Fire in the exhaust....

M

Mongo

Guest
Wife asked me why cars like the 2 have fire coming out of the exhaust. I explained that it is unburned fuel igniting.

My question is why is there even excess fuel in the exhaust? As highly tuned as these engines are, excess fuel/rich condition is something I would never expect from these cars.
 
I'm thinking it happens during the crank it time prior to the engine firing, or it happens because an exhaust valve doesn't close soon enough.
 
Think about the idle circuit beeing too lean to fire in the chamber but puts a near ignitable mixture into the huge volume of the headers, collector, "X" chamber and difusser...
 
With timing as close to tdc as possible.....at least that's the way I always liked to run....a little bit of a stick in the exhaust valve or slack in the belt/chain at back-off would not be unheard of
 
I agree, but I think the teams are playing with the idle and intermediate circuit air bleeds too. We got a DaVinci and a BG recently with their "standard" setup and they are WAY lean. The "out of the box" Davinci was still a touch lean up top. The car would nose over just a bit as RPM climbed. The BG was even worse in the high speed circuit, we thought we lost second gear in a G-Force clutchless 5 speed tranny! In actuality, the thing jump into neutral because the engine layed over so bad...gotta stay on the wood with those things...
 
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