Injectors

[uglyDougly]

 By tuning the cyl. separately, you don't need matched injectors. Since that's the only way I'll do an H-D, it isn't an issue.
  When someone sends me their Ducati ECU and wants me to put a good cal on it, the only way to have a chance to get it close, is to have a calibration that was done with matched injectors and then send the ECU and matched injectors.
  Now, cleaned injectors is another story. If you're going to spend the $$$$ for a tuning/re-flash system/device and the cost to create a custom calibration, cleaned injectors is a good place to start. If issues arise in the future (ie dirty fuel filter and possibly dirty injectors)(although rare, I have seen injectors loose 20% flow when the filter is overworked and super small particles get pushed thru into the injectors) a cleaning will get you back to your starting point.
  About VE max.
  Earlier systems, like the chip based M-M stuff and the first M-M H-Ds, the fuel table represented a Hexidecimal % of a set injector pulse-width. In the case of the H-D M-M system, the maximum is 24mS, represented by Hex FF. That means that there are 255 increments (plus 1 when you count the 0) to that 24mS. 128 is 128/256th of 24 or 12 mS, etc. This, is adjusted for inlet air temp and Barometric pressure.
  The shortcoming of that system is that the software can ask for more injector time than is available at high RPMs, and you can't get 100% duty cycle at low RPMs. Plus, the resolution at low pulse-widths is coarse (If your table value is 32 at idle, one increment is 1/32nd of the time, while 1 increment at max injector time is 1/256th. Finer resolution.

  Fast forward to the Delphi system where the VE numbers represent a volume of air which is different at each MAP (and, maybe at each cell of the VE table) so you have 1/256th resolution even at idle (emissions???)
And what is 127.5 in .5 increments?   255!!!

  Delphi has taken the Hex values right from the calibration file, divided by 2, and given us a decimal value that we can understand.
  I invite anyone to show me any NA engine that has a Volumetric Efficiency (VE) of 127.5%, especially with the throttle 1/2 closed.
  The pre-restricted XR750 is an engine with one of the highest VEs of any engine and that wasn't higher than 115% (it had tuned inlets too.)
  So, 127.5 is 255/256ths of some volume of air calculated by the system, based on the MAP (pressure drop across the throttle) and somebodies guess as to how much air a Harley can gulp per engine cycle. If that number is lower than your build (or, your build does better than the 'factory'), you run out of VE.
  I ran into this with the first version of the Super Tuner and tried to fix it with engine size. It didn't respond enough that I could detect it, so I turned to the injector flow. Assuming that injector flow rate was used in the calculation for pulse-width. Turns out it is. Or, at least, has that effect.
  Years later Ed Dahir told me that he uses displacement all the time to get more VE overhead.
  I still use injector flow because I have a spreadsheet that will change every cell in the fuel table based on the % change in injector flow, and can then proceed like I never had a problem. And, as Ed pointed out, you can paste in your spreadsheet VE tables with values higher than 127.5 and paste all the correct VE numbers back into your VE table.
  Sorry about being long winded.

   Doug

[joe_lyons]

I know the race tuner for fbw bikes and the very first super runners did have this issue with their engine displacement not doing diddly squat.  When I get those it does seem like they hit their 127.5 limit way easy and I had to do just like you did and play with inn. Size.  PS.  Hey Doug I talked to Kurt Musgrave about meeting you at the vtwin show and he said looking back now he wishes he would of had more of an open mind with other tunning devices but he said he is too old to learn anything new now.

[strokerjlk]

Years later Ed Dahir told me that he uses displacement all the time to get more VE overhead.

Me too . You can get there either way though.
Whatever your comfortable with.
Myself I put the correct injector size in the constant , increase ci 5-10% then check the sweet spot for ve headroom .

[FLTRI]

This is what I've found to work for me:
If I need small VE/AFR changes? I use cubic inches.
If need big VE/AFR changes? I use injector size.
Bob
PS - Hi Doug. Good to hear from you and good post.

[redmtrckl]

Bob--
Do you set the injector size to a smaller number in the tuning constraints in order to fool the software or do you replace the injectors.

[FLTRI]

Bob--
Do you set the injector size to a smaller number in the tuning constraints in order to fool the software or do you replace the injectors.

