Timing map comparisons... (post them and discuss)

[wishihadatalon]

I should not have grouped E85 and C16 together.

E85 does burn faster than gasoline or leaded gasoline, but it is the cooling effect in the intake charge and the lower heat of combustion that allows you to advance timing further to achieve higher efficiencies. The fact that E85 requires more fuel than gasoline is irrelevant.

I do agree that there is a point of diminishing returns when advancing timing to far. E85 is extremely knock resistant, and any tuner can advance a motor well past the point where it will not make anymore power, and still not see any signs of knock. When I cracked my 2.0L block, I had no signs of knock retard on any of my logs. But I was also running 23-24 degrees of timing advance and 35 PSI of boost pressure on E85. The main culprit that cause my block to crack was internal rust cavitation, but I'm sure the excessive timing created combustion pressures that were very high.

What I am saying is that there is a point where ignition timing will not make more power. You can advance and make less power. MBT (minimum best timing) is this point. My whole point was that just advancing timing till it knocks can be much worse than some think which is kind of what I was seeing in this thread from some people.

YouTube - MBT VS EGT here is a video that I guess could help explain it.


Also I don't know how you can say that the additional amount of fuel has zero effect on how much timing you need to run. You need more advance to have a proper burn of all of the fuel (~30% more). Its just another variable to take into consideration when building a timing map for e85 or adjusting your factory ecu map for e85.


P.S. I enjoyed your write ups on your site for dsmlink. I was only used to using map based stand alone systems and your stuff helped with my learning curve

 

[bling5tatus]

Wouldn't the fact that the e85 burns faster negate the fact that more timing is needed because there is more fuel?

 

[JayRolla]

What I am saying is that there is a point where ignition timing will not make more power. You can advance and make less power. MBT (minimum best timing) is this point. My whole point was that just advancing timing till it knocks can be much worse than some think which is kind of what I was seeing in this thread from some people.

YouTube - MBT VS EGT here is a video that I guess could help explain it.


Also I don't know how you can say that the additional amount of fuel has zero effect on how much timing you need to run. You need more advance to have a proper burn of all of the fuel (~30% more). Its just another variable to take into consideration when building a timing map for e85 or adjusting your factory ecu map for e85.


P.S. I enjoyed your write ups on your site for dsmlink. I was only used to using map based stand alone systems and your stuff helped with my learning curve

MBT IMO is not when you stop making power but the minimum timing ran to make good power. When you get to a point where less than 5whp is being made each degree added you have found MBT.

E85 has such good detonation fighting characteristics that you can keep adding timing and loose power before you get any detonation. I have ran up to 30* on my brothers e85 car and never had detonation or any loss in power per the butt dyno which in my eyes is pretty good since you can actually feel the difference.

 

[delta448]

Bling5tatus: The way I understand it is that E85 burns cooler than straight gasoline and it also leads to cooler charge temps before spark.

Colder charges of the same density burn slower, leave less chance for formation of a combustion chamber hot spot and will resist knock better, so couple that with the faster burn speed of E85 and you end up with a fuel that is much less knock limited as to the upper range of timing advance it can accommodate before it detonates. This is great for engines that are detonation limited since it allows either more boost or more timing or a nice compromise in the increased amount of both. It's not so good if you're of the mindset that more is always better, especially if you're only increasing pumping losses by adding timing, but MBT has already been mentioned. IMO, less optimal timing is a goal, since it puts more of the focus of the combustion pressure on a piston traveling away from TDC.

Things that affect your particular engine's ideal timing during any given combustion event:
type/mix of fuel, -including contaminants (such as engine oil)
pre-spark cylinder pressure (CR + boost)
AFR (with gasoline, a ratio of ~11.1:1 burns the fastest)
temperature of the incoming charge (burn speed increases as temps go up)
operation speed (rpm)

-Now all you have to do is home in on;
1) how much you have to offset the start of the burn for the burn to catch up to the moving piston and present the most Effective Pressure possible at ~15 degrees ATDC as piston speed (rpm) increases
2) how much you have to delay the start of the burn as load increases for a given rpm speed since more pre-spark pressure multiplies quicker when burning.
That gives you the timing values for your table, assuming the more minor variables that affect combustion speed are held constant.

