indeed), complete with terrible formatting (thanks Kinja!) but I've seen them long before that. Here they are for you, numbered for convenience. Advertisement Advertisement 1. One Top Fuel dragster's 500-cubic-inch Hemi engine makes more horsepower than the first four rows at the Daytona 500.—- This one is pretty easy to fact check. Estimates are Top Fuel cars make between 8000-9000 HP. Unrestricted NASCAR makes around 800 HP, but restrictor plate tracks (like Daytona, aha, tricky list maker) they only make about 450 HP (source: http://en.wikipedia.org/wiki/Restricto…). So, 2 wide, times 8, is 16 cars, at 450 HP, 16*450 is 7200. They could probably tack on another row if they wanted and say 5 rows. Whatever. This one checks out, but only because Daytona is a restrictor plate track. This means it's true, but misleading. edit: I'm an idiot and doubled the cars twice. There's only 8 cars in four rows, not 16. I doubled in my head, then doubled on paper. So it should be 8 cars * 450 HP is 3600 HP in the first four rows. So they actually way underestimated, I don't think they realized Daytona is a restrictor plate track. Thanks to Dusty Ventures for noting my mistake. Sponsored 2. A stock Dodge Hemi V-8 engine cannot produce enough power to drive the dragster's supercharger.—- This one is again in the "true but misleading" camp. Yes, the supercharger when in use on a Top Fuel engine takes about 800 HP to run. But if you put that same supercharger on the aforementioned stock Hemi V-8 it would run it just fine, at the amount of air and pressures that a stock Hemi V-8 would require. It only requires a lot of HP because they're running ridiculous amounts of air at 60 PSI. 3. With 3000 CFM of air being rammed in by the supercharger on overdrive, the fuel mixture is compressed into a near-solid form before ig-nition. Cylinders run on the verge of hydraulic lock at full throttle.—- This is the first one that stood out to me. I find it hard to believe they're compressing the mixture into "near-solid form". I know the compression ratio is 7:1, and they're flowing 80gpm of fuel at peak torque according to here. Peak torque is probably around 4k RPM maybe? 4000 revolutions, 80 gallons, 80/4000 is 0.02 gallons/revolution. But times four for each cycle is 0.08 (only get fuel once every four revolutions). Then divide by 8 for each cylinder, 0.01 gallons per cylinder per cycle. That's 2.31 cubic inches of fuel per stroke. Each cylinder is (500 cubic inches/8) 62.5 cubic inches. With compression ratio of 7:1 that leaves (62.5/7) 9 cubic inches compressed. So 2.31 cubic inches of fuel in a 9 cubic inch combustion chamber. That's hardly hydro lock. Did I do something wrong (I probably did something wrong). edit: Yeah, I did something wrong. A couple things actually. Shocking, I know. Dumahim pointed out that you get fuel every 4 strokes but every 2 revolutions. tc_corty pointed out that I forgot the 60 psi of boost, which significantly changes the compression ratio (duh, I've tuned turbocharged cars, I should know this). That being said, I have no way of figuring out the dynamic compression ratio of a Top Fuel engine. We can assume it's much, much higher than 7:1 though. A rough estimate is to use the amount of atmospheres and multiply compression by that. So absolute manifold of 60, 60/15 is 4, so 4*7 = 28:1 compression. I find it hard to believe that wouldn't pre-ignite, so it must be lower, maybe 20:1 or something. 62.5/20=3.1 cubic inches. But you're now only getting 1.15 cubic inches of fuel (because of my math error earlier), so my statement stands. It's a hell of a lot of fuel in a cylinder, but I don't think it's close to hydro lock. Advertisement Advertisement 4. At the stoichiometric 1.7:1 air-fuel mixture for nitromethane, the flame front temperature measures about 7000 degrees Fahrenheit.—- This is so easy to fact check it's ridiculous. The flame temperature of nitromethane is only about 4400* F. So, not correct then. Unless you consider 4400 to be "about" 7000. Zoom pointed out that the flame front may be a different temperature than the simple flame temperature in open air. And they're right. It looks like at high pressure and stoichiometric ratios, the flame temperature in constant volume is around 6700*F. So I think this one may actually be true. Damn that's hot. This is actually because of the main important property of Nitro, which is that it contains its own oxygen already.5. Nitromethane burns yellow. The spectacular white flame seen above the stacks at night is raw burning hydrogen, separated from atmospheric water vapor by the searing heat of the exhaust gases. Advertisement —- This seems to be wrong. Water dissociates at 2500* C. That's about 4500* F. Exhaust temperatures at the end of a run are under 2000* F. So this isn't really possible.6. Dual magnetos supply 44 amps to each spark plug. This is the output of an arc welder in each cylinder.