Balloon Powered LEGO Car Building Challenge

Build a balloon powered LEGO car that goes zooming across the floor!

This is a fun LEGO engineering challenge that kids can truly do with whatever LEGO bricks they have. You really just need wheels and basic bricks, and you can customize from there with the bricks you have.

This LEGO balloon car is also a great demonstration of Newton’s third law of motion. I’ll include the science explanation below.

This post was originally published in April 2013 and updated in July 2026.

We originally did our challenge this week as a playdate with friends, and it worked very well. We invited another family of four boys to join us, so that made EIGHT boys at our house! (It was really not that loud, in case you’re wondering! Just a lot of burping 🙂 )

Before our friends came, we separated out our wheels and plates so that it would be easy to find parts without everyone having to dig through the same tub. Then we also had a tub of bricks for building the cars.

This was the basic design that the boys used. As you can see, this project can truly be done with very basic bricks!

How to Attach the Balloon to the LEGO Car:

In the photo above, we used a 1 x 2 tile modified with a bar handle. These bricks are pretty common, but if you don’t have one, you can just use basic bricks to create a gap for the balloon as shown in the photo above that one.

We also used a 1 x 4 arch to create an opening for the balloon. The 1 x 2 tile with a bar does come off the car easily, so younger kids may prefer the design below. We used a 1 x 6 tile to secure the arch to the car, which made it very sturdy.

However, we did discover that the opening of the arch did not let the air out of the balloon as quickly, which meant that this car did not travel as quickly as our other designs.

Here’s another view of that car. This car also features LEGO wheels with the least amount of friction. If you’re a LEGO club instructor or if you run a STEM program, I would highly recommend investing in these wheels!

They are the Technic Wedge Belt Wheel and you’ll also need the separate Tire Piece.

You’ll need to hold the car up to your mouth to blow up the balloon! But it’s not hard to do.

Racing cars is very fun!

We had boys age 4 years old through 11 years old at our house, and everyone had fun building cars.  Our four year old friend was very focused on getting his car just right!

The Science Behind Balloon Powered LEGO Cars

Questions to Investigate:

• How far does your car travel? The farthest distance traveled by one of our balloon powered cars was 12 feet 3 inches!
• What kinds of modifications allowed your car to travel farther?
• What type of wheels allow a car to travel the farthest? Why do you think this is? (Wheels with more traction will create more friction and slow the car down.)
• Which travels farther – a heavy car or a light car?
• We discovered that the design of the car needed to hold the balloon up high enough that it did not touch the wheels. Otherwise, the balloon rubbing against the wheels created too much friction.

The best designs had a good balance of stability and light weight, as the heavier cars had a harder time getting started.

Some of the cars did hilarious tricks – like driving on the back two wheels or going in a circle.  By the end, the boys said their cheeks hurt – from so much laughing and so much blowing up balloons!

This project is a great demonstration of Newton’s Third Law of Motion, which says that for every action, there is an equal and opposite reaction. Air rushes backwards out of the balloon, which propels the car forward. We didn’t try this, but I think the cars would travel farther if you put a large piece of cardboard or something similar right behind the balloon to give the air something to push back against. It would be fun to try!

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