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Engine power understanding


wakecarved

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Hi guys hopefully this doesn't come across as a dumb question.
I'm wondering what factors determine the performance of certain motorcycle engines ie. A yamaha r6 vs a fz07.
They are both roughly 600cc but the r6 is a quick race bike. I understand the fz07 has different power characteristics and that the r6 is a 4 cylinder engine.
Is it just that the fz07 isn't tweaked internally for all out performance or just that it is a twin cylinder?
I am asking to get my head around if it would be ever worth it to "open up" the engine and have it built. I have an australian mt07 with a 2mm smaller piston so I have plans on bringing it up to the fz07 spec anyway which will involve internal work so I figured that when it becomes time in about a year that I could have head work and other mods done. What's everyone's opinion? I've spent too much on my bike already to "buy a bigger bike"

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Many factors determine the " powerband" ... The mt-07 was designed for " low-mid rpm powerband...the r6 was designed as a " high rpm" powerband... The mt-07 will beat an r6 in a 1/4 because it makes it power quicker than the r6 due to the powerband characteristics...in my view I would just trade the mt07 in for and mt09 if I was to bore/stroke kit, New ECU, etc..

2015 fz-07- Hordpower Edition...2015 fj-09- 120whp- Graves Exhaust w/Woolich Race Kit- tuned by 2WDW
 

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wickedtwister

The biggest difference between a 2 cylinder and a 4 cylinder is the rotating mass (pistons and rods) of the 4 cylinder is typically less. The engine is also better balanced and smoother feeling less vibrations. Typically speaking the larger twin engines build more torque lower in the power band vs the smaller pistoned counterparts. It also has a lot to do with how finely tuned the engine makes pair the cylinder heads, valve train cams, intakes ect to work with that Motor. Take the ducati 821 Motor it has nearly double the HP as the fz07 with only 200cc more. But the fz07 is a very budget bike and the ducs are highly tuned expensive precision machines. Hope this helps

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wickedtwister

I'm waiting to find a wrecked 09 and graft the drive train into my 07...I have the styling I want with the motor I want. Done.

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Thanks for those answers. I see what you mean with the ducatis, designing a twin with 120hp compared with one that makes 70hp would be added cost and the fz07 is aimed at a certain market.
So if you played around with the engine as in head porting and performance modifications you are still limited with the engine design and would only make marginal gains?
I've played a bit with cars and have noticed it takes extensive work on a small n/a vehicle to make good power, the other option is "forcing" air into the engine I guess haha. I wonder with the talk of the racing class for the fz07's and the flat trackers if they will do much engine work? In its most basic form is engine power just how much air and fuel you can compress and detonate?

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wickedtwister

Just porting the heads alone (probably) wont get you a huge increase. If you could bump up compression, change the cam and port the heads you would be better off. Without aftermarket support for these parts it will make it very hard to do. You could always add boost, pull the supercharger off of a mini cooper s, but the cost to do that is so high it would be cheaper to buy a different bike. I just don't think you'll get the gains from going into the engine that you think you will.

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Many factors determine the " powerband" ... The mt-07 was designed for " low-mid rpm powerband...the r6 was designed as a " high rpm" powerband... The mt-07 will beat an r6 in a 1/4 because it makes it power quicker than the r6 due to the powerband characteristics...in my view I would just trade the mt07 in for and mt09 if I was to bore/stroke kit, New ECU, etc..
Don't want to burst your bubble, but not really.  Ultimately, power is power and more is better.  You would have to launch and drive an R6 differently than an 07, but with a skilled driver the R6 will win hands down. http://www.sportrider.com/tech/sportbike-performance-numbers
 
FZ-07 12.38
R6 11.21
 

Why can't left turners see us?

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I'd say no on messing with it for more power. I'm not saying you cant get more out of this bike but the cost in the end is not worth it IMO. If you want more like said the FZ-09 is a good option if you like the riding position but if you just want to go fast a liter bike pick your brand there all fast. There has only been a few times where I wanted this bike to go faster and that was on on a long open stretch of road. I rarely come across another bike or a car that can keep up with this bike.
 

