How Top Gas Racers Bolted Two Engines Into One Transmission

The heyday for nan National Hot Rod Association's (NHRA) Top Gas dragster people was 1961 to 1971. Unlike their nitro-huffing counterparts successful Top Fuel, Top Gas cars utilized regular aged pump gas. Nitromethane makes crazy powerfulness acknowledgment to its much thorough combustion (more connected that later), truthful moving state was a terrible handicap. To beryllium competitory successful nan Top Gas class, you had to get creative. Lots of builders settled connected 2 engines arsenic nan solution, but really do you get them to play bully pinch a azygous axle? You could do for illustration Car and Driver did pinch its two-engined Honda CRX and conscionable put a abstracted powerfulness train successful nan back, but that's not really Top Gas attacked nan problem.

The all-conquering Freight Train dragster was moving astir 1,600 horsepower successful 1971, Top Gas's final year. Or rather, it was making 800 positive 800, because that fig came from 2 saturated and stroked 428-cubic-inch first-gen Chrysler Hemi V8s literally chained together to make a V16 pinch a abstraction successful nan middle. The 2 engines ran arsenic 1 because builder John Peters transformed supercharger thrust hubs into sprockets and utilized double-roll number 50 concatenation to link them, past routed nan rear motor done a two-speed transmission arsenic you would pinch immoderate normal power-train setup. 

Eddie Hill's Double Dragon utilized a brace of supercharged Pontiac V8s successful an opposed, side-by-side setup, moving for illustration copy linebackers shouldering their measurement down tracks together. Rather than link nan engines straight and unit them into lockstep, he gave each its ain flywheel, clutch, driveshaft, and individual ringing and pinion gears connected nan rear axle. It worked good capable for Double Dragon to deed 202.7 mph successful nan 4th successful Hobbs, New Mexico and rip chunks disconnected nan pavement from nan way successful Indianapolis. 

The twin-engined Top Gas dragsters near a lasting belief connected plentifulness of people, and location are modern re-creations pinch their ain ingenious ways of linking 2 engines to a azygous gearbox. One of nan much impressive, insane examples is Rocky Phillips' Evil Twin (above). He mixed 2 small-block Chevy V8s by letting nan flywheels enactment for illustration a brace of elephantine cogs. Of course, this intends 1 of nan engines has to rotation successful nan other direction. He managed to get nan correct valve timing successful nan backward-running motor acknowledgment to a camshaft from a Chris Craft vessel V8, which ran successful reverse by design. Phillips could past connect a clutch aliases torque converter to 1 of nan flywheels to tally done a transmission backmost to an offset differential.

While multi-engine setups are nostalgic for resistance racers, they're pedestrian astatine tractor pulls. As a kid, I saw tractors featuring nan astir diverse, unfathomably cool powerfulness trains that would person been a spot complete nan apical successful "Mad Max." You won't perceive thing much terrifying — and life-affirming — than a tractor pinch 3 Allison Aircraft V12s dragging a sled complete 320 feet. 

(Warning: if you return your kids to a tractor pull, they whitethorn unit you to thief them make a remote controlled mini tractor propulsion rig. Side effects see a consciousness of accomplishment and happiness.) 

While tractor builds vary, 1 emblematic setup gives each motor its ain clutch and driveshaft that way to a azygous gearbox, which tin beryllium crafted to recieve powerfulness from whetever number of engines you prefer. From that gearbox, nan mixed powerfulness of each nan engines will travel to a transmission aliases a single-speed portion that conscionable provides forward, neutral, and reverse.

Nitromethane burns pinch terrifying explosiveness and tin moreover negociate combustion without needing air. Gasoline, though energetic astatine 31,000 calories per gallon, balanced to 110 McDonald's hamburgers, can't compete. It takes astir 15 pounds of aerial to pain a lb of gasoline, but conscionable 1.7 pounds of aerial to pain a lb of nitromethane, erstwhile it does usage air. You don't request overmuch nitro for complete combustion. 

When dragsters first started utilizing nitro, speeds were getting truthful speedy that nan NHRA feared it mightiness suffer insurance, truthful it banned nitromethane successful 1957. When nitro returned successful 1963, Top Gas had been moving for 2 years. The cognition of Top Gas competitors toward Top Fuel whitethorn champion beryllium summed up by John Peters, builder of nan Freight Train tandem-engined Top Gas car, successful an question and reply pinch Greg Sharp successful 2011, republished connected Wagtimes: "Running gasoline is simply a challenge. It takes much than adding 10 percent and immoderate overdrive. Nitro isn't moreover a fuel. It's an excuse."

In 1978, Top Gas reappeared. It still required pump state arsenic nan only fuel, but eliminated supercharging and stipulated that nan cars usage torque converters. What didn't reappear were twin-engined dragsters, and not because they were banned. They conscionable weren't necessary. The supercharged dual-engine Freight Train's quickest clip by 1971 was 6.95 seconds, while Lena Williams ran a single-engined Top Gas car pinch nary blower to a 6.98 successful 1983. Multi-engine setups activity successful a tractor propulsion because velocity isn't nan extremity truthful overmuch arsenic earthy pulling power. In dragsters, weight and aerodymanics are larger inhibiting factors, and erstwhile single-engine powerfulness is precocious enough, adding a 2nd works isn't necessary. Case successful point, Brittany Force does conscionable fine, hitting 341.85 mph with 1 engine.