I have been working on a plan for what mods I should do this year. I've learned that the mods you do should complement your commute/driving. IE: Aeromods in the city don't yeild much. So I've been trying to develop spread sheets to predict a potential benefit from different mods or driving techniques that I've been contemplating. I've based both of these spread sheets on my paticular commute.
The first is comparing Engine Off Coasting Vs. Engine On Coasting. I have a 80mile round trip commute that takes about one hour with an average speed between 43-45mph. I am able to coast down hills for about 6-10 minutes of each commute. So I wanted to see what benefit there would be if I modified the car to so I could turn off the motor and coast. For me the benefit is very small, only 1 mpg per week, however it is interesting that the gap widens as the time increases. I'm not sure if most folks have looked at this, I always presumed that having an ATX and not being able to EOC was preventing me from getting much better mpg, however because I have few oppertunities to EOC and I have a low idle gph (0.17-0.22), there is not much of a difference, presuming my graph is correct
The second graph is an attempt to predict the benefit of running lean. I charted from 12:1 to 25:1 AFR's. I based these numbers off of MAF readings from my car cruising at 50mph. I chose 8.73 and 10.87 MAF because those represnt the normal variation I see at 50mph. The formula I used appears to be very close to reality, so I presume the potential benefit predicted is close as well. I am hoping to go from the 14.7:1 AFR to 18:1 AFR and the predicted benefit is almost 12%. Seems like a good investment...if I can get it to work. It is also interesting to see how this chart widens with the reduction in MAF readings...
Enjoy!
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