Taping hood/grill/headlight gaps...
 

Well...during my long trip out West and back...I decided to tape the hood, grill, and headlight gaps with packing tape to see if it would make a difference. Along with the dropped air dam, I was able to hit 25mpg fer the last 3 gas tanks...trucking along around 65-70mph. I was averaging around 23.5mpg on the West coast. The best I ever got before the tape and dropped air dam was about 22mpg. :D

Not sure if the added weight I had in the back made any difference or not...but I was carrying close to 700lbs of gear in the truck. I normally have about 300lbs or so.

So I'm thinking...since the packing tape won't last that long in the heat and stuff...about using the 3M clear bra stuff in strips over the gaps. Might have to hit up some of the tint places and see if they have any long strip scraps. ;)

Interesting, I'd reckon the airdam to be doing most of the work though. I used to think gap taping was a waste of time on most of the body due to 1/4 inch gaps being barely aerodynamically significant at low (sub 150mph) speeds. However, anything on the front of the vehicle is in a higher pressure area, and it appears it may make more difference up front than is worth it anywhere else. I'd figure that those with Cds in the 30s and mpgs over 30 might see half an mpg from it, if that.

I've been thinking about it as a "what next" thing after some more drastic types of mods, and thinking that the way I'd do it for anything like hood gaps and stuff that had to open, would be to stick one strip of tape half over the edge, leaving half of it unstuck, then get another strip of tape and fold it over the sticky half of the other tape, such that it would form a flap that would seal against the gap under pressure (but due to Bernoulli curse him, might flutter a bit in the airflow.)

Being that my truck was a former work truck and it had picked up some "character" on the nose of the hood...it doesn't fit as flush as it should. Although...some parts of the hood have some "tight" clearances with the grill. ;)

With just the air dam going out to the West coast (and 300lbs lighter)...I only got about 23.5mpg. So I figured I'd try some other things to increase the FE...like cheap tape! ;)

Maybe most of the efficiency came from the nose and not the sides of the hood gaps. Maybe it channels it more on my truck since it's got some character... ;)

What year/make/model is your truck?

-Jay

Strange as it may seem, I got my best mileage to date (54 MPG ) with an extra 200+ lbs in the car.
Everyone knows that the weight did more harm than good for my gas mileage, but I'm just sharing that to show how hard it is to accurately guage if some modification makes a difference.

Meh...weight doesn't make much difference unless it's a significant percentage of the car's weight and you're driving 100% stop and go race to the next traffic light driving or have a large net elevation gain between your origination and destination (elevation gain is always zero if you start at home and end at home). Some of my best tanks have been with extra weight.

The reason that lighter cars can do better is that they can come with less powerful engines; adding or reducing weight without adjusting the engine size/power won't have much effect. For all the energy it costs to accelerate extra mass, you get that much more momentum out of it.

1993 Toyota T-100 SR5 (auto trans, 2WD) with the standard 8' bed...it only came with the 3.0L V6 that introductory year. I think it was rated 16/20mpg.

Was that a mostly down hill trip?? :)

All I can think of is, that extra 200+ pounds caused you to take more care
in your driving.?. Maybe the extra weight made your shifting smoother?

After I took a lot of weight off my CRV, I found my cruise control was surging
up and down, giving the car a little jerk forward and slowing down a little.
It actually drove smoother with extra weight in the back.

Later, I found out my gas petal cable was a little loose. After adjustment,
the CC smoothed right out with light loads.

Where was the weight placed? Way in back, or in the front seat?

I just looked over my paperwork and found my gas reciept that I had my information on.
The trip was 184.7 miles with 130 or so miles at between 55 - 60 MPH.
I pulled in my ( single ) mirror and had a grille block on around 2/3 of the grille.
Dry roads . Little to no wind. Flat roads.
Gas was $ 2.58 that day. I used 3.427 gallons to travel 184.7 miles, giving me a figure of 53.895 MPG.

Now the part that doesn't make sense : I had not 200 lbs ...but 318 lbs of iron weights in the back floor board.*

Any explainations ??

*I used my car to move from Houston to Austin and made two trips. I forgot to remove the weights on the second trip since I had some clothes piled on top of them and didn't see them. When I got home, I took eveything out of the car and weighed it on my scale. Three hundred eighteen pounds.