ATTN: RaceGem

[MadWagon]

I was reading your post a couple of pages back about pinging, i think this is hapening to me i have a g180 with tx head and stage 3 cam running unleaded all recond, new piston rings, when am goin up a hill and the engine is under a bit of strain it makes a ratteling noise like a tin can as the other bloke described it, my engine also keeps running sometimes when its hot after i turn it off, can you tell me a little bit more about this pingin please.

[S N 3 A K Y]

I just finished work so i'm too fuggered to explain it in detail....
I found this after 1 mins worth of searching coz i couldn't be sexed getting right into it.
"Pinging 101.
Pinging is where the fuel explodes inside the cylinder, also known as detonation. In a normal combustion cycle the fuel burns evenly in a flame front from the spark plug out towards the edges of the cylinder and the piston. There are a number of factors that can cause it to detonate - compression too high for the octane of the fuel (typical in cars that were built before ulp and are now running on it), ingnition too far advanced, plugs too hot etc etc.
Too much pinging for too long can lead to bottom end damage (big ends) from the shock loading, and you can also melt a hole through the top of the piston.
I might be wrong, so anyone feel free to shoot me down in flames, but thats it in a nutshell as I understand it. Someone else can probably give you a more detailed/correct explanation."

"yes ash thats it in a nutshell.....i'll just add that like you said in a normal engine the flame front travels evenly and detonation occurs evenly, on a pinging engine the flame front travels out and depending on the severity it is met by another front travelling the other way or it travels evenly and then the rest of the mix is burnt instantly, creating a higher than normal pressure in the chamber, higher pressure than normal means higher heat, and the shockwave creates unduly stresses otherwise ok parts, generally not a happy engine environment.
cheers.
neal."


Ideal combustion is when the flame travels from one end of the port to the other. With pinging, the flame is being lit in all different areas of the port. This makes the flame collide. Think of burning a peice of paper from one end, you get a nice steady flame all the way to the other end.
If you lit the paper at both ends, they would eventually collide in the middle causing a small eruption of a bigger flame. In an engine this practice is magnified intensely, it's a little like throwing tiny TNT inside your ports, the collision of flame fronts litteraly explode and send shock-waves through various internal engine parts.
Doesn't sound like such a big deal when you hear it driving up a hill, but when you do know what it's actually doing you cringe and back off to save your engine.



S N 3 A K Y

[Racegem]

Let's put it even more simply.
Your spark plugs ignites your fuel/air mixture at say 8 - 10 degrees Before Top Dead Centre. By the time the mixture burns and starts putting pressure on the piston downwards, the motor has moved past TDC and the piston travels down the bore happily. As the revs increase, as does the speed of the piston, the advance in the dissy moves this spark up to 30 deg BTDC. This is because the burn time does not increase but the piston is moving quicker so the mixture has to be ignited earlier to keep up.
If your timing is out, ie; too far advanced, the mixture will burn too early and start to put downward pressure on the piston still moving upwards. You then have the situation where a force moving one way meets a force moving the other, a bit like a head-on collision.
The other cause is due to too much compression for the fuel being used. A build up of pressure causes heat. The higher the pressure, the higher the heat. Get enough pressure into a cylinder bore and this can generate enough heat to ignite the fuel before the spark plug does. This is called "pre-ignition". The higher the Octane rating of the fuel, the higher the pressure can be before "pre-ignition". Freshly built motors, even stockys, can find themselves with enough compression to have pre-ignition with a shit batch of fuel. Add to that incorrect timing via a worn dissy, and "PINGING" or "DETONATION" occurs.

So much for simple... but I hope it helps.

Yonnee.

[HighTeK]

Simple, Your timing is out. and by the sounds of it , way out.

Take it to a shop and tell them to tune it make sure the timing is set to 12deg.

My motor was pinging because the head gasket was blown between 1 and 2.

U don't need to know the physics of the sound it makes.

Cheers.

[HighTeK]

Correction,

U said u have a stage 3 cam, u will need the cam specs to give to the shop. and i think u will need to advance the timing past 12 Deg. (not sure).

[HighTeK]

Also, Why r u using Unleaded?, please don't say to save money.

Do u have special valves??

I use Leaded (that Leaded replacement shit), and lead adative (Flash lub or Valve master) just to be sure my vavles don't melt when i have the foot to the floor, and to extent the life of my motor.

OK , i'm done now.

[MadWagon]

i use unleaded because the engine is fully reconditioned and just gemis said use unleaded. the timings just been set at 10 degrees, sounds like this is the prob. cheers for all the input.