| Author | Message | ||
     Slaughter |
We have 2 VF500's in our garage Sunny's vintage race/track bike  Sunny and her VF500 streetbike behind our racebike  | ||
| Krassh |
What Bikes use v4s besides the v-max and the duc Desmosedici? Honda Interceptors, Magna's, Saber's. Yamaha Venture Suzuki Cavalcade I am sure that I missed some obscure or even obvious ones. I owned a 1984 Yamaha Venture. I would have to say it was the most nimble touring bike I have ever ridden.} | ||
| Teddagreek |
What Bikes use v4s besides the v-max and the duc Desmosedici? Aprillia's replacement for the RSV1000 is the RSV4, Rumor mill is a version will be under 15k.. | ||
| Blake |
"yet fewer cylinders can produce more torque." Not really. More cylinders will produce more power and more torque. Why? The four valves per cylinder times the four cylinders equals significantly better pumping efficiency (pumping air and fuel into combustion chamber) and thus better volumetric efficiency and thus more HP per cc and yes, more torque per cc as well. Whether the engine is tuned for more torque or for peak HP is anothe entirely separate issue. Honda Venture and "nimble" don't belong in the same sentence together. | ||
| Okc99 |
I guess my hidden motive was to find a reason to why my old Yamaha Majesty Scooter (396cc) got the same mpgs as my 1200cc Uly. I am a mathematician of sorts, so I would love to see someone propose a general equation for MPG. I'm guessing that neither weight nor engine size are statistically significant variables in that equation (when evaluated independently). Instead, I bet it is the ratio: Weight/Displacement. But then that doesn't make sense because the total weight for both my majesty and Uly is roughly the same. | ||
| Hexangler |
http://en.wikipedia.org/wiki/Honda_NR  http://en.wikipedia.org/wiki/Wankel_engine  | ||
| Ft_bstrd |
Hex, I remember seeing the "elongated" cylinder engine on a Discovery Channel show one time. Neat idea. I think they ended up having to scrap the idea for some reason. | ||
| Hexangler |
Yeah, that's Honda way to get v-8 performance out of a 4 cylinder requirement in moto gp(?) If I remember correctly, they had to hand-make the piston rings. I don't have the time at the moment to read the Wiki article, but some on this thread may enjoy the research. | ||
| Corporatemonkey |
There is a local guy with a Honda NR, It looks/sounds just like a gear cam Honda VFR. Very nice machine. Did anyone catch Jay's garage episode where he reviewed his wankel motorcycle. Another neat machine http://www.jaylenosgarage.com/video/video_player.s html?vid=234331 | ||
| Jlnance |
I'm not a mechanic, so don't take this as the Gospel. It's a different way to look at this question, and I'd appreciate any corrections to my thinking. Long stroke engines produce more torque and get better gas mileage than short stroke engines. Short stroke engines can spin faster than long stroke engines. This gives then an HP advantage on the top end. Now this is just math. If you hold the bore to stroke ratio constant, the more cylinders you have, the shorter your stroke is. So a 1L IL4 will have a shorter stroke than an 1L V2. Designers can adjust the bore to stroke ratio to some extent, so it's not exactly that simple, but I suspect it is close. So you could make a 1L thumper. It would have monster torque down low and get great mileage. It would shake your fillings out, but that's just part of the fun. It wouldn't rev very fast because the stroke would be so long. Or you could make a 1L Vtwin. Each cylinder displaces 500cc. It doesn't have the torque or mileage of the thumper, but you can spin it faster, so on the top end, you're pumping more air, making more power. It also delivers it's power more smoothly, and wont shake as much. You can keep going, using 4 250cc cylinders to make a 1L IL4. Stroke is shorter still. Less gas mileage, less torque down low, more power up top. Very smooth, no shaking. Or you could make an 8 cylinder engine from 8 128cc cylinders. The progression would continue, more top end, less bottom end. Gas mileage would suck, no vibrations, monster HP on the top. | ||
| Poppinsexz |
One thing that seems to have been missed in the I4, V2, HP, torque conversation is the RPM factor. Take an XB and spin in to 14,000 RPM there isn't an I4 that would touch it. We can only dream though. | ||
| New12r |
I guess I would like to believe that I'm driving an bike with an engine that is not "old tech" simply for aesthetic reasons of feel/rumble/and sound. I am so tires of hearing "old tech". So far the closest thing I can find to "new tech" it the Roehr. If you think a twin ohc 4 banger is new tech you are simply mistaken, that engine design is just a old as the one you are riding. | ||
| Ducxl |
Take an XB and spin in to 14,000 RPM there isn't an I4 that would touch it. We can only dream though. another term comes into play called, "piston speed".I know you stated "dream",but even the XBRR can't come close to 14000. In the HIGHEST classes of MotoGp and Formula1 car racing it's the oversquare engine that survives RPMs' like 14000. My Ducati 996 has seen 12000 and didn't grenade.and it's a vee-Twin.Why? New12r what do "Tires" have to do with "old tech" engines?  | ||
| Poppinsexz |
