White Gnat posts 60.9 mpg on 405 mile tank

[wmjinman]

This is now twice over 61 mpg and my 3 tank average is actually 61 now. Improvement is coming slower, though. Maybe time for a kamm back and belly pan.

Also a new record for range - 444 miles. Of course, the fact it only took 7.2 gallons indicates I could go a LOT farther if I pushed it. Inching my way up, though - fuel gauge reads above "full" all the time, and as much as I'd like to, I can't believe it's accurate.

[wmjinman]

More good news and mediocre news:

The good news is is the average mpg is still climbing, but slowly, and I made 16th on the "top gasoline cars" list.

The mediocre news is the mileage dropped again - after 2 consecutive tanks at 61+, this one was below 61. - - - 60.95. But I don't feel too bad, because I filled up in Sacramento while down there, then came back home and finished off the tank, to re-fill in Carson City - 4000 ft. higher elevation that it started at. So - 60.95 mpg in a tank that CLIMBED 4000 ft isn't too bad IMO.

[nemo]

Great news, just think how much you save over driving the Jimmy.

[wmjinman]

Originally Posted by nemo

Great news, just think how much you save over driving the Jimmy.

Yes, I DO think about that now and then. I am THRILLED with the performance I'm getting.

[wmjinman]

With the increased distance between fill-ups, the fill-ups are coming less frequently.

I've finally began work on what will hopefully become a kamm-back to boost my mileage at higher speeds (and all speeds)

[nemo]

A couple more MPG and you will be tripling the average milage of the Jimmy.


Remember to post the pictures of the kamm-back and results.

[wmjinman]

OK, good idea - ran out & grabbed a shot of it. 3 plies of fiberglass, using 6" wide fiberglass cloth "tape" with the middle one being at a 45 degree bias. The weave at the edges of the tape cause the ridges, the price to pay for the convenience of using tape. Hope it's strong enough.

As you can see, I'm using the roof as a mold. My plan is to just continue the curve of the roof back - nice & smooth. To do this, I cut two strips of wood with the curve so I can attach the fiberglass piece to it while the front half lays on the roof ahead of the kamm-back.

For the sides, I plan to use the rear side windows for molds (a little nervous about how to release it though - if it decides to "stick"). Although I haven't cut them out yet, I'm thinking of doing similar boards to hold the sides at a smooth continuation, too. Then hand-lay the transition between the top & sides with an increasing radius towards the rear.

EDIT: OK, just got it removed from the roof. The "trick" - use a long butcher knife to progressively work the separation between the roof & the fiberglass, blade first, then by lifting the edge up enough to get the knife's handle under it & keep progressing until it's all free. I alternated slicing motions and in & out "slow stabbing" motions to work it loose. I'm still not 100% confident this will work on the glass side windows, which will not flex *much* without breaking. But it worked on the top. There seems to be decent strength, even though it's probably not fully cured yet. It seems to want to warp, or twist. This is probably because I only used the tape to do the 45 degree bias in one direction - probably should have laid another with the tape edges running 45 degrees the opposite way on top of the first biased ply. Will probably be OK though, once the sides are attached and the whole thing is anchored to the hatchback.

[whatmaycome14]

Great job!

[Jasen]

Cover the mold area with clear packing tape as your mold release agent.

Congrats on the stellar FE

[wmjinman]

Originally Posted by Jasen

Cover the mold area with clear packing tape as your mold release agent.

Congrats on the stellar FE

Good idea - I might just do that!

I've actually used the packing tape for that purpose before, but not on something this big. I've also not always had it release that easily, but I suppose it's still far better than to risk having it bonded to the actual glass. In a worse case, I could probably keep dripping adhesive remover underneath it if there's any trouble. Eventually, I should be able to get it off!!