Timing question for high altitude

Sorta related:

http://www.auroragenerators.com/information/buyer-guides/59-diesel-high-altitude

when I tried to find some info on this, I did find research on "ignition lag vs altitude" but couldnt figure out how to access the full articles.

I guess what confuses me about the theory of more advance for altitude, is that if there is already smoke at altitude, and advancing timing WILL make more smoke, how does that make it better?

I like to know facts also, and it is a fact that my trucks run better with less timing, but is it just because of the reduced turbo lag?

Yesterday, i was planning on pulling a trailer, so I moved (as another experiment) my timing up to 8.5. It was extremely smokey, and very sluggish compared to a few days ago with timing at a full degree less.

late timing causing white smoke is pretty self explanatory, but how does advanced timing CAUSE black smoke??

I would say advanced timing = more lagging spool up = Black smoke.
Seems a lot of people with turbo engines have better luck with lesser advanced timing.

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Hey guys just gonna throw this in.

After much thought and discussion here and in my turbo install thread here and on FTE, I decided to have my mechanic time my truck to 6* BTDC. He has a diesel shop just down the road from my shop, and he has worked on many IDI's. (he claims) I did a bit of work for him on some projects of his, and he agreed to time my truck in exchange for some of the work. Got in done this morning. Just went out and took it for a test run. Again, didn't notice a lot of difference, but it did seem to pick up a bit faster on the bottom end. I can easily spin the tires when the boost builds in first gear. EGTs were very close to the same, maybe just a bit cooler if anything, and boost was a bit higher, if anything. Again, I do think it made a noticeable improvement.

Just thought Id add this to the discussion.

Thats good information. When I rent out my timing meters I suggest timing these engines to several differnt degrees of advance. Its simple. All you do is find what you want. then use a center punch to make a mark in the joint line between the pump and the gear housing. Now advance or retard the pump and make another mark. Do this 2 or 3 times. Say its fine at 8.0 dbtdc. then set it for 8.5 advance. then maybe 9.5 advance. Each time make a new mark in the joint line. Now write down what those marks means. No matter what. These timing marks are accurate for this particular pump only. No other pump will match these timing marks because they are all timed internally differently. You can remove the pump from this engine and align any of the marks and know what it is for timing. no need to retime or rent from me til you change this pump or the injectors. This is just a helpful tip to keeping out trucks running like we want.

The problem is, as pumps and injectors wear, does not the timing change a bit? So yes, the marks may be accurate for 50-70k miles, but may not be a be-all, end-all solution.

Also I have a feeling that most guys won't actually check or change their timing that often once they get figured out where they like it.

Not trying in any way to knock what you're saying. And maybe I'm over-thinking the situation. I have been known to do that before

Yeah, but after a lot of miles, move it to the next line.
But technically, if the pump and injectors are wearing at the same rate, the timing should stay nearly the same.
When injectors wear, they pop early. Which advances timing.
When the pump wears, they take a bit more to build pressure, so it'll advance timing.
I think that's right. Not 110% sure on the pump wearing though.

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problem is, as the injector wears, atomization gets crappy=more ignition lag (in theory). Wont see that with a pulse meter though.....

Over the weekend I drove Parley's Canyon unloaded. The truck was a dog and although it was 85* outside and I had the A/C cranked I could bury the pyro trying to exceed 70mph. The canyon begins at 4300ft and summit's at 7100ft. The higher I went the boggier the truck got. I was timed @ 8.5btdc. My boost was low at 10-12psi.

This morning I dropped the timing to 6*btdc. The truck starts easier and far less turbo lag. My cruising EGT's at 60mph MAY have gone up 25*. It's hard to tell as I had a mild headwind today.

I will run it here for a bit and report back, black smoke is still prevalent when really honking on it and when snapping the throttle but the engine response is crisper and the tone has mellowed out. The torque rise SEEMS improved as I can pickup speed by barely pressing the throttle opposed to lugging it while the turbo catches up.

I put another injection pump on my truck recently, and have been adjusting based on sound, feel, and smoke. I have it very close to what I feel is perfect for my truck. In the next couple weeks I will try to get a meter on it, curious to see where it is..... may blow my whole theory

Black dawg said:

I put another injection pump on my truck recently, and have been adjusting based on sound, feel, and smoke. I have it very close to what I feel is perfect for my truck. In the next couple weeks I will try to get a meter on it, curious to see where it is..... may blow my whole theory

Click to expand...

Very interested to see what you discover.

Today I plugged the wastegate and backed out when I saw 18psi...guess the turbo is still healthy.
The exhaust is heavier plumes of gray but not as black. At idle it reeks and stings the eyes...definitely not a complete burn. Maybe we'll try 9.5*.

At the retarded settings when cruising it feels like the engine never really unloads and "relaxes", does that make sense? It is like it is always tugging along opposed to running easy at 2k rpms.

really shouldnt be getting any stink at that timing setting? When you go to check it again, check at idle and at 2k