Post-up your Ignition Advance table!

[R/Tony]

Hey y'all

I have come up with the idea to share advance tables along with the mod list so we can see more than less in which points we can add or pull more timing... anyway I think its a good idea isnt it?

So Im starting with mine:


That is the total advance numbers since Im running DIS (distributorless)
Mods: A lot!!!... but basically is a 8v 782 ported head, 2.5 forged block, Holset turbo, roller cam, megasquirt 4bar, 783cc injectors, no meth, no alky, no race gas...

I know its pretty low and that is why I want to see more tables so I can have a better idea of how much timing can we run

Tony.

[zin]

It's always good to share data, I'd suggest adding a dyno sheet if available so everyone can see what the power curve looks like, as this might help to see where more or less timing is needed. Knock voltage/retard would be great too, but anything is better than nothing (which is what I have to share...).

As a side note regarding optimal timing. This will vary with any number of things, but out of boost they will all be pretty similar, with the combustion chamber design being the biggest variable (although compression ratio will play a part).

At any rate, the goal of any ignition event will be to put the peak pressure at the point the engine can best turn that pressure/energy into torque/HP.

Oddly enough, from gigantic ProMod "Mountain Motors" to tiny motorcycle engines, that "sweet spot" will be in the 15-20* Atdc range. From there it is simply a matter of how far Btdc you light the mix to achieve this. Most engines will be in the 36-38* range if an average combustion chamber is used. Smaller bores (less distance for the flame to travel) will not need as much lead, as is the case with very efficient combustion chambers (TIII, and most 4-valve heads, and some 2-valve designs ie Yates Prostock). Poor designs or very large bores will need more time, as will a slower burning fuel for obvious reasons.

As the mix is more tightly packed in, the flame can consume more faster, lessening the need for timing/lead. This is why when the boost comes up less timing is needed/desired. Nitrous is similar, though in it's case the faster combustion is due to the 14% more oxygen that is present, as well as the exothermic (heat producing) reaction of the nitrous molecule breaking down into nitrogen and oxygen, but mostly from the oxygen.

Sorry for the lesson on combustion there, but it did seem appropriate to the thread... just a bit long winded!

Mike

[R/Tony]

Cool !! nice input zin!

certainly I need every possible info I can get since Im tunning process, thanks for that !!, but I just thought that was a good idea to share ignition tables, the more tables we see the best tunned cars we will get