5.7L Ignition Timing Table - Feedback

[GoodysGotaCuda]

The following table is a lightly adjusted timing table from EFIsource, mostly just around the idle cells and it seems to work well in that area.

My 'Cuda has 100 or so miles on it and I am feeling more interested in tweaking the tune for power, since the drivability is sorted out pretty well.

Please provide feedback on the table below based on your experience, from what I read, the mid-range is probably a bit high..

The X axis is obviously RPM, Y is MAP [kPa]. 100kPa = WOT, ~45kPa = Idle

 

[port-holio]

Don't know specifically what numbers should be in there, but some things to keep in mind:

1. Modern engines with great squish and multiport EFI (especially dual plug!) have very efficient and fast burning heads. Mid 20's can be A LOT of timing, especially around peak TQ.
2. As you turn up the timing on such engines, you will start losing power way before you get audible or sensor detected detonation.
3. Doing a spark loop test on a steady state dyno is about the best $$ you can spend in this regard.

my $0.02
PH

 

[GoodysGotaCuda]

Thanks PH, can you fill me in on what a "Spark Loop Test" is? That's a new one for me.

 

[port-holio]

Thanks PH, can you fill me in on what a "Spark Loop Test" is? That's a new one for me.

Some people call it a "spark hook test". It's a series of runs (with cool down in between), where the advance is started low, and increased a couple of degrees each successive pull. On most engines with decent chamber design & quench, power will stop increasing at some point, slowly decrease, and eventually end up knocking. Go through the data, and pick the minimum spark that gets you near the power peak. AFR should be about 12.5 at peak torque, and about 13.0 around peak HP before you try this. All the better if your ECU uses a calibrated knock sensor and will pull timing when it hears detonation.

https://www.amazon.com/dp/1932494421/?tag=joeychgo-20

IMO this book is the best money you can spend on EFI. It explains everything.

 

[BigBlockMopar]

Why the 'blue dip area' from 900-1200rpm? Why would your engine suddenly like 4.5° less timing at that point?

Presuming you have an auto transmission, to find out what your engine likes best at idle rpm, just put it in Drive, adjust the rpm to what you want, and start playing with the ignition values 'around the active spot' until you get the highest engine vacuum.
Readjust the rpm in between if it changed up.
I think you should be able to get the kPa down well into the 30's

You know that kPa is Engine Load. An idle load of 45 kPa seems fairly high to me, especially at idle when there's hardly any work to be done.
My low cr 318 idles (in Drive) at 500-550rpm with 36 kPa load working with 24° advance (Propane powered+power steering).

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In your table, the advance numbers in mid range (900-2200rpm) seem to be going down, when looking vertically top-down at the columns.
That's reversed of what it should be.
- High load = lower advance
- Low load = higher advance

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Why is your table starting at 200rpm?
That's cranking speed, which you don't need to have in the table.

The rpm-scale in your table doesn't increase with equal steps, making it harder to 'see' smooth transitions.
I would start off with 100rpm lower than your lowest idle speed, say 500rpm, then increase every column with 200rpm, until your reach max torque area of your engine. Then increase with larger increments till redline, as you don't need detailed timing at those rpm-ranges like you want at lower rpms.

My timing table starts at 400rpm, increases 200rpm up until 2000rpm, from which it's increased with 250rpm until 3000, after which the last 4 columns in the table increase with 1000 to 6000rpm (which I'll never reach anyway with my engine).

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When I started playing with the timing map on my Megasquirted 318 I noticed an immediate improvement over the distributor timing curve I had before, which I had tuned and tweaked many times before that.
Everytime I make some noticable changes to the timingtable, I've saved the previous table for comparison. Since I started this, I've saved over 60 timingtables.
Every once in a while when I found that a certain table worked quite good, I put "OK/GOOD" in the table's filename, so I could always grab that table as a known good setup/reference.

 

[AJ/FormS]

I agree the chart is flipped. It will run your engine cuz the variations are so small. But it needs a ton of work to get it just close to a Distributor, then a ton more.
Your street-engine operates from about a hi of 26 inches vacuum to a low of maybe 4 inches. In Kpa this is a hi of 13 to a low of 80/85.
In your chart,
at 750, the timing varies just about 3*.
at 3500, the timing varies just about 7*.
at 4500, about 6*
at 5500, about 8*
None of the numbers are too big, and none of them are optimum.

My engine likes 14 at idle
and as to power-timing; the D adds .78 degree per 100 rpm from 1000 to 2800, so at 2800 the power-timing is 28degrees. From there to 3400, it pulls in another 4* making that span 600rpm and 4 degrees so this is .67degrees per 100rpm, for a total of 32*
My Eddie headed 367 burns 87E10 at 10.9Scr,8.7Dcr/180psi with this curve. This is without any assist from the vacuum advance system.
As to part throttle
Beginning at around 1600IIRC, the vcan starts to roll in the advance and by 2000 it is all in, and the amount is 22*. So at any cruising rpm, above 2000; up to 22* can be added to whatever the power timing might be. Ergo at 3400rpm it would total 32 plus 22=54* While between 1600 and 2000 the vcan is rolling in say 5.5* per 100 rpm. These are the maximum amounts of Vcan timing at very light throttle, as when cruising.
Therefor at 2000 rpm where the power-timing is 21.88, UP TO 22* more can be added for a total of say 44*. But as soon as you start tipping in the throttle the Vcan starts dropping out, so depending on the load, the timing could be anywhere in between those two numbers namely 21.8 and 44.
I don't see these kinds of variations in your chart.
I agree with what previous poster BBM said in post #5, especially as to the rpm divisions.


