Tuft Testing - "Vortekz" vortex generators on 2003 Jetta Rear Window

[Deezler]

Originally Posted by tasdrouille

What you are seeing on the sides of the rear glass are C pillar vortices IMHO.

Ah ha. Meaning that the flow is truly less attached than it appears? Either way I suppose there isn't much you could do about it other than put some VGs on the side of the vehicle. Wonder if my roof VGs on the edges can sort of "over ride" the C pillar vortices.

Tas, how did you get the green machine up to 55 mpg? Driving style? Quite the jump from the 44 mpg I recall you having earlier.

Thanks metro, and yes, that is the real question here. Probably will never know. I think I need to just clean up the underside of my vehicle a bit more, build some rear wheel skirts, and focus on driving style. Then be content with my results. hopefully.

[tasdrouille]

Originally Posted by Deezler

Tas, how did you get the green machine up to 55 mpg? Driving style? Quite the jump from the 44 mpg I recall you having earlier

Winter blend has quite a lot less BTU than straight ULSD. My daily commute is also only 7 miles each way, so outside temps play a big role there. I deleted my passenger side mirror and replaced my driver side mirror with a DTM cup style mirror, added some grill blocks and wheel deflectors also.

[bwilson4web]

Good luck on the experiments but I've not found any evidence of a measurable drag reduction with my 03 Prius. I observed the flow attachment with the vortex generators but it looks like the rotary motion at the base of the glass is not a major drag source.

My interest has moved on to reducing excessive cooling drag at the air inlet.

Bob Wilson

[wdb]

Originally Posted by MetroMPG

The $60,000 question [...]

Another indication of these difficult economic times?

[RandomFact314]

So are they worth what they cost? will you get it back in better FE savings?

[ConnClark]

wouldn't VGs on the side only increase the C pillar vortices ?

[Deezler]

Gotta see some pics Tas! Or did I just miss your thread?

HypeNoob, that question is hard to answer. But at $20 for the set of VGs, I only need to improve my FE by 0.2 mpg, or 0.5% if I drive another 80k miles with them on. So it seems plausible that they could pay off. But since I may never really answer the question of whether they are even beneficial in the first place, who knows.

Conn, good question. I am picturing attached flow over the roof edge and down the glass at the edges "buffering" against the vortices, so to speak. But I think we all know how terrible most people's aerodynamic imagination is....

[tasdrouille]

Originally Posted by Deezler

Gotta see some pics Tas! Or did I just miss your thread?

No Thread yet, but I added pics in the garage entry.

[basslover911]

Hey! That was me with the Mazda 6! And yes, I never saw anyone ever hit the mileage that i got from that car- 45mpg in the freeway was the top... till I sold it

Anyway, a few observations. You should place the VG's further up at the edge of the roof, not at the start of the window. This is because you want them at the edge of the turbulent flow, not at the start of the flow (if that makes sense- ie. a little before it starts).

I LOVED my VG's on my mazda, always got comments on the "cool" factor and set the car apart. They held up through anything that I put them on (power washes, automatic drive through car washes, ice, etc). I also LOVED how they kept my rear window clean most of the time.

Now, everybody look out for new testing with my new car (an Audi TT Quattro with 500hp which suprisingly gets 28mpg combined right now, and it has 275 tires in the back! Look out, who says you cant get a super gas saving sports car!

Again, thanks for YOUR testing! It really helps to add to the truth and fakes out there and to me these (NOT the airtabs) are a real gain.

[Don2001TDI]

Interesting. Anyone have any updates from when this was posted a year ago?