Detonation for Dummies
 

Well, I plan to be boosting shortly, within a month hopefully. And as all new users read and read and read, the scariest thing we come by is the word detonation. :o

So, I wanted to get a write up about detonation, what exactly constitutes detonation, how to prevent/detect it, and pretty much just get a good thread for the New User FAQ all about detonation.

Re:Detonation for Dummies
 

Detonation/pinging/knocking are essentially all the same.

Your engine will run out of balance, perse. When there is inadequate fuel being delivered and the incoming air is hot enough to actual cause ignition (detonation is thus ignition previous to when the cylinder fires).

This is bad because when a cylinder fires prematurely, especially with the intake valves open to have 'fire' actually travel backwards in the engine. Along with this, your connecting rod will shake (I believe this is what you actually hear when the motor is pinging) and this can cause it to slip off its bearing, shatter, fall sideways, etc...

All in all keep your ear open for sounds of tapping metal, especially something that sounds like a garden hose being crimped in a "V" right near the neck of the hose. Thats the closest thing I can think of to how detonation sounds.

Re:Detonation for Dummies
 

mmm... have a good sized FMIC, change the timing at a min. of 0.5 degree per psi of boost, and well.. your fuel management is everything... and of course an air/fuel ratio gauge / boost gauge so you can make adjustments.

I'll tell you right now my only problem I've run into with detonation is that small intercooler I used on my setup... I'm updating it with a conquest one to give a better temp drop. I've also discovered that it's smart to wrap up your chargepipes with exhaust wrap... seriously. I've run some tests and find that after driving around easy or hard, my chargepipes seem to collect a good amount of heat from the engine, so it's safe to just wrap 'em up or shield them in some way.

The only way I've been able to detect detonation is to go on some quiet road, roll up your windows, turn off the radio (etc...) and do a roll start from 3rd gear or so and floor it. While building boost you will obviously be monitoring your air/fuel meter, but listen from the engine for a sound that resembles marbles in a can filled with water while being shaked... I'm sure there are other ways to describe it, but that's what it sounds like and you'll hear it if you have any... again, it could also sound like driving over a gravel road and little rocks are hitting metal. I need to find a wave file on the net or something.

Re:Detonation for Dummies
 

Thanks for the input, both of you, some good stuff. The only problem with finding a sound file of pinging is that no one is going to make their motor ping on purpose so people can hear it, or at least I don't think they would want to do that.

Re:Detonation for Dummies
 

the couse:running to lean

The damage:To my understanding detonation is coused by an untimed explosion that ocurs on the fourth stroke as the piston comes up to expel consumed fuel out of the chamber (right before the exhaust valves open).The untimed explosion couses the upward moving piston(moving up becouse the adjacent piston is moving down on the third stroke,combustion) to all of the sudden stop resulting in damage to most commonly the piston rod and sometimes to the block.

the cure:a stand alone computer is the best but we all cant afford that.The next best thing is an afc hack.Though not as accurate as a standalone,with propper tuning a V-AFC(AFC if you dont have vtec)will alow the engine to run without the risk of detonating.An FMU is ok for 5-7 pounds.I wouldnt use one though.

Well thats all i know about DETONATION.Fell free to mock me if im incorrect ;D


Rafael

Re:Detonation for Dummies
 

Well, unfortunately, I am going with the FMU on a 6-7 psi setup. Hopefully with a BTM I won't hear any pinging.

Re:Detonation for Dummies
 

If your using a BTM you should be covered.

Re:Detonation for Dummies
 

detonation/knocking/pinging.. also another name for it is Pre-Ignition. which sounds self explainitory.

Re:Detonation for Dummies
 

i've never heard of the hose analogy. i've only heard the bb's in a can sound (my truck does it when low octane is used). are you talking about the hose sound with the bb's in a can? the hose sound is probably the turbo spooling up unless you can hear that as well.

Re:Detonation for Dummies
 

That brings up another point about your octane's rating involvement in pinging. How deeply does it correlate to pinging? (the octane rating on gas)