Get more performance without using a turbo

Bruno Gomes

March 24, 2018

Notice the Impulse Drum Charger on the side of this KTM RC 390. Photo credit: Alter Ego Hardware

By now, big motorcycle manufacturers are looking at alternative engine types like hybrid or electric. But there’s also another side of using new technologies, that is boosting performance of the engine using a turbo or a supercharger, like the one Kawasaki installs in the mighty powerful Ninja H2 hyperbike.

Some smaller companies also offer you the possibility to bolt-on a turbo kit on your bike.

But adding a turbo or a supercharger, besides all the advantages in performance, also has its downsides: it generates more heat, and the system itself usually means that the bike will be much more expensive than a naturally aspirated bike.

Now, Alter Ego Hardware found a similar solution to a turbo but at a much lower price range: The Impulse Drum Charger.

And what is the Impulse Drum Charger?

Similarly in looks to a conventional turbo, the IDC collects exhaust gases to create more pressure on the air-intake, but it doesn’t require any turbines or compressors, or any electronic system for that matter. It’s basically a drum with a carbon membrane in a cylinder shape connected to the exhaust in one side, where it receives the exhaust gases, and on the other side it’s connected to the engine’s air-intake system.

The exhaust gas enters and accumulates inside the drum every time the cylinder fires, building pressure thanks to the membrane and a valve, and when the pressure exceeds the membrane’s threshold, the first valve closes and the reed valve lets the pressurized air into the air-intake system.

This results in a pressure of 0.3bar being pumped out from single membrane drum charger, or 0.6bar for the dual-membrane charger.

According to Alter Ego Hardware, the system allows to increase engine performance in 15-20% in power and torque, the heat never goes beyond 50 degrees Celsius, all this coming from a piece of plastic, a carbon membrane and some valves that make for a total weight of around 1,5kg.

The downside to the Impulse Drum Charger is that it has to be fixed at a distance of 60 to 80 cm from the exhaust header, and it needs to be attached to the bike, which might be a problem because the drum needs to be around 220 mm diameter when each cylinder is less than 250 cc, and larger cylinders up to 400 cc require a 270 mm diameter membrane to get enough pressure generated.

And this is for each cylinder!

For example, if your bike has a two-cylinder engine, you’ll need two drums, three cylinders will require three drums, and so on.

Based in Rome, Italy, Alter Ego Hardware believes that their system is a good and valid option over the expensive aftermarket turbo kits we see on customized bikes, or even bikes coming from big manufacturers. Even though the Impulse Drum Charger doesn’t have a fixed price yet, the company says it’ll cost ten times less than a conventional turbo kit.

Here at iMotorbike we’re looking forward to see if this simple idea has some real-world results. Obviously, a liter sport bike won’t be able to use the Impulse Drum Charger, but we can see It being used in small or medium capacity bikes where the rider will benefit a lot from this improved performance.