Assuming 11:1 and pump gas that would require about 45 lbs/min at 21 psi. If you assume the 780s are behaving like 750s, as the x80 injectors so often do, it would be 43 lbs. I logged 49 lbs at 26 psi, so 43 at 21 is not too far fetched. At least not enough to raise the alarm. In fact the same car on the stock turbo moves it's 42 lbs at about 21 psi. This is all bench math of course, I'm just thinking out loud as I try to sort through this.

I'm a complete theory testing *****, but I just don't know enough yet about what your proposed test entails. I'd probably smoke my whole **** in the process. Hopefully someone can check on that to satisfy the curiousity.

 

I found on the stock injectors that they lost AFR control (ie there was a step change richer and then subsequent increases in IPW did not give a richer AFR) at 94% IDC. This is expected as a 6% space:mark ratio seems inadequate for them to close and re-open, so they just stay open from 94-100% IDC - I they behave like they have direct current rather than a duty cycle. I am calculating IDC on the basis of IPW*RPM/1200.

On the stock turbo with induction and exhaust improvements, on 98-99 RON (93 PON) I found that at stock fuel pressure I was in the low 90s at 11.5:1 AFR, all this with a Walbro 255 lph pump.

I wanted to run 10% in tank methanol, and at 100% IDC the AFR was a bit lean and I couldn't test higher airflows, so I raised the fuel pressure from 3.0 to 3.6 bar and then I could adjust the injector size in the ECU to get the AFR back to what I wanted and lower the IDC.

The stock FQ360 runs 100% IDC according to the scaling we are using in the loggers for IPW and my calc above. If you increase the boost it gets leaner despite the higher load areas having richer AFRs in the fuel map and it having an uprated fuel pump.

All the above has resulted in me concluding that the stock IX turbo is sufficient to max out the stock injectors with a Walbro. This is also a view passed to me from longstanding UK Evo tuners using variants of this turbo and these injectors on various ECUs for years.

 

at what injector scaling does this happen or does it make a difference?

 

i've got logs of a full bolt on evo 9 on stock turbo and stock injectors with a walbro maxing the injectors out. evoscan recorded over 17ms @ 7000 rpm which puts it at over 100% IDC. any adjustment i made to richen the car up had no effect... and it was running lean. the customer then put in 750cc injectors and immediately the AFRs came down to what we wanted, and IDC was to a far more manageable value.

i can post some plots if anyone is interested.

 

This was JDM standard at 542, but I don't think it makes a difference. The IPW in the logs appears to be the real thing.

 

I am beginning to think the same. For the record Kevin, with the new math that appeared in the last month I dont move 45lbs of air until I am running 26ish or more (30 at 6k, and 26.5 by 7500). On pump gas I am showing 40 lbs at a little more standard boost (24-25). The only thing that I can think of is my WB is WAY the heck off and I am at 78% and probably more like 10.5 than 11.5 AFR

 

This thread has the wheels turning in my head. Its nice to have a bunch of guys conversing on these topics. I'm gonna go try a few things and hopefully have some helpful input soon. :-)

 

Ok, so as crude at it may be, I found something that was simple enough IMO.

Seeing as the stock injectors are roughly 560cc and its scaled to 513cc I transferred over that percentage difference into my evoscan "eval" formula to see how it'd work out.

Here was my breakdown:

513/560= .916

The evoscan formula is [injpulsewidth]*[RPM]/1200

I took the 1200 and divided it by .916

1200/.916= 1310 (rounded to whole number)

I edited the "eval" formula to:

[injpulsewidth]*[RPM]/1310

I recorded a 3rd gear pull with both formulas for you to see. The highest IDC I recorded with the 1310 formula was 95.59% and the highest IDC recorded with the standard 1200 formula was 103.79%

It seems to be in the "ballpark" to me.

 

What exactly are you looking for as far as results? I am willing to go back to 513 scaling on my injectors and do a couple of logs and compare them to the logs with 472. What differences in the logs should I look for?

 

guys as I said in the other thread, use 2byte RPM.

regular RPM is a little "behind" 2byte RPM, so with 2byte RPM your IDC's will be even higher. over 100% in some cases...

Hence why I think you need to apply a scaling correction (scaling/actual inj capacity) to the IDC algorithm...

 

I get rpm from ECU rpm pin with LMA3. How does calculating IDC from tach signal rpm differ from 2 byte rpm?

 

I used 2byte RPM in my logs, I just transferred all of the 2byte ID's to the standard RPM location in the evoscan datalist

 

Just to see if the IDC changes in a pull that is pretty similar to one with it set at the other scaling level. As we have been discussing, I am now starting to waffle and expect that we will see identical IDC's. Curiosity however has me by the tail and I want to know for sure.

 

I will do it. So much testing to do. My car has become a test mule for a lot of ECU mods lately. I am flashing that poor ECU almost daily. But nothing comes close to the 1000 mark that you have crossed JB. You are the king of the flashers (pun intended)

 

My stock injectors were at 99% duty cycle when I put down 378whp on pump gas on the stock turbo. That was with AFRs from 11:7 to 11:9 at 7000RPM. I of course had a Walboro pump. Ran the car like that for over 30,000 miles!