Gen 4 fuel injection timing strategy - boundary settings

[NotSure]

I have read posts on injection timing until dizzy, and it seems there is a consensus that GM attempts to inject on a closed intake valve to aid in vaporization, though there are some other thoughts out there as well. I am working with a completely stock 6.2L L94 with a Whipple, 72 lb injectors, 8 psi, and have played around with injection timing some but recently it seems that I may be getting fuel dilution in the oil, which made me revisit these settings.

I'm plugging numbers into the wonderful spreadsheet that some generous genius created, and looking at the stock cal, it appears GM was NOT injecting before the intake opens, but just AFTER opening, at low rpm. I would think this is the time you would want to inject early? Beyond that, they start really advancing the timing (lower boundary numbers) in the higher rpm, to the point that injection is fully completed BEFORE the intake even opens? Kind of a pain to put each rpm possible into the spreadsheet, as the variable cam begins retarding around 2400 rpm. But it is definitely an early injection timing at high rpm, even taking into account the stock cam retard. Does this sound right? Seems backwards.


I am boosted so I know that changes things, but have delayed injection time accordingly, trying to get the full injection amount in the cylinders 30+ degrees before IVC. I am also leaving the stock cam in the locked position. Stock cam is 195/201 - 115 @ 0.050". So I don't have any overlap to be concerned about as most others do.

Attached is the stock boundary chart, the one I used most recently, and a couple of snapshots taken from the spreadsheet graph. For the recent injection timing, I added in 100 to the RPM Boundary chart, up to 1000 rpm, thinking that it would help to fully inject on the closed intake. Above that rpm, the RPM Boundary is zero'd so injection is targeted more towards the open intake.


0 512 1,024 1,536 2,048 2,560 3,072 3,584 4,096 4,608 5,120 5,632 6,144 6,656 7,168 7,680 8,192

Stock
Boundary 506 506 506 506 506 506 499 468 418 382 363 347 336 328 328 328 328
Normal RPM zero'd

Latest cal
Boundary 500 500 500 550 550 550 550 560 570 570 570 570 570 570 570 570 570
Normal RPM 100 100 (through 896 rpm)


The ECT chart was left stock, decreasing from 245 cold, ending at 110 when fully warm.
Makeup ECT left stock at 30
Makeup RPM left stock at 0


Just wanting to make sure I am not way off base here? Right now I think I will zero out the Normal RPM again, and leave the Boundary as it is, unless someone tells me I'm not just off base, I'm not even in the right ballpark, lol

[geneass]

ive been working on this myself. the only difference is I do have a bit of overlap. I think in your case as long as you make sure to inject after EVC in the lower rpm you'll be fine. the more I look at this the upper rpms don't seem to matter. I could be wrong. I wish there was a way of posting an Excel file on here.

[07GTS]

if overlap is doing its job then the higher rpm wont matter as it should be going in the cylinders but if ur boosted with too much overlap u can push some out the exhaust in higher rpm, also the PW is usually too long to even try to get it after the evc up top but also dont go too late as it can start to push back out the intake valve depending on your ivc events for low to mid rpm

[jsllc]

On your charts are your entering in overlap @ .006 or @ .050 of valve lift? Many give you the .050 spec not the .006 spec which his where short circuiting can start to occur.

[NotSure]

I am entering .050 as that is the only spec I have. But this is a stock cam, so the overlap is like -35 or something. I ran it today and with the 100 degrees advance (Normal RPM chart) taken out of the idle range, I did not see a noticeable change in fueling via wideband (open loop). But this was comparing to a couple of days ago, and it varies even without changes.

[Lakegoat]

Here is my boundary numbers. Cam has 0 overlap +-. I did this a long time ago and forgot how I arrived at the numbers. This is with a TVS2300 at about 12#

[jsllc]

I am entering .050 as that is the only spec I have. But this is a stock cam, so the overlap is like -35 or something. I ran it today and with the 100 degrees advance (Normal RPM chart) taken out of the idle range, I did not see a noticeable change in fueling via wideband (open loop). But this was comparing to a couple of days ago, and it varies even without changes.

Post your tune. There are items other than just one table.