Here is a handy convertor
Wallace Racing - Convert Pressures

 

[Map63Vette]

Hold on a second before you change anything. I don't agree with those above. The table is not flipped, it just has a different meaning than you guys are thinking. That is not engine "vacuum" that is being measured exactly. Higher kpa numbers does not mean more vacuum. The chart reads absolute pressure, so 100 kpa is roughly atmospheric (or wide open throttle), and 0 kpa would be near total vacuum. It's usually better to think of it as engine load as a percentage, though maybe that's not exactly 1:1 in ratio, but probably close enough since 100 kpa ~ 100% on a naturally aspirated engine. Boosted engines change this around some.

I think your max load numbers look pretty good. They say the modern Hemis don't like much more than 21-22 degrees all in and that appears to be what is in there. As for low load/cruising, you can probably get away with more, but it's up to you what you want to tune for. In datalogging the newer Challenger my dad once had and our Ram truck with Hemis, they would command nearly 40 degrees of timing at very light load. Realistically though, unless you are really trying to lean it out and optimize gas mileage in cruise I wouldn't worry about it much.

 

[BigBlockMopar]

We (I) didn't say the entire chart is flipped. Just the area between 900 and 2400 rpm is increasing/decreasing the wrong way.
I know what kPA means in relation to Vacuum. I run a digital ignition too on my Dart.

 

[myduster360]

The timing map is not in any way "flipped" lol.
Looks like he's put Tip-In spark retard into to his main timing table. Best to leave that separate since Tip-In is a transient condition. There should be a separate table for it.

For Reference here's a typical Stock 5.7L Timing(2006 Magnum). All 5.7 have TWO timing maps, one for Part throttle CLosed loop(A/F=14.7) and one for WOT(A/F=11-13)

Part Throttle

WOT

 

[port-holio]

Honestly, my spark table looks kinda like the one in the OP. Past about 2000rpm, it's really hard to get the engine to spend much time between 90kpa and 50kpa, so I sort of get the top two rows tuned for WOT, and never really got around to modding the middle of the map. This might be why the 1800 rpm column, etc. look a little odd. Most people just smooth the map cosmetically after the majority of tuning is done.

ps - timing is the easiest way to adjust for traction in low gear, in cells that you don't really see in 2nd or 3rd, and that can make the spark table look a little odd sometimes.

pps - if you have the cells/resolution to spare, starting your spark and fuel maps in the cranking rpm range is recommended by Banish and a few other pro tuners. The ECU uses actual cell values instead of relying soley on guesses or extrapolation, and also makes the engine less "stally". I took advantage of that going from a 8 column Holley Commander 950 to a 16 column Holley HP, and the improvement was undeniable. My engine doesn't even complete one full revolution on the starter before it roars to life.

ppps - the WOT values below 1000 rpm show good thinking. Small advance numbers in these cells really help the engine rev up when you goose it in park or neutral.

IMO, it's these intangibles that really make the move to EFI worth it. They might not ever show up on a dyno or timeslip, but make it act like a completely different engine.

 

[BigBlockMopar]

Goody, some feedback about our feedback would be nice too!

 

[GoodysGotaCuda]

Goody, some feedback about our feedback would be nice too!

I have a few comments to go around, I have been fighting other fires lately and have been trying to get some miles on the car!

• At a high level, I need to learn the in's and out's of the Megasquirt platform to best suit my needs. Primarily, I would love a closed loop and open loop timing table, I just need to figure out how to do it. My double-overdrive trans wants to run in the "high idle" area when going down the road, I need to help it define when I'm idling and when I'm at 60mph @ 1,800rpm.

• The Hemi does not want more than ~22° or so of timing, hence why it may look "backwards". My low load will take the higher timing with no concern for damage. This isn't an LA engine that needs that high timing.

• The blue area around idle is helping control any surging idle. Below target rpm, it bumps timing to recover, above, it retards timing to bring it back down. I am up to 350 miles on the entire build and have spent minimal time tuning the spark tables, I'm getting there however.

• I have 200rpm starting so that my cranking timing is defined as very low.

I'll go through the responses in more detail this afternoon and see if I can fill in some gaps!

 

[lxmodguy]

There are some serious out in left field comments in this thread. The timing depends on the heads. The heads depend on the year. The VVT motors take next to no timing to make power because they are moving the LSA on the cam as the rpm range goes up. The base tune from EFI source needs a lot of help. The base tune from holley needs a lot of help. Essentially they move over a lot of near stock table in an effort to make it start, run, and drive. I don't have nearly the time I used to, but with winter coming I can do some tuning if folks need help. I can dyno tune in Dallas (which I strongly suggest) because you really don't know what the car likes without it being on the dyno. It is NOT an apples to apples comparison. Putting a gen3 in a restomod is almost always lighter, there is far more trans slip (assuming you have a 727) and being that hemis are speed density tunes that are torque derivative, it throws EVERYTHING off for fueling calculations.