>The energy of an explosion is greater than the energy of a controlled burn even a pre-ignition. not necessarily but yes it is more violent since its flame front speed is incompatible with the involved hardware Pistons cant move that fast so shock Waves bounce around and cause standing waves concentrating energy in points that causes the fragmentation of pistons one typically finds Lean engines (magermotoren) can have stoichiometric regions more easily in which detonations (that's the way automotive pros refer to explosions versus deflagrations) occur so the question is usually to keep the fuel together in a smaller swirl, or to use things like water injection to provide slow burning areas anyhow Long term goal of the GoBox is to implement a Parallel processing FPGA based Ion sensing motor controller! Ion sensing is an important keyword here, it uses common spark plugs as sensors in between the times when thy are used to ignite the mixture! On 7/1/07, Rich wrote: > > If you are talking about pre-ignition pinging, it will occur is the fuel > mixture is ignited before the piston reaches its design position relative > to > top dead center. It will usually cause a bucking. However, if the fuel > explodes it can damage the engine. It can throw a rod or bread a piston. > The energy of an explosion is greater than the energy of a controlled burn > even a pre-ignition. > > The difference between burn and explode is extremely important. The > chemistry is quite mature and I think available on the net. If not it is > in > most chemistry books. > Burn and explode related to the IC engine is the same as Burn and > explode in a propane stove. When you cook, the oxidation rate of the > propane should be burn and not explode. The flame on an acetylene torch > can > be made hotter or less hot according to the oxygen mixture adjustment. > Rapid oxidation is involved in explosives. > An explosion will occur if the oxidation rate increases to the > specific > explosion point of whatever molecular structure is involved. In chemical > or > pharmaceutical plants as well as in mining there is a need to determine > the > Least Explosive Level (LEL). A company by the name (I think) is Mine > Safety > Equipment makes such detection instrument. > > > ----- Original Message ----- > From: "Gerhard Fiedler" > To: > Sent: Thursday, June 28, 2007 9:42 AM > Subject: Re: [EE] Simple fuel-saver, so they say lean mixture > > > > Lee Jones wrote: > > > >>> I don't know the difference between burn fast and explode. Does fuel > >>> burn fast and if the engine flies apart then the fuel was "exploding" > ? > >> > >> Modern engines have a knock sensor. The computer controller leans the > >> air-fuel mixture as much as possible, usually based on an O2 sensor in > >> the exhaust system. When it senses the fuel exploding via the knock > >> sensor, it enrichens the mixture "enough" to stop it. > > > > I don't think the "knocking" is fuel exploding. AFAIK it is fuel > expanding > > before the piston reached its end position. IIRC, you can make any > engine > > knock without changing the mixture, just by moving the ignition point > > forward. And you can make it stop knocking by moving the point back. > Since > > the time between the spark and the mixture expanding depends on many > > factors, and you want the mixture to start expanding right after the > > piston > > reached the dead point but not before, they control the ignition point > now > > with knock sensors. > > > > Gerhard > > > > -- > > http://www.piclist.com PIC/SX FAQ & list archive > > View/change your membership options at > > http://mailman.mit.edu/mailman/listinfo/piclist > > -- > http://www.piclist.com PIC/SX FAQ & list archive > View/change your membership options at > http://mailman.mit.edu/mailman/listinfo/piclist > -- Tobias Gogolin cel. (646) 124 32 82 skype: moontogo messenger: usertogo@hotmail.com You develop an open source motor controller at http://groups.yahoo.com/group/GoBox -- http://www.piclist.com PIC/SX FAQ & list archive View/change your membership options at http://mailman.mit.edu/mailman/listinfo/piclist