The percent of injection BTDC is the amount of the pulse width...say if you have a 3000 microsecond pulse width and 50% timing table via this calculator then 1500 microseconds would be bofore TDC and 1500 after TDC. Make sense? This is a simplified version of ideal, cause more parameters play into this equation than we will discuss here. Now, as far as whats best for race and/or mileae tunes...that depends on your particular setup. I have had the best luck with a 40/60 percent split for performance, and a 55/45 split for economy...but I have a big turbo. Just play with it and see how it all reacts...
Timing calculator v3
- Thread starter sweetdiesel
- Start date
if you want 50% of ur main injection pulse to be before TDC, and you would enter 50% into the field.
so like a 2000Us pulewidth at 2000rpms, and you want 50% of it before TDC, the calclator will tell you to you will need 12* of timing to have a 50/50 pusle before and after TDC (on paper)
I still play around with timing alot, looking for ideal timing for w/e so i cant give you the answer your looking for about the "best" timing
so what table is before and what table is after? 50% seems super low I am running 2900us PW at higher rpms in my hot tune. i am so confused haha.
So, for the average "Tow Tune", what would you use? I'm having a hard time grasping what your saying.
I guess my question is, what do you want your before and after TDC to be?
i was explaining it by using a scenario, not by what i actually run.
lemme break it down a little bit.
The amount of Degrees the injector will be open is based on RPM, and Pulsewidth.
lets say you are running at 1000 rpms and running a 1000Us pulse width at that instance/cell (based of how much fuel is being demanded from other tables). Do calculate how long the injector is open during at injection cycle you would have to pultiply the RPMs and the Us by .000006.
so 1000rpms X 1000Us X .000006 = 6*
6* would be how many crank angle degrees your injectors are open for during the injection pulse if you were running 1000rpms using a 1000Us shot of fuel.
now if you want 50% or 1/2 of that fuel shot to be delivered before TDC, you would then mult that by 50% and it would give you 3*
so in the timing table a value of 3* would be put in. Now i left out the part where you go though the pressure table and throttle base injection table. but it takes some looking though.
But what the calculator does is do all that calculations for automatically 100's of times over so you don't have to. and its easier to adjust for how much of the injector pulse you want before TDC.
This guys got you covered.
I would say, for the best all around timing, including the best power and economy for a tow tune I would run a 50/50 split. This should get you close to a good split between power/econ/EGTs.
Higher timing results in lower EGT (mostly) and higher cylinder pressure, and lower timing results in higher EGT and lower cylinder pressure.
Also something to keep in mind, timing injection on a diesel engine is nothing like timing ignition on a gasoline engine. When you are coming from the gasoline engine tuning mindset, what seems low is actually really high in the diesel world. I have a truck tuned to about 525 HP with not more than about 27 degrees of timing. that same HP would probably average about 35-40 degrees in a comparable sized gas engine.
any chance of updating the file so that it's compatible with the latest release of EFI Live? The tables now populate out to 4800 or 5000 rpm and have different scaling. Makes cutting and pasting hard and with the way the calculations are "in the background" in the cells adjacent to the tables, it makes it difficult to extend the tables to the left and not screw up those cells with the formulas doing the calculating.
Just wondering as I don't have time right now (studying for prof. engineering exam) to write my own or even modify the current one here or else I would.
Just wondering as I don't have time right now (studying for prof. engineering exam) to write my own or even modify the current one here or else I would.
Last edited:
no biggy. Was just curious. I should be able to spend some time on it after mid april. Studying for PE (prof. engr. exam) which is April 16. After that, I think I can sit down with it and get it straightened out.
Would you mind sending me the raw file with things not hidden off to the side? :angel:
Would you mind sending me the raw file with things not hidden off to the side? :angel:
That is all I have. Just unprotect the sheet and make the hidden stuff visible.
That said, I've recently used the timing calculator with the current EFI update, and everything was right. Have you changed the scaling in your tune or something? Maybe you can post a screen shot showing the table that is off?
Im assuming that it works the same with larger injectors as long as PW has allready been shortened?
GMC_2002_Dmax
The Still Master
Has anyone considered rpm in their equation ?
I was under the impression that it was already taken into account due to the fact that at full throttle my tunes comand the same pulse and pressure from about 1700 on up, but the timing advances with the RPM from what the calculator produces.
I didnt consider it but when i did the calc, i was with in a deg or two form what i allready had!
Has anyone considered rpm in their equation ?
Did you even look at the calculator? Or are just padding your post count.
If you had looked you can see RPM is figured in.