Power/Weight Ratio

[HyperMotard]

Hey guys how come if a modded YX160 have a higher power to weight ratio than a new Corolla or Yaris they'll do like 130 easy and do 100 at low rpm? I thought about it. I is the torque, the gearing, etc. Today I was on my Reign 140 Bigfoot, 1st is literally useless, 2nd is slow and revs like to !$#@!, 3rd is quiet if you're slow and is only there to get you to 4th, 4th at high revs still feels like I'm doing 80 and not like 120 and I'm only 56kg 5'6 right now. Is it the internal gearing because the rear sprocket will affect all gears. I never expected them to be like super quick but I imagined if they have a power/weight ratio of equal or higher than a Yaris. The Yaris not only weighs more but the drag coefficient is not even close. What do you think?

 

[HyperMotard]

Not to mention a 95hp Yaris is not at the wheels but at the crank.

 

[Dabomb]

what are you trying to ask?

 

[thump*140]

cubic capacity, torque output, and gearing will all affect top speed... Power to weight is less of an issue in regards to top speed.
I read your query, got confused, had a beer, re-read it, and still cant for the life of me figure out what it is you are trying to ask...
but basically a toyota corolla has a motor that is ten times the cubic capacity of a 160 horizontal engine, and puts out a squillion times the torque. it would also have much lower/taller final gearing ratio... it's the torque it puts out, and taller final gearing, that allows the corolla to cruise at a much higher speed, with much less effort than 160 pitbike, even if the pitbike has a higher power to weight ratio... which defines rate of acceleration more than top speed...albeit entirely dependent on gearing...
does that answer what i think was your question??

 

[HyperMotard]

Yeah it does but I mean for the weight shouldn't a pitbike be quicker.

 

[Dabomb]

the drive system of a pitbike is too small for it to compete with larger engine/drive systems of a car,which are built to cruise at low rpm, high speed for fuel economy and reduced wear.

 

[HyperMotard]

I guess so. For me speed is important I like pitbikes for fun. Would love to have an 1098 though but I'm saving.

 

[Dabomb]

speed or acceleration?

 

[headsmess]

torque torque torque...

much like bragging about the power of a rotary... heaps of power, no torque. great at moving an rx3 real quick but in something like a HQ? wouldnt move.

torque is turning force...power is how often that force is applied per minute. so low revs, hi torque can achieve the same power as low torque with hi revs...

another example...model rc engines... huge power, tiny size...but at how many rpm?

 

[TyD]

rc engines get upto like 40,000 rpm.

 

[Dabomb]

torque torque torque...

much like bragging about the power of a rotary... heaps of power, no torque. great at moving an rx3 real quick but in something like a HQ? wouldnt move.

torque is turning force...power is how often that force is applied per minute. so low revs, hi torque can achieve the same power as low torque with hi revs...

another example...model rc engines... huge power, tiny size...but at how many rpm?

add a turbo or 2 and uve got a high speed, high power high torque engine.

 

[HyperMotard]

headsmess nice write up explains it pretty good

 

[thump*140]

add a turbo or 2 and uve got a high speed, high power high torque engine.

you've also gotta take cubic capacity into consideration...
you could have a twin turbo'd, highly strung DOHC Jap v8 putting out 500hp...
then you could have a 14litre twin turbo'd low revving diesel six in a truck putting out 500hp...

but lets see that Jap V8 pull a triple road train....
ie same hp figure, vastly different torque figures. Yes, the high revving jap V8 will accelerate quicker, but they would be capable of similar cruising speeds and top speeds, if the truck was not restricted to 100kmh...

hmm... this seems like another pointless thread...

 

[skruba]

may we mention that a pitbike has a single piston firing where as a yaris has four of the lil buggers......

 

[Dabomb]

may we mention that a pitbike has a single piston firing where as a yaris has four of the lil buggers......

indeed. there is more torque in more cylinders.

 

[skruba]

^^^exactly pointless thread like *acceleration*