Is 42mpg too low a goal?

[QuickLTD]

Looks great but lose that tire lathe...

[Istas]

I am, those will be trimmed (or bent up to attach the mud shields to). I just didn't want to cut them off right away without thinking about it, and also wanted to give a bit more clearance to the tires.

[NeilBlanchard]

Now you're moving right along! Have you looked at the air flow out from behind the radiator, inside the engine compartment?

[Istas]

I've still to put the foam on either side of the radiator to seal the edges of it from the intake front, and there's lots of other little places for the air to go. After the radiator are the fans, and then the engine itself, no more ducting can really be done behind it. I'm pondering sealing the left and right edges of the hood, though, with foam tape.

Running out of time before the 2500-mile trip home, but I've got all the major components done that I wanted to, except the MPGuino. Hopefully I can figure that one out in the next few days.

[MetroMPG]

Just a note on the transition at the base of the new air dam to the undertray...

Note the radius on the bottom of the OEM version. The 90 degree angle on your version will cause flow to separate. Your partial undertray will be seeing turbulence, and likely a locked vortex up front. That'll add drag!

The transition radius doesn't have to be large to retain attached flow - even about an inch is enough.

[Istas]

Argh!! I had not thought about that at all. Ugh... this will not be a quick fix. Thanks for the clue-in though.

[MetroMPG]

Sorry! After seeing the work you put into it, I was really reluctant to be the bearer of bad news.

[Istas]

I'd rather have the bad news than be oblivious to it. I'm pondering ways to deal with it, not easy to make a shape like that with sheet metal obviously. Hmm. Perhaps some curved foam rubber affixed to the front of the airdam I already have on there. Ah well, what I have still has to be a vast improvement over what was before. I won't worry about it too much, but I will keep it in mind for future changes. Thanks again for the heads up.

[Istas]

Okay, what do you think of this idea, MetroMPG... An inch-diameter foam cylinder, sliced in half lengthwise and running even along the bottom edge of the airdam. It'll have a bit of a splitter effect, which isn't good because of more airflow into the radiator, but it would give the round transition to the undertray.

[QuickLTD]

What about a small splitter? Two inches of sheet metal