Aerodynamic Suburban or GM SUV (92-99)

[aerohead]

Originally Posted by gafhj

Can you clarify, 26% reduction was for such simplified body?
Less than I'd expect.

Yes,the drag reduction is for this simple wind tunnel model,which we know little about.
From what we know from public domain literature,the boat tail they tested could be improved substantially,aerodynamically.
*edge radii can be improved
*morphing into a more elliptical cross-section would honor Morelli's research

*their diffuser section is completely wrong,aerodynamically,however,probably a 'practical' concession to SAE departure clearances

With an 'active' diffuser,the angles could be maintained at the drag minimum 2.5-degrees to 4-degrees depending on 'long' or 'short'.
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If 26% translated to the actual vehicle,this would yield around Cd 0.28,which is pretty good for a full-size SUV.
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With 'corrections', we might expect to see 26+%.

[ChopStix]

Originally Posted by aardvarcus

Chopstix,

Yeah, the Suburban also needs some tire spats. I am thinking of a conveyor belt design that has been discussed on here a few times, that way it can stand up to road/offroad abuse. I want to figure out a way to fit the OEM semi-smooth hubcaps to stock 8 lug alloys so save some weight over stock 8 lug steels.

I understand about overheating GMs because of air flow, I had a 1991 k2500… one engine and multiple transmission repairs later I figure out the AC condenser is clogged up and won’t let air through the radiator. (FYI go check and/or gently clean your condenser and radiator.)

If you are looking to DIY a electric fan conversion, search on here for the one I did on my Tacoma. It wasn’t cheap, but it is reliable. Also look at ducting the air into the radiator so it can’t just flow around. I did a partial grill block on a car I used to have, but also ducted the remaining opening direct to the radiator and my temperatures decreased, mainly because the massive airflow from the huge grill opening was going around the radiator not through.

On the wheel topic, If possible, you should weigh the aluminum wheels before you commit to using them. Most are actually heavier than steel wheels.

Another idea is to copy the "knife edge" post in the mod list. I've pondered the concept of testing taped on plastic edges on the round rear corners of my van. Its suggests that it breaks the air better which could make a difference. Others can explain this better, but maybe it would help out the bricks we drive. Since a full on boat tail is not realistic when we have and use the rear doors on our vehicles. Plus it would be very easy to implement if it actually worked.


@freebeard, love the bug pic's!!! I will own a bug one day, though not for ecomodding reasons....

[freebeard]

Here's the bug I want to own some day. Actually, I do; but it's just a donor chassis up on jack stands, with two bills of sale and no title.



On the rounded trailing edge—the Morelli tail, from aerohead's album:



This what I thought would work about the time I built that model. When the air encounters a chamfered edge it will follow for a short distance. A V-shaped strip along the leading edge of the curve might do better than a trailing knife edge.


http://www.cruffler.com/Features/JAN-02/trivia-January02.html

[aardvarcus]

Chopstix,

Yes, I am aware of the typical unnecessarily heavy alloy wheels but I did weigh the wheels myself on a fairly accurate scale and they are 17lbs for a bare wheel. The bathroom scale and UPS shipping weight confirmed that this was close. The 2000 era 16” stock GM 8 lug “PYO” alloys are notoriously light, unlike the 2007-2010 17” Chevy 8 lug LTZ alloys on my other truck which must weigh at least 50% more.

[ChopStix]

My aluminum wheels were 40lbs heavier for the set. Going lighter on the wheels/tires made my pig handling van notably better and I gained 2mpg. I gained another 1mpg from removing the roof rack and rubber skids.

I will have some new advise coming soon as it looks like I am going to buy an engineering paper on aero related mods for brick shaped vehicles. I don't expect it to make an Earth shattering difference. But I'm hoping for another 1mpg.

[freebeard]

I am going to buy an engineering paper on aero related mods for brick shaped vehicles.

So tell us how it compares to the PDFs that get mentioned around Ecomodder from time to time.

[ChopStix]

Here's some downloads, but I have not found the one that I want for free online..... these may or may not been quoted on this forum previously.


Book Link

Book Link

Book Link

Originally Posted by freebeard

So tell us how it compares to the PDFs that get mentioned around Ecomodder from time to time.

Yeah I tried to ask some questions in a private email. Hopefully I get a reply to save some trial and error.

[freebeard]

I hadn't seen those, but they seem oriented to smaller vehicles.

The Aerodynamics of Heavy Vehicles_ Trucks, Buses, and Trains - Google Books_files

Some discussion after Permalink #33 in http://ecomodder.com/forum/showthrea...tml#post459937.

The significant work done by Englar at Georgia State is paywalled. Is that what you're thinking of? At least some of that is in there.

I use PMs for administrative stuff, and I see other use them to go off-topic from a thread. If you get your info via back channels, then the lurkers go wanting.

Doesn't anyone think of the lurkers?
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There's also the Aerodynamics section in this [first] post:

http://ecomodder.com/forum/showthrea...pers-1814.html

[ChopStix]

Oh I would certainly share any advise that I would get, and give credit where due. But I'm trying to refine what I'm trying to do first.

So three questions then.
How low should side skirts go?
How low should the spats go?
Lastly is it beneficial to angle the side skirts out towards the rear?

Ecomodding is addictive....its like the hotrod guy who keeps trying to go faster!

[freebeard]

How low should side skirts go?
How low should the spats go?
Lastly is it beneficial to angle the side skirts out towards the rear?

Since the 1950s (and probably due to tobacco industry propaganda, the standard measurement has been a pack of cigarettes under the front of the rocker panel.

• upright: clears speed bumps
• on it's side: low
• on it's back: stanced!

Angled side skirts=Skegs?


https://en.wikipedia.org/wiki/Oldsmobile_88