Hood lift at high speeds

[Walldodger]

Just on looking, Im pretty certain the quarter panel will need to be cut to vent the engine bay through the inserts.

[Gords_zenith]

Originally Posted by Basti

Suspension and aerodynamic changes are always the first things people try but considering that I find the suspension pretty optimal and aerodynamics better than in most current vehicles I'd prefer to leave them that way.

Seriously, up to a certain speed everything runs well until the hood messes it up so why not tackle the problem where it coours and not try to lessen its effect by peripheral albeit showy mods?

Replacing the fake mesh in Subaru's sharkfin fender-thingie won't be a problem IMO, it looks like it's just clipsed in place, anyway.

However, will that really do any good? This morning I checked the engine compartment and nowhere did I see a place to open it to the sharkfins.
Also not too eager to cut parts out of the chassis just to get that done, Subaru would have my a$$ Guarantee-wise.

Anyone have a photo on how the body looks underneath?

Google a open hood picture or open your own, now look near the back of bay to where the fenders meet, there should be a gap there that goes directly behind the vent. I just googled this myself as I'm at work and my car is stored. So I'm pretty sure all you would cutting is the fender it's self which has nothing to do with the structural integrity, also google the Subaru BRZ 300 race car and their fenders are VENTS.

[Basti]

Do you mean the part behind the suspension mount? Felt like steel to me. I'm also more interested on what's behind the fenders but I can't find pictures of that.

The BRZ 300's open fins look like vents for the brakes/wheels to me.

[Orthow]

Originally Posted by Fancy

I never noticed any lift with my oem hood... but I have a CF hood now and I know poeple experience the hood moving at bit at higher speeds... could go for some latches if it bothers you... put aerocatch latches on my new hood and its not going anywhere now.

Sorry to go offtopic but.. WOW.. this car with the simple addition of the hood looks fantastic. The agressive look is complimented by the agressive OE roof design..Only addition I would make would be a functional splitter with the dual prop rods sticking through the bumper attached to the splitter. I'd like to see this hoods affect on Intake Air Temps. Bet it helps nicely.

[PRORICAN]

Originally Posted by Fancy

I never noticed any lift with my oem hood... but I have a CF hood now and I know poeple experience the hood moving at bit at higher speeds... could go for some latches if it bothers you... put aerocatch latches on my new hood and its not going anywhere now.

Who makes this hood? And how much if you don't mind?

[tripjammer]

That is a pretty pimp hood!

[Kuzuri]

Originally Posted by Orthow

Sorry to go offtopic but.. WOW.. this car with the simple addition of the hood looks fantastic. The agressive look is complimented by the agressive OE roof design..Only addition I would make would be a functional splitter with the dual prop rods sticking through the bumper attached to the splitter. I'd like to see this hoods affect on Intake Air Temps. Bet it helps nicely.

Thanks! I am not going to keep it that simple though haha. I have my eye on the Rocket Bunny kit. Just gotta get the money saved up for the kit/wheels/paint... haha im broke.

Originally Posted by PRORICAN

Who makes this hood? And how much if you don't mind?

It's the Seibon DV style hood. I bought it from Evasive Motorsports and it was right around $815 shipped

[Gords_zenith]

Originally Posted by Basti

Do you mean the part behind the suspension mount? Felt like steel to me. I'm also more interested on what's behind the fenders but I can't find pictures of that.

The BRZ 300's open fins look like vents for the brakes/wheels to me.

Look where for the open space where the hood hinge would sit with the hood closed, there is a gap between where fender rolls over to the sill where the rest of the fender bolts to the chassis, that looks open to directly behind they fender vent.

[Black Tire]

Originally Posted by Fancy

It's the Seibon DV style hood. I bought it from Evasive Motorsports and it was right around $815 shipped

That's one seriously cool hood!

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 would really like to see what you come up with. Aero is very important and lightweight hoods tend to move around a bit. It is probably safe from a functional standpoint, but the distractions it causes the driver could be problematic. You could try the aero latches mentioned in association with the aftermarket carbon fiber hood above. This should result in a more stable setup with proper installation.

One of my favorite aero stories:
I had just bought my 1999 BMW M3 (used) and brought it to BIR (Brainerd International Raceway) to stretch its legs. I noticed that when I went over 120 mph going into turn 1 (full track), the front end would get light and have very little steering control. I compensated by backing off the throttle to go through turn 1, but I couldn't find the cause for a day and a half. Then near the end of the event, I found that the plastic under tray was cracked, so that at speed a piece would pull down, scoop up air and blow it into the engine compartment. Can you say lift?

(I think that this is essentially what is happening to our FR-S's, air is trapped under the hood, but from the radiator inlet instead of a broken plastic part.)

After the event I installed an aftermarket aluminum under tray. Problem solved; I was able to reach the speed limiter at 136 mph in turn 1 next time I was up at BIR and the car was rock solid stable.

[Shankenstein]

Does anybody know if there has been an attempt to make radiator shrouds that would work with hood vents?

I've seen them on GT40's, elises, and some serious race cars.


If we're in agreement that hood vents are in a low pressure zone, why not put that to good use?

[plucas]

Originally Posted by Shankenstein

Does anybody know if there has been an attempt to make radiator shrouds that would work with hood vents?

I've seen them on GT40's, elises, and some serious race cars.

If we're in agreement that hood vents are in a low pressure zone, why not put that to good use?

Wouldn't it require a lot more work by having to angle your radiator forward in the car? This has many advantages though!

[Mikepage]

Originally Posted by Fancy

I never noticed any lift with my oem hood... but I have a CF hood now and I know poeple experience the hood moving at bit at higher speeds... could go for some latches if it bothers you... put aerocatch latches on my new hood and its not going anywhere now.

Nice Picture, do you have a drop?

If yes, what is it?

[Kuzuri]

Originally Posted by Mikepage

Nice Picture, do you have a drop?

If yes, what is it?

I do! Tein S-Techs!

[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