Tweaking a 1966 F250 for better FE
 

I need a few more posts prior to being able to post photo's

I could use a bit of help in a front Air Dam for my 1966 F250.

I currently have a plastic one off a 2011 F150 but does not look very good and only extends to inner side of the front tires.

Truck started off with a 352 v-8 and manual transmission with 4.10 gears.

It now has late model F150 chassis, suspension, steering & brakes along with a 213 cu in v-6 and a 6R80 6 spd auto and a 3.15 rear axle.

At the moment the "tune" is more for performance, once that goal is met with a 12 second quarter mile I will shift back to Fuel Efficiency tune.

But as part of the 12 second 1/4 goal I need a bit of better Aero to get me there. Now short .037 seconds to the 12 second goal.

In beginning before the performance tuning and switch to E30 I did manage to pull off 30 mpg @ a steady 65 mph cruise.

Once the performance goal is met I will switch back to normal 91 octane pump fuel for further fuel efficiency testing.

Plan is to take the truck on a lower 48 State trip so MPG will be quite important.

Looks like I now have 5 posts so will try to post pics of with and without the Air Dam

Without.

http://img.photobucket.com/albums/v5...A08D443F97.jpg

With

http://img.photobucket.com/albums/v5...BEA1715D78.jpg

How much difference will it make to fab up a new airdam and have it extend further out on each side? In MPG testing I was seeing over 1 mpg @ 65 with airdam.

At this time inside of my box is not finished either, hoping to do that soon to see if the open area's have a effect on efficiency.

http://img.photobucket.com/albums/v5...07558DCC64.jpg

I have most of the pieces made up but need to get them welded in.

Trip meter set to 30 minute periods.

http://img.photobucket.com/albums/v5...9729233ADA.jpg

I channeled the cab and box down over chassis as far as I could so I can still fit in cab. LOL

http://img.photobucket.com/albums/v5...23130A7C93.jpg

http://img.photobucket.com/albums/v5...ps64e1a0ed.jpg

When I read your title, my first thought was LOWRIDER, but you beat me to it.

When you get it back on the road, look closely at the air flow over the hood. If there is a swirl in the middle of the hood, then reshape the leading edge of the hood to get smooth air flow over the hood.

Then look at how the windshield is installed in the cab and compare to modern vehicles. That mini visor at the top of the windshield is pure air drag.

Regarding your front chin spoiler;

1. I think perhaps a lot of air is being washed up into the engine bay - not so good of a thing.

2. I've had bad luck with plastic lawn edging, but it was not recessed and protected like yours. Other vehicles were parking by braille and damaging it on mine. Conveyor belt material is the superior choice but is many times more expensive.

3. My shortbox Ford van in the early 1980's I had installed a chin spoiler which did not quite cover the front wheels and stopped a little short like yours. As I recall I still enjoyed the majority of the benefits but there was some fruit left on the tree.

4. Regarding the cowl and chin spoiler, there may be a common aerodynamic treatment for both but I have not yet done it to my truck - see signature links below in my post.

I plan on installing plastic "Barrier Paver Edge" at the bottom of the chin spoiler as a "splitter" for down-force, and at the rear edge of the hood as a Gurney flap.

The Gurney flap just before the windshield wipers will according to an aerodynamicist I met with will kick the air up to meet the lower part of the windshield and not get messed up with the messy part of the wipers and such.................terrible description of what he said, but you get the idea, right?

Conclusion:

If you are getting 1 mpg more now with your chin spoiler, the best you can do is 1.5 mpg. Therefore you are leaving at most 1/2 mpg on the table.

Considering all of the other things you want to do to your truck, I say finish those things up, and by then the existing chin spoiler will require replacing by then anyway - based on my experiences with that material.

Barrier Paver Edge
http://greatnorthlandscape.com/wp-co...r-MAIN-5-A.jpg

airdam width
 

The conventional wisdom is to use a full-width,wraparound airdam,which cuts airflow off to under the vehicle,and brings it around on the sides as you see on late model pickups.
It's a torture chamber for air underneath
http://i1271.photobucket.com/albums/...d2/scan2_1.jpg
http://i1271.photobucket.com/albums/...2/HPIM1936.jpg
http://i1271.photobucket.com/albums/...2/HPIM1943.jpg
http://i1271.photobucket.com/albums/...2/HPIM1952.jpg
http://i1271.photobucket.com/albums/...2/HPIM1956.jpg
http://i1271.photobucket.com/albums/...2/HPIM1921.jpg
http://i1271.photobucket.com/albums/...HPIM1874-1.jpg
Consider leaving around 6-inches of ground clearance to prevent ripping your hard work off on driveway ramps 'n such.

Consider 3 1/2" of ground clearance. :)

That should be a nice truck. It sounds like it's drivable now?*

I failed to find it but there was a hatchback car posted here that had a massive air dam with a notch in the center I wanted to use as an example. It was some theory like wheel spats and a jet of faster air down the middle to pull air out of the engine compartment or something. Also additional clearance so you don't high-center on gravel roads. Maybe aerohead has an example.

It looks like in your case, a bellmouth or plenum on the intercooler/trans cooler would be called for.

Have you thought about a varnished redwood 'barrelback' airocap?

http://woodyboater.wpengine.netdna-c...Back-low21.jpg
https://www.google.com/search?q=chris+craft+barrel+back

Because I have. :)

Edit: *Okay, 13-second quarters. Got it.

AndrewJ had a massive airdam, but no notch in the center.

Gasoline Fumes's Nut Wagon has a notched "air dam" Details: Nut Wagon - 1991 Honda Civic Wagon DX Fuel Economy - EcoModder.com