Is there a calculation to convert IPW into IDC (duty cycle)? Im seeing around 17-18.5ms from 4500 on up and want to know the duty cycle of the injectors. Any info is appreciated.

 

Below is somebody elses math but maybe you can use it:

PW in ms max is based on where you redline is.

For example 6500rpm redline

Max PW = (60,000 / (6500 + 500)) * .85 where .85 is max IDC

Max PW in ms = 7.2 ms

So at redline the max available time for your injectors to be open is 7.2ms

18-19ms would be >100% IDC

 

IDC (%) = IPW*RPM/1200


Eric

 

Thank You Both!

 

Doing some quick math, this seems to be correct. I'm not sure where C6's derivations come from.

 

6500RPM * (1min/60sec) * (1cycle/2revolutions) = 54.1667 cycles/sec

invert

18.46 ms/cycle

So, 18.46ms would be 100% IDC @ 6500RPM

 

damn! I'm at 95% duty cycle from 5300-6500.

 

What mods have you done?

 

tbe, mbc spike to 24psi tapper to 20.5, ebay fmic, cone filter

 

That's nothing, I saw over 100% from 6500 RPM on up . I'm ordering bigger injectors this morning.

-Paul

 

I've got a set of 1000cc injectors sitting on the shelf. I just wonder if that will be overkill for my stockish setup. Also a little worried about controlling them with the ECUFlash as I've never scaled injectors or adjusted the latency before.

 

It looks like everyone is using an 85% duty cycle at peak power. Is 85% a verified number, or is it being assumed from common convention that stock fuel injectors are usually sized to be at 85% duty cycle at peak power?

Nevermind. I see that the other formula does not use 85% to get the IDC.

 

It takes time, but the trick is to start really rich, smaller size and leave the latency what is documented for the injectors (use the AEM calculator)

Then, you adjust the scale until your fuel trims at idle are very close to zero..

Then drive the car around for awhile, and see how off the long term fuel trims get after a long drive.. At that point you can adjust the 11v and 14v injector voltage latency settings until overall you get your trims while driving in check.. Then you'll have to adjust idle one more time.

What this will do is it should get your fuel injectors, to read "ROUGHLY" close to what your fuel map looks like by the numbers.. Its not quite right, but it should be similar..

Doing this will give you the best drivability and then you can tune your maps... Just remember to make the maps rich to start before you do too much..

 

I'm glad I caught wind of this thread. After getting the calculations for my IDC, I'm at 100% from 6k - 7k. Sigh, was hoping I wouldn't needed new injectors for a while. =(

 

My car starts at 78% @ 6000 and goes to 85.5% by 7000. Is that ok? My car has a TBE, Xede and whinebro.