List of aero mods you can do to your vehicle

[radioranger]

Originally Posted by virg

I wonder about a bracket up front with a ball or bulb leading the way, like that bulbuous thing on the hull of a ship that parts water. Make it a sliding-adjustable arrangement with the bulb leading the grille.

you might be onto something because of the air having to go over the vehicle,and reacting with all that is there , windshield etc, if you edged it to the side, the vehicle might slip easier through the vacumn created, , in effect tailgating yourself, but tailgating something that goes through the air easier than the base vehicle. it might be easier to push the air aside instead of up and i don't think you want to push it down , theoreticlly following a clear v shape in front of you . that you are pushing, I think I just destroyed the space time continium

[radioranger]

I wonder if it's better to push the air around to the side of the car or truck than lift it over the hood and have it hit the windshield again , take an older car style front end say a 39 ford or something, they were trying to push the air sideways, for a given car where you cant rake the windshield very easily would it be better to bulge out the front of the grill instead of making it an air shovel.

[serialk11r]

So I haven't seen this before, but with a flat undertray, side skirts, and reasonable ride height, directing more air under the car could allow a smaller wake via greater diffuser angle. The rear of a car is rarely long enough for good pressure recovery (is this what it's called?), and the sides of a car never taper in enough either...so how about the bottom?

[serialk11r]

Sorry for the bump, but any ideas on my theory of more air under the car + higher diffuser + smooth belly?

[ERTW]

more air under the car, provided the under body is perfectly smooth, is better. more air equally around the car is best, to minimize pressure gradients and vortices.

You can't use an aero device designed to work on one car, and use it on a different car, and expect similar benefits. So this general "aero mods" advice is of little practical value.

[Kincurd]

I think the front-air dam is generally a step up for any car, but ideally, shouldn't the front be more pointed. The closer it is to Jet airplane cockpit, the better? Here are some examples, but I can't find the main example I was thinking of (a concept car built around a motorcycle engine/chassis with a cockpit inspired heavily by modern fighter jets; edit: well there are plenty of examples of that, but I can't for the life of me find the one I'm thinking of).

Forgive me if I'm beating a dead horse, but the front air-dam is still in the sticky with no allusions to the pointy-front (which I guess makes more sense when you have a really smooth undercarriage). Or at least it's not very clear when one is better than the other.

[radioranger]

Back to a super simple idea, how about unbolting the hood at the rear and spacing it up a bit , say an inch or more to ease the air over the windshield

[MetroMPG]

Unfortunately, that also disrupts flow over the sides of the hood toward the rear, which no longer transition smoothly to the tops of the front fenders.

Aerohead did fiberglass work to the hood of his truck to raise the rear, while preserving the smooth transitions at the sides. If memory serves, I don't think he was able to detect any improvement. (Though it makes sense you should see some if you achieve a cowl-blocking effect, or more effectively hide the wipers.)

[NeilBlanchard]

On most vehicles, the windshield wipers are already in a pocket of higher pressure air, that doesn't move; making a cowl moot.

I think that a smooth underside beats an air dam; no contest.

[aerohead]

Originally Posted by radioranger

you might be onto something because of the air having to go over the vehicle,and reacting with all that is there , windshield etc, if you edged it to the side, the vehicle might slip easier through the vacumn created, , in effect tailgating yourself, but tailgating something that goes through the air easier than the base vehicle. it might be easier to push the air aside instead of up and i don't think you want to push it down , theoreticlly following a clear v shape in front of you . that you are pushing, I think I just destroyed the space time continium

Years ago we talked about this,but maybe at MaxMPG which is now defunct.
In 1990,at World of Speed,a guy was there,who I believe had just received a MS in aeronautical engineering.He had a streamliner which had a sphere mounted on a shaft which 'preceded' the streamliner's nose.
The premise was that the streamliner would ride within the turbulent wake of the sphere kinda like a rocket-powered torpedo riding within some of it's own exhaust shunted out the nose,or a Russian ice-breaker with 'bubbler.'
I have no record that the bulb was a success.
It's possible that it was too small,and already embedded within the Prandtl surface of discontinuity,hidden from the source-flow.Don't know.
It's certainly possible to do such a thing,but with any crosswind component,it would lose performance,as the vehicle would no longer be occulted by the wake.
The other thing is that you're looking at at least a double-deformation of the forebody flow field and most messengers publish that air should make only a single pass over a structure with zero circulation,and zero separation.The bulb concept would kinda violate the rulebook.