Engine Advantage

[blmiller93]

So i have 2 engines. a 3hp and a 5hp briggs and stratton. Both spin at 3600 rpm (according to tag) What is the advantage of a 5hp over a 3 hp engine on a go kart if they are both rated for 3600 rpm. I know 5 hp produces more watts than a 3 hp but if a speed calculator measures speed by rpm then what would be the advantage of using a 5 hp motor over a 3hp motor?

 

[fowler]

Wells 5 horse power one has more power

So more torque

Both of them will achieve the same speed if geared the same

But because the 5 hp one has more torque u can gear it higher for a higher top speed

3 hp is really too low for a kart

 

[blmiller93]

Yeah i know 3hp is low for a kart buts its all i got and all i can afford right now. im considering a 6.5 hp predator from harbor freight later this fall. My 3 hp is 127cc the 5hp i have is 206 cc and the 6.5 hp from harbor freight is 212 cc lol something doesnt add up D

I would use the 5hp but its being used currently on a rota tiller, so that is a no go. i dont plan to use this kart for anything but flat areas so its not like im gunna kill the engine or destroy clutches all the time.

 

[landuse]

cc's and HP don't have any real relation to each other, that is why they don't add up.

 

[Nodroz]

Like fowler said, both your 3hp and your 5hp engines will achieve the same top speed when gear correctly, however, the 5hp engine will get there much faster because it has much more torque.

 

[r_chez_08]

HP is a combination of rpm and torque.
HP = torque (in ft lb) x rpm / 5252
Torque is a twisting force which tends to cause rotation. Therefore more torque allows the kart to move easier.
CC or cubic centimetres is a measurement of displacement. There is positive correlation between displacement and torque, however there is not a calculation between the two, as there are many factors that change torque. For example, put on a really restrictive air filter and the torque goes down due to a rich mixture and incomplete combustion. Displacement stays the same.

A 3hp is fine for a light kart on flat/ easy terrain geared for under 20mph.