Turns out, these are my FMF charts/data that is most comparable.

(( My FMF chart using the DJ136/5n/#35 pilot/3.5 Turns out, is flawed in that the Dyno operator is sure that was a 3rd gear run - Not our usual 4th gear - So its' numbers are inflated and not usable.))







Previous Run - FMF is in BLUE

 

On this latest chart, notice the dip in HP and rise in AFR @ 8300 - 8900 RPM..

I'm still putting sense to the data, but a few things are pretty obvious when using the FMF system ( near sea level, lid off, MCM, etc), and perhaps any larger diameter header/midpipe system..

1.) Each DJ main jet increase gives an average .1 decrease in AFR up top.
2.) A proper AFR up top releases considerably more HP.
3.) Peak TRQ continues to arrive around 6.5k RPM (Standard cam timings would likely peak higher up in the RPM range - perhaps 500 rpm higher?)


Other Notes:
The DJ140 is still too lean at 13:1. A DJ144 should get to my target of 12.8:1 ..
I'm running retimed cams (MCM) - Standard cam timing could show larger increases up top.
UP to 6.5k , I am too rich - this must be retuned. However, there is more TRQ and more TRQ produced quicker than with the AFR's on the bottom chart.. Perhaps simply resetting the fuel screw to center from either side of idle drop ? It is now set toward rich from idle drop..

More eyes on this would be helpful.. Does it seem like the TRQ production likes an AFR of about 12:1 ?

 

It's admirable seeing all of the effort you are investing in doing dyno runs. I'm kind of curious to see what effect making jetting changes to get both exhaust systems at equal a/f would do for power output. Will the curves be similar when the a/f are the same?

 

Well, I just rechecked the charts and the AFR's are practically the same - too rich below 6.5k and up to 13:1 on top..Those two exhaust systems produce really close numbers and curves with that last run..I probably lost TRQ due to the fat AFR below 6.5k -perhaps more so with the DGR.. I've reset the fuel screw to about the middle between idle drops - maybe a little toward lean.. Also moved the clip to 3n.. Initial short test ride gave good results.. I guess I'm only going to use the FMF system due to the superior HP curve, which is quite noticeable to the seat-o-pants dyno..

 

How's the performance under the curve?? WOT Dyno runs are cool but under the curve is where it really matters...

 

Well, Matty, I'm not sure what your asking.. It's very true that a Dyno run is only a diagnostic tool creating a diagnostic data set.. I am determined to find what it takes to get and keep the AFR in the best power production range (12.0:1 - 12.8:1) so I'll know what is possible with our engine and simple mods.. I am leaning toward about 22 HP and 15.5 lb ft TRQ - but I'm not quite done yet..

 

I think what Matty is getting to is talking about peak HP/TRQ vs the area below the line in the chart. You could have one config that peaks at 22HP, and another that peaks at 21HP, but if the one with the 21HP peak has more 'area' below the curve, it will have more power all around and for most applications be a stronger setup.

Not a great example, but here's the idea: (graph on the left has more peak TRQ, but it's more 'peaky' whereas the one on the right has less peak TRQ, but is a 'flatter' curve and has more TRQ all around in all rev ranges. I know the 2 charts are actually comparing a diesel to a gas engine, but it's the 'shape' of the curves that I think he's referring to, and the calculated area below the HP and TRQ lines that can be significant.
https://encrypted-tbn2.gstatic.com/i...lMZmrhQcVNl_Ug

 

Oh, ok, Gotcha.. The answer is simple - the HP curve on the FMF is superior - there is more area under it - than the DGR .. While the numbers don't shout out that there is much difference, there most definitely is, and it is this "running under the curve" that you speak of..

I really shouldn't make assumptions about the curves below 6.5K due to the AFR being overly rich - I am working on that problem now..

The FMF gives hard pulling all the way to redline - the DGR "peters out" not far after 9K and requires short shifting.. With stock gearing, the FMF stays in its' "sweet spot" as you go WOT through the gears, revving to redline(ignition cutoff) - So in a race, there would be no contest..

I hate to say it but I guess I will, with the FMF, on a WOT test, I was not sitting fully forward as I usually do, it wheelied on the shift to second.. There, I said it...LOL