| Author | Message | ||
     Vaneo1 |
I never really did find out why our engine is a 1203CC or even a 900CC. In comparison to an I4 with a similar engine size, what makes them both classifies at their size if one is way fater than the other and one is mor "torquey"? Is there some idtentical aspect both engines I4 and Twin posses? ADAM | ||
| Jlnance |
The numbers come from the volume displaced by the pistons as they move from the top to the bottom of the cylinder. The total displacement of the 12 engine is 1203 cubic centimeters. | ||
| Snowhownd |
Wow, I know there are no stupid questions, but...  | ||
| Vaneo1 |
wow, so it has absolutely nothing to do with speed or torque? Im surprised how many people dont know that, the other day I was in Office Depot and some guy asked me what kind of bike I ride and I told him Buell, next he asked how big I said 1200. He said whoa thats fast. hee hee, what a misleading number. | ||
| M1combat |
The nine is a 984. The twelve is a 1203. The displacement is derived literally as the name implies. That's how much volume the engine will displace in one revolution. It'll suck 1203cc in on the intake stroke and push it back out on the exhaust stroke (with a squeeze and a bang in between). It's measured in cubic centimeters. The more important measurement in figuring out what an engine is capable of is swept volume though. That's the displacement (1203) times the maximum RPM (or whatever RPM you're looking at, but that's another subject). 1203X6800=8180400. That's how many "theoretical" cc's the 1203 can pump in one minute. This is a much better way of measuring engine capability than displacement alone. Then you throw volumetric efficiency into the mix  , and of course the weight of the engine and all of it's support systems is very important too. | ||
| M1combat |
"wow, so it has absolutely nothing to do with speed or torque?" "mostly" . This is why it takes a 1350cc Buell engine (or more correctly... air cooled, pushrod, 2 valve, 45 degree V-Twin no matter who makes it) to make roughly the same power as an IL4 600. Our engines take large gulps of air and turn them into power. Other engine configurations do it differently. Six of one, half a dozen of another if you ask me. As long as an engine is putting out a certain amount of power then the displacement itself is a useless metric. The weight of the engine and how useable its power delivery is matters more at that point. | ||
| Snowhownd |
It is measured exactly the same as a car engine is - 350 cubic inches = 5.7 liters = XXXXcc's (don't know the exact conversion factor without looking it up). And just like in the auto world the size of the engine isn't the only factor in how fast a car is - look at how many cars put out some huge HP numbers with just a tiny amount of displacement. Also, in general - the more displacement, the higher the torque output. This isn't always true, but in general. | ||
| Diablobrian |
5.7liters = 5,700cc | ||
| Vaneo1 |
ok so from now on Im gonna just tell ppl Ive got a 1.2 liter size engine just to see the look on their face. Second, I dont think insurance companies figured this out as I should be paying the same rate as if I owned a 600 since its a Twin. Instead the bike is still classified as a litre bike. Thats ironic, has anyone tried to explain this to there insurance agent, Im almost tempted to give mine a call tomorrow. | ||
| Kootenay |
some guy asked me what kind of bike I ride and I told him Buell, next he asked how big I said 1200 Whenever anyone asks me that, I tell 'em it's got a 52" wheelbase (shortest production bike made). Of course, they always want to know how big the engine is--but like M1 says, displacement alone is a "useless metric." When I tell 'em it's nearly 1,000 cc, they're always impressed, but I dunno why...(especially since I have the smaller one!) | ||
| Kootenay |
And no, the insurance companies haven't figured this one out yet--at least not the one I have to deal with. It pisses me off that I have to pay higher liability premiums than the squids on 600 supersports, simply because my bike is over 750cc displacement! | ||
| Jackbequick |
Vaneo, The insurance companies won't "get it" if you call them. The 600cc engine puts a similar amount of HP on the ground at the rear wheel (the RWHP). That is the number the insurance companies should be basing rates on more than just displacement. A number like the RWHP is a better predictor of speed/injury/damage. The big difference for riders is that, compared to an I4, the bigger V-twin develops most of its torque and HP starting at a much lower RPM and it produces much flatter torque and HP curves (i.e., the "power" can be used over a much wider portion of its usable RPM range). The I4 has a much higher maximum RPM and the power and torque curves are not as flat. So you ride using a narrower portion or the available RPM. For many of us that wider and flatter torque/HP curve or "enjoyment range" is one of the true keys to our preferring a Buell (or H-D) over a HoKaSuYa I4. And V-twins vary from one model to another. Examples: Buell = 1,203cc, 85HP, 6,800 RPM max, 400 lbs. H-D FXD = 1,340cc, 65HP, 5,000 RPM max, 600 lbs. Both of those can take my "having fun meter" to high numbers but they do it in different styles and conditions. Jack | ||
| Pisymbol |
What's interesting to note is that take the new speed king, the ZX-14. Under 5k, apparently this beast is pretty much sleeping. Over 5k, hold on for dear life. A lot of it has to do with design. The V-Twin has always been designed for low-end grunt (torque) by having a long stroke compared to the smaller I4s with a short stroke (in comparison) and high revs (high compression as well). In terms of fun, either one is fun. A lot of the times, on the I4s, you have to be higher up the rev meter to get the power which to some is fun and others a nightmare (take the new R6 as an example). |
