View Full Version : Here's a question for you bike guys:
04-30-2011, 10:12 PM
I've been really curious for the longest time how bike motors almost have F1 technology but aren't nearly as expensive... If you take an R1 motor for example, I'm sure with bigger plumming, an agressive ignition map, and some race fuel, you can get it to break the 200hp mark easy without any power adders. I also know F1 motors put out 300hp per liter. So it's not as technologically developed as an F1 engine but pretty damn close, yet costs nothing close to the half a million dollar price tag of an F1 engine. I would love to have some veteran bike guys chime in on this one. Thanks.
05-01-2011, 09:11 AM
I've had similar thoughts (since I'm always impressed that my bike engine makes something like 124 hp out of 675cc of displacement), but cannot give you specifics on this.
05-01-2011, 09:17 AM
my S1000RR made over 200WHP out of a 1l with just a tune exhaust and race gas.
05-01-2011, 09:46 AM
I'm sure it's like anything. It's easy to be within 90% of the laptime of the fast guys but that last 10 % is hard to get and takes years of practice and tuning. It's easy to get to 200HP per L but costs a crap ton of money to get that next 100hp without forced induction.
05-01-2011, 12:29 PM
There's a lot of power to be made when you can rev to 13-16k RPM.
There's not nearly the same kind of torque you have with a big car engine but then again, the bike does not need it so the trade-off is OK.
If you could feasibly rev a 2JZ engine to something like 13k-16k, you could make a lot of power for the displacement you have available. But you would have to sacrifice torque and your engine would be built with some serious unobtanium parts. Of course, the physics of that are not possible for mass produced machines.
Bikes can do it because the piston speed is slower. Compared to a 2J, a 600cc bike's stroke is almost half. Do the piston speed calculations at a typical bike RPM. Let's say 13k.
2JZ: 86 mm stroke = 122.3 feet/sec
600RR: 42.5 mm stroke = 60.4 feet/sec
1000RR: 55.1 mm stroke = 78.3 feet/sec
To get a 2J down to similar piston speeds, you have to bring it down to around 7500RPM (70.5 feet/sec), which is of course a typical limit most people rev their engines to. At their respective RPM limits, a 600cc engine, a 1000cc engine, and a 2JZ are all in the same ball park of piston speeds. So in other words, they are working with the best that physics and materials used allow but the bikes have close to twice the RPM with which to make power.
I don't pretend to be an engineer and understand all the dynamics of safe operating limits and I don't know figures for typical max safe piston speeds but you see what I'm getting at. I'm sure there are many other important factors like important head design. Also, don't forget that we're talking about sport bikes which are tuned and built very strong, power wise, as they are from the factory. Bikes generally do not see the same gains you would see in a car from basic mods. Consider that even for sports cars, they are not as race focused as a sport bike (unless we're talking exotics and then even still). With a sport bike, you get an engine that is pretty peaky (compared to maybe a more standard motorcycle) in an effort to make max power, light weight relative to other bikes, suspension adjustability you would pay thousands of dollars for in a car, and tires that are more performance oriented than you would find on a car. The kind of performance and race track manners you get from a bike off the showroom floor, you would have to spend a lot of money on a car.
So, in these ways, bikes are very advanced technologically and mechanically speaking. In other ways, cars have been ahead of bikes for years and still are. I'm talking about things like engine management and other electronics. Sport bikes only started using electronic fuel injection systems in the early 2000s. ABS, Traction control, and other electronic aids are the new wave in sport bikes right now. How long have cars had these things been commonplace in cars?
It's a lot of apples to oranges, really.
05-01-2011, 01:47 PM
Thanks OnejoeZee, the piston speed segment makes perfect sense. It's amazing how the F1 guys can rev a 2.5L to 19k RPM...
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