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Does higher revving = quicker bike?

L

Lumberjack

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Jul 10, 2010
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Z1K, Street Triple R
All other things equal, if you have two bikes, same aerodynamic shape to them, and each make let's say 100hp and 70ft torque - but one bike rev's to 14,000, and the other bike revs to only 9,000, will the higher revving bike be quicker and/or faster such as in a quarter mile sprint?

Is there anything about an engine spinning that fast that makes the bike itself move faster?
 
In general, higher RPM means higher HP, but there are countless exceptions. Your example engines don't exist in real life because the same HP at higher RPM would mean less torque.
 
no

you buy hp, but you use torque. i'm drugged up and just wanted to say that, lol.
 
If two bikes have 100 HP ( disregard the torque) and one revs to 5000 rpm and the other to 10,000 they will have the same 1/4 mile time, more or less, if geared appropriately.
 
if the HP and TQ are the same then 9,000RPM in 9,000RPM out 14,000RPM in 14,000RPM out. It also depends what the HP and TQ curve is. If the 14,000RPM bike makes highest HP/TQ around 8,000RPM you start to lose power above that. But regarding the info you have given it just depends on the RPM and your gearing.
 
Lumberjack said:
All other things equal, if you have two bikes, same aerodynamic shape to them, and each make let's say 100hp and 70ft torque - but one bike rev's to 14,000, and the other bike revs to only 9,000, will the higher revving bike be quicker and/or faster such as in a quarter mile sprint?

Is there anything about an engine spinning that fast that makes the bike itself move faster?
Click to expand...

no, cuz rpm/hp/torque are all related, i dont think the situation you put forward can exist :|
 
since we're generalizing then you need instant torque to be quick but you need horsepower and revs to be fast
 
n8x said:
no, cuz rpm/hp/torque are all related, i dont think the situation you put forward can exist :|
Click to expand...

It not only can't exist because Lumberjack said HP equal on the two bikes...This tread can't go well, either.

Fast is a very complex word...depends on so many things.

But rather simple at the same time.
 
HIglesias said:
no

you buy hp, but you use torque. i'm drugged up and just wanted to say that, lol.
Click to expand...

As long as you can keep it in the powerband, an engine with higher HP will always be "faster", regardless of torque.
 
Sure this can exist. The one that gets to it's peak power first will be fastest.

Horsepower is JUST a formula. Plug the 70 ft lbs and 100 hp into the formula, solve for rpm, and you get 7503 rpm. Both bikes will make the same power at this rpm.

After we contemplate this conundrum, we shall go the the more complicated solution for power curves, which will require imaginary reciprocating weight, bore and stroke, and a bunch more junk, depending on how accurate you want the curve. Then we can really determine who will win the quarter mile. Sort of.
 
all things being equal I'd expect the engine that revs out at 9K to be quicker in the quarter mile, but the one the revs to 14K to faster around the track.
 
I was pondering this because of the recent Sportrider mag where we have this situation:

Quarter mile times for the 600's in the shootout were all mid 10's..

Quarter mile times for the FZ1 and Ninja 1000 were mid 11's..

The FZ1 and Ninja 1000 both make substantially more hp and way more torque than the 600's, but rev only to about 11,000rpm..

Now, I know the rider makes a huge difference, and aerodynamics come into play, and the 600's are about 60lbs lighter.. But I figured it has something to do with the high revving engine..

Or is it related to how fast the engine revs?
 
tuxumino said:
all things being equal I'd expect the engine that revs out at 9K to be quicker in the quarter mile, but the one the revs to 14K to faster around the track.
Click to expand...
Why? They both have the same torque and horsepower. I just posted the rpm where they BOTH will make this power. Maximum RPM changes nothing. Your power curve will just keep going down after 7503 rpm. It is useless.
 
clutchslip said:
Sure this can exist. The one that gets to it's peak power first will be fastest.

Horsepower is JUST a formula. Plug the 70 ft lbs and 100 hp into the formula, solve for rpm, and you get 7503 rpm. Both bikes will make the same power at this rpm.

After we contemplate this conundrum, we shall go the the more complicated solution for power curves, which will require imaginary reciprocating weight, bore and stroke, and a bunch more junk, depending on how accurate you want the curve. Then we can really determine who will win the quarter mile. Sort of.
Click to expand...

This.

There are no simple answers except, go drink a beer and think about something else. Trying to figure this out will only turn your brain to mush. 'Much better to let beer do that.
 
OldFatGuy said:
As long as you can keep it in the powerband, an engine with higher HP will always be "faster", regardless of torque.
Click to expand...

is that why the diesels in le man's, which have far more torque than hp keep losing?
 
Lumberjack said:
I was pondering this because of the recent Sportrider mag where we have this situation:

Quarter mile times for the 600's in the shootout were all mid 10's..

Quarter mile times for the FZ1 and Ninja 1000 were mid 11's..

The FZ1 and Ninja 1000 both make substantially more hp and way more torque than the 600's, but rev only to about 11,000rpm..

Now, I know the rider makes a huge difference, and aerodynamics come into play, and the 600's are about 60lbs lighter.. But I figured it has something to do with the high revving engine..

Or is it related to how fast the engine revs?
Click to expand...

I think part of it may be that it's trickier to launch a high HP, high torque bike. Did they post 60-foot times?
 
As previously mentioned, the comparison isn't valid due to the numbers not matching real-life situations. One thing about higher-redline is that you can use lower-gearing and get higher torque-multiplication. So you can be in 2nd-gear on the higher-revving bike and have higher acceleration than the other bike in 3rd-gear. It can also be helpful on the track where you can save yourself a shift down each straight.

What it really boils down to is linear-thrust at the contact patch. Work through the equations and convert torque at the engine into torque at the rear-wheel and plot versus RPM, like a dyno-chart. Divide out the weight of the bike with thrust at the rear-wheels and you'll get acceleration at each RPM-point. Integrate with respect to time and distance and you'll get a real 1/4-mile time. Lots of calculus involved to get accurate results.
 
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