WAI: does no power loss = no mpg gain?
 

As I tinker to try and raise my WAI's out temperature I've noticed I still cannot perceive any power loss. This got me thinking about the theoretical foundations of WAI improvement and makes me ask: can you get a noticeable mpg improvement while also having no significant power loss? Seems like they'd go hand in hand (assuming any mpg gain at all), although driving style would effect how obvious the difference would be.

If the change results in more efficient combustion then you get more power from the same fuel but it may also mean less MAXIMUM power at full throttle since you may not be able to support that power level without knocking or excessive heat in the engine. However you may not be able to preheat the air as much at high flow rate anyway so it may self limit.

I guess it comes down to the relationship between pedal and throttle as to whether or not you'd need to push down more or not at lower power levels.

during my experiment (which is almost over, thank goodness) I don't notice much power difference unless I need a lot of throttle. usually during take offs but still trying to keep it out of open loop. when the throttle position is 3/4 or so, then it is noticeable. I think it just cuts off the top end.

Since I drive like such a weeny I probably won't notice much then. Good to know.

I have noticed between 3-5 percent gain in my experiment. I haven't ran the numbers to see exactly where I am falling but it is in that ballpark.

I haven't noticed a huge difference in power but, like you, I don't use a lot of power.

my test wasn't stock to WAI but more a temperature delta. I couldn't convert mine back to fully stock. my "stock" was actually running around 20 degrees above the average temp for the day where as when it was actually stock, I only saw about a 5 degree difference at the most.

the delta between warm and cold (you know what I mean) stayed around 50 degrees.

the mileage difference is pretty consistant and my driving style didn't change during the experiment. I have about 125 miles left on this tank and then I hope to end this experiment. I have been working on it now for over 2 months. I'm sick of taking manual data, data logger would have been real nice for this one.

Just to make sure I got this:

stock = ambient + 5 F tops
"cold" = ambient + 20 F
"warm" = "cold" + 50 F = ambient + 70 F

roughly there abouts.

what I did was recorded the time, IAT, and date of each trip (mine are usually 20 miles or longer) I recorded the IAT at the end of the trip. those figures were averaged along with the temperature of the day. I can't remember the web site but it gives you the weather for a certain day in a certain area. you get to chose both. theholycow hooked me up with that.

those figures 20 over ambient and 70 over ambient are apprximates. like I said, data overload will come soon. I am thinking about posting just the results of each tank (averages and what not) and then more data if needed.

On my truck I don't start to notice a power loss until I hit temps of 180 - 190. I think it just depends on your vehicle. Most often while hypermiling you're not using much power anyway.

Focus is slower
 

I just got the Focus and drove it back to Baltimore and the first thing I did was take off the grill ram air and I saw my mileage go from 29 to 32 mpg. One thing I could feel was less torque on hills, previously I could take a decent hill in OD and the engine would pull with the air on. Now with the intake tube drawing from inside the engine bay I have to turn off the AC or it will drop down a gear. I also notice freeway on-ramp acceleration is just a tick slower, I got to put my foot in it more. I plan to construct a dedicated WAI tube, we'll see if it takes down anymore performance, but hey its one step closer to 40 mpg. Soon I will get pictures and cross country mileage logs posted.