High-compression, twin-plugged ignition curve please?

[JohnJL]

Could someone please share their ignition curve on a similar engine (or offer guesses?)

Am implementing ignition control today and further tuning, looking for a baseline curve.

Engine is 3.0L 10.2:1 compression, twin-plugged.

Thanks all

[JohnJL]

Pls....? Search and workshop manuals seem to be showing an average 12-14 deg idle and ramping up to 32 deg from 1300 to 3000 and max (32) there out.

However few of the contributors list their engine configuration and my engine tuner (ECU provider) says there numbers are very different from other makes he usually works with (Mazda and BMW)


Any help is much appreciated.

[CruiseControl]

John, I also have interest in twin plug ignition timing. Have twin pluged on recent rebuild. Will be a couple of weeks before turning over the engine. At this time I have reduced max advance by 10deg, with lesser reduction as timing gets closer to TDC.
Comp ratio I have is 10.1:1 and using 98RON
If you wish PM me, and I can email preliminary ignition MAP which is the revised single plug MAP. It will be a few weeks before runing on dyno to revise the MAPS for twin plug etc...
What ECU are you running?

I second the call for assistance on proven ignition timing for the twin plug setup.

Paul

[cstreit]

Heres some comparisons I've used to set up my 3.0 (and subsequent 3.3L)

[CruiseControl]

Chris
Thanks for the provided detail

Could you advise me of how you include / convert the spreed sheet data to a .JPG, so it can be included in the post.

Paul

[cstreit]

Paul, you're welcome

I highlighted the range in Excel and did an Edit->Copy... I then opened MS Paint and just hit Edit->Paste (didn't know it would work, I was just hopeful). Then I did a SaveAs and selected type of JPG.

BTW you can probably tweek this curve. It was my starting point and works well. I timed the lower plug to fire just 1 degree after the top one.

[JohnJL]

Chris,
Thanks for the help. What's the theory on doing one after the other? Did you do this on intuition/theory or learn it from someone else? I'm intreagued!

[Laneco]

Cstreit,
We have the twin-plug electromotive on our car. 3.2 (from a 3.0) with 10.5 to 1. Trying to decipher your diagram - hope I'm not off base, so please bear with me, I'm new at this.

Looks like 8 degrees initial with 30 total at 3k? I can't get anywhere NEAR that on pump gas... I have it set at 8 initial and 24 total (16 at the 3k setting). Anymore than that and when its hot outside or I can't find 93 octane, I'm entering the danger-zone for pre-ignition...

Is 24 total an expected amount of total advance on the electromotive twin-plug with 10.5? Or am I in mis-tune and leaving HP on the table? angela

[cstreit]

JohnJL, I "heard" this from some "reliable sources". Never dyno'd it. Might be worse then better. The theory is that the spark follows the flame front and gets a better burn...

Laneco... I'm running 10.2:1 on 93 octane on 100mm pistons with this curve... No detontation... On hot days (93+) I mix in 100 octane 50/50.

[Laneco]

Thank you! I'll experiment a little with the mix on hot days as I can get 100 octane down here (medford). The engine builder had me aiming for about 27 - 28 total, but I just couldn't quite get there and still feel "comfortable", at least on regularly available pump gas down here at over 100 degrees.

Thanks!
angela

[cstreit]

Yeah, if you have to love on 90-91 I wouldn't push it much.

Are you saying "comfortable" as in "detected detonation" or as in "I'm just worried enough to lose sleep?"

The reality for me is that my engine rarely sees the rev-range between 1500 and 4500 RPM, it's either idling or flat out, so I'm rarely in that detonation danger zone...

[Jeff Alton]

With 91 octane 24-26 is about all I would expect. Up the octane a little and maybe you can go a little higher.

Chris what sort of AFR's are you running with that timming?

Cheers

[JohnJL]

Laneco, when you say you're in the danger zone, have you observed/monitored detonation with det-cans or something else?

[cstreit]

220, 221 whatever it takes... (12.7-13 on average Jeff)

[Jeff Alton]

Good info, thanks.


Cheers