Delta Wing Vortex Generators
 

Hi,first post and my vehicle is not at all aero efficient due to its intended use so please no suggestions to un-modify the car.

For info, car is a FZJ105 Landcruiser with 4spd auto and 4.5 L6 gasoline engine. Basically, like the old US model LX450 but with the 100series body.
Basic mods;
Suspension lifted
Steel barwork front and side steps
Intercooled+turbo setup
Unichip Q piggyback ECU
Snorkel
Exhaust
315/75R16 tires
Stage 2 auto valvebody

My main goal with the VGs is to get more stability at highway speeds (100kmh/62mph).

Anyway, I made up some delta wing VGs out of 2024 T3 alloy to try out on the rear edges of my car since it's a tall, square backed wagon.

There are 8 positioned along the top at the rear of the roof approx 100mm from the edge. These are 75mm long with a 25mm height and 25mm base.

I have also made 8 smaller ones to position on the sides of the car. Plan is 3 down each C pillar and 1 in front of each rear wheel well. These will also be placed approx 100mm from the edge. Smaller ones are 50mm in length with the same 25mm height and base as the larger ones.

At the moment the roof mounted ones are mounted as 4 each side of the roof centerline. All 8 have their leading edges angled in towards the centerline of the roof with the center 4 at 15deg to the airflow, then 2 at 10deg and the outermost 2 at 5deg.

Initial tests at 130kmh show the car to be a little more stable and wash coming off trucks travelling in the opposite direction don't upset the balance as they pass. Happy so far.

I just want to know if I am placing these VGs correctly and what other suggestions people have for me. Mainly degrees to airflow. Should they all be at around 15deg?

Cost so far has been $5.50 for a can of black spray paint so I thought its worth my time to investigate these VGs further.

Thanks for reading and I look forward to your responses.

Sorry, the above should say that the smaller VGs will be mounted down the sides of the rear D pillar.

Also, the roof mounted ones are approx 200mm from the rear edge of the roof.

Just an idea, I used to do this as a kid. Use a pressure washer from a few feet away so the water mists up, and point it at the front on the car. Like a wind tunnel with smoke, you'll see the water mist flowing over the car and hopefully the fins too. You might have your own set up, but as a kid I used to like seeing how the water mist flowed over the cars curves, you might get some new ideas.

Sounds like an idea. Thanks mate, will give it a go.

When I had my '98 Honda Accord I installed these AirTabs on it to reduce the turbulent air flow behind the car. Even though the fuel savings were insignificant (I figured $30 per year), it helped a lot when I was towing my motorcycle trailer. After installation, the straps holding the bike down didn't flap in the wind and there was less dirt and dust on the bike after towing. You could see the AirTabs working when it was raining hard on the highway. Here are some of the pics:
https://www.fuelly.com/attachments/fo...fa05d18ce5.jpg

https://www.fuelly.com/attachments/fo...6932a86006.jpg

https://www.fuelly.com/attachments/fo...ff4bfdd77f.jpg

https://www.fuelly.com/attachments/fo...ca0a21ad52.jpg

https://www.fuelly.com/attachments/fo...bce9a63e91.jpg

https://www.fuelly.com/attachments/fo...a5ecd37739.jpg

https://www.fuelly.com/attachments/fo...200bb610dd.jpg

Website:
Airtab | Aerodynamic Fuel Savers | Welcome

Thanks mate, bit hard to get hold of the Airtabs in Oz. One supplier across the country from me. Also a fair bit more expensive here. They look pretty good on the Honda too and I considered AirTabs in the beginning.

I'm sticking my smaller home made delta wing VGs on the sides of the D pillar this afternoon, not sure how its going to look but will post a pic when done.

So here are the smaller VGs on the rearmost D pillar of the Landcruiser wagon. Not sure on aesthetics, but hopefully it will work and help the roof mounted ones with increasing the highway stability. I'm quietly confident.

I think they might be spaced a bit far apart and maybe I should have put 4 on each side....?

Thoughts?

So I had a better go at mounting the VGs on the rear D pillar. I think this is much better. Now I've used four per side so nothing in front of the rear wheel wells for now.

Plan to do some tuft testing (or similar) as well as the water spray idea to get to some idea of fluid flow over and around the body.

Can hardly find anything with regards to FE so I will do some ABA testing for those interested. Have done it previously without the VGs and best I got was 15lt/100km (18.83mpg) with an average of 16.5lt/100km (17.12mpg).

That was AC off, tires at 45psi, driver only, 95lts of 98 Octane fuel with cruise control set at a GPS indicated 99kmh. No wind or traffic travelling in a 100kmh zone. OAT of 30deg C.

Anyway, I'll test FE soon.

I have AirTabs on my Ford F250 pickup truck with a campertop over the bed, and I also have them on a 27-foot travel trailer I tow with it. Although the fuel savings are minor if at all, it does help stabilize the outfit. On wet roads one can see the smoother airflow via the pattern of water flowing off the rig. One can also observe less dirt on the rear of the vehicles.


About your homemade design, I don't see how anyone can really comment on it. You will have to rely on your empirical testing. I know the AirTabs were tested extensively before being released to the market. Of course, the price reflects that.

Yeah cheers mate. They are definitely providing me with greater stability at 100kmh (62mph) highway speeds here.

No 'whoosh' from trucks going past either. This used to upset the balance a bit due to tire size and suspension height.

I'm not sure the side mounted ones help much m9re than the roof ones. Seem to keep the window cleaner but I might remove them at some stage.

I don't think it will make any difference to FE either, but I was curious to do a quick test and see.

So far it's been a success with my goal of attaining extra stability. AirTabs are probably better due to the RnD involved, but for $5.50 and a couple of hours work, I'm pleasantly surprised. Longest part of the process was waiting for the paint to dry.

The idea of the VGs is to create a swirl of air that ends up behind the vehicle reducing the low pressure behind it thus reducing the drag. So for your side VGs you need to look at the resulting swirl and add more if it doesn't do the job. I think that double fins on each like the airtabs may also increase their effect ... The idea is to kick the air up away from the body laminar air flow as smoothly as possible and have it return behind the vehicle. Having a Scion xB really has me thinking about installing some but the return on investment is questionable and the potential winter conditions here may damage them increasing the cost. I may try to 3D print some if it could create the proper shape with the cad drawing programs I have.

I'm glad I didn't pay money for them. Yes the AirTabs will probably be better but not convinced about these used as a MOD to solely give you better FE. Mine hasn't changed but the extra stability at speeds above 60mph has been great. More stable the faster you go, well up to 75mph is all I got to here.

The problem I have with the side VGs is the turbulence created by the large side mirrors and snorkel on right side. The air is turbulent all the way to the rear so the VGs on the D pillar are doing nothing really.

Anyway, for stability they work well. For FE, not convinced.

Sounds like you need to put a tail on the snorkel to reduce the turbulence!

Will look at doing something with the snorkel. The wind noise is annoying as well since its on the drivers side A pillar :-(

Was measuring up for a partial kammback/kammback spoiler last night too :-)

About 480mm long off the roof would work well as it would be level with the rearmost part of the car (rear edge of read bumper). Worked out measurements for the sides as well.

I can also make some fairings around the front end as well. These will help the air flow better but without any increase to frontal area or compromising off road clearance.

Was looking at some ideas BMW use in their vehicles. Air curtain etc etc

This stuff is pretty interesting :-)

Would a spiral wrap, like on the radio antenna, help on the snorkel?

Teardrop shape it the most aerodynamic so making it round on the leading edge and just a taper on the trailing is best, it should look like a symetrical wing going vertically.