Been looking in many places, but still didn't find any useful and reliable information about injection timing for common rail diesels.

One theory is to keep EOI stock - when increasing injection duration, SOI has to be advanced so much, that EOI remains intact. That is one theory, I suppose is far from optimal according to performance and combustion efficiency, it's more likely that it is optimised for ecology.

I know engines are different, combustion chambers have different sizes, head/valve/chamber configurations etc, but I'd like to know a bit more about how to set SOI to have EOI for max performance per IQ (and least smoke) without spending a fortune for renting a dyno.

What does different EOI setup mean for economy, ecology, performance, EGT, smoke? At what rpm?

You don't just have to advance SOI for increased injection duration to maintain the stock EOI.

Increasing rail pressure also has an affect on EOI even if SOI are untouched since in the rail pressure map as the pressure increases the opening time of the injector is shorter so when you leave SOI stock and increase rail pressure you are reducing the EOI. But increasing the rail pressure and injection duration you can leave SOI untouched and achieve the same EOI.

For max torque usually in my files around 2200rpm I have latest EOI at 10degrees ATDC and go to around 6 at 4000rpm depending on what I want to achieve. But best rule of thumb is not to go over 10 degrees as this will cause poor mpg from unburnt fuel and high exhaust gas temperatures so I've been informed. And in doing this I have not had one problem yet :D

I completely agree with what is written about EOI and increased FRP.

When I work on other cars, I leave EOI around stock, so no real math is involved. It is just fine for a basic tune.

But as I've looked to my SOI maps, EOI is almost never ATDC in higher revs??

What would be (roughly said) in theory the most optimal EOI setup to achieve maximum torque at WOT? :eh:

At what point (talking about degrees ATDC) should combustion process reach all areas of a combustion chamber, at what point of injection process does it start, and of what combustion speeds are we talking about (ok, I could find the last answer on the net)?

Or should I ask on a specific case:
stock setup:
IQ = 45 mg/str (the highest value on the axis):
EOI = 0,81 ATDC @ 1000 rpm
EOI = 2,34 ATDC @ 1250 rpm
EOI = 5,25 ATDC @ 1500 rpm
EOI = 3,93 ATDC @ 1800 rpm
EOI = 3,26 ATDC @ 2000 rpm
EOI = 0,02 ATDC @ 2250 rpm
EOI = 0,04 BTDC @ 2600 rpm
EOI = 3,12 BTDC @ 3000 rpm
EOI = 6,44 BTDC @ 3500 rpm
EOI = 9,23 BTDC @ 3800 rpm
EOI = 16,68 BTDC @ 4200 rpm

These values seem a bit funny, maxbe even too advanced. Injection duration is very short: around 2,1-5,7 degrees 1000-4200 rpm (FRP 800-1600 bar). But when I calculate duration for let's say 80 mg/str, I get 6,88-16,68 degrees, so SOI has to be advanced quite a fair bit.

I extended SOI maps to 90 mg/str (stock were only to 45 mg/str) and kept the EOI stock for 45 mg/str. I know this is far from optimal, so I guess I can't safely inject 96 mg/str with a 45 mg/str EOI setup.

If I advance EOI (if the memory serves me right) combustion noise will increase, EGT will be lower and exhaust gasses will be worse. But what happens with combustion efficiency (and output power, exhaust smoke) if I advance or retard EOI for let's say 0,5 or 1 degree? :oops:

I think you got it all around with those numbers my friend. At full power it will end considerably late after TDC, so those 16° you see are for sure ATDC. Those lower values you marked "ATDC" are actually BTDC because of emissions and EGR action in that area.

Should it not be determined by injector pulse width?. There is a limit with this before larger injectors are required. I believe a 50 % before tdc and after should be used.

Andy