Ducxl-exactly just trying to add that it's not the fact that it's an I4 or a V2 it's the mechanics of the engine that limit. long stroke an I4 or pushrod one and your back to a lower RPM. RPM capabilities is what gives the modern I4 it's HP advantage and limits the XB | ||
| Hexangler |
Alright, here's one more: http://www.coatesengine.com "The Coates Spherical Rotary Valve Engine is the most advanced in the world, with the most positive valving system ever built. The breathing capabilities of the system are almost double that of a poppet valve. For instance: a static test of a five-litre poppet valve engine on an airflow machine produced a reading of 133 cubic feet per minute (CFM) with valve fully opened. The five-litre Coates Spherical Rotary Valve Engine on the same machine, however, produced a reading of 319 CFMs fully opened; a colossal advantage in airflow comparison. A five-litre poppet vavle engine tested on a dynomometer under the same loads and conditions at 5500 produced 480 BHP and 454 foot pounds of torque. The maximum RPMs on the poppet valve engine were 5700 RPMs; the Spherical Rotary Valve Engine in comparison reached 14,850 RPM's, The Coates Spherical Rotary Valve comprises two spherical rotary valves assembled on two separate shafts - one for inlet and one for exhaust. They rotate on ceramic carbon bearing with no oil lubrication, the spheres do not make contact with any part of the housing. The seals are a floating type and are also made of a ceramic material. They have two piston rings and are floating in a small cylinder-type chamber, they are activated by the compression and the combustion strokes of the engine which allows 100 percent sealing effectiveness, when compressed."    | ||
| M2nc |
A part of this of this topic I haven't seen is efficiency of the engine itself. How well is it designed to reduce power loss due to the motion of its internal parts. The XL engine is old tech, but not because it is a two valve v-twin. It is old tech because HD has done little to reduce power loss due to weight and friction of the moving parts of the motor. Buell did when he asked HD to put a lighter flywheel in the Buell "Spec" motors. Other changes in oil pump in '08 has the motor turning over 7k rpms now and that is the reason the Buell 74ci v-twin hits 80-84rwhp while HD's 96ci v-twin only hits 60-64rwhp. Heck even the big bad 110ci motor only matches the much smaller Buell "Spec" motor in peak HP. General Motors has the best practical example of what I am talking about. The 3.8L V-6 started life in the late sixties with about 110bhp. The motor survived for almost 40 years. General Motors instead of changing to the multi-valve engine worked on reducing the loss of power due to the motion of the motor. The last generation of the 3.8L was over 200hp. Most of that horsepower gain was due to improvements in friction of internal parts and reduction of rotating mass. Mazda presently has the most efficient engine design in the Rotary. The RX-8 has a 1300cc motor equal to the Hayabusa in size. I believe the present Hayabusa has 60bhp less than the Mazda rotary. Why? The rotary engine has less moving parts. It also has a lighter rotating mass, so less power is loss in the motion of the engine parts. (Ask Ulywife about her RX-3) That said, if efficient you mean fuel mileage, less is more. The V-twin design is a great for the street because the motor can produce adequate power with less moving parts. With equal displacement and effort in engine efficiency, the less the number of cylinders, the better the fuel mileage. Motors with less cylinders have fewer moving parts so it loses less power in the motor's mechanics. A Suzuki 600cc I4 does not get the gas mileage of a Suzuki 650cc V-Twin. The I-4 makes more power because it has more power strokes per cc. The V-twin gets better fuel mileage because it less moving parts. You can take that line of thought one step further with the two-stroke engine. Motors of equal size, the two stroke I-4 will have more power than the four stroke I-4. The two-stroke motor has less moving parts and more power strokes per cc. So the latest effort to combine power and fuel mileage is to have deactivating cylinders. This way you are running less cylinders when you do not need them. This does help, but a V-6 all things being equal will still get better fuel mileage and make more power than a eight cylinder with two-cylinders deactivated because of the added rotational weight of the two extra cylinder. That is all I can add to this discuss. | ||
| Etennuly |
I too am tired of hearing that phrase "old technology" associated with V twins. After all a Model T had an inline four. | ||
| Blake |
With all else being equal (bore to stroke ratio and # valves per cylinder), the more cylinders you have the more total valve area you have. This allows the shorter stroke engine not only to operate at higher speeds (revs), but to also enjoy less restriction to flow of air/fuel mix into and hot exhaust gases out of the combustion chambers. In terms of efficiency, the more cylinders allow for a more efficient pump. In terms of fuel mileage (fuel efficiency), higher engine speeds result in significantly higher frictional losses (lost in mechancal efficiency) and less efficient combustion (reduced thermodynamic efficiency). (Message edited by blake on September 28, 2008) | ||
| Xl1200r |
