Hood lift at high speeds

[Walldodger]

Originally Posted by Basti

I recently read a test where they measured the aero facts @200kph, among other things.

Could you post a link? Would be great to have look at.

[Argento_FR-S]

Hey all... I've been meaning to post something up about a similar experience I had but had no clue as to where to put it. Anyways I was doing roughly 90mph and when I crested a hill at this speed the windshield end of the hood actually buckled up about an inch or so with a loud popping sound. Twas a little frightening, but I haven't been able to recreate it. Anyone else have this happen? Sorry for the thread jack...

[Basti]

Originally Posted by Walldodger

Could you post a link? Would be great to have look at.

It's actually in german and i have it on paper but i will get you the exact numbers when i can. Im currently skiing, though

[plucas]

Originally Posted by Basti

I recently read a test where they measured the aero facts @200kph, among other things. Turns out the toyobaru generates some upforce which is probably what i felt on the hwy. I'll have to see what i can do bout that, cutting out the part where the fake mesh sits seems to be quite easy as that wannabe-mesh is just glued if certain posts are to be believed

Almost all stock street vehicles create lift and not downforce so this is not surprising at all. Also my cfd study showed that the car in stock form created lift. I would love to see the study you read :happy0180:

[OrbitalEllipses]

Originally Posted by Basti

It's actually in german and i have it on paper but i will get you the exact numbers when i can. Im currently skiing, though

That would be great!

[Basti]

German car magazines are EXTREMELY biased but the study i have reads like "vw golf = 0 upforce on the front, some on the rear axle while the toyota gets quite some lift in the front and still some in the rear"
I blame that on both the huge front of the vw which should be worse for the cw overall but good on the downforce and the toyobaru's lifting hood

[Walldodger]

Originally Posted by Basti

It's actually in german and i have it on paper but i will get you the exact numbers when i can. Im currently skiing, though

No worries, happy to wait for this sort of info.

[Basti]

OK here we go:

according to my source the GT86 (sorry, no values for the BRZ) produces a lift of approx. 40kg on the front and roughly 30kg on the rear axis @ 200km/h, cw value 0,33.

Just for reference, they measured a Golf GTI @ 1/30 kg F/R, a Mini JCW even at 16/21kg

(values rounded so I don't get into any kind of trouble)


Am I the only one who finds this weird? Even though I can, unfortunately, not provide cw values for a/m cars I can only suspect them to be significantly higher as both are so increadibly bulky.
Apart from making them ugly imho, that would of course create some nice downforce on the wheels.

I really wanna tackle this issue somehow... How does one call those aero fins one may drill to the side of the front bumper?
The lift would probably manifest in the hood budging and likely worsen the effect

[Gords_zenith]

Originally Posted by Basti

OK here we go:

according to my source the GT86 (sorry, no values for the BRZ) produces a lift of approx. 40kg on the front and roughly 30kg on the rear axis @ 200km/h, cw value 0,33.

Just for reference, they measured a Golf GTI @ 1/30 kg F/R, a Mini JCW even at 16/21kg

(values rounded so I don't get into any kind of trouble)


Am I the only one who finds this weird? Even though I can, unfortunately, not provide cw values for a/m cars I can only suspect them to be significantly higher as both are so increadibly bulky.
Apart from making them ugly imho, that would of course create some nice downforce on the wheels.

I really wanna tackle this issue somehow... How does one call those aero fins one may drill to the side of the front bumper?
The lift would probably manifest in the hood budging and likely worsen the effect

I think then the best method of reducing front end lift would be to get a vented hood....like the one I seen on this thread. The front end is pretty closed off but I would hazard a guess that the airflow through the radiator at speed, is the cause of lift.

[Basti]

my point exactly, great to have some actual numbers to go w/ the observation.

Though a vented hood is a serious mod which creates problems for those driving the Toyobaru as a daily (aka: me )

U know, rain and snow and leaves and dirt and s... falling in through there and on the engine when parked...
I prefer an easy to use day-to-day car which will also not have issues during low temperature operation so sth. like temperature-controlled auto-opening flaps would be good (and cost a fortune, I believe).A Bonus would be to know that your oil has reached proper temperature. Still, I think it'd be so difficult it's ridiculous

[Gords_zenith]

All very valid points....I still think the side vents may be the best option than. Good luck with it.

[GTB/ZR-1]

Originally Posted by Basti

I guess it started at about 180km/h.

Okay, I've now seen this myself now... Hitting ~115+ on Roebling's front straight this weekend--I noticed it happening over 105--it ripples. Disconcerting...

[Black Tire]

I think this car seems to have the best downforce potential of any low priced car I have ever seen. The bottom is nearly flat which could, possibly with some reworking (suspension, splitter, maybe exhaust mods), create a really effective rear diffuser, not just a cosmetic one.

The front/hood seems to be a real problem. Maybe the designers didn't consider aerodynamics at high speed. On the other hand, perhaps the design folks won out over the aerodynamicists. A scary thought: maybe they designed lift into the high speed aerodynamics intentionally to give the driver a "warning" feel which they felt was safer (it seems form other stories as well that some people at Toyota are VERY conservative). Still, significant downforce can be a dangerous play-thing for inexperienced drivers.

I think with the right hood and/or side vents the front end could be al least neutral at high speed. My guess is that the hood pictured above is at least neutral. I like the tilted radiator with downforce-producing hood vents idea. Perhaps this can be made to work.

Maybe someone has access to a high speed rolling wind tunnel for a week with Adrian Newey and a carbon fiber prototype lab so we can work this out.

[Basti]

true, I had been hoping that the diffusor on mine would be anything more than cosmetical, yet I was proven wrong. Though I think that some body shops might easily be able to prolong it to cover the entire rear end yet still look Stock to the casual observer.

I also agree on the car's potential, not having the obnoxious hood grille of many bigger cars is, imho, a plus for aerodynamics.

This just came to mind: how about using the BRZ's "mustache" to generate downforce? Just change the OEM one w/ a kind of Spoiler? That could work, though it'd probably be ugly as hell.

Oh and BTW: I LOVE serious downforce, though it's certainly something which needs a bit of skill to control in fast corners.