Cars & Driving

How many plungers does it take to match the Roadster's 2 G of suction?

Musk says the new Roadster's fans pull 2 G, enough to drive upside down. We did the math in plungers, octopus suckers, geckos and bounce-house blowers.

Oct 16, 2026 · 6 min read

About 220. According to our calculations, the 2 G of suction Musk described, pulling a 2-tonne Roadster against a surface with twice its own weight, equals about 220 toilet plungers, 250 octopus suckers or 30 very determined geckos. Keeping it up takes about 70 Shop-Vacs running at once, and that's with good seals.

Tesla's own clip: the Roadster drives up the wall, hangs there on its fans, then drops, flips and lands. Tap to watch.

"We have a fan suction system on the bottom of the car that can pull up to two g's in order to make the car go upside down."

Elon Musk, at the reveal (Drive Tesla). Tesla's website adds that the suction can hold the car upside down even when it's standing still (Electrek).

What does "2 G" mean?

One G is the car's own weight. To hang upside down, the fans have to pull at least that hard, or the car falls. Two G means pulling with twice its weight, enough to hang on with weight to spare, or to press the car down hard for grip on a track. At the reveal, it really did climb a ramp until it was nearly upside down, about 170 degrees by Tesla's on-screen numbers (Paultan).

So how much suction is 2 G, in things you have at home?

The 2 G suction scoreboard

🪠
220
toilet plungers
At about 40 lb of grip each. Forty would do it if every plunger got a perfect seal, which never happens.
🐙
250
octopus suckers
The big ones on a giant Pacific octopus hold about 16 kg each. One large octopus has enough. Please don't ask it.
🦎
30
geckos
If every tiny hair on their feet grabbed at once. Geckos never all agree on anything, so bring spares.
🌬️
2–108
bounce-house blowers
That's how much air the fans must move to beat the leaks: about 2 with tight seals, 108 with no seals at all.
🧹
70
Shop-Vacs running at once
With tight seals. With no seals at all, about 3,500. Each one can suck hard enough, but only through its little hose. The car needs that suction across its whole floor while air leaks in.
💨
240 mph
air rushing through the gaps
That's how fast outside air tries to sneak in under the seals at full 2 G suction. The fans have to throw it back out just as fast.

All numbers according to our calculations, for a 2,000 kg Roadster against a perfectly smooth surface. Plunger hold from a University of Kentucky physics demo, octopus suckers from Wikipedia, geckos from UC Irvine, Shop-Vac airflow from Shop-Vac, blowers from Zoom Blowers' specs.

Suction is really the air pushing

Here's the trick. Suction doesn't pull. When you squash a plunger flat, you push the air out from under it, and the air all around us, pressing on everything at about 14.7 pounds per square inch, shoves it against the wall.

The air is already pushing on the Roadster's floor with about 58 tonnes of force, the weight of about 29 Roadsters. For 2 G, the fans only have to take away about 7% of the air pressure underneath. According to our calculations, that's only about 1 pound per square inch.

Just to hang there, it takes half

Parking upside down only needs 1 G, the car's own weight. That halves the grip: about 110 plungers, 125 octopus suckers or 15 geckos, and about half a pound per square inch. With tight seals, it takes about 30 Shop-Vacs running at once to keep up with the leaks.

So why does it need big fans?

Leaks. A car isn't sealed to the ceiling like a jar lid. Tesla says the Roadster has seals along the bottom edges, called "ground sealing," a bit like a mini hovercraft skirt (Electrek, Drive Tesla). But no seal is perfect, and at full 2 G suction, air rushes through any gap at about 240 mph.

The suction itself stays the same. What grows is how much air the fans must pump out to keep it, and it grows fast. At the full 2 G:

Gap around the edges Air the fans must move In bounce-house blowers Fan power
2 mm (tight seal) ~2,800 cubic feet a minute ~2 ~19 kW
5 mm ~7,000 ~5 ~46 kW
1 cm ~14,000 ~11 ~93 kW
2 cm ~28,000 ~22 ~185 kW
10 cm, no seals at all ~140,000 ~108 ~930 kW

With no seals, that's close to a megawatt, so the seals are the whole trick.

