Gasoline Ignition Temperature?

[Birel99]

Hi,
What is the approximate temperature at wich gasoline ignites in an internal combustion engine.
Im aware that literaly everything has an effect on the ignition temp, type of fuel, pressure, temperature of air and gas, etc.
My thinking is this= on the exhaust stroke of a two cycle engine, when fuel is treveling out the exhaust port, why doesnt it ignite with EGT's around 1300F?
Thank you for your help!

[Carlos]

At atmospheric pressure, gas ignites at 260 C. A lot of mixture can exit the cylinder, depending on port timing, in extreme cases, sometimes burning outside the exhaust port, which can't be very good for an engine, not good at all. Honda introduced an engine in 2003 with a pivoting valve on the exhaust porting that improves the many problems of the two stroke. It may be of interest.
http://www.motorcycle.com/manufacturer/ ... 14293.html

[riff_raff]

Birel99,

The autoignition temperature of a gasoline/air mixture depends upon a lot of variables. Most importantly, what is the air/fuel mixture (equivalence) ratio? What is the ambient pressure? Is the mixture homogeneous or stratified? Iso-octane reference fuel will auto-ignite at stoichiometric, 1 atm conditions at about 600degC. Lean air/fuel mixtures are notoriously difficult to ignite.

The charge temperature in the expansion chamber of a loop-scavenged two-stroke engine is likely far less than 1300degF, due to the mixing of the cool intake scavenge flow with the trailing end of the exhaust flow, prior to the acoustic reversion pressure wave driving them back into the cylinder.