Spray Angle vs Timing

[Bdubbz]

I have an 03 ECM and 06 engine (dragonflys, intake, exhaust). Truck has run pretty well but has some haze due to the fundamental differences so I bought HpTuners to try and dial it in and learn more about tuning. Have played with many variables and am getting a pretty good feeling for the ECM.

My question is about the injection timing, main and pilot. I'm having a hard time creating a good map that produces little smoke, and no pinging, etc. I've used the timing calculator here for a few different tunes, but still getting better results from the stock 03 timing tables and scaling/smoothing those tables. I'm a little afraid of producing a map from the calculator (main) with numbers above the 'safe' 27-ish degrees. I used one today with 65% split producing peak timing values around 29. 75% goes into the 30's and I'm afraid to test that table without asking first....

I made a rough sketch of the fundamental differences and very roughly approximated the degrees of crank rotation vs piston travel. I know the piston bowls are different and my sketch is from rough measurements of an 06 piston, but it gives you a pretty good idea of what's going on.

I am coming up with roughly 6.33mm of piston travel from the two different spray angles which is roughly 23* of crank rotation. With the piston bowl differences, its probably much less than this, but I had to sketch something up.

So I'm assuming this will translate into my pilot event timing as well, but do I really just need to advance the heck out of my timing? I keep going back and trying to refine the stock tables, 03 and 04.5+, more to avoid using a map from the calculator that is like 75% or greater.

Just putting my pride aside here and asking for some re-assurance of my thinking so I don't ruin my setup.

Thanks for any help.

[Turbo_Mike]

I'll jump in on this one.

Firstly, compare the 2004.5+ pilot quantity to your 2003 and you will notice a huge difference. If you aren't asking for an unreasonable amount of fuel or rpm, you can run the pilot event at all RPM, and the engine will operate a lot more clean and quiet. Smooth out the qty and timing tables, run pre injection event all the time, your truck will be much happier. The 2003 file will disable pilot injection around 2200 rpm most of the time IIRC.

Here's the easy way to not be scared about breaking the rule about spraying outside the bowl. Look at your pilot timing table. That's in degrees before the start of the main injection event. Do you think that fuel goes anywhere near the bowl or piston? There's only so much opportunity you have to get the fuel in there, and as rpm increases, your window of opportunity closes. And there's only so much time past TDC that continuing to inject fuel makes power instead of EGT. CR pressures and atomization allow us to inject fuel with a lot of leeway without having to worry about that. I run a lot of trucks past 30 degrees. That's a key part on getting them to rev.

[Bdubbz]

Thanks for the input, very much appreciated.

First thing I tried to do was 'convert' over to rail, timing, pilot, adders and coefficients of the 04.5+ tune. That didn't work at all. So I've been trying a bunch of variations to see what works.

Currently, and so far the best tune I have going is a mix. I'm using the 04.5+ pedal map, and boost map with 03 smoothed rail and timing created from the calculator. Stock pulse map, stock pilot table. I was recently able to drive over a high elevation pass with decent egts, and only a small rise in ect and only a little injector ping from some extra cruising timing. Need to move my ramp in a little, so I drop timing a little sooner. So with that under my belt I can just keep refining that base timing map.

I actually can't run very high timing overall without it being a hot, smokey mess.

I'm glad you talked about the pilot, that's where I have been very timid. I tried the 04.5+ stock pilot timing with adders and coefficients and while it ran ok, was pretty pingy and actually had it cut out on me (fall on its face) when I got the rpms and load up a little and just into the 2000 RPM range. At that point I pulled over and put in another version, too scared to keep driving it.

Now that I have a handle on how to create/shape a timing table, I hope to start playing with that pilot timing again. The 03 stock pilot shuts off above 2000 rpm and 45mm^3 of fuel. At lower fuel volumes it stays on till 2600 rpm. The 04.5+ pilot is almost twice as advanced as the 03 even with the adders and coefficients for each. The base timing table of the 04.5+ is much lower than the 03, so 55* of pilot out ahead of the already lower base wasn't too much too swallow, but now create a base map totally different and then add the stock 04.5+ pilot at 55*+ adders.....whoa.......I'm still nervous. At least its a small shot.

Again, I really appreciate the input.

[Turbo_Mike]

Thanks for the input, very much appreciated.

First thing I tried to do was 'convert' over to rail, timing, pilot, adders and coefficients of the 04.5+ tune. That didn't work at all. So I've been trying a bunch of variations to see what works.

Currently, and so far the best tune I have going is a mix. I'm using the 04.5+ pedal map, and boost map with 03 smoothed rail and timing created from the calculator. Stock pulse map, stock pilot table. I was recently able to drive over a high elevation pass with decent egts, and only a small rise in ect and only a little injector ping from some extra cruising timing. Need to move my ramp in a little, so I drop timing a little sooner. So with that under my belt I can just keep refining that base timing map.

I actually can't run very high timing overall without it being a hot, smokey mess.

I'm glad you talked about the pilot, that's where I have been very timid. I tried the 04.5+ stock pilot timing with adders and coefficients and while it ran ok, was pretty pingy and actually had it cut out on me (fall on its face) when I got the rpms and load up a little and just into the 2000 RPM range. At that point I pulled over and put in another version, too scared to keep driving it.

Now that I have a handle on how to create/shape a timing table, I hope to start playing with that pilot timing again. The 03 stock pilot shuts off above 2000 rpm and 45mm^3 of fuel. At lower fuel volumes it stays on till 2600 rpm. The 04.5+ pilot is almost twice as advanced as the 03 even with the adders and coefficients for each. The base timing table of the 04.5+ is much lower than the 03, so 55* of pilot out ahead of the already lower base wasn't too much too swallow, but now create a base map totally different and then add the stock 04.5+ pilot at 55*+ adders.....whoa.......I'm still nervous. At least its a small shot.

Again, I really appreciate the input.

You don't have to run 55 degrees pilot timing. I don't. It's such a small pulse you can run half that timing and still have time for it to complete the event and do it's job.

[Bdubbz]

Ok, thanks.

I actually tried just trimming the top of the table at one point and that didn't go over well either. The maps are different sizes between 03 and 04.5+, so the trimming and importing did provide a kind of goofy pilot table, even matching the axis to extent of the smaller 03 tables. I think it cuts off around 2600 rpm and 110mm^3 of fuel IIRC.

If you're trimming yours maybe I'll use the adders and coefficient tables (smoothed-eliminate the erroneous 5's) from the 04.5+ so I get less qty and smooth and trim it again and see what I get.

I think what I'm grasping for this pilot event is advance it a little and cut the quantity down, smooth it and extend the event through out the entire rpm range to produce a cleaner, quieter combustion process.

Thanks.