I'm sure there's more I can add, but that's what I can pull out of my migraine at the moment.
Feel free to add, question or correct, anyone versed.

 

[JayRolla]

Bling5tatus: The way I understand it is that E85 burns cooler than straight gasoline and it also leads to cooler charge temps before spark.

Colder charges of the same density burn slower, leave less chance for formation of a combustion chamber hot spot and will resist knock better, so couple that with the faster burn speed of E85 and you end up with a fuel that is much less knock limited as to the upper range of timing advance it can accommodate before it detonates. This is great for engines that are detonation limited since it allows either more boost or more timing or a nice compromise in the increased amount of both. It's not so good if you're of the mindset that more is always better, especially if you're only increasing pumping losses by adding timing, but MBT has already been mentioned. IMO, less optimal timing is a goal, since it puts more of the focus of the combustion pressure on a piston traveling away from TDC.

Things that affect your particular engine's ideal timing during any given combustion event:
type/mix of fuel, -including contaminants (such as engine oil)
pre-spark cylinder pressure (CR + boost)
AFR (with gasoline, a ratio of ~11.1:1 burns the fastest)
temperature of the incoming charge (burn speed increases as temps go up)
operation speed (rpm)

-Now all you have to do is home in on;
1) how much you have to offset the start of the burn for the burn to catch up to the moving piston and present the most Effective Pressure possible at ~15 degrees ATDC as piston speed (rpm) increases
2) how much you have to delay the start of the burn as load increases for a given rpm speed since more pre-spark pressure multiplies quicker when burning.
That gives you the timing values for your table, assuming the more minor variables that affect combustion speed are held constant.

I'm sure there's more I can add, but that's what I can pull out of my migraine at the moment.
Feel free to add, question or correct, anyone versed.

Very good post. I agree that you want to find the lowest timing like you say. Thats whats great about e85.

From what I have read e85 does burn faster than gasoline but has a longer ignition delay during the slow burn phase so the engine doesnt have to do so much negative work fighting rising cylinder pressures due too high ignition advances. Meaning you can run a good amount of timing with less stress.

I love this fuel.

 

[wishihadatalon]

MBT IMO is not when you stop making power but the minimum timing ran to make good power. When you get to a point where less than 5whp is being made each degree added you have found MBT.

E85 has such good detonation fighting characteristics that you can keep adding timing and loose power before you get any detonation. I have ran up to 30* on my brothers e85 car and never had detonation or any loss in power per the butt dyno which in my eyes is pretty good since you can actually feel the difference.

Did you watch the video? The have peak tq values at a sustained engine load and rpm. Peak tq happened at MBT which was 15 degrees before they saw any knock. Opinion is much less effective than a scientific test. After this value, you are just multiplying the stress placed on your internal moving components because you are igniting your charge too soon resulting in your piston having to fight an expanding mixture on its up stroke (pumping losses). There is a reason it is called minimum best timing, because it is the lowest amount of timing that gives you the maximum amount of power. Its the correct amount to give you the perfect burn for peak pressure at ~15 degrees atdc, just like Delta said.

All of this is backed up by professional tuners who use a dyno or some sort of data acquisition system that utilized a high sample rate gps to determine if there has been an increase in acceleration.

Delta, thank you. I enjoyed your post very much.

Bling, it does burn faster hence why you run less timing than gasoline when you run it on a lean burn. When you increase the volume and add in the cooling effects of e85, you need to run more timing at wot to have a proper burn.

 

[JayRolla]

Did you watch the video? The have peak tq values at a sustained engine load and rpm. Peak tq happened at MBT which was 15 degrees before they saw any knock. Opinion is much less effective than a scientific test. After this value, you are just multiplying the stress placed on your internal moving components because you are igniting your charge too soon resulting in your piston having to fight an expanding mixture on its up stroke (pumping losses). There is a reason it is called minimum best timing, because it is the lowest amount of timing that gives you the maximum amount of power. Its the correct amount to give you the perfect burn for peak pressure at ~15 degrees atdc, just like Delta said.

