Is there a recommended max timing at lower boost levels?

[RarlyL8]

As stated, I run 26° at 0.75bar, there is one data point for you.


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[Tippy]

Originally Posted by bpu699

Thanks for the input guys... Folks are posting what timing they run at beak boost... There are tons of threads on that... And I probably read them all until my head hurt... Twice...

What hasn't been hit on, is with a programable system, what setting is safe a lower boost? That's the part I don't get...

If you are running stock, it's easy. Anything past 5psi the system retards 10 degrees so regardless of your settings, you are running a flat timing curve...

If you run 28 peak, you are running 18 under boost... Whether 5 psi, 10 psi, or 15 psi...

But if you can run adjustable timing, what could you run at 5 psi, 10 psi, 15 psi? What do folks with the programable units like the msd al2 run at these boost levels?

Not sure if I am asking the question right...

356-911 was running 28 degrees at 5 psi, 24 at 9 psi, 18 at 12 psi... Using the msd btm...

Is a real 24 degrees at .5 bar ok? Asked another way, at what boost level do you start taking timing away???

Will post some info as soon as I can get the btm to work... Installed it today, and now my ignition won't work. Sigh... More putzing tomorrow...

Thanks all...

You start pulling timing once the threshold is crossed from no vacuum into boost, tapering to peak boost.

Because, cylinder pressure starts increasing at that point and continues getting higher and higher requiring less and less timing.

[Tippy]

Look at the thread with EFI timing maps posted

[bpu699]

Thanks guys... I appreciate the info.

Bo

[JFairman]

Some states or parts of states have 93 octane premium gas and others have 91 for the highest octane or somewhere in between. I think you need to take that into consideration when asking this question.

[John at J&S]

A knock controller can be thought of as an octane sensor that can change ignition maps with octane number.