What about parking overnight? Hanging there only takes 1 G. According to our calculations, with a tight 2 mm seal that's about 7 kW, or about 52 kWh for 8 hours upside down. With a 1 cm gap it's about 260 kWh. Tesla hasn't said how big the battery is; it promised 200 kWh back in 2017 (Wikipedia). Park on the ceiling for the selfie, not for the night.

Could you really do it with plungers?

In theory, yes: about 110 plungers stuck to a perfectly smooth ceiling to hang it, or 220 to match the full 2 G, with the car's weight shared evenly. In practice, plungers slowly leak, one pops, and then everybody pops. Glass installers use the same idea every day, carrying windshields with hand-held suction cups. Just don't try it with a car.

Show our math

Our assumptions. Tesla hasn't published the car's weight or how big the sealed area is underneath, so we guessed carefully:

  • Car weight: 2,000 kg (about 4,400 lb). Marques Brownlee quoted Tesla calling it a "4000+ pound car" (TechCrunch).
  • Sealed floor area: 5.6 m² (3.5 m × 1.6 m), our estimate for a low two-seater.
  • A smooth, flat surface. Seal edge 10.2 m long; gaps from 2 mm to 10 cm.

Weight (1 G): 2,000 kg × 9.81 = 19,620 newtons (about 4,400 lb of force). 2 G: 39,240 N (about 8,800 lb).

Suction needed: force ÷ area. 1 G: 19,620 ÷ 5.6 = 3,500 Pa = 0.51 psi = 3.5% of air pressure = 14 inches of water = 36 cm of water. 2 G: 7,000 Pa = 1.02 psi = 7% = 28 inches = 71.5 cm of water.

Air already pushing on the floor: 101,325 Pa × 5.6 m² ≈ 567,000 N ≈ 58 tonnes of force.

Plungers: about 40 lb each (University of Kentucky): 8,800 ÷ 40 ≈ 220 (2 G), 4,400 ÷ 40 ≈ 110 (1 G). A perfect vacuum on a 15 in² cup gives 14.7 × 15 ≈ 220 lb each: 40 (2 G), 20 (1 G).

Octopus suckers: 16 kg each: 4,000 kg-force ÷ 16 = 250 (2 G), 125 (1 G). Geckos: 133 kg each: 30 (2 G), 15 (1 G).

Shop-Vacs: a 6-gallon Shop-Vac moves at most about 85 cubic feet of air a minute with nothing blocking it, and less as the suction rises; its full sealed suction is about 55–60 inches of water (Shop-Vac). At 2 G's 28 inches it's roughly halfway, so about 40 cubic feet a minute (our estimate): 2,800 ÷ 40 ≈ 70 Shop-Vacs with a 2 mm gap, 140,000 ÷ 40 ≈ 3,500 with no seals. At 1 G (14 inches) about 64 cubic feet a minute each: 2,000 ÷ 64 ≈ 30. A Shop-Vac can reach the suction level, but only over its hose opening; the car needs it over 5.6 m² while air leaks in.

Leaks: speed of air through a gap = √(2 × pressure ÷ 1.2): 108 m/s (240 mph) at 2 G, 76 m/s (170 mph) at 1 G. Flow = 0.6 × 10.2 m × gap × speed. At 2 G: 2 mm → 1.3 m³/s (2,800 cubic feet a minute); 10 cm → 66 m³/s (140,000). A bounce-house blower moves about 1,290 cubic feet a minute.

Power: pressure × flow ÷ 50% fan efficiency. 2 G: 18.5 kW (2 mm) up to 930 kW (10 cm). 1 G: 6.6 kW (2 mm), 33 kW (1 cm), 330 kW (10 cm); 8 hours = 52, 260 and 2,600 kWh.

These are our own estimates from the assumptions above, not Tesla figures. How the fans and the moving wing work.

Sources:

How this was made: researched and written with the help of AI, then fact-checked and approved by a person before publishing. Every fact links to its source. This story first ran on roadsterflies.com, another site from the same family. Spot a mistake? Tell us.

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