timming and af ratios

[b_diddy]

well i htink i know why i was running rich at 20 psi, lol. i was retarding to 9*. thats not good correct?

we got it set now at around 17 psi or so, with lowest timming at 4k @14*, and in the higher rpm band at 19-22*

is this where it should be?

when the timming was retarded it was at .91 volts o2, now its at .95-.96.

again, are these where they should be, or should i be trying to hit different numbers?

[ryanman]

Sounds good to me. How the hell was it only getting 8 degrees advance?

[b_diddy]

ok, forgot to ask this too

what is considered advanced, and what is considered retarded?

and i have no clue, i dont understand the whole timing thing actually now that i think about it. so if someone could explain it...

[v413nc3]

Timing is regarded as the number of degrees before the piston reaches top dead center (BTDC) when the spark fires. The earlier it fires the more fuel that gets burned and the more power is made, but also the greater risk of detonation and knock. So 20* of timing means that 20 degrees of rotation (1/9th the rotation of the crank) the spark fires. Lower means it fires later.

[b_diddy]

Timing is regarded as the number of degrees before the piston reaches top dead center (BTDC) when the spark fires. The earlier it fires the more fuel that gets burned and the more power is made, but also the greater risk of detonation and knock. So 20* of timing means that 20 degrees of rotation (1/9th the rotation of the crank) the spark fires. Lower means it fires later.

ok, so whats "normal" whats retarded, and whats advanced.

[sbiggi]

its all relative too the timing you want to run.....

base timing is 5 deg Before Top Dead Center or advanced 5 degrees

when we say your timing is retarded, its still advanced, but not as much as it should be.

You want 20-23 degrees of total advance under WOT, any less then that and you could say that the timing is being retarded by X degrees

-Seth

[_=X=_]

Timing "advancement" is nessesitated by RPM. At lower RPMs less is needed to insure that the combustion chamber is seeing peak pressure at 14-17* ATDC. Which is what most would say is best for power. The opposite is true for higher engine speeds. You'll need more advance to keep peak pressure at 14-17* ATDC, because the flame front is still moving at the same speed(based off fuel and swirl, mostly), but its surroundings are moving much quicker.

I hope this is easy to get. Its what I've pieced together from way to many overy-complicated essays[sic].

There are a few other variables to what you should run, but this is the most... relevent?

But as you can see, there is no 3k=7*, 3.5*=10, etc etc. It needs to be tailored to your car and motor to preform to its fullest. Also do a search for " igintion retard and more boost" or something to that effect. Good stuff.

[Hal]

Timing, in DSMLink is represented as a positive number.

Timing retard due to knock is represented as a positive number and is the number of degrees of timing being removed.

If you look at the timing graph and the knock graph, for every step in the knock line there will be an opposite step in the timing line.

Hal

[hoffman]

First, log your car in 2nd and 3rd gear starting at 3k rpms and let it run to the top of the gear. Catching a quick shift from second to third only makes reading it confusing. Shift easy.

Hopefully your timing will will start at around a modest 10* and climb to anywhere from 16-19* by 7k rpms. I have never heard of a stock DSM hitting 22* advance unless they set the base timing wrong.

When you look at your timing curve, any spot where advancement stops, levels out, or drops, and you don't have timing control, is suspect to knock or timing being retarded.

Remember, timing numbers will peak higher in 2nd gear than in 3rd.

[v413nc3]

22-23* total advance is what you do want to see in the end though... so tune to achieve that by adding fuel and timing to remove knock yet gain power.

[b_diddy]

and this is why i need to visit a dyno...

thx for all the help guys!