Determining ignition timing for modern combustion chambers

[mk e]

Can't go far wrong pulling out a little more spark than necessary (at least at first) rather than a little less...

I think that is the right answer to get started.

On the few I've done with engine originally spec for 87 octane and going up to 91 octane I ended up pulling out nothing until 5 psi, then like 1 degree at 6 psi, 2 at 7, 3.5 at 8, 5 at 9 and 7 at 10psi.....something like that. The air gets a LOT hotter as boost goes up, with an eaton roots I was seeing IAT of 260+ at 10 psi but bacisally no change under 3 psi. This was on an engine that liked about 32 degees naturally aspirated....if yours likes more timing it will probably want more timing pulled out.

[David Redszus]

I ran across a new tuning toy.
It connects to the OBDII port and send MAP, MAF, ignition timing and torque readings to my cell phone.

Its hard to use since I almost crash the vehicle watching the display.

[Belgian1979]

I ran across a new tuning toy.
It connects to the OBDII port and send MAP, MAF, ignition timing and torque readings to my cell phone.

Its hard to use since I almost crash the vehicle watching the display.

Yeah these things are dangerous addictions.

[Amilcar]

I ran across a new tuning toy.
It connects to the OBDII port and send MAP, MAF, ignition timing and torque readings to my cell phone.

Its hard to use since I almost crash the vehicle watching the display.

You better find some knowledgeable guy, who introduce you to the datalogging tech world.
I know one .......

[Xnke]

I ran across a new tuning toy.
It connects to the OBDII port and send MAP, MAF, ignition timing and torque readings to my cell phone.

Its hard to use since I almost crash the vehicle watching the display.

I use a laptop with a USB-to-ALDL cable, and datalogging software called TunerPro RT. It also allows me to modify the contents of the computer-but it only works for OBDI GM/Ford cars for the full feature for sure. There are many other makes supported but I don't know how limited they are-basically if someone has written the ADX file (datastream interpreter) file, it's supported.

OBD2 logging works with it, but I don't know how well supported the OBD2 computers are for re-programming. All the edits can be done but reflashing the ECM's may need a 3rd party program. I know the ECM that I'm using for this truck project requires a 3rd party program, and the LT1 cars also need it. (Although EEhack is will do the LT1 cars all-in-one now!)

[user-23911]

You're about 15 years late.