Truck aero improvements
 

I took a hard look under the truck today. It's about as un-aerodynamic as it gets:

• Front sway bar is inder the axle and in the air stream
• Transfer case skid plate is way below the transfer case
• Fuel tank shield protrudes about 1.5 inches below the tank
• Spare tire in the airstream, but easily removed and stowed in the trunk
• Helper springs and jounce bumpers (not really in the air stream, but heavy)
• Muffler: is a more aerodynamic shape available in the aftermarketp?
• Rear

bumper protrudes 4" under the tailgate across its full width.

Most aero improvements cost money, but removing stuff is free. I was thinking of just removing a lot of the junk under there as an experiment. Anybody think that it's worth it?

yes, I think it would be worth it, even if you made smoother transitions should help, fill in some of the scoops and so on.

I think it is worth a try. Nothing ventured, nothing gained.

well its a truck... its a box(i have one and yes has all the mentioned crap except the bumper). but if you go down dirt roads or bumpy areas id leave the gas tank shield. its there so you dont hit anyhtign and cause a crack in the tank and well leak... the only more aero dymanic muffler is a glaspack. you can find cheap ones from advance autoaprts (or any auto parts store) but it wont do jack to your mpg...most of that stuff wont but the rear bumper may cuz they often weight pretty close to 100lbs so see if u can find a roll pan or somehing.

Bad aero
 

My vote is don't bother with removing the parts. The improvement you may or may not see is probably barely measurable at best - it's just a big aero mess under there.
I'm in the same situation as you but with a Ranger based truck. I'm just waiting for a screamin deal on sheet steel, aluminum, plastic, whatever and some time to make a full length underbelly pan. I really think that is the only way to get the next significant (measurable) gain with aerodynamics.
Hey sludgy is there a way to alter the timing on diesels that improves FE but reduces power? Seems with all the high fuel prices someone must have a chip that works by now.

what are you guys talking about? trucks are great candidates for boat tails.

yea but then ya loose the whole purpose of the truck to begin with...that and full sizes have huge beds and a whole lotta space to fill. sure it will be more aero friendly but ya gotta consider the weight of the boat tail to begin with. that and ya still got a huge pretty much flat frontal area/windshield

a boat tail will help a lot more than some kinda thing in front of the windsheild.

it really cant be too hard to make a cap like a boat tail that you can open to store things and you would know if you had to move something larger than the boattail so you could just take it off.

where is the good old american ingenuity ???

Makes sense to me. By doing this all of those items you're concerned about are retained and functional. Also, a pan should aerodynamically outperform what's there now even after some things are removed.

trucks are a pain ours is horrible yet my parents love driving it

I'll just say that according to the stock mileage computer on ours (which seems to be within a tenth or two on accuracy per tank), the biggest draw on our fuel is the time we spend idling at lights and drive-thrus. On the ten mile round trip to drop my kids off at a school, waiting 5 minutes at the Starbuck drive-thru on the way back loses us about 10% of our economy. Frequent stop and go drags it down even further.

Even if we improved our aerodynamics substantially, the impact of city driving would still drastically reduce the benefit.

I tried a Mileage Miser chip from Granatelli Motorsports. The mileage got worse, and the motor ran like a bag of ****. I took it out. Not into chipping the truck now.

I like the underbody cover sheet plan. Assuming you spend significant time at 50 mph or better.

Somebody posted that their biggest fuel killer was idling at lights and drive-thrus. True that idling kills mpg. However for your highway driving, air drag is your biggest killer. On a decent hill if the aero is decent, the vehicle will accelerate. Or at least coast without losing speed. If drag is bad enough this won't happen, you need lots of engine output to overcome what you lose to drag. Of course on level ground what you lose is the same. it's just that on a hill you see it easier - you lose speed when you should be gaining it from the hill.

My Volvo is also about as aerodynamic as a brick and I'm doing what I can bit by bit. The advantage with a truck is that there's tons of room underneath to build what you need. Lots of ground clearance; you probably don't need all of it so whatever you lose to your new underbody treatment is OK.

It case you didn't know who phil knox is. here is his truck:

https://www.evworld.com/images/pknox_toyota.jpg

Well, the problem with a belly pan on a truck especially a 4wd is there not practical. My belly pan took a beating just from ice alone. You also must consider that both axle's must have room to move up and down. Also factor the the frames flex under heavy loads. I'd also be worried about exhaust heat. Remember this truck has 325hp diesel engine, its going to produce a lot heat, towing. I'd be worried about melting something.

I agree with the clencher, those high performance trucks are rediculous. Trucks do make sense for hauling heavy loads...and if you do this frequently or for a living, an underbody pan or a boat tail would make a lot of sense. But in the long run, if you are not hauling things all the time, a nice beater honda or toyota would be good to have for all other trips when not hauling. The best way to save gas with a truck is to only start it up when hauling a trailer or over 1,000lbs.

I know this is an obvious one but: Do you have a grille block? that might help the truck warm up faster and get better mpg on the hwy...remember to remove it when towing on hot days!

Yes, I have a nice canvas grille block.

He's not trying to make the truck something that it is not. He still wants for it to be a truck. He just wants for it to be the best possible truck it can be.

