Hood lift at high speeds

[Huehuecoyotl]

the rippling is very real and while I'm sure they accounted for it as engineers, I think I am going to get me some hood pins, anyone here see a thread that details how to DIY on hood pin install?

[Basti]

Originally Posted by Captain Insano

How common is this in other vehicle models? Seems like it would be very common. For example, I noticed this yesterday driving my 2012 honda pilot on the highway at 70ish mph. Is this really a problem up until the point the hood is ripped off? Nobodys hood has been ripped off yet.

Of course there's no danger of anything ripping off at all.
I also don't think the grimmspeed struts will fix anything but i'll report my observations once i built them in

[GrimmSpeed]

Originally Posted by Basti

Of course there's no danger of anything ripping off at all.
I also don't think the grimmspeed struts will fix anything but i'll report my observations once i built them in

Ever since you posted in the hood strut thread I've been curious about this issue as well. Naturally, I started following your posts on here because I find it VERY interesting.

Unfortunately, as designed, the gas springs will exert a force that is perpendicular to the motion of the "rippling hood" while the hood is closed. This is one of the features that is designed in to make the hood "drop to close." For that reason I am with you in doubting that the hood struts will have any effect at all, but I can't wait to see!

Keep it up Basti, I'll be watching!
Chase
Engineering

[Huehuecoyotl]

I had a datsun 510 back in the day

remember those??
loved it

well, one day, at 85 mph on a windy less than ideal sorta bumpy forest road rated for like 40 mph, my hood flew open, the latch failed, I was 17 years old, driving way too fast and admitedly it was a unsafe choice I made then, I did some amazingly stupid things then

... luckily this car had no AC, and windows were already down, I came to a stop fast, and was very very lucky, with my head hanging out and trees on both sides, on a undivided road

so, no its not SUPPOSED to rip off, but accidents happen, ya know? stuff like latches can fail when you track, consistently go really fast, add FI to your car etc...
@GrimmSpeed can you make and sell a hood pin kit please? templates etc?

[Basti]

@Chase: My thoughts exactly, thanks for clarifying. Any stabilizing effect the struts might have would most likely be miniscule, if there is going to be any at all. However, that's OK since it's not their intended purpose anyway.


Here's a list of potential solutions to the issue which come to mind:

-Front blades. Will create some downforce and maybe counter the negative effects of the hood lift at least partially. Treats the symptoms, not the disease.
-Hood pins at the area of max bend, ergo center-left and right of the hood. Will give added strenght to the structure of the hood. Very ugly IMHO
-Hood stabilizers mounted to its underside. I dunno...
-Actual fender vents. Might at least help w/ the issue, though very hard to do. Apart from a custom fender garnish, modifications to the fender would be necessary while maintaining the original points of fixation. Very much work/cost, maybe even on par w/ a custom hood, though likely to only deliver little results.
-Custom hood. Most definite (supposed) fix for the issue to date, however also very impractical. Would need very costly mods and automation in order to be useful as a daily.

I will, of course, keep the issue in mind and I'm pretty sure that I'll be reminded of it quite regularily
ATM I'm still busy w/ other parts of the Toyobaru, though. Thankfully, knowing that aftermarket tuners are working on ever new parts, some solutions may just come all by themselves, over time ^^

[Black Tire]

The hood is definitely an issue. Just now had time to add another 2¢. Here is they type of hood we need for downforce. Air through radiator and then used to create downforce. Notice also the vented fenders and other aero enhancements. Total custom build (with $$$), but does solve the problems we have been seeing.

http://www.ft86club.com/forums/showthread.php?t=30819

[rene0023]

I also happened to me the issue of hood and I noticed that there is a gap between the headlights and the hood. Although there is a rubber flap sealing that part, this seat is very soft and the air pressure comes very easily. If you managed to seal the gap the problem would be solved.

[Kefuddle]

Rene,

See here, http://www.ft86club.com/forums/showthread.php?t=38375. As an experiment, I have used some duct tape to hold those wedge shaped seals forward so that they rest in front of the lip on the top of the headlights thus blocking off a fair amount of airflow into the engine bay. Although this has not cured the issue, it is a big improvement...especially the flapping due to the turbulent air typical of a busy highway.

