Injection Timing Assistance Requested

[Eaglegoat]

It does take less time but more in crank degrees because there is less time between degrees of crank rotation. Attachment 66806

Are you just leaving the same time in there with the thought that it will all wash out in the end? What is the 24.5ms time based on?

[Niemer]

Using this spreadsheet and the info in here changed my trims from +/-3% to less than +/-1%, pretty crazy.

[IARLLC]

I realize that adjusting injector timing is much more important when using an aftermarket cam but we do like to give our clients the best possible service. With this in mind, where do you find factory cam specs? Does GM publish them?

[07GTS]

I realize that adjusting injector timing is much more important when using an aftermarket cam but we do like to give our clients the best possible service. With this in mind, where do you find factory cam specs? Does GM publish them?

i have seen stock LS cam specs somewhere they are in a list but is all .050 im not sure on the .006 specs

[realcanuk]

Just read this whole thread and my head hurts. LOL

[barum]

It does take less time but more in crank degrees because there is less time between degrees of crank rotation.


Attachment 66806

This looks really familiar.

[Michael_D]

General question.....

Do you guys find it a better practice to zero out the normal rpm and/or normal ETC and focus primarily on boundary changes? Or, do you use all tables? I've been playing with the spreadsheet and the combinations of different iterations to hit targets is kinda mind numbing.

[barum]

Since the end result is based on a linear equation, it doesn't really matter.

However,
- since we can't be 100% sure that the boundary is not related to any other function, I'd make as minimal changes as needed in there
- ECT is intended for taking care of the warmup and other non-std ECT situations, so I'd make changes in there only if something can be directly identified to be temperature related

Conclusion would be to use the RPM table for most of the needs and then change boundary only as much as is needed in the areas where you run out of adjustment range.

[schpenxel]

Just read this whole thread and my head hurts. LOL

Me and you both

I posted one of the original sheets that got it started and my head still hurts... it got taken a bit further than I've ever seen (or heard of) before

[schpenxel]

Best and most straight forward advice I can give - aim to keep ppv right in the middle of eoi and soi except for high rpms where you will keep eoi after fuel to port time is included at around 15 to 20 degrees before ivc... Especially where your running a PD blower The eoi is about 15 to 20 hp sensitive - you can loose that much with it being off that little and then more if it's off more...

I just spent like an hour going through this thing. Really wish I had my cam specs @ 0.006 but only have them at 0.050. I used those for now

Basically I've got it to where PPV is right in the middle between SOIT-FRC and EOIT-FRC for 0 to 2048 RPM's. For mine that works out to SOIT-FRC always being after Exhaust valve is closed.

Then for 3072 and up I'm targeting EOIT-FRC to be 20-25 degrees before IVC.

For 2560 to 3584 it's somewhere between what you said to do for low RPM's vs. high RPM's. A transition if you will

Am I reading it right? I've removed a few lines but here is what I have right now. I got rid of the actual SOIT and EOIT and left the "FRC" versions since I'd think those are more important.

Capture.JPG

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The "graphs" tab is really the best one for me visually. Once I understood those fully the graph in the "table" tab started making more sense. There is a LOT of info on that one.

[GHuggins]

Maybe don't fully retard it until 5600 and then flatline the boundary there - otherwise see how it does

[schpenxel]

Will do, gotta finish putting exhaust on first. It's shaking the ground at the moment without any mufflers

[scottt28]

Same here... not sure who came up with the original graph, but the final (?) version turned out great. I tend to look at the graphs (the black ones), then back to the tables for slight tweaks. I'm not totally convinced that the FRC stuff is critically important, but the logic is sound.

[schpenxel]

I'm claiming responsibility for the original graph

But that's about it

I've messed with the sheet some more and I really like it

[Eaglegoat]

Same here... not sure who came up with the original graph, but the final (?) version turned out great. I tend to look at the graphs (the black ones), then back to the tables for slight tweaks. I'm not totally convinced that the FRC stuff is critically important, but the logic is sound.

I'd be curious as to how much time it's actually taking for the FRC and also if maybe it's somehow accounted already in the OE tables.

[Michael_D]

Since the end result is based on a linear equation, it doesn't really matter.

However,
- since we can't be 100% sure that the boundary is not related to any other function, I'd make as minimal changes as needed in there
- ECT is intended for taking care of the warmup and other non-std ECT situations, so I'd make changes in there only if something can be directly identified to be temperature related

Conclusion would be to use the RPM table for most of the needs and then change boundary only as much as is needed in the areas where you run out of adjustment range.

Thanks. Your input makes sense to me. Any idea why the RPM table stops at around 4900 rpm?

[GHuggins]

Use boundary and ect - leave the rpm table zeroed... The injection timing your already running should be really close to what you need even with the new cam Michael...

[Michael_D]

I actually changed the tables from last year a bit for the new cam and smaller injectors. I just HAD to use this super-cool spreadsheet!! Had to guess on the injector pulse widths, seeing how I hadn't logged any runs yet.

[mowton]

Best and most straight forward advice I can give - aim to keep ppv right in the middle of eoi and soi except for high rpms where you will keep eoi after fuel to port time is included at around 15 to 20 degrees before ivc... Especially where your running a PD blower The eoi is about 15 to 20 hp sensitive - you can loose that much with it being off that little and then more if it's off more...

I also try and place the idle injection timing right around the PPV (thanks Greg :-)) and after the Exhaust valve closes to compensate for inefficiencies as a result of not injecting against a closed, hot intake valve in large overlap cam setups. I believe it optimizes the fuel/air mixing and minimize cylinder wash.

Ed M

[jsllc]

Are you just leaving the same time in there with the thought that it will all wash out in the end? What is the 24.5ms time based on?

Calc is based on the time to travel a certain distance (injector to chamber). In the case of most LS applications the injector is placed in the same location ie same distance.