327_TPI_77_Maro

iTrader: (8)

Hi guys, has anyone ever extended the spark table in a 6E bin to exceed the factory 4800? I am running 6E on a 327 that sees over 6000 rpms and would definitely be able to use the added capability of high rpm spark tables.

kevm14

Between the sloped adder and the fact that all your timing is probably in WELL before 4800rpm, you don't technically need to customize SA past 4800. That didn't answer your question, of course...

327_TPI_77_Maro

iTrader: (8)

My timing is mostly in before 4800, but not completely. I have 200 psi cranking compression and I do get knock counts if I try to ramp say 34 degrees of timing all in by 3500. I can get 30 in by 3500 and 36 by 4500 and I'm okay.

kevm14

Just for the sake of argument, my Camaro's stock extended timing table looks exactly the same as the highest point on the main timing table (which ends at 4000rpm). I don't think you'll gain much, if anything.

bjankuski

I have often wondered about how to get higher then 4800 RPM spark tables. If you reduce timing after your peak power point you can extend your power curve, so there is an advantage to being able to control timing at 6000 or 7000 RPM.

Fast355

iTrader: (2)

I don't see why you would want to reduce timing after peak power? Cylinder pressure is on the downward slope after peak torque.

kevm14

Plus the combustion cycle has less and less time to complete, and since things burn at the same speed, you need to light it off sooner as RPMs rise...or at least the same.

327_TPI_77_Maro

iTrader: (8)

Dragracers definitely do retard timing at high rpms. The cylinder temperature and combustion chamber pressure increasing begin to negate the need for lots of timing at really high rpms

Fast355

iTrader: (2)

Racers OVER advance the timing in the low-mid range because of the cam. If the advance continued at higher RPMs it would fry pistons. That is where the retard comes in.