Not really, since all the numbers are adjustable you are merely moving the goal posts.
It's not like hanging the IAT out the window to fool the engine to make changes (richen) based on incorrect (not really IAT) data.

The software has to make assumptions based on the bikes they've tested (stock and mild builds) and those assumptions are subject to change based on actual changes to the way the engine breathes, ie: cam timing, compression, porting, exhaust design, etc.

If we were able to make changes to the software behind the scenes we could adjust the VE tables to never run over 127.5 which is just the software's limit as written.
HTH,
Bob

[strokerjlk]

Bob--
Do you set the injector size to a smaller number in the tuning constraints in order to fool the software or do you replace the injectors.

It dosent matter either way you get more head room.
Add ci or decrease injector size . It dosent matter .
One isn't for small changes and one for big changes . Each can be used to increase or decrease ve headroom equal . You just have to know how to get the same % of change with either way you choose to change the constant .

[FLTRI]

Not sure changing ci does the same thing in the background as changing injector size.

VEs are based on cylinder fill...so logically if you want more VE head room change the size of the engine.
On the other hand changing injector size, while works to get more headroom, it also affects a few perimeters in the background the way I understand it.

From a bit of fooling around I have found improvements from changing actual injector size...and not necessarily for necessity.

Think cam timing and on-time of the injector.
Bob

[strokerjlk]

On the other hand changing injector size, while works to get more headroom, it also affects a few perimeters in the background the way I understand it.

enlighten us on the few perimeters that injector size effects ,that ci dosent

[joe_lyons]

Fuel mileage calculator on PV lol.  I'm just a weird stickler at just doing CI and leave injector size at what it is and haven't had any issues with it.

[strokerjlk]

Fuel mileage calculator on PV lol.

really? interesting .
havent messed with that on PV yet

[joe_lyons]

Just saying that it uses fuel flow, pulse width and road speed to figure things out for it

[strokerjlk]

Just saying that it uses fuel flow, pulse width and road speed to figure things out for it

Makes sense . Never really though about how it worked .
To busy  playing with the other stuff.

[joe_lyons]

Me too but they say you will go blind but I don't believe them. lol

[FLTRI]

On the other hand changing injector size, while works to get more headroom, it also affects a few perimeters in the background the way I understand it.

enlighten us on the few perimeters that injector size effects ,that ci dosent

As soon as you provide your dynojet @13.2 AFR vs voltge graphs so we can see if the voltage closely follows the AFR.

Be sure to expand the graphs well enough to see trending.
Once we have that data we can make some determinations based on your own testing...which is much less prone to conspiracy theories of why the OP in the first place.

[strokerjlk]

Bob
Your in the wrong thread .
I don't use the dyno jet graph to tune to 13.2 ( except carb)
There is much better technology to gather Afr data with.
Not like your DA days

[FLTRI]

Bob
Your in the wrong thread .
I don't use the dyno jet graph to tune to 13.2 ( except carb)
There is much better technology to gather Afr data with.
Not like your DA days

Just suggested to use the dynojet graph because it's simple to use for comparison.
Any other recording will suffice...just make it easy to compare the voltages with the Winpep7 AFR graph.
Bob

[uglyDougly]

  This isn't to say that my way is the best way. Just sayin' why I use it.

  Sure, injector size is used for other perimeters, but as far as I can tell (and the real 'guys who know' don't include me in the loop) injector flow is used in the calculation for pulse-width along with AFR Target and the atmospheric corrections. Basically, the fuel table values represent a volume or air. That volume is determined by the MAP and RPM, which is why you can have the same (or larger) value at low MAP and hi MAP. Since each MAP row and possibly each cell has a different potential air volume, and I don't know what a change in displacement does to that, I can't depend on the changes I'll get in each cell.
  By changing the injector flow I can get the same percentage change in every cell. A spreadsheet gives me the correct % change of each and every VE number.

  No, I haven't taken the time to prove this because one runs out of VEs earlier in the tuning process before all the VEs are corrected, but after I've done this, it's like I didn't change a thing. I can even use the calculated VE numbers that are above 127.5 to make that correction and get the hi values close by doing that.

  Or, I'm completely wrong about all of this and just too stupid to learn. Sad ain't it?

   Doug

[joe_lyons]

Doug your way is the best for you because it works for you.  More than one way to skin a cat.  How's your new pants doing by the way Doug?