Engines Exposed: HEMIs That Make 7,000 Horsepower


That many zeroes was not a typo.

For some people, cars like the Ferrari LaFerrari or McLaren 650S are the physical manifestation of what they could only dream about as children. For others, the handling of sports cars morphed their fantasies of racetracks into realities. While for some gearheads, raw speed is enough to conjure up feelings of jubilance and ecstasy. A lucky few that find themselves in that third category get to experience the pinnacle of jet engines, splitting land-speed records in half, subsequently ripping their skin from the bones of their skull.

To attempt to understand the God-like power of top fuel dragsters is a monumental accomplishment. Besides the unreal horsepower figures, the amount of fuel and downforce, rubber and g forces involved stretches the fabric of physics so far that when an engine explodes or dragster flips over it's as if a hole has been torn through space-time. To start, the weapon of choice for top fuel dragsters is typically a second generation Chrysler 426 Hemi V8 engine, which can be found in almost all Dodge sports cars from the '60s and '70s, including Chargers from 1966-71 and some Barracudas. The reason they picked that motor? It was the biggest, and capable of the biggest displacement at the time.

For dragsters, the engine is made out of aluminum, producing about 7,000 horsepower. That horsepower figure gets the car a mid-four second quarter mile at over 330 mph, a 0-100 mph time of less than a second and it takes 15/100 of one second for all that power to reach the rear wheels.

At launch, the dragsters hit over five times the force of gravity, which according to NHRA's website is about the same as the space shuttle while it's leaving Earth. This creates up to 8,000 pounds of downforce, which is handled by the dragster's rear wing. This is all possible because of a few factors. First of all, the amount of fuel used is ludicrous. Dragsters use a fuel pump that spits fuel at a rate of 65 gallons per minute. However, the biggest catalyst for the insane amount of horsepower might lie in its fuel. These 426 Hemis use what's called nitromethane, which is (very basically) gasoline mixed with some nitrous oxide. The big advantage of nitromethane is you can burn more of it than gasoline in a single cylinder, which means more power per stroke.

Instead of needing to burn 15 pounds of air per one pound of gasoline, nitromethane requires less than two pounds. It also burns a lot slower than gasoline, so when you see flames coming out of the exhaust that's the fuel the spark plugs didn't get a chance to ignite. The engine is aluminum, a V8, 8 liters strong (at least in the Super Coupe Club Of Iowa), uses flat-topped piston heads and rods big enough to second as battle-axes. The engine needs to be rebuilt after every four-second pull, so it's hardly economic, but at least the mechanics can do the job in 40 minutes. The scope of top fuel dragsters and what one is capable of is staggering enough to dwarf the fastest super and hyper cars imaginable, and even sometimes unimaginable.

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