alanderson1978

iTrader: (1)

I accidentally tried that this weekend. Was trying to be conservative with spark, and the IAT adder drove it negative. Even a few degrees negative advance makes it a DOG

That's with a stock cam though.

Spoolin

iTrader: (8)

Ok so check this out, did some research and this is what I found.
Detonation/pinging/knocking occurs after the spark plug fires and starts the combustion process and Pre-ignition occurs before the spark plug fires and starts the combustion process so they are in fact two different ignition problems.

The optimal degree to develop peak pressure is 14-18 Degrees ATDC.
So that being the case, detonation/Pinging/knocking is when that peak pressure is derived sooner than 14-18 degrees due to a sudden ignition of the unburned fuel/air mixture from an external source other than the flame front(post spark plug firing). That external source is usually and in most cases a shock wave which is produced my the flame front and is magnified by the environment inside a combustion chamber causing an instantaneous increases in pressure and resulting flashing of the remaining unburnt air/fuel pockets in the cylinder. The higher the Octane rating the less likely the remaining unburned pockets of fuel/air will ignite before the flame front reaches it. (The higher the pressure in any environment the lower the ignition or Flash point of a combustible material.)
If the detonation arrives after TDC it will cause the engine to operate improperly, lose power, and lag because it is not able to convert it's potential energy at the precise moment where it will do the most good (14-18 degrees ATDC). If detonation occurs prior to TDC it can cause an engine to break apart, either pistons, cylinder walls and in the lucky instances it will lift the head and blow a head gasket.

Pre-ignition is when the Air/fuel mixture is ignited before the spark plug fires by glowing carbon deposit, hot valves, bad plugs, etc... and can lead to total engine destruction in bad cases and in others you'll see flames shooting out the intake manifold...still not good.

Stoichiometric

iTrader: (10)

Here's my timing.

alanderson1978

iTrader: (1)

What mods and engine do you have?
Are your IAT and ECT advance tables back to stock?

I have HPT, so It will take me a while to compare (axes are switched)

Thanks

Stoichiometric

iTrader: (10)

Radix supercharger, Alkycontrol, GT-7 and bolt on stuff.

Spoolin

iTrader: (8)

Hey Henry, what's the units on the Horizontal Axis? Trying to figure out how to read it which it makes sense, as the RPM's increase you add more and more timing but I don't completely understand what the Gram's/Cylinder is all about. I would assume it's the amount of fuel injected per cycle??

alanderson1978

iTrader: (1)

That is Dynamic Cylinder Air. If you are using HPT, the axes are swapped from EFI Live. It is basically the mass of the air charged into each cylinder.

Spoolin

iTrader: (8)

Oh ok... I'm not familiar with that yet.
I realize that psi is a measurement of resistance and nothing more and the important information is air flow which but I'm not familiar with what's considered good amount of flow and what not.

gmforlife

iTrader: (2)

Ditto That, doesn't matter, you are decelerating, who cares.