Spark plug hot or cold?

[DSM10000]

Rebel without a clue. Who radicalised you? Who brainwashed you into believing being a member of a smaller flock is in some way superior?

I find with these that is generally a case of more horsepower than IQ points.

 

[BlackC55]

If you have pre-ignition then the map is bad. No need for different plugs after a re-map.

 

[ALFAitalia]

Even after a significant boost increase?

 

[StMarks]

Even after a significant boost increase?

I'm sure that both you and BlackC55 are better placed to know than me, however fwiw... : My little 675 is slightly enhanced, and re-mapped. It runs on the OE specification iridium plugs. Other versions I know of are far more highly tuned for racing. Whilst some of the teams do use "race plugs" instead of conventional ones, no one has changed specifications to a colder/harder version afik.

 

[190]

I’m wondering if anybody can give me some insight on wether I’m in need of changing my spark plugs (hotter or colder)

I don't know if you can hear anything from the engine but here's some guidance on abnormal combustion events.

A spark plug that is too hot may cause Pre-Ignition which is abnormal combustion that occurs before the normal ignition spark. . Pre-ignition is initiated by glowing carbon or a spark plug that is too hot. Because the mixture is ignited far too early it builds pressure for most of the compression stroke and so can be very destructive melting plugs and holing pistons quickly. If someone can say what pre-ignition sounds like as thankfully I've never heard it on one of my engines. I imagine it sounds like a knock at cylinder firing frequency unlike pinging.

Pinging more correctly called detonation is abnormal combustion that occurs after normal combustion has already been initiated by the spark plug. As the combustion pressure rises spontaneous combustion occurs in some parts of the combustion chamber before the normal flame front has managed to get there. The noise you hear is a pinging metallic resonance of the cylinder affected and it is characteristic of the noise that it sounds to be at a faster frequency than the cylinder firing frequency. The reason for this is there may more than once instance of detonation occurring in different parts of the combustion chamber on each cycle. Detonation can be destructive but it is not usually instantly destructive and an engine might run for some time with occasional periods of mild low speed detonation.

 

[markjay]

I don't know if you can hear anything from the engine but here's some guidance on abnormal combustion events.

A spark plug that is too hot may cause Pre-Ignition which is abnormal combustion that occurs before the normal ignition spark. . Pre-ignition is initiated by glowing carbon or a spark plug that is too hot. Because the mixture is ignited far too early it builds pressure for most of the compression stroke and so can be very destructive melting plugs and holing pistons quickly. If someone can say what pre-ignition sounds like as thankfully I've never heard it on one of my engines. I imagine it sounds like a knock at cylinder firing frequency unlike pinging.

Pinging more correctly called detonation is abnormal combustion that occurs after normal combustion has already been initiated by the spark plug. As the combustion pressure rises spontaneous combustion occurs in some parts of the combustion chamber before the normal flame front has managed to get there. The noise you hear is a pinging metallic resonance of the cylinder affected and it is characteristic of the noise that it sounds to be at a faster frequency than the cylinder firing frequency. The reason for this is there may more than once instance of detonation occurring in different parts of the combustion chamber on each cycle. Detonation can be destructive but it is not usually instantly destructive and an engine might run for some time with occasional periods of mild low speed detonation.

When I used to tune engines (when the dinosaurs roamed the Earth... ), you'd advance the ignition by slightly rotating the dizzy until the following occurred: when picking up slowly from very low speed at a high gear, some mild 'pinging' is heard. This pinging will not be present during normal driving, because you'll rarely do that (picking up slowly from very low speed at a high gear), and it was an indication that the ignition was as advanced as it should go. This went out the window when I bought my fist strobe, BTW

However, the above does suggest the 'pinging' is related to the spark being generated too early?

 

[E55BOF]

Anyone else thinking "Crap map"...?

 

[StMarks]

Anyone else thinking "Crap map"...?

Quite a few of us, I suspect

 

[Bellow]

it is characteristic of the noise that it sounds to be at a faster frequency than the cylinder firing frequency. The reason for this is there may more than once instance of detonation occurring in different parts of the combustion chamber on each cycle. Detonation can be destructive but it is not usually instantly destructive and an engine might run for some time with occasional periods of mild low speed detonation.

The pressure wave generated by detonation bounces around the chamber hence the higher frequency. It also scours the boundary layer exposing the piston crown to full combustion heat which is why it is so destructive.

However, the above does suggest the 'pinging' is related to the spark being generated too early?

Only in as much as it can be eliminated by retarding the ignition timing. Switching the engine off achieves the same.

 

[SpikyMikey]

Anyone else thinking "Crap map"...?

Given the way 'pops and bangs ' are created.....yep.