Are Hellcat fuel trims fat by default?

So I was going through some logs today and I noticed on my stock Hellcat the the fuel trims are kind of fat. Is this to make sure nothing goes boom or is it required to ensure max power? So some starter knowledge that I learned during looking at the logs and trying to walk it back. Stoichiometric for the cars is 13.85. I found this value bye doing 1/FAR. FAR in this car stock is 0.0722. The next thing I learned is that the Command EQ Value directly correlates to aircharge or pressure ratio. I don't know the inner workings but I'm assuming this is accelerator pedal commanded or throttle position where the tables switch over or perhaps a blend of both. So as an example I found the following values in the log:

RPM: 4803
Aircharge: 1.40
Pressure Ratio: 1.72
EQ Ratio Commanded: 0.76
FA Enrichment: 0.0227

0.0722 + 0.0227 = 0.0949
1/0.0949 = 10.53 AFR
10.53/13.85 = 0.7602....

So the math checks out! Glad I figured out how to work back the numbers, however I am trying to figure out why the default fuel trims are fat. Is this from the factory that way? Is this to make the car happy? Is it required? I know I plan on making the two tables FA Power Enrich PRatio Based and FA Power Enrich PRatio Based the same and shooting for 11.50 as the number in both tables but is there anything to be gained from this? Will the car perform better instead of washing the cylinders with gasoline?

Attachment 104000

Attachment 104001

Yes... they want to keep it safe

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Originally Posted by Ben Charles

Yes... they want to keep it safe

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Would it be unwise to flatten the tables by making them the same and targeting 11.50 throughout? I think with a leaner mixture would it have the potential to run better?

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Originally Posted by fumanchu182

Would it be unwise to flatten the tables by making them the same and targeting 11.50 throughout? I think with a leaner mixture would it have the potential to run better?

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I asked the same question, looked through the forums and no strait answers, I know other tuners like 11.7 AFR and on these forums I seen in the forums that these cars make the best power around .83 about 12.0 AFR a bit to lean me on average setup with pump or unleaded race gas. You were the guy with the go pro on the roof behind me last friday at MIR correct. If you have cats your going to see a lot of fuel in the 10s, if not and your running mids turn off all those COT parameters for racing you just have to dial it is till it making power and your not getting any gains from leaning it out then I fatten it up a tad personally. Do not get greedy on the timing! I think your running stock boost correct or do you have a lower?

Unless someone tells me different I will be looking for 11.3 on my next track rental and once I am confident I can make clean passes with data to compare and not hit limiters like i did last weekend i will lean it out to around 11.7.

My 19 red eye uses aircharge for PE and it was set at 110 from the factory so .722+110=832 1\ .0832= 12.01. for P ratio I am setting the lower tables the same till i get a handle on when or if p ratio is used on demon and red eyes, since it is not selected in the tune. I actually targeted 11.3 for my track rental coming up and will work from there, .722+160=.882 but this with mid pipes and enrichments turned off for them.

well a stocih is stoich and from what i have seen hellcats crusie at 14.7 if you use a wideband hooked up to the car , the evic just displays the 1 lambda to be equal 13.7

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Originally Posted by malikib

well a stocih is stoich and from what i have seen hellcats crusie at 14.7 if you use a wideband hooked up to the car , the evic just displays the 1 lambda to be equal 13.7

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.722 is stoic in my hellcats calibration, 15% ethanol. Stoich is Stoich=1 lambda , under part throttle and cruising great no problem using the method outlined in these forums, 1 lambda for any fuel is Stoich i get that , what I'm taking about is once you get into boost, your PE starts to come in and is added to to that .722 as calibrated stoich, these cars have factory wideband sensors so I have not bothered to install stand alone system at this point , I am working on WOT passes on the track in my case 93 pump for street tune and 100 octane for my race tune until I feel proficient enough to move on to other fuels, I believe I met the OP and he was doing the same.

I got myself confused over that dash readings for a day or 2 on initial short bursts testing, not even practical to look at going down the track, Ill focus on the data the car and track provides for now.

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Originally Posted by joeapple

I asked the same question, looked through the forums and no strait answers, I know other tuners like 11.7 AFR and on these forums I seen in the forums that these cars make the best power around .83 about 12.0 AFR a bit to lean me on average setup with pump or unleaded race gas. You were the guy with the go pro on the roof behind me last friday at MIR correct. If you have cats your going to see a lot of fuel in the 10s, if not and your running mids turn off all those COT parameters for racing you just have to dial it is till it making power and your not getting any gains from leaning it out then I fatten it up a tad personally. Do not get greedy on the timing! I think your running stock boost correct or do you have a lower?

Unless someone tells me different I will be looking for 11.3 on my next track rental and once I am confident I can make clean passes with data to compare and not hit limiters like i did last weekend i will lean it out to around 11.7.

My 19 red eye uses aircharge for PE and it was set at 110 from the factory so .722+110=832 1\ .0832= 12.01. for P ratio I am setting the lower tables the same till i get a handle on when or if p ratio is used on demon and red eyes, since it is not selected in the tune. I actually targeted 11.3 for my track rental coming up and will work from there, .722+160=.882 but this with mid pipes and enrichments turned off for them.

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Yeah brother! That was me, next time you go down to MIR let me know, good to know there are some cats in the area that go down. I believe we talked about my windows tablet and how I eliminated my laptop from shooting forward in the car. :)

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Originally Posted by malikib

well a stocih is stoich and from what i have seen hellcats crusie at 14.7 if you use a wideband hooked up to the car , the evic just displays the 1 lambda to be equal 13.7

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No the hellcats cruis at 13.85, it's a fat fuel trim, keeps temps down and adds in error for ethanol.

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Originally Posted by joeapple

.722 is stoic in my hellcats calibration, 15% ethanol. Stoich is Stoich=1 lambda , under part throttle and cruising great no problem using the method outlined in these forums, 1 lambda for any fuel is Stoich i get that , what I'm taking about is once you get into boost, your PE starts to come in and is added to to that .722 as calibrated stoich, these cars have factory wideband sensors so I have not bothered to install stand alone system at this point , I am working on WOT passes on the track in my case 93 pump for street tune and 100 octane for my race tune until I feel proficient enough to move on to other fuels, I believe I met the OP and he was doing the same.

I got myself confused over that dash readings for a day or 2 on initial short bursts testing, not even practical to look at going down the track, Ill focus on the data the car and track provides for now.

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I don't even look at the gauges. I'm looking at the christmas tree. :cheers:

This friday 16th, but its a private track rental, after trying to do an actual test n tune and getting 2 crappy passes last Sunday, I paid for a private track rental so I can get a handle on the new power and torq limits, everything was easy stock :), OCT 23 MSHS will be next public event I suggest you buy your tickets online!