Is a 5:1 ratio really that bad? I wanted it to have a faster top end speed. I was told that 5:1 is the minimum gear ratio but still okay.
well, someone might have told you that
in fact in some circumstances (as Tihm pointed out) a 5:1 ratio is perfectly okay...
In MOST it's NOT!
Here's Hilliards calculator for example:
AS you can see, a 9HP engine on small wheels.. and it's STILL complaining....
And so would mine...
KartInfo by kartcalc.net:
Code:
[FONT="Verdana"]
[B][U]KART[/U][/B]
[INDENT][I]RW diameter[/I]: [B] 27.94 cm | 11 in[/B]
[I]Total weight[/I]: [B] 150 kg | 330.69 lbs[/B]
[/INDENT]
[B][U]ENGINE[/U][/B]
[INDENT][I]Original HP[/I]: [B] 9[/B]
[I]Asummed HP[/I]: [B] ~9[/B]
[I]Torque[/I]: [B] 17.8 Nm | 13.13 ft lbf[/B]
[I]RPM[/I]: [B] 3600[/B]
[/INDENT]
[B][U]TRANSMISSION[/U][/B]
[INDENT][I]Final ratio[/I]: [B] 5:1[/B]
[/INDENT]
[B][U]PERFORMANCE[/U][/B]
[INDENT][I]Max Wheel Torque[/I]: [B] 89 Nm | 65.64 ft lbf[/B]
[I]Acceleration[/I]: [B] 4.25 m/s² | 13.94 ft/s²[/B]
[I]Top Speed[/I]: [B] 37.92 km/h | 23.56 mph[/B]
[/INDENT]
[B][U]PROBLEMS[/U][/B]
[INDENT]
[B]You might burn your clutch/belt![/B]
[B]Gear ratio too high![/B]
[I]Suggested final ratio[/I]: [B] at least 5.6:1[/B]
[/INDENT]
[/FONT]
Again, 9HP, small wheels, and with 150kg not exactly heavy either.
mine stops complaining at 121 kg (266.76 lbs) with a 9hp engine.
A weight that'd still require a
5.9:1 ratio with a 6.5HP engine (your average 212 predator)
to run 5:1 with 11" wheels and a 6.5 engine the kart -with you in- it mustn't weigh more than 87kg (192 lbs)
and that's a lightweight kart and a kid....
So.. yeah.. I still go with "
YES" that ratio is at least not exactly good
'sid
