WOT Spark Advance

[Superdave]

Just curious how much PE spark advance you guys with modified gen3 engines are running.


I ran 25 degrees last year with premium and like 10.4:1 scr.. could have ran more but didn't need it. This year with the SCR dropped to 9.8:1 it's a total dog in PE. I'm thinking about kicking it up to 28-30 degrees.. too much?


Dave

[viper15230]

I ran between 25 and 27. Never made any passes with it but for some reason anything over 25 seemed slower on the butt dyno

[3400-95-Modified]

I think my current peek with a stock 3500 spark table is 25 at WOT... I may bump it up a little later if necessary.

[Guest]

28-30 will probably work. Meaning, I doubt its too much.

[treeZ24]

i had good luck in the 30-32* range, anything less and the power dropped a bit

what was your DCR ?

[3400-95-Modified]

wow guys, 30-32... I'm impressed it can go that high and not knock.. is this only with high compression motors? or is it less likely for a lower compression one to knock? I'm around 9:1 i think, 3400 lower with 3500 heads, nothing shaved down... Not sure exactly what compression that nets... but Its low enough to where I wont be afraid to hit it hard with N2O later.

I was thinking there was plenty more power in my spark table but I didnt know that it was at least 5-7 degrees worth of tuning in it.

[gectek]

well the point is not just giving an arbitrary number to spark advance, under WOT, you can add good amounts at the beginning, then in the middle rpms back it off, then in the upper rpm you usually fade a little more in. I just got through working on a car and added no advance over stock to the lower rpm, lower tp, but added a good amount(from 16-20 to about 19-24) and added about 3 to the upper rpm upper tp limits and blended it a little, gained fuel economy and power. im not saying this will happen in each case, but in this case gm designed the timing curve and numbers very badly. i get about a max of 3-4* of knock at wot, and most of it is at about 4-5k, after that, i could prob add more spark and maybe before that, but if i get too agressive, then itll be a dog in the lower rpms i have found

[Superdave]

it seems to like 28 degrees.. judging by the butt dyno of course...

[3400-95-Modified]

I'm gonna have to bump up my spark table and see what I can get out of this POS...

[z284pwr]

I know this is an entirely different setup, but I run 30-40* on a stock 3.1 with a Haltech E6k with no problem at all. The weird thing is I couldn't feel any difference between 20 and 35-40? Maybe the 3rd GEN motors respond better?

[gectek]

sequential > batch fire any day

[3400-95-Modified]

I noticed a difference from my stock table to the 05 3500 table... Not so much when going from 25 to 30 which is where I am now... But then again I haven't dynoed this thing yet. The spark change could just expand your peak power but not make it all that much higher...

sequential > batch fire any day

No argument there but remember our SFI motors go to MPFI mode after a certain RPM due to mechanical limits of the injectors.

[gectek]

yes, and if you increase the timing too much, you may not get knock, but you will build high cyl pressures and temp...not good for any component. i dont think there is really a need for anything over 30-35 unless you have a high comp monster but each engine is different

[3400-95-Modified]

I'm not going much higher than 30 right now till I get it on a dyno, I may drop it down to 28, but I currently have no registered KR at WOT, so I think I should be ok.

[Superdave]

sequential > batch fire any day

they only idle at SFI.. they go to batch fire above that..


besides, i'm running the 3500 as MPFI