Off road friendly aeromodding... My lil beast

[cRiPpLe_rOoStEr]

Maybe some exhaust-wrap could be useful to decrease the overheat issue while using an under-belly pan.

Originally Posted by freebeard

Or maybe a high stagnation point and prow like a boat?

I was also thinking about something like a boat-hull.

[oil pan 4]

Originally Posted by chillsworld

2/3 airdam? Like 2/3 of the way to the ground? Do you have any frame or structure to keep it firm at hwy speeds?

Its made of lawn edging hung from heat treated 2024 aluminum alloy. Its only 2/3 because of the low slung intercooler. The lawn edging is very stiff, I further firmed it up by inserting 1/2 inch PVC pipe into the loop at the end of the edging.

I have A/T tires and they are over kill. I have 3 brand new highway tires, will start by putting 2 up front. Then run the A/T tires on the back.

[chillsworld]

Originally Posted by freebeard

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This Commanderwagen has a field modification that is a roller for the front valance. Something like this could establish a low stagnation point.

Did the roller function? If so, that's a slick piece of offroading genuis right there! Can't believe we don't see this more on modern trail rigs and such... Would be great on the rear bumper of trucks too.

Originally Posted by freebeard

Or maybe a high stagnation point and prow like a boat?

Originally Posted by cRiPpLe_rOoStEr

I was also thinking about something like a boat-hull.

OK, so the picture linked of the Baja truck is what I was talking about in the first post. How would a boat hull-esque front, impact FE and other mods that are normally done for FE? It would drastically change they aerodynamics of the vehicle by forcing more air under the car, the opposite of what we normally do right? Although it would be a much smoother and controlled flow, would it lead to decreases in FE, would it generate lift or cause dangerous conditions at high speeds when combined with full underbody tray?

In regards to design, would it need to be a tapered design like a true boat hull?




Or could it be flat like the duck tour amphibious trucks?



Clarification: would you want it tapered to try and cut through the air forcing air around the truck like the wake of a boat, or flat simply to try and provide a slippery angle for the air to hit and slide down under the truck? This is about as far from traditional aero mods as it gets, from what I can tell...

Originally Posted by freebeard

For the belly pan, consider Grimco - Substrates: Max-Metal, MAX-metal HD. It's like Polymetal or OmegaLite, but the aluminum skins are .30mm, about twice as thick. It's available in 4x8 and 6x10 sheets.

I'll check it out, .30mm seems pretty thin though. Traditional Aluminum skid plates are 1/4 to 3/8 inch thick, 4-6mm. Of course I wouldn't need it to be super thick the entire underside of the truck! I just wonder how easily it would rip or crease under stress. Of course that would be remedied by having a cordless drill, patch sections, a rivet gun, and silicone caulk in the back of the truck

Originally Posted by cRiPpLe_rOoStEr

Maybe some exhaust-wrap could be useful to decrease the overheat issue while using an under-belly pan.

I had actually thought about heatshield on the underside of the truck and on the belly pan facing the exhaust... Although that wouldn't lower heat in the space, simply protect things from the heat. Exhaust wrap might be the answer! Although I'm not sure how that will impact performance or longevity of the muffler with out it's natural ability to be cooled in the wind stream under the vehicle


~C

[chillsworld]

Originally Posted by oil pan 4

Its made of lawn edging hung from heat treated 2024 aluminum alloy. Its only 2/3 because of the low slung intercooler. The lawn edging is very stiff, I further firmed it up by inserting 1/2 inch PVC pipe into the loop at the end of the edging.

Ok, that makes sense! Thanks for the clarification!

I have A/T tires and they are over kill. I have 3 brand new highway tires, will start by putting 2 up front. Then run the A/T tires on the back.

I have AWD, so having different tires isn't an option if I value the mechanical aspects of the AWD system. My particular tires, are pretty far from over kill. I pick aggressive Light truck tires or mild A/T tires because I like even wear given the amount of hwy/road time they see. My tires look like slicks compared to the rubber on my brothers truck hahaha

~C

[aardvarcus]

I don't know how well exhaust wrap would hold up on an offroading vehicle, I have heard if it traps water it can make things rust out sooner. I have considered getting my exhaust ceramic coated, that would greatly decrease the radiant heat escaping from the exhaust. I think doing vertical walls to the sides of the exhaust to keep it from heating up the rest of the underside would definitely be a good start, but I don't know if that would be enough to be able to seal the pan off under the exhaust. If you don't have some sort of cooling or airflow the heat would eventually start to build, it just might take longer.

[aerohead]

Originally Posted by chillsworld

Ya don't say, putting cars to shame eh

In regards to the airdam, That's really all you think would be necessary? That in conjunction with a belly pan? Does the belly pan need to be as low as the air dam in order to prevent an eddie or swirling pressure zone behind the air dam?

