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Adjusting a tune today from a dyno sheet with AFR's. Tune leans out a fair bit in the mid RPM area. (n/a 355 V8 with small hydraulic cam)

Using a spread sheet before/after AFR target to get new VE from the useful spread sheet thread. I plug in all the data. In the lean area the new VE number is 101.3%

I had adjusted the kinjflow number to suit larger injectors as well as the stroker engine and had included some "fudge factor" like that factory kinjflow number seems to have (I had 0.0900, the spread sheet worked it out as 0.08387)

Now what I am worried about is the injector duty cycle. The engine is fitted with super6 injectors which should equate to about 34lbs/hr with 43.5psi fuel pressure and should be good for about 430hp @ 80% DC so their is no way I should be maxing out the injectors however isn't the VE number closely related to the injector duty cycle?

I'm thinking that I need to adjust the kinjflow number down to what the spread sheet worked out and then the VE table to suit?

Any advice is much appreciated.

Thanks

The VE has no direct relation to injector DC, in the logs you will be able to calc DC from the injector PW and RPM - most ADXs are setup to have this already, 12P and 11P this is a ECU calculated term thats been added and will be logged.

If you are only just running out of VE with slightly over 100%, then the kinjflow will need a minor tweak higher. You want to fudge the ECU to say the injectors are slightly smaller than actual.

We are still using $11 based tune. Yet to change it over to 11P.

I just copied the Injector DC Calculated value from the 11P ADX to the $11 ADX i'm using however when I play a log I'm only seeing 29% DC? Could that be correct? I also added the Injector Duty Cycle value but this didn't show anything at all?

I do remember something in another thread about the Injector DC calc been altered? Maybe I'm still using an old ADX?

I've added the ADX

Use "(((x / 65.536) + 0.7) / (1000 * (1/(Y/60)))) * 100"

This also assumes a 0.7ms opening time to give a rough actual delivered DC calculation, can adjust that part to match your injector table.

LOL. I just changed the calculation and now I'm getting 102% DC calculated using the above formula.

+0.7ms I assume is based on the Injector bias table?

So, just to confirm, the maximum number I should have in the VE table is 100 (1bar)?

If you had 29% with the orig calc, it should be roughly double. If you post a log can confirm the DC numbers, but if correct and actually above 100% there is no bin fudging that can fix it.

Try saving a number higher than 100% in the ve table, when you open it again will be 99ish %. The table must have values below 100%.

If I change the above calc and put * 50 instead of * 100 I get 54% DC. Doing some quick calcs based on the injector size based on theoretical HP @ 100% DC and the approx power this engine is making that seems to be about right.


OK. so I just have one cell in the table that is above 100% but which will save as >100%. In theory If I leave all the other cells as is and leave the kinjflow number as is I would expect it to go a touch leaner than I want. I'm looking for 12.8 but if it goes a touch lean there it shouldn't be the end of the world. I doubt it wouldn't be much, maybe 13:1 or something close.

This is the log I'm working with.
edit: nope, that doesn't work for the DC calc either, I forgot to change Kw to Hp Based on power output I should be seeing about 68% DC

at this point I would normally add 15% to the kinjflow, and then remove 15% from the VE table, then you will be back to where you are now but with 15% headroom to go richer

Jayme wrote:at this point I would normally add 15% to the kinjflow, and then remove 15% from the VE table, then you will be back to where you are now but with 15% headroom to go richer

I think I'll go with this just so I'm all under 100%.

Just to double check, when I use the kinjflow calculator, If I make the injectors bigger the kinjflow number actually gets smaller So all I need to do would be multiply the kinjflow number by say 0.85 and multiply the VE table by the same 0.85 and I'm done.

no. kinjflow is like this.... higher number makes everything richer, lower number makes everything leaner. so multiply VE by 0.85 to make it smaller, then multiply Kinjflow by 1.15 to make it higher.