Motorcycle Engine HP

[YamiLionheart]

Hey everyone, was just reading the stats on the new zx14r for the hell of it (it's way too much of a beast to even begin thinking about trying to ride) and saw that its motor puts out just over 200 bhp.

This baffled me. How does a 1441cc engine put out so much power? A car with a similar displacement engine doesn't put out anywhere near that much power. For an exaggerated example, a new 2012 mazda3 i with a 2.0L engine puts out 163 hp, and it has roughly 600cc more displacement.

Is there something I'm missing? Or is the motor just that well designed and efficient?

[krolinked]

Fuel Efficiency perhaps?

[YamiLionheart]

Originally Posted by krolinked

Fuel Efficiency perhaps?

ZX14R - 35 mpg (Overall?)
http://www.kawasaki.com/Products/Pro...scid=24&id=711

2013 Mazda3i 25city/40highway (32.5 Overall)
http://www.mazdausa.com/MusaWeb/disp...ehicleCode=M3S

Obviously those mpg ratings take into account the weight of the vehicle, if the car weighed as little as the bike did, it would be much more fuel efficient.

I still feel like there's something else at work here though.

[YamiLionheart]

Answered my own question:

http://uk.answers.yahoo.com/question...9082028AAUfkeQ

Just the way they're designed.

Has to do with how high bike engines can rev based on smaller parts, alloys used, etc.

With that though comes the reliability issue. Generally a cars motor will outlast a bikes motor mileage wise. They're designed to be quieter, more comfortable, more fuel efficient, less costly to repair, etc.

Supersport engines are about maximum performance.

[Motofool]

Very interesting question and response, Mike !!!

[AFazakerley]

What about compression ratio?

[choneofakind]

^^ That too. Don't forget aggressive cam profiles, advanced ignition timing, 4 valves per cylinder (surprisingly not all cars have this) etc.

They also do things with the throttle bodies and intakes. For example, Kawasaki has a habit of putting massive TB's on their sport bikes for top end power, but they have a second set of butterflies in them that give more control of small throttle openings so the bike doesn't bog like it would with over-sized TB's. Another example is Yamaha and their YCC-I system, which allows them to tune the intake resonance for a broader range of rpm's by being able to adjust the length of the intake runners in accordance to engine speed and load.

YCC-I info in this video:

Link to original page on YouTube.

YamiLionheart, you're correct. supersports are all about forcing as much power out of a given displacement engine as they can without making a bomb.

[Racer x]

What I find interesting is with 200 hp the 14 goes 190 mph and our little ninja goes 100 with 26 hp.

[Falcor]

Originally Posted by Racer x

What I find interesting is with 200 hp the 14 goes 190 mph and our little ninja goes 100 with 26 hp.

Weight to power ratio? I imagine the easiest way to get power is displacement but bigger engine = more weight and at a certain point there are probably diminishing returns.

[Alex]

If speed goes up linearly, drag goes up squared, horsepower required goes up cubed.

Easy example is 100 mph to 200 mph. Speed goes up 2x. Drag goes up 4x. HP goes up 8x. It's why 25 hp gets you 100 mph, but 200 hp is necessary for 200 mph. (everything else being equal on the vehicle)

[psych0hans]

Originally Posted by Alex

If speed goes up linearly, drag goes up squared, horsepower required goes up cubed.

Easy example is 100 mph to 200 mph. Speed goes up 2x. Drag goes up 4x. HP goes up 8x. It's why 25 hp gets you 100 mph, but 200 hp is necessary for 200 mph. (everything else being equal on the vehicle)

hp and speed aren't directly proportional. For even a slight increase in speed, the increase in hp required would be exponential... Or as alex said, raised to the power of 3... Which is why, modding your bike by adding exhausts etc... Does not give any significant gains in top speed, rather than the overall power delivery of the bike...

[Alex]

This website lays it out very clearly: http://robrobinette.com/top_speed.htm

It's fun to play with. So you take that 200 hp motorcycle that can go 200 mph, and bump it up to 300 hp, and its new top speed is only 229 mph. It takes 400 hp to go 252 mph. And if you want to hit 300 mph, it's going to take 675 hp. But you want to make it to 400 mph? Make sure you have 1,600 hp.

[Somchai]

Originally Posted by Racer x

What I find interesting is with 200 hp the 14 goes 190 mph and our little ninja goes 100 with 26 hp.

Don't underestimate the wind - that's the battle you've to fight...

[KawiKid860]

Good ol mother nature putting us crazy riders in our place I guess

[ninja250r81]

you need to talk the "torque"

before you walk the walk

[choneofakind]

I was also under the impression that Busa's and ZX14's were limited to 186?

