Detonation (engine go boooom!)

[Smokin' Rubber]

Alright I know kinda what detonation is but can anyone explain something to me... does it happen only because there is too much pressure in chambers for the engine to take? In other words the metal of the engine isn't strong enough to deal with the high levels of combustion going on in the chamber?or is there some other reason?

[MadBill]

Detonation is the spontaneous explosion of the fuel/air mixture in the cylinder ahead of the advancing flame front of the normal combustion event (which is a rapid burn, not an explosion). It occurs after a short delay when the combination of the fuel mixture's temperature and pressure, plus the radiant energy from the normal flame front exceeds the detonation resistance or octane rating of the fuel. The pinging sound you hear is the metal of the head, block, etc. ringing like a bell from the high frequency pressure waves ricochetting around the chamber. The resulting sudden pressure spike can damage rings, pistons, valves, heads, even trash bearings...

[Smokin' Rubber]

So say if you could modify an engine in any way at all as if you were building one from scratch what would be the best way to prevent detonation (and assume that you already have obsurdly high compress 13:1 running a turbo for further obsurdity)?

[MadBill]

There are a lot of tricks that can be used to get away with higher compression:o A long duration intake cam "bleeds off" some cylinder pressure at low RPM, where due to the time factor, detonation is more of an issue.o "high swirl/turbulence ports and combustion chambers promote a rapid burn and thus reduce the time for detonation to develop.o High "squish" (close clearance between the piston and the head) similarily improves flame speed.o Positioning the spark plug so that the flame path length to hotter areas like the exhaust valve is shorter.o A cooler thermostat lowers the cylinder temperature.o Water injection systems to cool the charge.o Ceramic thermal barrier coatings on the head and pistons to reduce the heat radiated into the mixture.o Within reason, retarded spark timing can ward off detonation without robbing too much power.o Similarily, a knock sensor system such as used on most modern engines will retard the spark when detonation develops and can usually prevent damage.o And of course there's always racing gasoline or alcohol, with octane ratings up to ~120!

[Smokin' Rubber]

Lol ya know I don't think your car will run for more than a couple minutes on rubbing alchohol wonder how good your hp would be tho hehe. So do you think it's actually possible to modify any of the things you mentioned in terms of the 2zz?

[satur9]

alcohol/ water injection is usually methanol instead of rubing alcohol although people have used such. regular engines not designed to run on alcohol cant.plus alcohol eats rubber fuel injector rings and stuff.water injection involves a separate pump and system to spray small amounts of alchohol and or water into a engine. the water reduces heat and hence detonation adding alcohol does the same slighly better cause it absorbs more heat than water and some it burns as high octane fuel. this setup is used on a couple of matrix superchargers and stafford turbos. you can use water injection and or race gas on a 2zz with higher compression pistons than stock.but if going forced induction its best to lower it. you can raise it but you have to run 5 dollar a gallon race gas and the engine still would be very prone to blow at the slightest error. also do a search for j&s safeguard very cool device

[Smokin' Rubber]

Lol I wonder is there anyway we could mod the engine to have 3 cams (plus obviously a new ECU since the old one would only be programmed for 2) because that really would be seriously awesome, might have to rebuild or replace the top part of the engine above the valves but you gotta admit to have 3 cams would be interesting