Setting up an initial ignition timing table

[wildman]

search at turbo124.com for a completed spreadsheet. i believe limits were put in place to stop negative numbers and ridiculous maximums at the borders of the logic.. the algorithims needed limits.

[milesinfront]

No joy locating at turbo124... Why not post the link?

[wildman]

http://www.turbo124.com/forum

[wrenchdad]

No joy locating at turbo124... Why not post the link?

Here is a link that I found.

http://www.turbo124.com/forum/viewtopic.php?f=2&t=5591&p=49960

wd

[Mark_Marine]

What does everyone think about this as an initial spark map?



This is a 1600cc 4AGZE big port with 8.5:1 compression, forged (stock) internals, t25 making around 15PSI boost on the best pump gas I can find.
My boost threshold is fairly high (small displacement, medium turbo, large-ish intercooler) I don't see full boost until about 3600-3700 rpm, so any of the higher boost/lower rpm values are irrelevant
I just want to find a good base map that I can start tuning on the road from, and when I've got it at the 75% mark I plan to bring it to the dyno so I can safely dial in all the high load/high boost areas. I built this from some interpolation and extrapolation of the suggested map in the megamanual.

[PSIG]

I'd say that looks very conservative and a good place to get your first tuning runs in. I understand that you don't have cruise timing in yet as it's not tuned, though I would find your best idle timing before leaving the driveway. Once that's set, start tuning NA. Since you are basing all your advance and retard against timing at atmo (~101kPa), that is your primary tuning goal - finding MTBT (minimum timing for best torque) through the entire rpm range at 101kPa (or whatever yours runs at WOT off-boost). It would suck to get to the dyno only to find the engine really wants 23° or 29°and you have to re-do your table. Do you have a plan on how to do that on the street? If you don't, I have developed a method that works well for me that I can pass along if you haven't already read it.

David

[R100RT]

CAn you provide a link or copy of that "street" method, I'd love to read it.
Lorne.

[HidRo]

I would be interested as well.

[Mark_Marine]

Yes, I'd be very interested as well. I just want something safe enough that I'm not going to hurt anything, but close enough that I'm not p*@#ing my money down the drain at the dyno, paying for runs that just tell me I'm really really far off.

[Mhm]

I would also be interested in reading that method of setting timming on the road, just for a start to get going.

[sedd]

Attached is a spreadsheet that is based on research from the net. I have attached this before in other posts. I see very recent activity in this one. I am not saying this is fully correct, I want to create some feedback from others who are a lot smarter and more experienced. I feel that the dyno effort and testing may be the only way to get this correct. So this is a first step toward that.

The theory of this spreadsheet it that it uses torque values and the curves from similar engine and cam combinations, and then also adjusts the values higher as the MAP values are decreased, when the throttle is not as far open. The torque is supposed to be an indication of where power is being created and those areas of highest torque need less advance. The entire effort allows the tuner to create much more detail and fine tuning than the old mechanical and vacuum advance set ups.

I had been concerned about the high values at low rpm and was reluctant to set them per the table. Still a bit leary about that. I feel the only reason the old mechanical vaccum distributors had the low values at low rpms was to allow the engine to start. Those old distributors didn't have the seperate starting advance settings like the MS systems. The MS uses a low value at start and then switches to the table which can and should be much higher. I am thinking there isn't much to use from the old distributor settings except the data from full throttle efforts and then only at higher rpm. Those old distributors had to be set for full throttle and had no way to adjust properly for lower MAP = not full throttle.

I am sorry this spreadsheet is not very well designed as it takes quite a while to figure out what is happening, even for me. I feel one nice thing is that is does create a smooth 3D plot.