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Old 01-23-2015, 01:48 AM   #2 (permalink)
In Lean Burn Mode
pgfpro's Avatar
Join Date: Apr 2009
Location: Pacific NW
Posts: 1,427

MisFit Talon - '91 Eagle Talon TSi
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90 day: 41.03 mpg (US)
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Wow!!! Looks like your making some major progress.

As far as ignition timing advance goes, I think you will be the only one that will be able to tell what works for your particular car.

On my lean burn setup, on my last test run I didn't get enough seat time to really see what does what. My personal best so far at 65 mph is 38 mpg. That's with hot EGR enable and lean burn at around 30:1. I was more just testing making sure everything was working and not fine tuning for FE so I think I should be able to get over 40mpg @ 65 mph pretty easy during the winter months.

How much timing should I add when going from stoich to such lean mixtures?
What I do is I use a long stretch of road that is extremely flat. Make runs both ways. I start with a low timing and just keep adding timing until there is no more improvement on my instant mpg readout. Also keep a close eye on the knock sensor. I then save that log. Then take more fuel away and repeat.
I also attach a MS word weather condition file with that log.
tracks Air Density Online

Tonight's local conditions.
Spokane Raceway Park in Spokane, Washington
temperature = 33.0 deg f
relative humidity = 92 %
uncorrected barometer* = 27.98 Hg
corrected barometer* = 30.45 Hg
density altitude = 679.83 ft
dew point = 30.9 deg f
saturation pressure = 0.188 Hg
vapor pressure = 0.173 Hg
grains = 27.0
air density (w/o water vapor) = 99
air density (w water vapor) = 98

My test road around 5 miles long, very few cross roads and very flat.
Pressure Gradient Force
The Positive Side of the Number Line

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