[ninjamunky85]

Limited to 299 kilometers per hour. Thus the the 'busa and ZX-14 have the same top speed as any liter-bike, unless you reprogram the computer.

[Racer x]

Stock they bearly hit 189mph. At least in a mile. But with a thing that tricks the computer into thinking it is still in fifth gear you can go faster. But 200 hp will really have a fight to go faster than that. Liter bikes are no where near 200 mph

[ninjamunky85]

The Gixxer 1000 will do 299 kph stock, which is just less than 186 mph. Haven't you ever watched Ghostrider? His 500 hp naked 'busa did over 220 mph while doing a wheelie.

[choneofakind]

For comparison purposes:

here's a dyno of a BMW S1000RR with a slip-on. These have a history of being the most powerful liter bike out there.

and here's an older video (yes, I know it's a re-post here) comparing the Busa, ZX14, RSV4, and S100RR for top speed. I know this isn't exactly a well sanctioned race like Eric does, but it gets the point across. I wish they would just give us the numbers instead of telling us to read their dang magazine

Link to original page on YouTube.

[lgk]

Originally Posted by choneofakind

I was also under the impression that Busa's and ZX14's were limited to 186?

those guys run modded ecus, and disabled that feature.

[Samer]

Do not confuse the factory limited speed with the theoretical limit.

Back to the topic at hand. I do believe the OP was talking about power per CC and how it is much higher for motorcycle engines than for car engines.

I am equally intrigued as you, it is astonishing isn't it. Especially considering the fact that the bikes are naturally aspirated, and they still beat out most if not all of the turbocharged cars in terms of power per displacement.

I'm not an expert on this but basically since the dimensions for a motorcycle engine are smaller, they can rev much higher, and as long as the engine can breathe, power will go up with RPM. 14K RPM redline vs. 7K RPM = more power. [Power will generally go up with RPM, Power = Torque * RPM in every case]

Now, the obvious question is why wouldn't you put that kind of engine in a car. Well, you could, but there would be consequences. First, the gearing would probably have to change because a relatively heavy car requires much more low end torque. You'd have to rev the hell out of the engine to get the power. Not pleasant for getting groceries. The other big downside is of course engine life, which is inversely proportional to RPM.

Now, for bonus points, has anyone wondered why the power curve starts to drop at the high end of RPM of all IC engines? I know the answer. I could teach you, but I have to charge (milkshake song anyone?)

[choneofakind]

Originally Posted by Samer

Now, for bonus points, has anyone wondered why the power curve starts to drop at the high end of RPM of all IC engines? I know the answer. I could teach you, but I have to charge (milkshake song anyone?)

Yes I've wondered, but I don't know.

[Motofool]

Same that happens to you when you run too hard for too long: you run out of air.

The engine cannot breath well enough at high rpm's and combustion and torque suffer.

[choneofakind]

Is it really that simple? That's what I was thinking, but I didn't want to be wrong

Turbo desmo-ninjette. no floating valves, and runs out of air later.

[Samer]

Yes, the answer is air and the size of the intake.

In a naturally aspirated engine, there is a limit to how much mass flow of air each cylinder can suck in. That limit is reached when the intake valve openings are choked (Mach 1 at the throat). This is the cause of the power curve turning over.

In a turbocharged engine, theoretically, there is no limit to how much air can be pushed into the cylinder. Obviously there is a limit to how much pressure and temperature the cylinder walls and engine case can take. Not to mention knock limitations for a petrol engine, etc. etc.

[psych0hans]

It's the law of diminishing returns yo!!! Motonomics!!!

[ninjamunky85]

I just watched a show about the newest Koenesegg. It's now the highest horsepower per liter of any car. I believe it made about 900 from a 5 liter V8. Thats about 3 horsepower per cubic inch.

[Racer x]

I just go by the looks on the faces of people that showed up at Maxton and said I am going to 200 mph . I got a pipe and a new ecu . And then they go 192 mph.

[ninjamunky85]

Correction: The Koenigsegg Agera R makes 1,144 hp from it's twin turbo 5.0 liter V-8. In comparison the Bugatti Veyron needs 3 more liters and 2 more turbos to make 1,184 hp. The Koenigsegg makes over 3.8 hp/ci.

http://en.wikipedia.org/wiki/Koenigsegg_Agera_R

Link to original page on YouTube.

So let's see,... your standard liter-bike makes maybe 180 hp stock. 1000cc = 61ci. If you have a modded liter-bike that makes 200 hp, then it's making about 3.3 hp/ci. Obviously a heavily modded/ turbo bike can make a lot more power. It looks like the motorcycle can make a lot more hp/liter than the car can.