All of this is backed up by professional tuners who use a dyno or some sort of data acquisition system that utilized a high sample rate gps to determine if there has been an increase in acceleration.

Delta, thank you. I enjoyed your post very much.

Bling, it does burn faster hence why you run less timing than gasoline when you run it on a lean burn. When you increase the volume and add in the cooling effects of e85, you need to run more timing at wot to have a proper burn.

No I do agree. When your on the dyno usually you stop adding timing when you stop gaining 5 or more whp per 1* added. Since we cant use knock to find MBT I have to use the dyno to show im not making anymore power.

 

[bling5tatus]

This is all very good information that I'm glad you guys are posting.

So, it was mentioned earlier that the 1g timing values already have the ecu's latency calculated in them and they're not "actual" values.

Would everyone agree that the 2g has a better timing table for pump gas and the 1g has a better table to start with if you're using e85? I'm trying to get a few different tables that will work on stock cars, but in different configurations. Say someone has high CR pistons and e85 vs. someone w/ high CR and 93 octane. Those two cars will probably want two different starting points for their timing tables.

 

[JayRolla]

Yes I agree with that. On pump gas I would always start with a 2g map. On e85 I run a 1g map with just a little added down low so it doesnt drop as low and stays at 17* during onset of boost.

 

[soldave]

OK, I'll mix things up a little and post up my timing map. Note this is from an Evo 1 which is a 7-bolt engine. Meth injection which will account for the slightly strange timing figures at high loads. It also needs a tune which will adjust the timing at the top a little too.

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[JeffGST]

Would everyone agree that the 2g has a better timing table for pump gas and the 1g has a better table to start with if you're using e85? I'm trying to get a few different tables that will work on stock cars, but in different configurations. Say someone has high CR pistons and e85 vs. someone w/ high CR and 93 octane. Those two cars will probably want two different starting points for their timing tables.

1G Timing Table = Designed for 7.8 to 1 compression
2G Timing Table = Designed for 8.5 to 1 compression

I would not "start" with 1G timing just because you are using E85. I would use what timing you currently have and add advance slowly. Even with my 1G on E85, I retard the timing at the 6000 RPM point. I know you have heard it before, but every car is different. Your motor and another motor with similar mods may have a much different timing curve.

 

[bling5tatus]

Jeff, why did you retard timing at 6k rpm? Don't you want "more" advance? I know, obviously, that more can become bad if it's too much.

Also, thanks Soldave for posting that map, can you match the CR of the pistons w/ that map, and maybe provide the stock one that isn't modified for meth? You posting that is exactly what I was interested in when I started this thread. I want to see what Mitsu did over the years to differ their design.

 

[JeffGST]

Jeff, why did you retard timing at 6k rpm? Don't you want "more" advance? I know, obviously, that more can become bad if it's too much.

The reason is that the stock 1G timing map targets 22 degrees of advance at 6000 RPM. It then rapidly drops after that to 17 degrees as you get closer to redline. I really don't know what Mitsubishi engineers were thinking when they designed that timing map.

As you get closer to redline, you are going to need to increase advance due to increased piston speeds. So what I do is limit my timing to around 20 degrees BTDC with E85. Any additional advance did not significantly increase WHP or increase my trap speeds. I rather keep the timing limited at 20 degrees and instead increase boost pressure to make more power since I have the fuel system to keep up with it.

 

[bling5tatus]

Ah, that makes sense. I think I was told by someone else too that there's a high spike of timing in the 1g map that they always remove when they tune a car. Maybe the mitsu engineers thought the car would be shifted before redline and the stock car didn't make more power past 6k rpms... I'm sure a stock dyno sheet could prove this or disprove it.

 

[soldave]

Jeff, why did you retard timing at 6k rpm? Don't you want "more" advance? I know, obviously, that more can become bad if it's too much.

