Aerodynamics

[toddz69]

Consider this?
Here is an example of hood venting with regard to cooling
http://www.oman4x4.com/hoodvents.htm#theory

Thanks for that article, Paul. Although it's a TJ, it pretty much confirms what I thought in terms of where the best place would be to place louvers. Bernoulli would tell us on the long flat portions of the hood (maybe slightly towards the front) and his graphic seems to confirm it.

Todd Z.

 

[toddz69]

I've thought about it a lot. One thing I always wanted to try but never did was a little air dam under the front bumper. An airdam off a 1st gen Ranger/BroncoII looks like it would be pretty close. Done right it should help with high speed stability and cooling. Trim out some of the under carriage airflow and the front end lift from air packing under the front end will drop and that will also allow air to exit the engine compartment better.

But they don't look cool.

I think that would definitely help too, Tim, but as you say, people wouldn't like it because it's not cool.

Todd Z.

 

[AC932]

Ran a few more models. As far as inputs for the program, it's just velocity of the fluid and boundary conditions. It sees the object as stationary, though I set the wheels as a spinning boundary layer. Once it's done calculating, you can select faces of the object to see how it thinks the fluid would interact with them (there's other options too, but that seems the most useful for this stuff).

Like before, this is simulating the truck moving @ 60 mph. I made a couple tweaks to make the gaps at the spare tire and core support more accurate.

No real surprises with any of these. First is standard passenger side exhaust.

Next two are rear exhaust, the first is level with the rear bumper, the second is set 5" back.

Next section is more interesting I think. I modeled the radiator as a rectangle with a bunch of square tubes it in. Was gonna do fins, but my computer didn't enjoy that. I didn't include a fan cuz I have no idea how to do that. Here the arrows are only showing flow that contacts the face of the radiator.

Section cut eliminating the front grille:

Section cut eliminating the grille, the driver side of the truck, and everything above the hood:

This is really making me wanna fabricate some air dams.

 

[englewoodcowboy]

Love it! We are currently experimenting with an under belly air dam but having to do it with simple trial and error. I’d love to see what a 3” chin spoiler would do under the front bumper as well. I have 2 builds that have been experiencing heating issues, it turned out to be a series of bad Hayden fan clutches out of the box (go figure with awesome parts QC these days) and a bad radiator. But it got me noticing that at highway speeds above 60 it would warm up to 210 ish. Slow down below 60 and it would drop to 197. So the experimenting has begun by looking at what they are doing to modern vehicles. Keep in mind that this is also with a malfunctioning fan clutch that is only operating mostly disengaged. I would still love to improve on it as it will help with the higher horsepower options and that being a big limiting factor to the fun when watching temps.

 

[73azbronco]

Well, my 2020 ram 1500 comes with two aerodynamic options, a retractable lower air dam that drops into place above 60 mph, or what I have, an air ride suspension which lowers the nose and whole vehicle a few inches above 60mph. So it's a thing, but do you really want an air dam off road?

 

[WheelHorse]

One of the fastest ways I dropped engine heat, at highway speeds, was opening the two holes on my K Bar S hood scoop. This was on my '69 Bronco.

Not everyone is into open scoops though. Maybe a functional cowl hood would be just as effective.

 

[nvrstuk]

I'd like the "auto height lowering option". Lower my rig to 1" above my bumpstops at 60+ mph... sweet!! Then have a button to do the same when parked.

 

[Digger556]

Got bored and curious and whipped up a crappy cad model to see just how bad the aero on these trucks is. Some of y'all might find these interesting.

Solidworks prolly ain't the best for modelling this, but it's what I got. Modeled at 60mph with 30" tires.

Great thread. Thanks for posting!

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