<div class="FTQUOTE"><begin quote>Originally posted by: Jayblazer

the ranger 500 is not the H.O. version of the motor.</end quote></div>

Ditto. It's non-H.O. like the '97 Sp 500 I had.

 

The Ranger uses the smaller 34mm carb and shorter duration cam,same cam is found in the EFI Ranger as well. Our 97 Sportsman is rated at 30hp also.

 

So the 08 800 has 12% more power than the 07 800 just because of a RZR cam?

 

Sounds right,back when Polaris changed the cam and carb on the SP500 they claimed a 20% increase in power.

 

Iv'e been into sports cars the last few years and know that some cars can gain as much as 60 rwhp on just a cam swap. I found a really good deal on a 06 800 that I'm going to try to get this Friday and if they gained the 12% just from putting a RZR cam in it that's the first mod I'm doing. It's amazing how restriced a motor can be due to a cam.

 

Before polaris made the first SP500 H.O in 2001 ,people were are ready making there own H.Os by instaling the 500 Scramblers carb and high duration cam in there exsisting 500 Sportsmans.

 

Ok, so give me some detail as how the cam helps. Does it increase the length of the stroke or when the stroke happens or what? Sorry, but I am a chemist, not a motor mechanic...LOL. Just trying to "edgu-makte me-self" here....LOL.

 

The bore and stroke aren't changed at all. The cam changes the timing and duration of the valves opening and closing. It takes advantage of the huge amount of fuel and air that the bigger carb delivers. I'm not exactly sure how because I'm not a mechanic either. The 500 H.O. clutch is different too. 3 C's - clutch, carb, cam.

 

I have a little bit of experience here, so I will throw it out and see where it goes.

Cam curves and duration all relate directly to clearing the dirty air (exhaust) and getting in more Clean air and Fuel(intake)
They play with actual duration that the Cam keeps the valve open usually measured as from x thousands of an inch the valve is open to x thousands before it is closed and that is measure in Degrees of duration. The longer the valve is open the more dirty air it can exhaust or the more Clean fresh air fuel it can bring in. (To a point)

Next they talk about "Lift" How far the cam moves the rocker to open the valve resulting in a larger opening of the valve for a longer period of time. The wider a spigot in this case a valve is open the more dirty or clean air can flow through it.

Then they take into account overlap. the actual time in degrees that both valves are open. With the outrush of hot dirty exhaust you can acutally leave the valve open for a few degrees while the intake is opening This creates a pressure differential and you get some additional cc's of cool air rushing into the cylinders.

All of this adds up to a bigger charge in the Cylinder that is compressed and combusted hence more horsepower on the downward stroke. In essence it is almost like increasing your Compression ratio although on a much smaller scale and without those detrimental effects too.

You can also degree that cam a few degrees retarded or advanced to get a different performance curve. but it is a give a take situation just like adding the cam in the first place.

Caming an engine or even changing the timing are usually very productive, but it isn't a magic bullet. You give something in one place to gain something somewhere else. i.e more top end horsepower will usually mean less in the bottom end, or more bottom end grunt will usually mean less topend horsepower or speed.

What it all comes down to, there is no replacement for Displacement, to balance the best of the low end Grunt and High speed Topend world.

 

Cool, that makes a little more sence.