2015 FZ-07 2003 2014 GSXR 1000

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RPM. Mostly it is RPM. All engines are air pumps. The more air in, the more air out, the more power made. The R6 accomplishes that with RPM. It spins to 15,000 RPM. Astronomical for an internal combustion engine. The R6 has a comparatively shorter stroke, higher lift camshafts, light valvetrain, forged crankshaft, higher compression ratio, and a few other bits of engineering wizardry to make it spin up that fast.
 
By comparison the FZ-07 engine is a heavy old clunker. It needs a second balance shaft to keep everything happy, the bore stroke ration favors torque, it's valvetrain assembly was designed to work below 10,000rpm, it's compression ration is lower, and I could continue, but I think I've made it sound expensive at this point.
 
You could, in theory, build an FZ-07 engine that produces upwards of 100hp. You would need a lot of money. You would need a valvetrain capable of spinning up to 12,000RPM+, a larger bore, a higher compression ratio, and all of the necessary fueling to go with.
 
Can it be done. Certainly. Do you have the engineering prowess, time, and money to make it happen... I will let you answer that one.

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OK
FOR THE SAME TOTAL ENGINE DISPLACEMENT ie engine capacity AND same volumetric efficiency ( air flow, camming, throttle size, valve relative size)
The torque is a function of actual length of stroke and diameter of bore.
So if you had 3 600cc motors, one with one cyl, one with 2 cyl and one with 4 cyl and cammed them the same, the single would have a 600cc piston, the twin 2 300cc pistons and the four 4 150cc pistons.
BUT...the pistons in a motor with more than 1 cyl do not produce power at the same time, but sequentially so the single will produce 600cc ( the product of a 600ccpiston/stroke) of torque per fire, the twin 300cc of torque per fire, and the quad, 150cc of torque per fire.
BUT the twin and quad will produce more fires per 4 strokes ( the 4 stroke cycle). The torque will be each piston capacity amount but the power will be greater ( happens more often per 2 rotations) .
Best way to check this out is the smaller capacity ( 250's for instance) motor power/torque graphs where the smaller size forces engine designer to push all engines to high HP/displacement outputs. Good example is a VTR250 twin and a CBR250RR 4cyl graphs ( not withstanding the stupid 2into1 exhaust on the VTR). VTR good torque no HP low rpm (even the spada only spun to 14000rpm), CBR tiny torque, substantial HP and insane rpm (19000-20000rpm). Both motors were very sophisticated designs.
Larger capacities can have more leeway to make engines more tractable or more HP.
 
In short on a racetrack multi's will rule, on the road a twin or triple will be MUCH more pleasant to ride. And offroad where torque, traction, lighter weight and tractability are prerequsites, singles will rule.
My 2 cents worth.

Go forth and modify my son...go forth and modify...

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Your local college library (hopefully) has shelves on engine design and engineering. You'll be reading for the next 10 years. It's a sickness. ;-)

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Your local college library (hopefully) has shelves on engine design and engineering. You'll be reading for the next 10 years. It's a sickness. ;-)
I second thus comment... but 10 years is an understatement.
ive only gotten through the first row on mine... and still havent learned much other than not to mix nitro with your oil

ATGATT... ATTATT, two acronyms I live by.
 

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Just remember when you modify to make more power one part or slight change may affect everything. I hope you know what you're doing. Good luck! It seems to me that if you sold your FZ you could surely buy a good used, more powerful liter bike to scratch your itchy itch or are you wanting to have the fastest Aussie FZ? Is your bike red? If not try switching to red.

