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[quote][i]Originally posted by Gambit[/i] XEDOS - u are thick as pig shit, i was tryin to refrain from this, but that last statment jsut lit the touch paper for me..... so here goes Basically, on a poorly mapped road car or aggressively mapped motor sport car the mapper will often only really spend time mapping at full throttle load points and neglect the part throttle map often running the car rich at these load points on the map (running to much injector duty at these load points). This is what causes the black smoke/yellow flame on lift off/gear changes.. Cooling of the cylinder chambers as u call it can't happen by igniting fuel/fuel vapour in the exhaust or the exhaust manifold when it is hot!! this just makes things hotter as it is an uncontrolled burn of fuel. Lift off correction, this term is total cr@p in your context. U can have fuel correction tables that are referred to by the map but these are used in conjunction with temp correction maps. Both of these tables are referred to when running MAP sensors and air temp sensors (usually ECU's such as Motec, Gems, Autronics for motor sport) or as with the majority of turbo cars a MAF (mass air flow) sensor which creates a Karrman Vortex within the MAF (use of cylinders to interrupt airflow and create a vortex behind the cylinder). The Frequency is then measured to determine air mass and flow figures. This frequency is measured In Khz (Karrmen hertz). Fuel cut on a standard EVO 6 is 1500Khz i.e the point where to much air is being introduced and the engine could run lean. Overrun - Overrun is what happens on cars when the combustion chambers have carbon deposits on them due to running too rich and not achieving a correct burn. The the red hot carbon deposits then ignite any remaining fuel vapour in cylinders after turning off the engine cause it to overrun.. Overrun may also be used as term for retarding the ignition on throttle lift off, but this is being used in the wrong context as it relates to antilag. What you are trying to say is : You run slightly rich at certain load points on the map, usually where the Torque and bhp plots would cross on a dyno print out and also at the top end. This is where the engine is under max load and is the hardest point to map. Running a little rich helps to keep down detonation of the fuel/air mix due to the increased cylinder pressures at this point. (Cylinder pressures increase in the midrange (usual point of max load) as ignition settings are advanced in the map to create power, boost is increasing rapidly as the turbo is spooling up hard and spiking as the actuator attempts to control boost). Running a little rich also help retard the flame front within the combustion chamber causing a slower burn (hence less hot) which cools the top of the piston crown area.. Running a little rich at the top end where max ignition advance is being run is also done for the same reason to stop det. When u run a little rich you don't get a full burn, hence partially burnt fuel is mixed with exhaust gasses and ignites in the manifold and sometimes the exhaust causing the flames. the only reason u see the flames is cause the CAT has been removed other wise u wouldn't see it. Running too rich and actually igniting raw fuel the exhaust manifold is a really bad thing creates mega heat and kills turbos + manifolds.. You need to closely monitor EGT's (exhaust gas temps) on turbo cars when mapping, EGT's should not be past 900 - 950 deg C. running very rich will also cause problems with bore wash (fuel getting past the piston rings and getting into the oil in the sump). Igniting raw fuel in the manifold is only usually done when running aggressive anti lag (aka rally cars where they change turbos after every event). Anti lag is method of keeping the turbo spooled up between gear changes and when off the throttle. This is achieved in a no of wayz, but the most common is using a throttle kicker (jacking the throttle open), retarding the ignition so the extra fuel remain unburnt and then igniting it in the manifold keeping the turbo spinning. This causes the loud cracks/bangs and flames u see with rally cars. Running aggressive antilag all the time on a road car would cause the turbo to expire in less then a couple of thousand miles.. [/quote]
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