Prove my friend wrong!!!

[aj992]

I have a kart with 18" golf cart tires on it and a governed Predator 212cc engine. I say the ratio should be about what I have ideally a bit BIGGER (I currently have a 7.5:1 but 8:1-ish would be ideal). He says we should go lower - closer to 1:1 to get the clutch to not smoke.

Which is more accurate? If neither please give us your thoughts, we've been arguing about this all night lol.

 

[DirtyDamage]

If you ran 1:1 the clutch would last all of 20 mins. If IRC you should be running a TC with those large of tires....

 

[Poboy kartman]

You are correct...you need to head that direction....ummmmm....I have no idea why. someone ^ would say that clutch would last 20 minutes........maybe a typo...try 2....

 

[DirtyDamage]

Hey poboy, let's do an experiment....

 

[landuse]

If you had a typo and meant 11:1, then your friend is right. If not, then your friend is an idiot. You need to have low gearing with tyres so large

 

[kevbo22]

You are correct...you need to head that direction....ummmmm....I have no idea why. someone ^ would say that clutch would last 20 minutes........maybe a typo...try 2....

Okay, thats it! Poboy is the forum shenaniganator...
The more threads I read, the more i love it lol.

but ya even ive come to learn 1:1 is no good my friend. Put a TC on it!!!!! with better gearing* 7:1 maybe? I like it

 

[itsid]

If you had a typo and meant 11:1, then your friend is right. If not, then your friend is an idiot. You need to have low gearing with tyres so large

I wouldn't dare to put it that way... BUT THAT!!!

REMEMBER:
LOWER ratio means HIGHER numbers up front (p.e. low ratio 8:1);
HIGHER ratio means LOWER number (p.e. high ratio 4:1)

in case it is a typo.. 11:1 would be much closer to the
needed ratio than 7.5 or even 8:1 is

say we talk about 157 kg (kart plus rider)

then 11:1 would be spot on
KartInfo by kartcalc.net:

[FONT="Verdana"]
[B][U]KART[/U][/B]
[INDENT][I]RW diameter[/I]: [B] 45.72 cm | 18 in[/B]
[I]Total weight[/I]: [B] 157 kg | 346.13 lbs[/B]
[/INDENT]
[B][U]ENGINE[/U][/B]
[INDENT][I]Original HP[/I]: [B] 6.5[/B]
[I]Asummed HP[/I]: [B] ~6.5[/B]
[I]Torque[/I]: [B] 12.86 Nm | 9.48 ft lbf[/B]
[I]RPM[/I]: [B] 3600[/B]
[/INDENT]
[B][U]TRANSMISSION[/U][/B]
[INDENT][I]Final ratio[/I]: [B] 7.5:1[/B]
[/INDENT]
[B][U]PERFORMANCE[/U][/B]
[INDENT][I]Max Wheel Torque[/I]: [B] 96.45 Nm | 71.14 ft lbf[/B]
[I]Acceleration[/I]: [B] 2.69 m/s² | 8.83 ft/s²[/B]
[I]Top Speed[/I]: [B] 41.37 km/h | 25.7 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 11:1[/B]
[/INDENT]
[/FONT]

let's increase the weight by adding another passenger (two seater kart)
KartInfo by kartcalc.net:

[FONT="Verdana"]
[B][U]KART[/U][/B]
[INDENT][I]RW diameter[/I]: [B] 45.72 cm | 18 in[/B]
[I]Total weight[/I]: [B] 250 kg | 551.16 lbs[/B]
[/INDENT]
[B][U]ENGINE[/U][/B]
[INDENT][I]Original HP[/I]: [B] 6.5[/B]
[I]Asummed HP[/I]: [B] ~6.5[/B]
[I]Torque[/I]: [B] 12.86 Nm | 9.48 ft lbf[/B]
[I]RPM[/I]: [B] 3600[/B]
[/INDENT]
[B][U]TRANSMISSION[/U][/B]
[INDENT][I]Final ratio[/I]: [B] 7.5:1[/B]
[/INDENT]
[B][U]PERFORMANCE[/U][/B]
[INDENT][I]Max Wheel Torque[/I]: [B] 96.45 Nm | 71.14 ft lbf[/B]
[I]Acceleration[/I]: [B] 1.69 m/s² | 5.54 ft/s²[/B]
[I]Top Speed[/I]: [B] 41.37 km/h | 25.7 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 13.9:1[/B]
[/INDENT]
[/FONT]

and 14:1 would be your goal!

but in the end.. a Torque converter is what you want:
KartInfo by kartcalc.net:

[FONT="Verdana"]
[B][U]KART[/U][/B]
[INDENT][I]RW diameter[/I]: [B] 45.72 cm | 18 in[/B]
[I]Total weight[/I]: [B] 157 kg | 346.13 lbs[/B]
[/INDENT]
[B][U]ENGINE[/U][/B]
[INDENT][I]Original HP[/I]: [B] 6.5[/B]
[I]Asummed HP[/I]: [B] ~6.5[/B]
[I]Torque[/I]: [B] 12.86 Nm | 9.48 ft lbf[/B]
[I]RPM[/I]: [B] 3600[/B]
[/INDENT]
[B][U]TRANSMISSION[/U][/B]
[INDENT][I]Final ratio[/I]: [B] 6:1[/B]
[I]TC type[/I]: [B]  series 30 6" driven[/B]
[I]Lowest ratio[/I]: [B] 16.2:1[/B]
[I]Highest ratio[/I]: [B] 5.4:1[/B]
[/INDENT]
[B][U]PERFORMANCE[/U][/B]
[INDENT][I]Max Wheel Torque[/I]: [B] 208.33 Nm | 153.66 ft lbf[/B]
[I]Min Wheel Torque[/I]: [B] 69.44 Nm | 51.22 ft lbf[/B]
[I]Acceleration[/I]: [B] 3.3 m/s² | 10.83 ft/s²[/B]
[I]Top Speed[/I]: [B] 57.45 km/h | 35.7 mph[/B]
[/INDENT]
[/FONT]

(even higher ratio [6:1] and much better speed

'sid

 

[landuse]

I have a kart with 18" golf cart tires on it and a governed Predator 212cc engine. I say the ratio should be about what I have ideally a bit BIGGER (I currently have a 7.5:1 but 8:1-ish would be ideal). He says we should go lower - closer to 1:1 to get the clutch to not smoke.

Which is more accurate? If neither please give us your thoughts, we've been arguing about this all night lol.

So.....what did you tell your friend?