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Comment by emrah | Hacker News Reader

On a single "largest motorcycle tank ever used, designed and built in-house with a whopping capacity of 108 liters (28.5 gallons)" kind of tank that is, but still an amazing achievement

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Not a moto rider, but wouldn't that be really hard to drive? It feels like sloshing would cause significant balance issues.

It shouldn’t be a big issue, fuel tanks of that size aren’t just empty spaces. They have baffles inside to prevent sloshing.

I'm guessing they've probably implemented baffles within the tank, but even if there wasn't it shouldn't be too much of an issue. Once they are able to get going and are not stopping quickly for emergencies, they should be as stable, if not more stable, compared to a regular bike.

Guessed wrong, they definitely found it to be an issue: "After a grueling 304-lap test, Acerbis found they needed to use sponges to combat the sloshing inside the tank at the expense of losing some volume. The final tank weighed 15.2 kg (33.5 lbs) and could hold 108 liters."

From the article:

> After a grueling 304-lap test, Acerbis found they needed to use sponges to combat the sloshing inside the tank at the expense of losing some volume. The final tank weighed 15.2 kg (33.5 lbs) and could hold 108 liters.

It's also common for the track bikes to reduce sloshing

> to combat sloshing, add sponges

I love this sort of simple yet effective solution.

It is commonly used in racing and off road applications to prevent sudden starvation of the fuel pump in rough situations.

Why not use baffles?

The porous structure of sponges effectively acts like a baffle.

Basically, this. ^

I fitted an off road style fuel tank on a truck I had, but I opted for the version without sponges/baffles. It would try to stall when stopping on a low tank.

In the article, it says they added sponges in the tank for that exact reason after they had a lot of sloshing during testing.

Putting this into perspective, my Honda Civic has a 50L[0] gas tank.

0- when it reports that there's 0km left in the tank, I can only fill it up by 40L, so is it really a 50L tank? Hard to say.

Typically there’s a reserve of 10-15% of the tank capacity ‘hidden’ from the time to empty indicator.

10 liters seems on the high end though.

I suspect smaller tanks get relatively larger reserves, I had an old MR2 with a 40L tank and its fuel light came on after 30L too.

counterpoint, my yaris has a 42L tank. The light comes on around 36L to 37L in. I know if pretty well so I've pushed it to 38.5L (another ~30km past the light) but never risked going any further.

To be fair, my MR2 was an '87 model so maybe it's changed since then. I wonder how old the Civic was?

Nice... bigger fuel tank than 2023 Ford F-150 (26gal). lol...

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