The smaller engine will always have the advantage when it comes to hp/liter due to less friction. The car will always have the advantage when it comes to top speed due to the massive amount of hp, and the way that aerodynamics work. Given the choice I would take the Koenigsegg over any bike. That thing is just crazy, plus I could sell it and buy like a thousand motorcycles.

[Racer x]

Not friction pumping pressure inside the crankcase.

[ninjamunky85]

Hmmm, I was just assuming that smaller engine means smaller parts and somehow less overall friction.

[Racer x]

It does and the smaller parts will rev faster. But i think the big issue is pumping pressure. The two strokes suffer from this more than four strokes.

[Motofool]

Originally Posted by ninjamunky85

Hmmm, I was just assuming that smaller engine means smaller parts and somehow less overall friction.

Smaller parts mean less inertia.

Less inertia means higher rpm's without damage.

Ship's engines, having huge pistons, cannot rotate much more than 100 rpm.

http://answers.yahoo.com/question/in...1193822AA6hl1R

Higher rpm's mean higher HP at lower torque.

Torque is what overcomes aerodynamic drag.

A car at speed creates much more drag than any bike; hence, the engine must be able to develop relatively high torque.

HP = torque x rpm's

A bike's engine can have the luxury of high rpm's and low torque, a car's engine just cannot.

[YamiLionheart]

Does my heart proud to have seen this thread blow up so nicely

I was searching way down the forum listing to see if anyone else had responded and was surprised when I came back up and saw it near the top!

Thanks for the responses all, makes a lot of sense.

I always knew higher HP granted a higher top speed and more torque makes you accelerate faster (for cars at least)

Me and my buddy have a similar argument frequently. His mazdaspeed3 can keep up with my 3.8 genesis coupe till about 65 70 since his engine has slightly more torque than mine 280 lb/ft vs 266, but past that my car pulls ahead due to a higher hp, 305 vs 263.

Your torque can only haul your ass as far as your hp can support it

[Motofool]

There is nothing else than force between the contact patch of your tires and the pavement; HP is just a concept, just like acceleration, torque and speed.

The other real things involved in the performance of any vehicle are mass, time and space.

Your car is only an energy transformer: from chemical energy in the fuel to mechanical energy at the contact patches.

Having similar masses, the car able to transform more energy in less time wins the race.

[Alex]

Originally Posted by YamiLionheart

Me and my buddy have a similar argument frequently. His mazdaspeed3 can keep up with my 3.8 genesis coupe till about 65 70 since his engine has slightly more torque than mine 280 lb/ft vs 266, but past that my car pulls ahead due to a higher hp, 305 vs 263.

Your buddy needs to put on the Mazdaspeed cold air intake on to that bad boy. $200 - $300 or so, and it adds 25 rwhp, still under factory warranty.

[Jiggles]

Originally Posted by YamiLionheart

Me and my buddy have a similar argument frequently. His mazdaspeed3 can keep up with my 3.8 genesis coupe till about 65 70 since his engine has slightly more torque than mine 280 lb/ft vs 266, but past that my car pulls ahead due to a higher hp, 305 vs 263.

Not quite. HP = torque X rpm / 5252. HP and torque are always related, they are just calculations of eachother.

If you want to understand the acceleration of your car you look at the HP numbers and the gearing. But you need to look at the hp numbers on a dyno, not the max. If your buddys torque peaks in the low end and yours peaks in the high end then he will have more hp in lower revs, but as the revs climb eventually the hp of each car will equalize and then yours will come out with more. Likely your car revs higher than his.

It also has to do with the gearing on each car. Your car makes the same amount of hp in ever gear, yet it accelerates at different rates.

Just wanted to point out that your interpretation of torque and hp isn't correct and just going by peak numbers doesn't tell the whole story.

[Motofool]

Just impressive, Sean;..........really !!!

Good reading for Mike:

http://en.wikipedia.org/wiki/Hp

[Samer]

Originally Posted by Jiggles

Not quite. HP = torque X rpm / 5252.

actually, no.

You did not specify that 5252 only works if torque is in lbf.ft

That's what most people use here in America but the rest of the world uses SI.

In that case, torque would be in N.m and power would be in KW and that factor would be different.

The general statement is 'Power equals torque times rotational speed'. Most people say RPM and in that context, it is not relevant that RPM is a specific unit. You should always check units when doing any calculation.

Also, it is not exactly 5252, in a recent thread I went through where that number came from.