—- This one is true. The cheapest arc welder at Harbor Fright is 70 A, so yeah, it just barely beats the cheapest POS arc welder. Advertisement Advertisement 7. Spark plug electrodes can be totally consumed during a single pass. After half-distance, the engine is dieseling from compression plus the glow of exhaust valves at 1400 degrees Fahrenheit. The engine is shut down by cutting the fuel flow.—- This is a myth that was maybe true 30 years ago, according to the CarCraft article linked above. "Top Fuel is also a place where myths abound, especially in regard to ignition systems. Just 30 years ago, Armstrong says fuel engines ran on far less fuel, making them leaner, which turned spark plugs into glow plugs, which continued combustion even after the ignition system failed completely. But with today's fire hose-like delivery of fuel, Armstrong says, "You couldn't do any of this without a strong ignition system."8. If a spark plug fails early in the run, un-burned nitro can build up in the affected cylinder and explode with sufficient force to blow the cylinder head off in pieces or split the cylinder block in half. Advertisement —- Well, yeah, duh. Nitro blows up.9. In order to exceed 300 mph in 4.5 seconds, dragsters must accelerate at an average of more than 4 g's. In order to reach 200 mph before half-distance, the launch acceleration approaches 8 g's. A Top Fuel dragster reaches more than 300 mph before you have completed reading this sentence.—- 200 mph is 293 feet per second. 8 g's is 258 feet/s^2, not 80, that's meters, because I'm an idiot. Thanks to Arch Duke Maxyenko, Now With for pointing out my mistake. It would take 1.12 seconds to get to 293 feet per second, or 200 mph. That makes me think 8g is probably too high, since if they got to 200 mph after only 1.12 seconds. Here, I'll let someone else do the math, since I clearly can't handle it. They show it's actually more like 5g, so false here. Yet again. Advertisement Advertisement 10. With a redline that can be as high as 9500 rpm, Top Fuel engines turn approximately 540 revolutions from light to light. Including the burnout, the engine needs to survive only 900 revolutions under load.—- Redline is actually more like 8250-8500. And they only run 1000 feet now. But whatever, it's basically true.11. Assuming that all of the equipment is paid off, the crew works gratis, and nothing breaks, each run costs an estimated $1000 per second. Advertisement —- I have no way of checking this exactly, but it doesn't seem unreasonable. Tires are $1000, last about 3-4 runs, fuel is $20/gallon, they use 20 gallons or so, which is $400 per run right there.12. The current Top Fuel dragster elapsed time record is 4.441 seconds for the quarter-mile (October 5, 2003, Tony Schumacher). The top-speed record is 333.25 mph as measured over the last 66 feet of the quarter-mile (November 9, 2003, Doug Kalitta).—- This was true at the time. It's 3.701 now, but that's at 1000'. Advertisement Advertisement 13. Putting all of this into perspective: You are driving the average $140,000 Lingenfelter twin-turbo Corvette Z06. More than a mile up the road, a Top Fuel dragster is staged and ready to launch down a measured quarter-mile as you pass. You have the advantage of a flying start. You run the Vette 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, but you hear a brutal whine that sears your eardrums, and within three seconds, the dragster catches you and beats you to the finish line, a quarter-mile from where you just passed him. From a standing start, the dragster spotted you 200 mph and not only caught you but nearly blasted you off the road when he passed you within a mere 1320 feet.—- This is pretty easy to do the math. They ran 4.5" for 1/4 mile, which is right at 200 mph average. So they couldn't even get this one right. You would actually exactly tie if you were averaging 200 mph. He would pass you at the line doing 320 mph, but you'd still tie. So, false, I guess.