2007 - New Spy Pic!

I think the new Yamaha will be a new lightweight frame design, new front end as in the picture, new skid, seat and tail section similar to a dirt bike with twin under seat exhaust from the twin 250 four stroke motors from the dirt bike line-up. As for the rest of the line, Yamaha always surprises me, maybe a high powered APEX.
 
the front of the trailer has already be explaned on a previous page. its a wedges nose and angles down in the front and the back. the door is still parell with the to of the roof befor it angles down.
 
What's a competitive HP-weight ratio?

[Forgive my estimates here, i didn't have exact numbers]

2006 Apex RTX:
~540 pounds
~150 HP
== 3.6 lbs/HP

2006 F7 EFI:
~450 pounds
~140 HP
== 3.2 lbs/HP

So, split the diff here and let's say 3.5 lbs/HP is the sweet spot.

What does that mean we should be looking for in a competitive new sled from Yamaha:
~400 pounds
~100 HP
== 4 lbs/HP

Running the equation backward tells us that a 100 HP sled would need to weight about 350 lbs to hit our 3.5 lbs/HP sweet spot. It also tells us that a 400lb sled would need to have a little better than 114 HP to hit that sweet spot.

Question: Is this good enough? I realize my numbers may be off but I want to stress that talking just weight or just HP is only half of the equation when it comes to performance.

Let's figure out what that sweet spot is that we're hoping for. Oh, and this argument totally disregards torque. Can any smart guys out there help us figure out the kind of torque numbers we'd be looking for to be competitive in the ditchbanger/snocross class?
 
Either way of computing it really tells you the same thing. You want a smaller number when looking at it as lbs/HP (less weight to push for each horse) and a bigger number when looking at it as HP/lb (more horses to push each pound). Here are the computations done the other way (given our current number, call it x, one is just the reciprocal, 1/x, of the other):

2006 Apex RTX:
~540 pounds
~150 HP
== 0.278 HP/lb

2006 F7 EFI:
~450 pounds
~140 HP
== 0.312 HP/lbs

New Yammie speculation?
~400 pounds
~100 HP
== 0.25 HP/lb

Sweet spot: 0.286 HP/lb

Meaning a 100 HP sled needs to weigh in at around 350 lbs to hit our 0.286 HP/lb sweet spot. It also tells us that a 400lb sled would need to have a little better than 114 HP to hit that sweet spot.

You see, both calculations tell you the same thing: Either we're hoping for a 400 lb sled that has about 114 HP or we're hoping for a 100 HP sled that's only around 350 lbs. :)
 
Who deemed the F7 as the standard to achive? Yamaha colud obtain those weights vs. HP if thay wanted to build something that cheap and chinsey.
 
I think the f7 is sort of the standard for the majority out there. it is well known for being light and easy to handle, and makes great power. not for everyone, but it is sort of the current king of lightweight. the rev is not really that light, not as light as doo claims at least
 
I just picked some sleds to use for comparison in an attempt to get a "baseline" lbs/HP number to shoot for. Plug in the numbers for any sled that you think exhibits decent performance and see how close I am. Brand doesn't matter to me (for this argument, at least. :)), just performance.
 
1 Trick Viper said:
If the twin 250 motors are true, it will be a little underpowered.
Click to expand...

Well the 250f makes 34.5hp stock so we would be looking at a ~70hp with a 500 twin based on that, maybe 80hp if the up the RPM's more.
 
This fixation on just the max HP output of a motor is sophomoric. The HP rating of a motor is indicated at it's peak, at a given RPM, go 100 RPM over or under and the HP output will be lower, go 500 RPM over or under and it's much lower. What seld runs at a constant RPM? None. Also, any specification of HP without indicating at what RPM it's taken at is not a useful specification. So saying such and such sled has 120 HP means little unless the RPM of that max output reading is included. What's much better is looking at a graph of HP as it relates to the operating RPM range, which is the power curve. A motor (motor:A) with a relatively flat power curve developing 60-70HP in the 5000-9700RPM range is much better than a motor (motor:B) with a steep spike of 80-120HP only in the 8600-8900RPM range if it has dramatically less HP outside that range, say 48HP at 6000RPM and 9700RPM. But the motor-A will be listed as 70HP (its max) and motor-B as 120HP, but motor-A might blow the doors off motor-B given it's ability to deliver consistent power through a much wider range of RPM.

Another thing to consider is this: what accelerates a vehicle is torque, which is force. Force = Mass*Accel so Acceleration = Force/Mass. So you want better acceleration, either increase the torque or reduce the mass, has nothing to do with power.

Ask yourself, what's better: acceleration or top speed? What do you think is going to be the focus of this sled? Top speed? No. Power is force applied over a distance, and in motors this "distance" is RPMs, so power (HP) is really how much force (torque) can be produced at a given RPM. The same torque at 5000 RPM produces half the HP as it would at 10,000RPM, yet both would "feel" the same acceleration force - since the torque is the same. HP is needed for maintaining top end speed, torque is needed for acceleration. Torque is what you feel, not HP.

This SnoRaptor or whatever it's going to be called will be just fine with 60HP if it's got the torque, given its expected 400lbs and not being targeted to lake racing. Personally, I don't care about competition and racing, I just want to have fun, and acceleration is fun, more so than top speed in my opinion. We're not going to know how much fun this sled is going to be until we ride it. Just looking at an HP number isn't going to tell us jack shit about its fun potential since a driver doesn't even "feel" HP and the HP number is merely a max output number at a given RPM and doesn't correlate to acceleration. A vehicle's acceleration matches directly to it's engine's torque curve, 100% direct.
 
JLSXR700 said:
I just picked some sleds to use for comparison in an attempt to get a "baseline" lbs/HP number to shoot for. Plug in the numbers for any sled that you think exhibits decent performance and see how close I am. Brand doesn't matter to me (for this argument, at least. :)), just performance.
Click to expand...

baseline" lbs/HP number Hmmmm....... Exciter ! ! !
 
I recieved this pic from Yamaha Canada this mourning !!!!
 

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