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Hey everyone, first time post. Just wanted to ask some people with knowledge in the area how much effect weight has on posting a fast lap time in a go kart. The track is a really bendy one, you can see the map at http://www.acekarts.com.au, my best time is a mid 39 second lap. My friend who comes with me has also set a mid 39 second lap but roughly 1 tenth slower. He weighs 60kg and i weigh 115kg.
So what impact is it possible my excess weight is having on my lap times, if any?
weight has a very important roll to play in go -karting.
there could be several factors that play on the timing sheets
1. he does not know how to go-kart as well as u.
2. it could also come down to fuel loads
3. how old or new the machinery could be..
in any form of racing weight plays an important roll
The weight is very important especially on tight twisty tracks usually found in indoor circuits. The acekarts website shows a very wide large corner track, there is not even a hairpin. So weights is not as important for in such a track.
I went with 3 friends to an indoor kart track and it was clear that the weight of the person matters on that track. luckily, I was the lightest so I end up on top. after the driving experience, we discussed it and I found out my friend had to touch the brake to slow the car down at the hairpin whereas I just lifted the throttle, let the tail loose, begin the turn in and full power again to continue the turn. All the while, I could enjoy the sliding of the kart and screaming tires.
SO the weight can affect you if you have to slow down on a track. but on a wide and relatively straight track and flat track. then there is no effect.
In Formula 1, each 10 kg slows the car down roughly 0.4% (around 0.3 seconds a lap on a normal track). In a much lighter Go Kart, this effect increases proportinally. The kart, including driver, weighs roughly four times less than an F1 car, so each 10 kg extra weight probably slows the kart down by at least 1.6%. You are 55 kg heavier than your friend, so your weight disadvantage should increase your laptime by around 9%, or 3.5 seconds over the 39 second lap. In other words, for your friend to claim he is actually a faster driver than you, he would need to break into the high 35's...
Now, to be honest I don't really like comparing my eco racing with karting so I don't know how relevant this is BUT every 10kg lost gives you an extra 0.4mph of available energy all depends on gearing etc as to whether you use it.
I used to say same thing, im a fairly good karter and always win work events even with people lighter than me. I do this by making sure I have traction coming out of a bend and being last of the late brakers coming into bends as well as no fear of cornering. But get me on a straight with the lighter guys and I have no chance. I know buckmore park near me had 2 classes of karters, below and above 12stone, great idea but im 13.3 stone lol.
Last week I went to BsAs kart track with some friends. The karts we were running were 2 strokes 125cc IAME Sudams, with reed valve and racing carb they have 42HP at 19.000rpm.
Only one of my friends had tachometer. I weight 72Kg and my friend 82Kg. With the same kart he reached 17.100rpm in the straight and I reached 17.500rpm.
We were running a long ratio (10:78) in order to preserve the engine.
Tires have a 280mm diameter. You do the math to calculate top speed diference
Lap times where not comparable, he has been running that track for years and lapped with new tires. I used his kart when tires where already worn out and was my first time out on that track layout. I only gave 5 laps, just to "feel" his chasis.
"You need great passion, because everything you do with great pleasure, you do well." -Juan Manuel Fangio
"I have no idols. I admire work, dedication and competence." -Ayrton Senna
Very simple test - put your friend in kart with 55kg of ballast and see the effect on his lap time!
Not saying that if he is 5sec slower you could gain 5sec by dropping down to his weight, but would give you idea.
Driver weight makes a MASSIVE difference in Go-karts. I drive karts as a hobby (may start racing next year) and when my mate drives my kart (a 100cc Rotax 2-stroke) there's a noticeable difference. He's only 168cm whereas I'm 185cm so obviously I weigh a lot more and it's very obvious.
As others have said, weight makes a massive difference in karts. I am of the bigger persuasion and when I race against my friends who weight less than me but are not as good of drivers, they often make my lap times look silly. Yet when we go autocross a Miata or an RX-8, I am faster consistently. Maybe I'm just a poor kart driver, but I'd chalk a good bit of the lap time difference up to weight.
Now you said you guys both ran the same times but your friend weight about half as much as you? Then you must be a really good driver!
Belatti wrote:With the same kart he reached 17.100rpm in the straight and I reached 17.500rpm.
We were running a long ratio (10:78) in order to preserve the engine.
Tires have a 280mm diameter. You do the math to calculate top speed diference
Contributing to an ancient thread, but it wasn't me that resurrected it
For bicycle speed meters, which typically measure the number of wheel rotations, you have to measure the roll-out distance of the wheel (how far you travel per revolution) with yourself sat on the bike to get accurate speeds. If you calculate it using pi*d you will get a different (larger) answer to what you get if you roll the bike unloaded, and that in turn is larger than what you get if you roll the bike with yourself on it. This is because the compression around the contact patch reduces the effective radius of the wheel-tyre system, and that compression is larger the more load is on the tyre.
So Mr Heavy is even further disadvantaged than the numbers above indicate (unless he increases his tyre pressures) because the wheels are effectively smaller for him than for Belatti.
However: I used to be about 2% slower than my colleagues when I weighed 115kg to their ~80kg. So either I'm the second coming of Senna or there's more to it than this
Recently I got a friend to agree to taking turns karting with 20 pounds of ballast. ( 4, 5 lb. weights in our pockets)
I weigh about 220 pounds, my friend about 180 pounds, so the ballast represents half the difference.
We each took our assigned Karts through 4, 12 lap sessions, two with added ballast.
I compared a weighted average (ignoring the slowest 4 laps) of lap times for each session. I also compensated for the warmer tires and other factors that affected times between sessions by finding the average lap improvement from one session to the next for the non ballasted drivers.
Based on our (not yet as large a sample as i'd really like) data, in a ~30" lap 12 turn lap, the penalty worked out to .03"/lb., drving a Sodi RT8 Kart
It was at TBC in Richmond if that means anything to anyone.
As far as the other factors that affect lap times, there are many, and sometimes, it is the kart that makes the difference. On previous sessions, at the same track, we've swapped karts between sessions and swapped results, from my friend besting me by 4/10ths to me beating him by 2/10ths, we both set our personal bests for that track in that Kart.
I'll post more when I've got a larger collection of data, I want to get more drivers in on the deal.
- 600 meters kart track
- AMB Timing system
- Sodi RX8 - 6.5HP
Me: 90kg, my friend - 70kg. He's 1.5 seconds faster than me, and we both push hard, knowing the ideal racing line quite well. Just a practical example, which could vary due to many factors.