[Basti]

Any idea i currently have for fixing the hood is either unpractical, bad-looking or not worth it for me atm.
So i was thinking, maybe the jdm STi body kit w/ its awesome looking front lip would probably at least help lessen the issue. I have yet to see that lip in a detailed picture but it could help the airflow in a way which increases downforce, thus eliminating not the visible but at least the handling issues

[Red2Liter]

Originally Posted by Basti

Dunno whether this comes up much butI've heard of this issue several times already:

Upon reaching more "interesting" speeds, the hood starts to lift slightly. Well, it's still hinged safely in place but when it happened to me on a particularily even strip of highway I got shaking from that interference and driving above that speed neither felt reassuring or safe anymore.
I guess it started at about 180km/h.

Now I know that I'm kinda spoiled when it comes to anything aerodynamics-related but this is just wrong.

Knowing the physical background of this phenomenon I want to try and fix it.
Before carving vent ducts into the hood I'd favor opening those sharkfin side panels the BRZ generously already provides.

I'm thinking of opening the fake plastic... "mesh"... , exchanging it w/ the real thing and then installing a kind of tunnel to the engine compartment. I hope that this will relieve the difference in air pressure created by air being forced into the engine compartment.

That should equalize the pressures at least enough th make 200km/h w/o trouble.
However, does any1 know whether it'd be possible to create such a venting system? I don't know how the area behind the side skirts looks so any insight would be appreciated. Also, if you've already solved said issue, let me know.

The BRZ Limited comes with both a front splitter and a modest rear spoiler. I haven't encountered any lift during the few times and appropriate places I've approached VMAX. It's really stupid to do this in inappropriate conditions; wait for a track day to wring it out. We've had the BRZ to 135 mph under controlled, safe conditions. There is nowhere off-track that I'm willing to approach those speeds. Too many deer, slow moving obstacles and hidden driveways. I suggest enjoying the cars' fine points at sub-lethal speeds.

[Basti]

The rear spoiler is mandatory in my country, though ican't fimd info on any front splitter the limities got that's any different from ANY brz front

[NissanGuy]

Originally Posted by Basti

Now I know that I'm kinda spoiled when it comes to anything aerodynamics-related but this is just wrong.

Ha!

[Aqrab]

i have this same problem any fix for that ?

We don't want this to happen to our car

[ame="https://www.youtube.com/watch?v=pikq4awljug"]Hood flying in 3D - Autounfall / ident de voiture / incidente d'auto - YouTube[/ame]
[ame="https://www.youtube.com/watch?v=oDMVqJWEl8E"]Hood flies open and smacks the windshield on a Mustang while driving on the freeway. - YouTube[/ame]
[ame="https://www.youtube.com/watch?v=EleNAB4txa8"]valvoline rally bonnet blows up - YouTube[/ame]
[ame="https://www.youtube.com/watch?v=WvZUyyZo3KY"]Car hood flys open and smashes against window while driving - YouTube[/ame]

[waynesel]

Originally Posted by Basti

Dunno whether this comes up much butI've heard of this issue several times already:

Upon reaching more "interesting" speeds, the hood starts to lift slightly. Well, it's still hinged safely in place but when it happened to me on a particularily even strip of highway I got shaking from that interference and driving above that speed neither felt reassuring or safe anymore.
I guess it started at about 180km/h.

Now I know that I'm kinda spoiled when it comes to anything aerodynamics-related but this is just wrong.

Knowing the physical background of this phenomenon I want to try and fix it.
Before carving vent ducts into the hood I'd favor opening those sharkfin side panels the BRZ generously already provides.

I'm thinking of opening the fake plastic... "mesh"... , exchanging it w/ the real thing and then installing a kind of tunnel to the engine compartment. I hope that this will relieve the difference in air pressure created by air being forced into the engine compartment.

That should equalize the pressures at least enough th make 200km/h w/o trouble.
However, does any1 know whether it'd be possible to create such a venting system? I don't know how the area behind the side skirts looks so any insight would be appreciated. Also, if you've already solved said issue, let me know.

I have had the same issue. At about 80 mph the hood flexes up at the hump in the fender about 1/4". Scared me a little thought the hood may come up. Coming back from Arizona over xmas had a really bad head wind and had the same result.
Had my FRS in for it's first service Saturday 2/13 and logged it in with them. They said the Hood Flexes. But it is now on record if it does become a big problem.