The amount of misinformation here is glorious. I guess the bottom line is that as long as everyone is happy with what they ride, then why does it even matter. I've ridden fours, threes and twins of all sizes, over and undersquare-ness, valve numbers, etc. A twin will always be my first choice. | ||
| Ducxl |
I've been doing some reading.Yup.One article points out that the Vee-Twin,or engine with fewer cylinders will respond more forcefully than a bike of the same displacement but with more cylinders.Even though it may have less peak torque. Sound about right Blake? I like your last post. If Xl1200r has any corrections..well  | ||
| Blake |
Duc, Thanks Duc, sometimes I can actually write intelligibly.  Actually though, it's not the number of cylinders that govern torque output capacity of an engine. For instance, a longer stroking IL4 will produce, all else being equal, more torque than a shorter stroking version. Just take a look at the torque output of a GSXR1000. it's better than any 1200cc Buell street bike. My old compact pickup truck has a 2.4L IL4 engine that only revs to 6,000 RPM or so. It has great torque. | ||
| Reepicheep |
I really don't want to argue about it again... But I will happily build you a 1000 foot pound motor, that gets infinite miles per gallon. I'll sell it to you for $100. For that much, I can even throw in shipping. You build me a motor that makes only 100 HP and gets only 1000 MPG, and I'll give you $1000 for that. Now tell me which is meaningless, and which is real. Here's a hint. You torque your crank nut to 120 foot pounds to put it back on. You can do it. Do you think you are stronger then a 90 HP XB motor? | ||
| Cityxslicker |
This reminds me of a story problem about two trains leaving distant stations... I never did get those right. I got the Pulley, Thanks Reep. I will get the other one pulled for you soon. | ||
| Court |
The motor that rotates the Space Needle in Seattle was 1/2 HP. I always look forward to this annual event when the folks who excelled in engineering school engage in spirtied debate with car salesmen, linemen, refrigerator repairman and dentists about engineering. Good thing the rest of us were not called on to grade Blake and Reep's homework? Right dudes? . . . .let me hear a big ooooorah from the bar! We're on for Dino vs. Synth about Thanksgiving, right? | ||
| Bombardier |
14000 RPM. The Ducati will rev to that if pushed but only because of the valve actuation it uses. The Buell v-twin as you know uses cams with followers, actuators(rockers) and valve springs so there is a considerably larger mass involved in each valve opening or closing. The Duc uses a hairpin type spring which has very little mass in relation to the valve as it is hinged away from the area of movement and as such only a portion of the spring is actually moved and the valve is opened and closed by the actuators. The engine will rev to a higher rpm without valve float which is usually the limiting factor in an overhead valve engine. Piston speed is also another area which could be a factor however if the engine was engineered to rev that high a suitable piston would be used. | ||
| Danger_dave |
I want an electric motor too. Those babies are all torque. | ||
| Hexangler |
+1 electric. | ||
| Ducxl |
Electric is cool.Is the power controllable though? They say the torque is instantaneous. Bomardier,those valve springs on the Desmo valvetrain of the Ducati can be removed to lessen frictional losses further.It CAN run without them.They're ONLY there to take up that last .005"-.010" clearance to seat the valve.You cannot have zero lash or friction increases.Racers run without the springs,but the engine idles poorly. I'm not sure,but think we've been mocked by a construction worker Engine tech is cool  | ||
| Xl1200r |
If Xl1200r has any corrections..well It's not so much confusion I'm reading, as it is folks focusing on one single element of an engine design - bore/stroke ratio, number of cylinders, displacement, number of valves, frictional losses, etc. You have to look at all sides of engine design to come up with the "answer", if there were such a thing. This has been mentioned (hyperfocusing on a single element), so I didn't feel the need to reiterate. We have some very knowledgable folks in here that speak well about these sort of things - I have a pretty good understanding, but I know that my views will only be seen as opinions and won't change anybody's mind in the matter. As far as "effencieny" goes, it's also been addressed - in what context? A GSXR600 makes more HP than my XB, so it's more effecient in a HP/cc argument. My XB gets better gas mileage, though, so it wins the MPG/cc argument. It also makes it's peak power at a lower percentage of the rev range, so it also wins the torque/% of redline argument. It goes on and on. The bottom line is specific engines are designed to do specific things. That last I4 I rode was a Kawasaki ZX10. It had PLENTY of down low torque, and screamed when you got the revs up. You didn't have to rev the hell out if it to have fun. But, that said, I have more fun on my XB, so that's the bike for me... until my 1125 shows up. | ||
| Rainman |
I'm so confused. I think I'm going to just stick with my Blast and not worry about how many cylinders are better. As long as I've got one, I've got it covered. P.S. I don't have to worry about defining the term "horsepower," either.  O |