Also, thanks Soldave for posting that map, can you match the CR of the pistons w/ that map, and maybe provide the stock one that isn't modified for meth? You posting that is exactly what I was interested in when I started this thread. I want to see what Mitsu did over the years to differ their design.

Compression rate for that map and for the Evo I is 8.5:1. Have a couple of other maps that might be of marginal interest.

Evo II standard timing map (CR 8.5:1 and I think the same base map as Evo I).

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Evo III standard timing map (CR 8.8:1 but very little difference from the earlier map)

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[matthewdesigns]

Soldave, are the values in the lefthand columns of those two ^^ charts gm/rev? What is the unit in your first chart, in post #35? Or is that a generic load value?

 

[ed_GST]

when i had my EPROM ECU tuned with TunerPro
i burned a chip with this timing map...

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my but dyno said that there was a huge improvement over stock timing
i had a BIN for my 2G with 1G timing curve, i never got the change to try it
of course i would have used race gas with it

maybe now with the reflash i will

 

[soldave]

Soldave, are the values in the lefthand columns of those two ^^ charts gm/rev? What is the unit in your first chart, in post #35? Or is that a generic load value?

The initial map just showed generic load, whereas the second 2 wee showing gm/rev. Apologies for the inconsistency. Have just got the code for map tracing so after this weekend I might be able to put actual boost levels on at least some of the load values.

 

[matthewdesigns]

Thanks for the clarification. Just want to make sure we're all aware of what we're looking at

 

[JayRolla]

The reason is that the stock 1G timing map targets 22 degrees of advance at 6000 RPM. It then rapidly drops after that to 17 degrees as you get closer to redline. I really don't know what Mitsubishi engineers were thinking when they designed that timing map.

As you get closer to redline, you are going to need to increase advance due to increased piston speeds. So what I do is limit my timing to around 20 degrees BTDC with E85. Any additional advance did not significantly increase WHP or increase my trap speeds. I rather keep the timing limited at 20 degrees and instead increase boost pressure to make more power since I have the fuel system to keep up with it.

Thats why I add timing above 6000k so it hits 22* and stays there.

 

[jeffo]

The reason is that the stock 1G timing map targets 22 degrees of advance at 6000 RPM. It then rapidly drops after that to 17 degrees as you get closer to redline. I really don't know what Mitsubishi engineers were thinking when they designed that timing map.

The biggest problem with the 1G timing maps is that the highest load map was <15psi! 22* at 6000 rpm might have worked fine for stock boost, but its really bad when you start turning it up. That's one thing you need to keep in mind if you are trying to just drop 1G maps into DSMLink with a 2G, the map scaling doesn't line up, so you need to retune everything >15psi before attempting to use them.
keydiver

 

[twdorris]

The biggest problem with the 1G timing maps is that the highest load map was <15psi! 22* at 6000 rpm might have worked fine for stock boost, but its really bad when you start turning it up.

Absolutely.

That's one thing you need to keep in mind if you are trying to just drop 1G maps into DSMLink with a 2G, the map scaling doesn't line up, so you need to retune everything >15psi before attempting to use them.

With V3 ECMLink, we have rescaled all the maps to normalize everything. A timing map from a 2G will drop into a 1G and vice versa. We also scaled various EVO maps to drop in as well. You can find some samples here:

Sample ECMLink Timing Maps


Not sure if that's what you were referring to or not.

Personally, I LOVE the EVO8 map on my own Talon. I've run it on both my 7.8:1 and 8.5:1 motor and really find that it works well. But that's only going to work if you're running ECMLink (V3). Those maps aren't going to drop into anything else without rescaling again.

Thomas Dorris
ECMTuning, Inc.

 

[toofast82]

Thanks for that page! Its a good resource for having all the different maps listed for comparison.
It's on my fav list now!

 

[soldave]

Some info which might give you a little perspective on the maps I posted up. Row 0.9 is equivalent to 0psi of boost (give or take) and row 2.2 is equivalent to about 24 psi.