I believe that the term "pre-ignition" applies to the fuel/air mixture igniting before spark has occurred. wheather it occurs from a "hot spot--i.e-hot piece of carbon" or too high a compression ratio for the fuel and it ignites without the spark. I believe most fuels, regular and premium, are similar in composition, with the exception of additives to increase the octane, and possibly shorter chained hydrocarbons in the premium.

Detonation refers to what happens in the combustion chamber, after the iginiton sequence, and instead of a smooth flame front and burn, you get a detonation, like an explosive. It hammers the piston and shocks the rings(can easily break them), and is like taking a sledge hammer to you piston, with the pressure spike.

Course, its been along time since I had my aircraft mechanics school, but I don't think the physics have changed since then.

 

Thank you. Physics hasnt changed, so youre safe.
As long as nobody starts telling me that low octane fuel will cause deflagration, I'll be happy

 

Just guessing, the ECU can only compensate so far for inadequate octane.

 

Shoulda melded this thread with yesterday's "add moth ***** to gas thread". Oh crap, now I've done it!

 

Not really, we're talking combustion by pressure which is not spontaneous, fuel in a non compression state in a motor would only ignite with spark not pressure.

Nothing wrong with debating this process, it's not about who's wrong or right it's a good question and one folks can learn from, actually if you only speak of heat causing the pressure induced combustion then my cold diesel motor on my tractor would never start, but it does.

 

Rockrat made my point more eloquently.

 

As stated before, octane does nothing more then increase the limits of compression and temperature before detonation.

87 octane burns faster and earlier. Despite how advertising makes people think that 93 is "high test" or "premium", 87 is actually a better fuel. Provided the temperature and compression of the cylinder doesn't require a higher octane.

They also put some cleaning additives in some of the fuels to help justify its increased cost.

Try to tell someone this that puts 93 in their Mercedes because it makes them faster and they will laugh to death.

With some people, the more stupid they are the more that they think they're smart

Wait..............wait...............wait......... .......I think I'm one of those people!! LOL!!

As far as knock sensors, the motor will still knock a few times before the computer can retard the timing. Just like the traction control on my Charger. I can still smoke the tires for 3 full seconds before the traction control kicks in and stops me. (it's nice that they put a button on the dashboard so I can turn it off and smoke out my whole street)

 

Thats ok. I knew where you were coming from. It's nice to know that someone paid attention in auto shop.
I'm still trying to figure out how diesel technology got into the conversation. Thems is two completely different ways of doing things, and no way to compare the two. And dont even talk similarities, cause there aint none

 

What about energy drinks?

"Energy — the high-octane kind that pumps up the most stressed-out bodies — is only a sip away."

How does that high octane work?

 

For the highest horsepower increases, I use Fitch Fuel Additive