View Full Version : OT: HEMI info for Trud

12-30-2004, 11:56 AM
Hey Dave......

Ran across this recently. I know how you like HEMI's. Thought you'd be interested.
I presume the info is factual, but you know how those "urban legends" get tossed around....

Sorry for the OT guys........but it does involve a MACHINE.


Top Fuel Dragsters
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 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. At half 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).

There is no existing axle/wheel dyno that measures over 5000 Horsepower. So HP of top fuel dragsters can not be measured, only calculated.

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.

12-30-2004, 12:08 PM
The piston engine is far from dead, but everybody wanted jets back in the 40s and 50s, so development of ultra high performance piston stopped.

The problem is engine burn out on the hemi dragster. Every thing you mentioned would eat up an engine quickly, plus how many of us can afford the fuel for such beasts? But it would be nice some days to be able to haul a&% when sitting next to a boom car.

Last summer at National Trails, I got a lesson in dragster fuel, it's 90% Nitromethane and 10% gasoline, because the nitro is too volatile at 100%, something about engine explosions when using 100%.


12-30-2004, 12:12 PM

Top fuel dragsters have long been a fascination of mine. It is totally amazing to me what they are capable of. Thanks for posting that info. It puts things into a different perspective.

12-30-2004, 12:25 PM

My brother is a Chrysler mechanic and we were discussing the hemi a couple of weeks ago. He sent me this info. I was skepical of the 540 rev from light to light, but after doing the math, it makes sense. Considering the parameters, a 1/4 mile isn't really that far (unless your pushing a peanut with your nose). http://bbs.homeshopmachinist.net//biggrin.gif

Glad you liked the info......Rodg

Spin Doctor
12-30-2004, 04:34 PM
Smokey Yunick once remarked that the amount of power that an engine could produce was simply a matter of how much air you could get in and out of it and how long you wanted it to last. True the Keith Black Hemis produce an ungoddly amount of power but the secret is that they don't have to do it for very long. Now if they could produce that power for the time frame of a F1 race (car or bike) plus qualifying or the output time frame of a Space Shuttle Main Engine I would even more impressed than I am by the Top Fuel engines

12-31-2004, 01:10 AM
Sheesh..makes my 572 Rodeck blown alky motor look like a mosquito motor http://bbs.homeshopmachinist.net//biggrin.gif !!! I just can't imagine what it'd be like to unleash one of those. I'd like to have me just one of those MSD44's. They make so much spark that you have to use a special air switch to kill them. A friend of mine put one in his puller...the spark kept jumping across the conventional switch he tried first. The nitro is the magic. When my motor was new they dyno'd it at over 2200hp on nitro and kicked a rod out the side. Needless to say...the previous owner had more cash than I do! Spooky stuff! http://bbs.homeshopmachinist.net//eek.gif

12-31-2004, 04:00 PM
<font face="Verdana, Arial" size="2">Last summer at National Trails, I got a lesson in dragster fuel, it's 90% Nitromethane and 10% gasoline,[/B]</font>Actually, NHRA nitro racers's used 90/10 nitromethane/methanol last season. I think they mandated that tamed down mixture to reduce the number of spectacular engine explosions so it took less time to clean up the gallons of oil that got splattered all over the racing surface. Gotta keep the show going y'know! http://bbs.homeshopmachinist.net//smile.gif Not sure what the '05 rules state about fuel mixture.

After the Timothy McVeigh Oklahoma City bombing thing and now the war on terrorism, I suspect nitro is going to go away before too long. http://bbs.homeshopmachinist.net//frown.gif Geez, my Cox model airplane engines gotta have the stuff!

12-31-2004, 04:11 PM
a friend of mine used to race Outlaw altered's, all it had was a 8-71, a single Mallory "arc welder" and a single fuel pump for a 426 Iron block with factory heads and a nitro cam. It made 3000HP. In a 1800lb altered that's a low six second quarter mile. I think the car cost him under 10 grand. Yeah Nitro is expensive, but keep in mind the cost of building an Alcohol car that can do this kind of acceleration. Outlaw nitro is the best way to go scary fast for cheap. AA/FD (the Pro class) are the fastest accelerating vehicles on the planet. zero to 100mph in less than a second. They average about 6000HP. They also don't last very long. The outlaw motor would need new valves, rings and bearings on a regular basis, but the crank lasted north of 50 passes. here's an article he wrote for Drag Racing monthly:

As for the Z06 comparison I don't see how it really applies. The cars aren't really built for brute acceleration, but more for top end speed.


This Old Shed (http://http:thisoldshed.tripod.com)

12-31-2004, 05:29 PM
I've seen this many times before, being that I'm a long time car nut and former drag racer. Other interesting trivia is that they hit 100mph in under 100 feet. They run a secondary oiling system on the mains pressurized by a tank of nitrogen to combat the tremendous force pushing the crank into the bearings. Top Fuel cars MUST run a dry sump oiling system simply to evacuate the crankcase of the explosive Nitro/oil slosh generated by the blowby. The wicked flames exiting the exhaust are white were the heat rips the hydrogen molecules out of the air and burns them, the flames are caused by Nitros high octane number, thus it burns slowly and is still burning after the exhaust valve opens.

I've got a list somewhere of all kinds of facts about these motors, even though they only last a short time they are at least to me very impressive.

-Christian D. Sokolowski

01-01-2005, 06:46 PM
nothing like the smell of nitro, unless it's the shock waves bouncing off your body!

01-01-2005, 07:33 PM
RSR911, I think the Nitro motors still run a wet sump setup that is deliberately overfilled to deal with the real nasty harmonics that these motors generate. Tony was running something like 12 quarts in a 6 quart pan for this reason. They do use a big ass oil pump, though...


This Old Shed (http://http:thisoldshed.tripod.com)

01-01-2005, 07:40 PM
Another thing I heard was that they run no coolant right? they fill in the waterjackets with filler material to act like a bigger heatsink, because more heat equal more hp, and the engines will auto shutoff if they get too hot. Thats what my auto shop teacher told me in HS.

[This message has been edited by BillH (edited 01-01-2005).]

01-01-2005, 07:45 PM
They original AA/FD's used to run filled blocks, nowadays, they just get them from the manufacturer cast without them.

The reason they don't bother with it is that the motor generates so much heat in so short a time, it would be just another head ache. Keep in mind that they're only running on the pedal for less than five seconds. It's easier just to run the motor hard and let it cool off. The KB blocks are junk after less than a two dozen passes even with perfect tuning and no "hiccups" and how often does that happen?


This Old Shed (http://http:thisoldshed.tripod.com)