so i just got one and i have an idea of what it does but if anyone can chime in on the real benefit of having one . only thing i know of is crankcase pressure. can i get any king of horsepower gain at all?
<TABLE WIDTH="90%" CELLSPACING=0 CELLPADDING=0 ALIGN=CENTER><TR><TD>Quote, originally posted by killer bee »</TD></TR><TR><TD CLASS="quote">can i get any king of horsepower gain at all?</TD></TR></TABLE>
Increased crank-case volume means less back pressure. HP is not wasted fighting that back pressure. At least that's what I've been told.
Plus... it's made out of CF. Isn't that enough reason to have one?
<TABLE WIDTH="90%" CELLSPACING=0 CELLPADDING=0 ALIGN=CENTER><TR><TD>Quote, originally posted by Mental998 »</TD></TR><TR><TD CLASS="quote">
Plus... it's made out of CF. Isn't that enough reason to have one?
The main reason for using a corsa (race) set-up is to deal with the additional blow-by that is the typical by-product of a higher compression motor.
Piston rings act as a seal between the high pressure created in an engine’s combustion chamber and the lower pressure in the crankcase. Blow-by occurs as the rings become worn - or fail to seal properly when new - and they allow a small fraction of combustion gases to leak into the crankcase.
The consequences is accelerated contamination of the engine oil, as well as excessive release of hydrocarbons to the atmosphere - unless a crankcase ventilation system is used to route the gases back to the engine intake to be burned.
On Ducati engines, excessive blow-by can cause unusually-large amounts of entrained engine oil to be forced through the crankcase ventilation system and into the air-box. It’s not unusual however, to occasionally see a light deposit of oil in a Ducati air-box.
A small number of Ducati 998's, maybe one percent, have been reported to build up so much crankcase pressure at high revs that excessive entrained oil is forced/sucked into the air-box through the crankcase ventilation system, resulting in excessive oil consumption.
Blow-by occurs in all engines to varying degrees as they wear, but when it becomes excessive, an engine rebuild with new piston rings is in order.
In particular, crankcase ventilation is used for three reasons:
• It reduces crankcase pressures to nearly atmospheric pressure in order to avoid oil leaks from seals and gaskets.
• It reduces crankcase pressures at the bottom of the pistons to provide an increase in the differential pressure across the piston compression rings, and consequently provide an increase of torque and horsepower. A larger differential pressure across the piston oil rings also aids in control of oil consumption.
• It reduces pumping losses. In a running engine, the size and shape of the crankcase boundary changes with the movement of the pistons. Ventilating the crankcase reduces parasitic horsepower losses involved in compressing and moving this air volume about, so net power output is increased.
The larger the crankcase volume, the less-compressed the gases it contains become, so the lower the losses. If you vent directly to the atmosphere - through a sufficiently large vent hole (like in the corsa system) - the crankcase can’t attain positive pressure, even at the highest engine rpm. Further, if you create a vacuum in a crankcase, the effect on pressures is the same as increasing the crankcase volume.
The simplest way to ventilate the crankcase is to create crankcase openings to the atmosphere large enough to permit any combustion gases that have made it past the piston rings (called blow-by) to rush out. In this case, a filter element is needed on the opening to prevent dirt from entering the engine. This system was used on engines for many years until environmental laws required a modification that prevented direct release of this effluent to the outside air.
The design result of such laws is a positive crankcase ventilation (PCV) that uses the lower-than-atmospheric pressure that normally exists in the engine intake tract to extract the crankcase gases. These are then are burned along with the normal mixture of air and fuel. This system has a one-way valve that allows outward flow only, and a oil separator that acts like a maze for any entrained oil droplets that try to leave the crankcase. This (normally) small amount of oil then drains back into the crankcase instead of entering the engine intake.
On Ducati street bikes the one-way reed valve is located at the engine case opening. During certain conditions of high engine rpm and light load, more oil is entrained so the reed valves’ small drain holes have difficulty returning the additional oil to the sump quick enough. The oil separator can fill with oil and get sucked into the intake tract. Higher compression engines or worn piston rings have more blow-by, so the likelihood of oil being puked into the air-box is greater.
Because of this, corsa bikes that live at high-rpm use a somewhat different arrangement than the street bikes. A much larger oil separator box is used to effectively increase crankcase volume that reduces pressures and pumping losses. This effectively doubles the crankcase volume and can result in an additional three to five horsepower at high RPMs.
On the superbikes, the factory under-seat corsa style piece has a built-in condensate tank and it uses intake vacuum to pull fumes from crankcase, so the only difference is that it allows any oil to drain back and not go into air-box.
The corsa box is connected to the crankcase with a large diameter hose and located a greater distance away from the crankcase opening, under the tail. The one-way reed valve is now located at the air-box connection of the 3/4-inch vacuum line running to the oil separator. This design reduces the chances of contaminating your intake charge with oil. It also provides a large enclosed system that safely contains the oil if an engine blows.
Except for the larger oil separator volume, the advantages of the corsa system can be implemented in the stock system by hollowing-out the reed valve to remove the constriction on drainage. Alternatively, STM valveless breather connector can be used. Then use a one-way reed valve at the air-box connection. A 748RS remote breather valve works well here.
Finally, a few words on K&N breather conversions.
The K&N breather is sold on the premise that venting to the infinite volume of the atmosphere - instead of the vacuum in the air-box - increases horsepower. It eliminates the one-way valve so it needs an air filter to prevent dirt from entering the crankcase under a negative crankcase pressure differential (pulse) when a piston is on an upstroke. Under positive crankcase pressures, the K&N device simply vents oil droplets direct to the filter medium - and beyond when it becomes saturated.
People usually buy them because they look trick mounted on the engine case. Therein lies its main disadvantage. Its location on the engine case is directly upstream of the rear tire. Since its installation also eliminates the oil separator, the increased chance of an oil mist being released onto the rear tire makes this location an unwise choice. Avoid overfilling the oil sump and wheelies with this arrangement.
Consequently, some owners have plumbed to the K&N element located in the tail where, at least, any effluent is away from the rear tire.
<TABLE WIDTH="90%" CELLSPACING=0 CELLPADDING=0 ALIGN=CENTER><TR><TD>Quote, originally posted by motobum »</TD></TR><TR><TD CLASS="quote">somebody lock this thread nothing else needs to be said.</TD></TR></TABLE>
<TABLE WIDTH="90%" CELLSPACING=0 CELLPADDING=0 ALIGN=CENTER><TR><TD>Quote, originally posted by CPalacay »</TD></TR><TR><TD CLASS="quote">Does anyone know why they don't offer one for the 749 or 999, other than that new exhaust and seat configuration take up all the room? </TD></TR></TABLE>
On the 2003-2004 RS's it's in the fuel tank, and I heard they moved it to the RH fairing for the 05' models.
<TABLE WIDTH="90%" CELLSPACING=0 CELLPADDING=0 ALIGN=CENTER><TR><TD>Quote, originally posted by tricklidz1 »</TD></TR><TR><TD CLASS="quote">
BTW: Who painted (powdercoated) the wheels? Do you know the color code or name? They match the bike nicely
i know this guy in my area who does it as a hobbie but he charged me $40 per wheel and sub frame. no color code here. i just matched the color options he had, the color i used was catipillar yellow. not perfect match but damn close
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