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robof16
December 28th, 2011, 05:01 PM
No answers in my search…

Without a wide band O2 sensor, how do we have any assurance that our PW’s are close enough for good power without going overboard and wasting fuel?

Garrett web site claims 22:1 AFR is good for power with little to no smoke. B.S. flags?

Anyone calculating desired PW using injector flow rates combined with rail pressure to match air flow rates for a sanity check in their tunes/logs or am I way behind the learning curve?
I know this is pretty well sorted out by the tuners but I’m curious how you build a PW table.

THEFERMANATOR
December 28th, 2011, 05:21 PM
With a diesel your air fuel ratio isn't really that important IMHO. Watch your EGT's and make sure they are under about 1400 pre turbo. As far as how low you can go, some have checked and gone down to 11:1 on the ratio. I know I just built up a 20% over pulse table(ramps up from 10mm3 to 120mm3 to 20% over), and I set it up to reach close to 120MM3 of fuel on the top end whereas stock would only hit around 100 in those areas. And it didn't even hardly haze with only 25 pounds of boost.

robof16
December 29th, 2011, 04:05 AM
I was wondering if a spread sheet like Josh's timing table would be useful. The advantage is that there would be fewer variables... I think.
In theory you know how much air (Lb/hr) it takes to support a given HP for a given displacement and at what RPM, etc.
You also know the fuel required (Lb/hr), and injector flow rate for a given PSI per hr.
Can you convert those figures to a fuel per revolution and divide by 8?
Wait, do you divide by 8 to get PW?
I’m struggling a bit with this as my answers aren’t passing the common sense test.

killerbee
January 1st, 2012, 02:31 AM
I think your question is best answered with the "equivalence ratio" custom pid. You will probably find a calcpids file in this diesel forum if you search for that term. It is essentially a fuel/air ratio.