Calibrated success DVD SOI explanation and fuel pump help

[HeavyChevy305]

To dredge this up again did anyone do the testing they talked about? Or just land on 280 in the whole table and let it adjust on its own? I have seen Brett pray post that he found 20whp on a car heads and cam that had it adjusted wrong. I wound think it would have to me the airmass was way off and it was commanding up into the high 390s or 400. The few cams I have looked at most are grinding them with exhaust closing and intake opening in the tdc range 360 degrees give or take a few degrees at least with the pd blower cams.
If the ecm is adjusting up then going to 280 gives a margin of error for sure and I guess the thinking on this. I might be able to do some dyno testing this afternoon so will test some out just curious if anyone else found anything.
Thanks.

I wouldn't let it adjust any more than 370.

[cmitchell17]

I thought the latest consensus on this was just to leave the stock table as it is?? regardless of how inconsistent, discontinuous, and ugly the stock table looks I thought it was concluded to be the best? I was thinking the only time you needed to change it was if you had a huge cam with a very late EVC?

[supercowboy]

To dredge this up again did anyone do the testing they talked about? Or just land on 280 in the whole table and let it adjust on its own? I have seen Brett pray post that he found 20whp on a car heads and cam that had it adjusted wrong. I wound think it would have to me the airmass was way off and it was commanding up into the high 390s or 400. The few cams I have looked at most are grinding them with exhaust closing and intake opening in the tdc range 360 degrees give or take a few degrees at least with the pd blower cams.
If the ecm is adjusting up then going to 280 gives a margin of error for sure and I guess the thinking on this. I might be able to do some dyno testing this afternoon so will test some out just curious if anyone else found anything.
Thanks.

I found 280 ish up in the higher rpm worked well. When I increased to 300 ish I was seeing more knock from the change. It would settle down with the advanced with lower values. The car would see minimal gains but would run smoother with this dialed in correctly. There would be less knock from fuel change and loading the cylinder with fuel. I'm not seeing much afr change in adjusting this. I have noticed with larger cam The lower rpms can benefit from this more than the upper range due to the airflow characteristics. Im still working on this a bit. Im doing a supercharged car this week. Ill move the values around and see how this works with forced induction.

[cmitchell17]

I found 280 ish up in the higher rpm worked well. When I increased to 300 ish I was seeing more knock from the change. It would settle down with the advanced with lower values. The car would see minimal gains but would run smoother with this dialed in correctly. There would be less knock from fuel change and loading the cylinder with fuel. I'm not seeing much afr change in adjusting this. I have noticed with larger cam The lower rpms can benefit from this more than the upper range due to the airflow characteristics. Im still working on this a bit. Im doing a supercharged car this week. Ill move the values around and see how this works with forced induction.

I wish I had an engine dyno to test this on, but to me unfortunately this is just a huge big guess, like a lot of other things in tuning. I was hoping I could use this table to improve idle combustion stability with a cam, but just like experimenting with WOT high rpms, I see absolutely no confirmed and reliable, consistent difference changing this table.

Also here is something else interesting:
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This is from GM's SAE paper they wrote after development of the GEN V and LT1. Note design D is the production LT1 design how it exists now, and design A was basically a GEN IV carryover combustion chamber and port where the fuel injector was just kind of squeezed in and the spark plug location remained unchanged. It appears to me they are trying to convey that not only did the production design show higher IMEP (average cylinder pressure), but it showed it at a predictable and consistent around 300 degrees SOI. Besides that I don't think we can really get much of anything useful out of it but I thought it was interesting, and what I found most surprising was how much different the design A would have been. It also looks like we don't need to worry about fuel pressure either.

[eficalibrator]

This is from GM's SAE paper they wrote after development of the GEN V and LT1. Note design D is the production LT1 design how it exists now, and design A was basically a GEN IV carryover combustion chamber and port where the fuel injector was just kind of squeezed in and the spark plug location remained unchanged. It appears to me they are trying to convey that not only did the production design show higher IMEP (average cylinder pressure), but it showed it at a predictable and consistent around 300 degrees SOI. Besides that I don't think we can really get much of anything useful out of it but I thought it was interesting, and what I found most surprising was how much different the design A would have been. It also looks like we don't need to worry about fuel pressure either.

So basically, just like I said in my training video. Most of the time, DI prefers to have the injection event happen during the intake stroke. This gives good evaporation and mixing (which leads to more complete combustion).

[emperors61]

Does someone have a reference/link to the GM paper? My Google search skills elude me.

[LSxpwrdZ]

SOI table isn't a boundary it's a definable table that tells the injection when to start. The EOI is what is adjusted based on the PW needed to meter the fuel delivery. Unlike prior LS stuff where the SOI was back calculated and the EOI was defined in the tune. Injection timing is a rabbit hole because optimum SOI and EOI are key and both can be changed by the raw fuel demand and the pressure you are running in the rail. This is where dialing in those injection times while also dialing in the desired rail pressure greatly increases efficiency and complete burn.

[Higgs Boson]

SOI table isn't a boundary it's a definable table that tells the injection when to start. The EOI is what is adjusted based on the PW needed to meter the fuel delivery. Unlike prior LS stuff where the SOI was back calculated and the EOI was defined in the tune. Injection timing is a rabbit hole because optimum SOI and EOI are key and both can be changed by the raw fuel demand and the pressure you are running in the rail. This is where dialing in those injection times while also dialing in the desired rail pressure greatly increases efficiency and complete burn.

Unless the description is wrong, EOI tables are for dual pulse fueling, which is only enabled at startup.

[LSxpwrdZ]

Unless the description is wrong, EOI tables are for dual pulse fueling, which is only enabled at startup.

I don't think I explained it right. The EOI isn't user adjustable. It's a result of the injection duration and RPM. You can leave all the SOI injection tables alone and crank fuel pressure up and move the EOI quite a bit with FP alone. Point being SOI isn't the magic value when trying to make power throughout the curve... it's still EOI which means one SOI table isn't going to work in all applications.

[Ghostnotes]

This is one of the things I got the first time while I was learning these vehicles. Your cam, if you changed it will decide where your window lands. Just do the math. Then to get a little more window, make the fuel pressure adjustments. My EOI is stock. Never have black smoke. Is it only when you go WOT from a standstill. And/or does it do it while moving and going into WOT?

[Jonblarc7]

Mine blows smoke the most from a stand still WOT run clean cleans up as you get into the rpms. But still does it some from a rolling WOT run. AFR is .87 to .88

With a L86 and TSP 218/226 32% fuel lobe