~C

The Mountaineer's nose is already superior to one with healthy attached flow.

The airdam,if a little bit lower, would get the air around the nose,and restrict its access to underneath.The air below the airdam would have a straight shot to the rear.

The bash plate would be DIRECTING air under the Mountaineer,and even with a full belly pan it's a no-no.A great way to create front lift.
From your sketch it looked like you could maintain your off road approach angle clearance if the airdam was even with the bottom of the suspensions naughty bits.
The belly pan would be dead even with the bottom of the airdam.
And if you do the pan,then you can think of a diffuser,which will kick in a little additional efficiency.

[freebeard]

Did the roller function?

Yes. I don't know why it fell out of favor. The M3 scout car used something similar



I would favor the DUKW nose, with a roller in the bottom edge and a diverter. It would have angled arms on either side of the roller that hinge on the same centerline so it would stow up and forward under the nose or drop down to horizontal to do what diverters do.

Nip off the two rear corners of the hood, and run the exhaust up one windshield post and a snorkel up the other.

[cRiPpLe_rOoStEr]

Ceramic-coating in the exhaust pipes is a good option too. The heat concentrated inside the pipes would actually improve the flow.

Originally Posted by chillsworld

In regards to design, would it need to be a tapered design like a true boat hull?




Or could it be flat like the duck tour amphibious trucks?

A flat underside would be better.

[chillsworld]

Originally Posted by aardvarcus

I don't know how well exhaust wrap would hold up on an offroading vehicle, I have heard if it traps water it can make things rust out sooner. I have considered getting my exhaust ceramic coated, that would greatly decrease the radiant heat escaping from the exhaust. I think doing vertical walls to the sides of the exhaust to keep it from heating up the rest of the underside would definitely be a good start, but I don't know if that would be enough to be able to seal the pan off under the exhaust. If you don't have some sort of cooling or airflow the heat would eventually start to build, it just might take longer.

Originally Posted by cRiPpLe_rOoStEr

Ceramic-coating in the exhaust pipes is a good option too. The heat concentrated inside the pipes would actually improve the flow.

Ceramic coating is a wee bit out of the starting budget for this hahaha... BUT that would seem to be the way to go!

I suppose, if I managed to get a true sealed belly pan... Then air from the engine compartment would vent within the belly pan and I could vent out the rear via a smooth duct to get clean the airflow back up before introduction to the rearward flow? That might alleviate some of the "heat" issues to begin with. And if it didn't work enough, I could throw on some mini electric fans to pull air out the back? I think that would also combat the dead zone of drag behind the vehicle if it were placed just right.

Originally Posted by aerohead

From your sketch it looked like you could maintain your off road approach angle clearance if the airdam was even with the bottom of the suspensions naughty bits.

The belly pan would be dead even with the bottom of the airdam.
And if you do the pan,then you can think of a diffuser,which will kick in a little additional efficiency.

Ok... rear diffuser, front spliter, full belly pan, air dam... As stated above, if I managed to do all of this, would venting the engine bay between car and pan be a good idea? Would a rear vent incorporated into the diffuser or even higher, allow for assistance in filling the void that causes drag?

Also, your truck has a fully belly pan correct? Do you have any links or could you post any pictures of the belly pan? I'm having a hard time wrapping my head around how the rear axle/leaf springs fits into the equation when attempting to do a full sealed pan. I'm guessing you went under the axle since you have minimal suspension articulation and are low to the ground for aerodynamics.

~C

[chillsworld]

Originally Posted by freebeard

Yes. I don't know why it fell out of favor. The M3 scout car used something similar



I would favor the DUKW nose, with a roller in the bottom edge and a diverter. It would have angled arms on either side of the roller that hinge on the same centerline so it would stow up and forward under the nose or drop down to horizontal to do what diverters do.

Nip off the two rear corners of the hood, and run the exhaust up one windshield post and a snorkel up the other.

You know the real name of the duck, and you pull out vintage military pictures with ease... I think you're my kind of guy haha I do recall seeing them now that you posted that pic, and i would be willing to bet that modern day ground clearance on deuce an halfs and the bigger 5 tons is the reason we don't see the rollers. They have at least twice the clearance of the older versions... And now we have Hummers and Tacoma/Hilux to fulfill the duties of the older and smaller vehicles of days past. Not to mention the duties of "scouting" are done with small UTV's, diesel dirt bikes, fast action rail buggies, and the Toyota Hilux

And that would be pretty sweet to run a snorkel and exhaust that way... But might be a bit much for my current daily driver I think you would have to run it up the pillar and then flatten it out along the hood to make it aero friendly? That way the exhaust was released evenly with contour of the roof?

~C