14+14+14 baseline ignition timing testing

Propane, Butane, LPG, GPL, C3H8, C4H10
Post Reply
BigBlockMopar
Posts: 332
Joined: Sun Sep 02, 2007 3:29 pm
Location: Netherlands
Contact:

14+14+14 baseline ignition timing testing

Post by BigBlockMopar » Tue Jun 13, 2017 6:08 pm

Having a digital programmable ECU in my car for a number of months now, I can change and alter the ignition advance table on the fly.
Mentioning of the generally advised baseline ignition setting of 14+14+14 degrees let me to try this setting in the ECU and compare it to my own current advance table, which I've been tweaking for best performance and economyt ever since I installed the ECU.

The tuningsoftware (TunerStudio) has the option to enter 2 different timing maps, which can be selected or switched to, even during driving by a simple switch on the dashboard.

So just for fun, I tried out the 14+14+14 timing map the other day to compare it to my current ignition map.
During regular steady state driving there was no obvious difference to be noticed.
Only during accelerations I noticed the 3x14 timing map felt a tad slower then my regular timing table.

Below are some screenshots of the timing maps.
Here's the 3x14 timingmap as I filled the cells with, with full advance at 2750rpm;

Image

For comparison, here's my own 'evolved', streettuned timingmap, taken shape by daily/weekly tweaking certain rpm and 'load' areas;

Image


14+14+14 map in 3D-view;
Image


My evolved, 'work-in-progress' ignition table in 3D-view
Image

Note:
The left vertical column is Engine Load in kiloPascal.
kPa = engine load, or a reversed vacuum scale.
50 kPa = about 15" vacuum
100 kPa = full throttle (almost barometric pressure)

The top most row (100 kPa) in the tables, is what should be seen as the initial ignition curve like in a regular distributor, when no vacuum advance would be at play. Here you have the initial advance and 'mechanical' advance.
Down the table is where vacuum advance comes into play.
The lower row of the tables (<35 kPa) are when the car is coasting, so hardly no engine load is present.

My 318 engine idles (with transmission in Drive) at just under 600rpm and has the most intake vacuum with 24 degrees of advance.
The 24 degrees of advance let's the engine produce the most intake vacuum at 19+" (±36 kPa).

I've even had the engine idle at 350rpm in Drive once. Gets a bit choppy bit it still kept running.

My highway rpms hover around 2200-2400rpm.
kPa at those rpms and steady speeds is usually between 40 and 50.
https://www.bigblockmopar.com
'73 Dodge Dart - 318ci - IMPCO E vaporizer / 425 mixer - A518-OD trans - 3.55 gears - 225/50/17" tires.


storm
Posts: 559
Joined: Wed Jan 10, 2007 10:10 pm
Location: NSW, Australia

Re: 14+14+14 baseline ignition timing testing

Post by storm » Wed Jun 14, 2017 1:12 am

The similarities between your own tune and the 3x14 tune are pretty close in many segments. I'd be interested to know how the car runs if the timing for each segment is optimised for maximum vacuum/lowest kpa. To do that properly and to verify the result would need dyno time though.
Every job is a self-portrait of the person who did it. Autograph your work with excellence.

Fuel flow requirements calculations viewtopic.php?f=5&t=1638

BigBlockMopar
Posts: 332
Joined: Sun Sep 02, 2007 3:29 pm
Location: Netherlands
Contact:

Re: 14+14+14 baseline ignition timing testing

Post by BigBlockMopar » Wed Jun 14, 2017 3:04 pm

One thing I forgot with the 3x14 table, is to change the number in the lower left corner of the table. It should be 28 instead 26.
This would only have a slight effect on the other values.


I recently installed a toggle switch in the car, hooked to the ECU, so I could try running two ignition tables while driving.
First table was my regular table, the second table was the same table, only entirely 3 degrees advanced.
Flipping the switch during driving did nothing for the engine vacuum, neither on my dash gauge nor in the log files of the ECU.

Also tried an ignition map with 4 degrees retarded advance, compared to my regular table.
Same time, couldn't notice any difference during regular steady driving.

I expected to see at least some change. Tried to keep speed and throttle position as steady as possible while flipping the switch. This can be seen back in the logs, but no change can be seen in vacuum or engine speed.

Only during mid/heavy acceleration, I could feel a worthwhile difference in the seat of the pants.
This kinda led me to believe it's more important the cell values follow up perfectly on each other when the engine's rpm and load-point goes through/climbs all the cells on its way.


Here's an overview of which areas of the table one is using during various engine 'states';

Image
https://www.bigblockmopar.com
'73 Dodge Dart - 318ci - IMPCO E vaporizer / 425 mixer - A518-OD trans - 3.55 gears - 225/50/17" tires.

storm
Posts: 559
Joined: Wed Jan 10, 2007 10:10 pm
Location: NSW, Australia

Re: 14+14+14 baseline ignition timing testing

Post by storm » Wed Jun 14, 2017 6:11 pm

Ah ok, another instance where LPG doesn't behave the same way as petrol. When I tune petrol I can watch the vacuum readings change and was hoping LPG would be similar.
Every job is a self-portrait of the person who did it. Autograph your work with excellence.

Fuel flow requirements calculations viewtopic.php?f=5&t=1638

BigBlockMopar
Posts: 332
Joined: Sun Sep 02, 2007 3:29 pm
Location: Netherlands
Contact:

Re: 14+14+14 baseline ignition timing testing

Post by BigBlockMopar » Wed Jun 14, 2017 6:32 pm

For setting idle-rpm timing, I've done exactly that and ended up with 24° of advance where after careful eyeballing the vacuumgauge, the engine made highest vacuum/least kPa-load at 500-600 rpm in Drive.

I recently tried doing the same with upping the engine speed to 1000rpm against the stall convertor, with the brakes on, and then play with the advance. But it was already quite a bit harder, to settle for a good advance number what the engine liked best.
The load applied on the engine on a fully stationairy drivetrain to reach 1000rpm, is not something the engine will see very often anyway.

One thing I did find out on a highway trip once, that the engine liked a bit less ignition.
This was about the only time I noticed a slightly higher average engine vacuum during a trip.
I recall it was running at first at 35° advance at 2000rpm, while later I found the engine liked 31° better at the same RPM and load. (Same AFR, same roadsituation).
https://www.bigblockmopar.com
'73 Dodge Dart - 318ci - IMPCO E vaporizer / 425 mixer - A518-OD trans - 3.55 gears - 225/50/17" tires.

BigBlockMopar
Posts: 332
Joined: Sun Sep 02, 2007 3:29 pm
Location: Netherlands
Contact:

Re: 14+14+14 baseline ignition timing testing

Post by BigBlockMopar » Fri Jun 16, 2017 5:33 pm

Had a closer look at the ignition table today and noticed over time, I had upped the advance again in the highway rpm-areas.
Pulled some advance (about 2 degrees across a number of cells), smoothed the transition to nearby cells and noticed an increase in engine torque and drivability again during the commute to work.
https://www.bigblockmopar.com
'73 Dodge Dart - 318ci - IMPCO E vaporizer / 425 mixer - A518-OD trans - 3.55 gears - 225/50/17" tires.

Post Reply