Beemer

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The biggest difference between a 2 cylinder and a 4 cylinder is the rotating mass (pistons and rods) of the 4 cylinder is typically less. The engine is also better balanced and smoother feeling less vibrations. Typically speaking the larger twin engines build more torque lower in the power band vs the smaller pistoned counterparts. It also has a lot to do with how finely tuned the engine makes pair the cylinder heads, valve train cams, intakes ect to work with that Motor. Take the ducati 821 Motor it has nearly double the HP as the fz07 with only 200cc more. But the fz07 is a very budget bike and the ducs are highly tuned expensive precision machines. Hope this helps
Point taken. But the 821 Monster makes 96 HP RWHP. The FZ has been dyno-ed at 65 (that 70 hp is at the crank and means pretty much nothing). So not double, but 50% more from about 20% more displacement. I'll own another Aprilia before I ever have to deal with cog belt driven cams and desmo valves.   
http://www.motorcycle-usa.com/2015/04/article/2015-ducati-monster-821-comparison/
 
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A properly ecureflashed FZ or euro MT with a decent air filter and exhaust should rearwheel more than 65HP. Mine is Dyno'ed at 65HP and is the Aussie LAMS 655cc/11:1 compression motor, not the proper 688cc/11.5 compression ratio motor. The real MT/FZ07 should easily output around 70 rear wheel cleaned up and probably a bit more.
The MT is a virtual Vtwin 90/270 crank it SHOULD have, like the Ducati a 2 into 2 exhaust, NOT 2 into 1. That would give a power boost as well( and probably a torque boost as well as the pulse phase is almost perfect bad with 2 into 1!) . Remember this motor is specifically cammed for low /mid power. Simple sharper camming would give this bike a serious boost because it is SO undercammed for ultimate HP. Especially if you added an extra 20% capacity to the motor to equal the Ducati's 821cc's. ASIDE from the massive compression ratio difference that is ( Ducati is 12.8:1 which is getting pretty close to the current theoretical limit for a normally aspriated cyl compression pressure).
 
An interesting though experiment:
Just what would a MT07 with 12.8:1 pistons , bored to 750 ( a nice racing class size), with 50mm throttle bodies, a 2 into 2 proper length exhaust, proper Blair shaped resonant tuned inlet stacks, and cammed for max power at 10,500rpm ( being conservative to be able to retain most of the std MT hardware (maybe)).I am guessing it would have be pretty close to 90 HP EASILY. That would be without bigger valves I reckon.
Interestingly the Yamaha says the throttle bodies are 38mm but I have measured them at 41mm???
 

Go forth and modify my son...go forth and modify...

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All you have to do is send your motor and a check to Zoran@TwinWorksFactory in AZ(?), or the guys at Speedwerks in Delaware, or Greg Spears of Spears Racing (Cali). I mentioned the 3 guys because they have a long history of getting the most out of mid-displacement twins aka SV650 and EX650 so the FZ would be right up their alley.
 

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OK, 66 hp http://www.cycleworld.com/2015/02/06/2015-yamaha-fz-07-naked-motorcycle-dyno-run-video-and-performance-chart/ Not much point revving this motor in stock trim much past 8.5k
 
Everything's a trade off. Give it more power - better make the brakes, suspension and frame able to deal with it. Then, up goes the weight (that Duc Monster was the heaviest in that group), up goes the cost, up goes fuel consumption, up goes the size of the tank to deal with the loss of range, up goes the weight again.
 
on it goes

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Actually I disagree with the 8500rpm shift ( when riding solid) . I think it is properly useable 5(ish) to 10,000rpm. The shift would be dictated by the gear ratio differentials . You want it to drop into the power/torque happy area after shift and I suspect that 8500 would drop you below that if after really good acceleration ( though I haven't analyzed the individual gears because it is aroad bike not a trackie).
 
The beauty of this motor ,though, is that the low rpm torque is really brilliant for non spirited riding. You can way short shift and the motor happily pulls away. It is just wonderful in city traffic or when you want to fast cruise. If you minor stuff up and short shift , it still pulls smoothly away. Really pleasant touring motor and a great proof that you don't need a kilo bike for touring, even loaded.

Go forth and modify my son...go forth and modify...

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Yeah, that was a street biased opinion. Our avatars say it all. lol.
 
Depends on the RPM drop between gears of course, but the HP and torque drop off quite a at 10k, maybe 9.5 would be a better choice if you really wanted to stay on the boil.
 
This motor can probably massaged into making more top-end HP, but it'll come at the cost of losing that wonderful low end torque. That's why the other bike in the garage is a Futura and not a Mille.

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