SPARK THICKNESS & LENGTH

A small spark would ignite a small amount of gas particles, which would then ignite further gas particles, and so on. It would be a mathematical equation of exponential growth. A thicker and longer spark would ignite more particles to start with, and so on, leading to quicker ignition of the entire contents of each cylinder. A faster flame front, not through faster particle-to-particle ignition, but through faster propagation.

My thinking.

yeah, the flame will still propogate at the same rate though, but it will take less time as a greater volume of particles will initially be ignited by the bigger spark (ie, with a smaller spark less particles will be ignited, but the flame will still follow the same exponential equation if all the other factors are the same).

But then there's the factor of whether the flame propogation shape will be different due to the spark being longer....from which the flame will still propogate at the same rate, but the actual mass will be different due to the shape change.

Exactly why people play with indexing and plug types.



About time the 6cyl section had a good technical discussion, instead all the crap that has been going on lately.

we index the plugs on the race car and have found it to improve the performance of the car based on times around the track.

We later accidentally were given plugs of the same manufacturer that protruded further into the combustion chamber, which again made a rather large difference to times for us on the track.. so much so that it had a few of the other drivers quite upset..

I haven't tried the autolite plugs, but it looks like they'd be worth the test anyway, as the improvement from flush to protruding made quite a difference.

We use NGK V-Power 9s currently.. we've tested many different brands over the years but these are consistent.

But there are some good comments in here, i recommend having a play around and measuring the differences, you'd be surprised what little things combined can achieve.

these autolites would be about an NGK 5 heat range. they also have a very very long projection. I wouldn't recommend you use them on a circuit racer.

i read before that you don't recommend them on a circuit car, but for the price its worth the effort.. we usually buy 20 plugs or so and get them as close to exact as possible when indexing.. I don't see how these are less likely to give good results, once indexed the plugs will just end up firing that bit closer to the centre of the cylinder on our head (horizontal plugs not vertical)

we clean the plugs on the car after every race as the car will foul the plugs unles it's pulling, so the warm down lap and driving through the pits make the plugs pretty black. This will burn off pretty quick, but we have the ways and means so may as well take advantage of it.

I'll look into getting some autolites sometime in the early part of the season when we have all the new regulations sorted, and get some back to back results (even if it's on a test day..)

What would the NGK V-Power 9 heat range convert to on the autolites?

Cheers, I commend you on your topical creation Tickford 6

here is the heat range chart for autolite.

 

 

Attachments:

ASP2007AutoliteHeatRange.pdf [32.18 KiB] Downloaded 336 times

What is the mechanical difference between plugs that have different heat ranges?

How can you tell if the plugs you are using have a too low or a too high heat range?

Sorry to bring up an old thread but MaTTeB did you manage to do the test so that we can find out the findings?