Slipstream

How much of an effect does slipstream have and how can drivers best get it on the racetrack. Slipstream is something we see a lot in open wheel race cars. Thinking of F1, when they've got their DRS open. The reason for that is, they're trying to get less wind resistance. They open their rear wing on the straights, more wind flows through that space, it doesn't hit the wing to slow them down.

Suddenly, they're gaining an extra five, 10, 15 kilometers an hour on the straight, which makes it a lot easier to overtake, but also makes that car a lot faster, because there's less wind resistance hitting it.

When it comes to a go-kart, we don't have wings. It's our body that sticks out of the kart the most. For myself, being 6"2', I sit rather high in the kart, and there's a lot more wind hitting me than there would be for a cadet driver whose head is only just barely going over the steering wheel. But slipstream still has a major effect in karts, because if you are the driver who's chasing another kart, and you're within proximity, you will have less wind resistance.

Anywhere between two to five kart lengths behind the driver in front, that's where the slipstream will get activated. If you're anything more than that, if you're 10 to 15 karts behind, by the time the wind hits the driver in front of you, it goes over their head and then it's going to go back into you as well, so it doesn't have that slipstream effect. But if you are close enough behind the driver in front as the wind's hitting them first, it's going over their head, over their kart and going over you as well in the same instance. That's where you get the real benefit.

Now with our cadet drivers, it does help a lot because, we're looking at low horsepower engines. If there's less wind resistance on a lower performance engine, that can gain you one, two, even three kilometers an hour on the straight. If we're in a shifter kart and we were to gain two kilometers an hour, but we're going at 150Ks an hour, it has less of an effect rather than a cadet kart going 90 kilometers an hour, but also gaining those two kilometers per hour on the straight.

That's where we see the low performance classes gaining a lot more with our slipstreams. They're sitting on the straights for longer as well. If it's a 200-meter straight and they're driving for five seconds rather than the shifter kart sitting there for two and a half seconds, that's why the low performance category is gaining a lot more time when it comes to the slipstream effect.

It's super important that when you are trying to gain the slipstream that you're not too close to the kart in front of you. If you're just pushing the kart in front of you with the bumper on the straight, then although you are getting a little bit of a slipstream effect, you're not really helping yourself because the faster you go, you're only pushing the kart in front of you faster as well.

If it's in a race and you're trying to get away from a chasing pack, that's okay, but if you're trying to do an ideal lap time in qualifying, you've got to time your slipstream so that you are gaining an advantage. So, you're catching the kart in front because there's less wind resistance, but you're timing it so that you're not having to push that kart two or three times in the same straight. Otherwise, all that speed that you are gaining, you're just wasting by pushing another kart faster themselves.

When it comes to slipstream on a faster kart, it still has an effect, but where you're going to get caught out is if the engine that you are driving has a rev limiter. A Rotax or an X30, has a rev limiter, so there's not much faster the engine can go. Even though you're gaining that slipstream, you might be going a little bit faster, the engine can't go anymore. You don't get as much of an advantage on engines that have a rev limiter.

Now, drivers need to be mindful that if there is a lot of slipstream, it depends on the wind as well, because if you're going into a massive headwind, that's going to play a big effect. If you're going into a tailwind, it's going to have less of an effect.

We also want to make sure that if you are the lead go-kart, that you are not just helping someone else slipstream off you. Although you want to do your fastest laps, sometimes by helping someone else out, they're going to get that two or three 10th gain being behind you. It's about knowing how to position your kart in a spot that either you are gaining a slipstream so that you're going to be gaining lap time and speed over your competition. Or if you can't really find yourself in a position, don’t help someone else get a slipstream because you can't.

To conclude on how much slipstream does have an effect, for the cadet classes it's super important to be gaining a slipstream. On some tracks, it's going to be worth up to half a second per lap, so that's crazy. If you think that some of these fields could be half a second between the top 20 go-karts. That could be the difference between qualifying on the front row, on the 10th row just by timing your slipstream run perfectly.

It has a lot less impact when it comes to our faster categories, but it still does work. Try and position your kart so that you're between two to five kart lengths behind that kart on a qualifying lap because you can gain that 0.2 to 0.5 a second if you time it correctly. If you do time it correctly, you won't be pushing the kart in front of you in the middle of the straight. That just means that you've gained a little bit of momentum, but then unless you're overtaking someone, you can't really use that to your full advantage as well.