Like for me. I have the Element because I want an Element. I could have a CRV, but I don't want one. I could have an Accord, but I don't want one. I want an Element. But, I still want for it to get the best mileage it can get without losing the utility(value) that I derive from it.

What? I need a 6000lb truck to get milk from the store!

Ooh my favorite vehicle ever was my 91 dodge, cummins powered. I cranked the pump and did some minor mods. It was actually fun to drive. It ran a 16.2 spinning badly through second. Easy 15.8s with a locker. Smoked like a frieght train for tailgater removing.

That was me a couple of years ago, then I saw the light. Now the truck gets less than 1000 miles per year, only used when I need to haul.
I spent lots of time and money trying to get better mpg with the truck, in the end going from 12 to 14 mpg wasn't enough for me.

Ditto that.

We just sold our truck today. My parents have a truck we can borrow when we truly need one, so now in addition to our $200 lower payment, hopefully our fuel cost will be cut in half as well.

I check my mileage at every fill up. This site posts gaslogs? Where?

Ya know, a truck is nice to have, being able to average ~30mpg and all. If I got it up to ~50mpg (unloaded ~50mph cruise) I'd be happy.
On the tabs right under the logo at the top of the page, click on garage. From there, click on 'add gaslog entry' to the far right of your truck. Fill out the form and click on the 'add gaslog entry' at the bottom of the page.

Enter your vehicle in the garage....

You won't lose functionality. My air dam in the front was way low last summer and I didn't have any problems even when going to the cabin and running across the yard.

My aero mods.

I didn't read every post here, but wanted to add that you can get free coroplast signs at your local recycling center( Or at least I can at mine ) with which to make a smooth underbelly.

Just use some short self tapping screws and drill right into the frame. ( You only need a few so don't go wild, as this may weaken the rigidity of the frame.)
I try to think ahead to which parts of the chassis flex up and down or need to turn before covering them up .
I also think about areas that would allow water to enter between the chassis and the coroplast, since you don't want the stuff to rip off when you go through heavy rain.
To cover my gas tank, I used the tank's straps to hold the coroplast in place. ( The last thing you want to do is drill into the tank !!! )

Keep at least a couple of inches clearance from the exaust and other hot areas as well. If your truck has a drive shaft, I would keep some clearance there too ( friction would create a fire )

I just did a half arsed job of drilling some coroplast to my car, and have to say it has been a resounding sucess !
I have not had any problems, despite driving through loads of rain and hundreds of miles.
Since the stuff comes white and looks stupid hanging off of your car, I used black tempera paint to paint it ... just to see what it would look like ...and despite tempera paint being waterbased, it still has not come off yet.
( And I didn't have to pollute the air with enamel paint fumes either ;-D )

im guessing you dont get much snow or salt do you in texas...

if i were to do that up here i would trap so much saltwater it would rust out every little bit more than it already is...but i can see how it might be plausible if you can get the stuff for free. so props to you for doing all this for prolly under $10 (paint and screws).

but i hate to tell ya, i did your paint fumes damage for you...7 spray cans of flatblack to paint by truck bed...cost a whole whopping $7 too :D amazingly hasnt flaked off or scratched off dispite all the crap ive thrown back there. but if it does then ill spray some more paint over the scratch..

How about a cover like this? Has anybody used one and noticed a difference?
https://www.central4wd.com/_files/_im...176.4panel.jpg

Actually, I just found something in another thread:
https://www.autobloggreen.com/2006/08...tonneau-cover/

From what I have read, a simple tonneau cover is probably the most effective and easiest fuel economy mod for pickups, providing around 10% improvement. I forget where I read that though, and it might have been at a website trying to sell tonneau covers FWIW.

I'm working with a Nissan Z24i I4 gas engined 4x4 that I hope to coax 25 mpg mixed from.

Baseline is around 20 mpg mixed. Have it up to almost 22 mpg mixed.

All I've done so far is to change out the gear oil in everything and add a moly additive. Moly in new engine oil and new plugs/cap/rotor. Fixed a sloppy timing chain. Upped the tire pressures.

For your diesel might try:

* Condensator or PCV jar

* acetone or Diesel Kleen with Cetane Boost

* moly additives in gear oil and engine

* spiral muffler

https://www.spiralturbobaffles.com/semiinfo.html

* fuel heater and 195F thermostat

* airtabs

best thing you can do in a diesel is turbo and supercharge the hell out of it. Diesel can run way leaner than gas, as you can already tell from 19 mpg in a one ton truck. Not to mention it has higher BTUs so better mileage even NA. You have a SG2 for that 2002? I agree with the clench, if you can help it don't drive a beast. Get something economical for DD or even all the short trips that aren't for work or whatever. It adds up.

I was standing along the side of the road out in the country when some guy in a "slammed" S-10 or Ranger 2wd pickup came by. He had it lowered and handling real fine...no screaming rpms...just whish thru the doglegs. Didn't even hear him coming.

I'd bet that with a low air dam on front and staying off the pedal it would do real well in the mpg dept. Wouldn't haul much though.

He also had an undercover cop on his tail....doubt if he caught up.

True, but a pickup will never run 100% loaded, even semis have some empty miles, so given how simple improvements can be, it's worth changing some stuff as long as it's easy to undo the changes and do truck stuff as well.