No worries dude.

 

[img]i/expressions/face-icon-small-wink.gif[/img]I'm guessing this guy was drunk or loaded up?I ride with all brands. We give each other a hard time, but this guy sounds like a prozac candidate. too bad he was on a pred. [img]i/expressions/face-icon-small-cool.gif[/img]

 

head027 "I hate math."

and it shows...your signature should read:

"i see dead people" because fast predators are the equivlant

and your alittle over sensitive...i was reffering to myself, as far as being schooled. and i'm thankful that he allowed me to drink of his cup of knowledge.

but since you've over reacted...yeah...your starting to look like a jackass. you have nothing to back up your claim of 60hp Preaturds...and dismiss hard facts and numbers with "i hate math"....Hee Haw.

 

Should have given him an "accidental" gravel roost. A piped turtle could probrably outrun my wife's Blazer. Who cares, I'm in it for the fun.

 

I'll line up with him anytime he wants to test out that 60 hp machine. Just make sure you have your video cam out and rolling.

What number was on this preddy?

 

Me and my Buddies Pred are very close in a race, his is stock just like mine. I went up north this weekend and raced a Pure Polaris Piped Pred and I beat him, we even switched quads and the Raptor pulled away again. Every quad runs different but between the 2 it can go either way. There very close Stock. Yamaha restricted the Raptor to much. If both quads were at full potential the 660 would tear the 500 up. Thats what I think

 

Pretoria is the capital of South Africa.

Yes we do ride ATV's here, and no we don't have to worry about wild animals killing us on the rides. [img]i/expressions/face-icon-small-happy.gif[/img]

head027, you are just digging yourself a deeper hole.

Let me inform you why math is so important and accurate. A 4 stroke motor breathes air. The only part of air that helps the fuel to burn while ignited is oxygen. The atmosphere has 21% oxygen, the whole world over. Then, you have a fixed capacity on your motor. The piston cannot get bigger without you changing it. Your bike uses the same fuel as the rest of the ATV's. The best air to fuel ratio for power is 12:7:1. Any richer or leaner causes power loss.

Everything is constant, so therefore the same math applies to all 4 stroke motors. You CANNOT have a motor that break these rules.

I also explained to you, that there are two ways to make HP. The 1st way is to have a big capacity motor, like the Raptor 660cc. The second way is to have a smaller capacity motor, but make it rev much higher than a big capacity motor. The raptor uses the big capacity and it is able to make max power at 7000 RPM. The YFZ uses a smaller capacity, but it makes max power at 9500 RPM. Big difference. The Predator makes max power at 8000. It therefore is a motor somewhere between a raptor and the YFZ450. Because is does not have the capacity of the 660, nor the RPM of the 450, it CANNOT make more power that either of the Yamaha motors.

Maybe if you did some math, you would learn a thing or two.

PS. the math is so easy. You only have to multiply and divide, something a 10 year old can do.

O, since I have posted two independent web sites that claim the Predator does not make more that 42HP, where is your Dyno runs showing us a 60HP stock Predator. If you don't have any dyno runs, how come you know it makes 60HP?

I had a rethink about that constant value they use.

There are two different things in the air than can effect the HP a motor produces. 1st is air pressure. The higher you go above sea level the less pressure. Less pressure causes the gas molecules in air to be further apart. This means that there will actually be less oxygen inside a motor at higher altitudes. Less Oxygen, less power. The formula takes into account air pressure. The 2nd thing in air effecting HP is the air temperature. The hotter the air the further the gas molecules move apart. It again causes less oxygen inside the motor and less power. Every 5 degrees C or 9 Degrees F rise in air temperature causes 1% power loss. For example, I am 4700 above sea level and most days it’s around 35 degrees C or 95 degrees F here. Any 4 stroke motor actually makes about 22% less power here than the same motor sea level and a day temperature of 65 degrees F.

To make things equally I believe that the constant in the formula assumes some kind of standard for air temperature. It might even include some other standard things. I might be wrong.

 

Just a little something to throw in too guys. "Horsepower" as we know it is a somewhat fictional number. The actual number figured, based on a mathematical formula, is a function of torque and rpm.

Say you have an engine that only turns say... 2000 rpm but cranks out 1000 ft lbs of torque. It makes roughly 380 HP.

Now let's say we have an engine that turns 10,000 rpm but only makes 200 ft lbs of torque.... It comes out to 380 HP.

Pretty interesting huh!

I guess my point is, don't take horsepower to heart. This all falls back on the ol' Volumetric Efficiency thing. All engines have a certain rpm where they have peak volumetric efficiency, which quite honestly is where the engine is making the most torque. This will not change unless an engine uses something similar to what the Honda "VTEC" uses, which is variable camshaft timing, something we in the quad world are not privy to at this point.

Basically, it comes down to how much air/fuel you can get in and out of the engine and how efficiently that works. It's based on cam timing, (you guys with bigger camshafts will realize more "HP" and torque due to increased VE at a higher rpm) and intake and exhaust flow (PORTING) primarily.

This isn't as simple as it may seem at first glance. There are so many subjects to talk about in this kinda topic.

Did I just throw a big ol wrench into the debate??

 

LOFL!!

 

I would like to thank Freez and Blackwidow for posting such intelligent answers to this thread. Members like you make this forum worthwhile and we should recognize you for efforts and for being so thorough in your answers.


Freez,

I did some calculations of my own regarding the constant affore mentioned in the formula you got from the RPMOutlet website. It seems to me that their constant is based on the conversion of the equality needed to change the units of input (psi*in cubed*rpm) into the units needed (hp = 746 W = 746 kg*m2/s2). The units of the constant would then need to be (lb2*in3*rad)/s3. It seems that temperature is considered standard in this equation and can be assumed to be 24 C. A simple adjustment according to boyle's law would allow this formula to be manipulated to include a variable for external temperature. I apologize for not being able to draw this out better but the restriction of using html or images on this site prevents a clearer depiction of the functions.

~HoundDog