heat management, CF hood alternative
 

When tracking the FRS/BRZ under boost heat management because a concern. Larger radiator, oil cooler etc are the initial reactions to the problem. Some of us have modified the front bumper in an attempt to increase airflow. But the limitation to the system is not air INTO the engine bay its air OUT of the engine bay.
Proof of this can be seen by hood flutter even at highway speeds. A vented hood in my opinion is a must. For aero and cooling reasons. But some/most weigh MORE than the factory hood and dont generally fit as well as OEM. I also have a tuff time stomaching the price of a poorly fitting heavier than factory hood that i still have to paint match.
Robispec an early pioneer in the frs tracking community was thinking the same thing and louvered his hood. Sometimes hard to find someone who can do that. But i searched the internet and found Trackspec Motorsports.
((I am not affiliated or sponsored by them))
They make a simple low cost rivet in hood vent that's used by hundreds of time attack/NASA racers in the southeast. I literally see these things on corvettes, camaros, BMW's, porsches etc all the time.

They sent me a vent kit for the S2000 and asked if i would get some feedback from the FRS/BRZ community. Their vents are in the mid 300$ range and they make many sizes. They come with a simple template i measured from the four corners of the hood and taped it with painters tape. Drilled a hole in at one corner to insert a cheap fine tooth airsaw and cut out the template. Laid in the vent drilled a few more holes and put in some rivets. I had a significant reduction in front lift, 30+* drop in under hood temps and my BOV and other turbo noises are louder now. (ha) For 1/3 the cost of some CF vented hoods.

thats cool as hell

thanks! i was very impressed with it myself in function, price and how it looks now.

where are they selling?

tracspec motorsports. i contacted them via their facebook page https://www.facebook.com/Trackspec-M...5927/timeline/ since the s2000 vents were not on their website yet http://trackspe.nextmp.net/

@nelsmar @csgmike

I've been wanting to go this route as well, cut vents not a CF hood.

I considered doing this at one point... I know some other companies have been looking into producing some rivet install parts. I have also been considering louvering the hood for a long while now... But for the price of these vents I think I would rather louver the hood even though this would probably be a bit more beneficial but it stands out so much more on a street car than some louvers!

A lot of the CF hoods also have something that blocks air, or the edge going into the bay may disrupt flow. The ones you installed actually go above the hood line which should help evacuate in the way a wing works to lift an airplane up. I am kind of surprised that there doesn't seem to be any manufactures focused on making a functional evacuation hood. Putting a heavier carbon hood that doesn't dissipate heat as well as aluminum is "meh". I mean sure the vents they add nullify the fact that carbon doesn't help with heat conduction but.. =/

I was also considering just cutting out some panels on my hood and adding in a mesh so it didn't stand out too much but by not having a leading edge you don't get the benefit of the high velocity air going over the hood helping siphon the air out of the bay.

If they had a more subtle looking setup or if I had a black car (hah)... I would be more open to giving a setup like this a try! But my car is a street car and that looks wayyyyy too aggressive for me =(

I tested louvers in a wind tunnel and came up with the same results robispec did. You would have to do the whole hood for them to work. They are not very efficient at the angle our hood is at.

U r my hero!! @CSG Mike

We installed those vents in our carbon fiber hood and fenders for added venting. We've had nothing but great results.

Here's a picture of the vents on the race car.

http://i.imgur.com/31fIjvz.jpg

@crazyfrenchbiker which fender vents did you use from them?

I like. I may get a set for next summer. Though I would prefer smaller ones I could put closer to the front of the hood, over the belts. Usually that area has lower pressure than further back on the hood.

the further back you can get the vents the better they will work. You want them close to level otherwise air will build up on the rear slat of each vent and choke off the vent in front of it since its a flat plane. Mounting over the belts works with vents that have less fins and more negative drop from the hoodline plus some ducting from the radiator up. not possible with my front mount turbo. you can see in the pictures my turbo is still pretty close.

heres some wind tunnel testing of closer spaced vents moved further forward and why i chose the current design/location. In the video you can see the front vents on the gtr dont do anything. Thats because the vent angle is too steep causing air to "pack up" on the slat behind each vent. The rear vents are at a much shallower angle. The same angle as my trackspec vents in there current location and function much better.
https://www.youtube.com/watch?v=UIkF...ature=youtu.be

how are these in the rain? Do they have some sort of rain guard?

Thanks, great video.

why would you use a rain guard? you do realize an engine compartment has a GIGANTIC hole in the front that water comes through at 65mph when driving in the rain right? The only drawback to a vented hood is if your coolant overflow tank burps(if its over filled) it comes out the vent.

I guess it's car dependent. I wish there was a pressure map for the front of the twins, but I don't think anyone who's invested the money to generate one wants to share.

The GTR as pictured in the video has a very small low-pressure area at the front of the hood, so that would explain the video.
http://www.worldtimeattack.com/wp-co...TR-567x381.jpg

But some cars have a larger low-pressure area at the front of the hood:
http://gallery.ensight.com/Images/Ke...wiseload-L.png

I do admit that the hood shape of the twins shares more with the GTR than the GC Impreza however.

30*F ambient temp drop!?! Any difference in IAT's or fluid temps since in isn't an oven anymore? I'm all for this but, really I only think this will look good on a full track car or a twin of darker color like yours.

nice find. the video i posted is from a shop i work at. we're hopefully sending the shop brz/or my frs to the wind tunnel this fall/winter. We also have a guy that does cfd and 3d car scanning so its all only a matter of time.

it looks pretty docile on my car. But i think any other color you might want to color match it. Either way i took the pictures in lighting and angles that made them stand out since that was the point of the picture. When the car is dirty or not under florescent lighting it looks less aggressive.

I honestly didnt log as much as i usually do last track day. its all subjective since it was a different track with different weather conditions. you would have to run back to back on the same track same day. But running a 450hp turbo frs in the south and not having cooling issues hot lapping it is doing pretty well. I have a completely stock cooling system minus the oil cooler. temps were 200 water 230 oil running 20 minute sessions hard enough to destroy a set of tires. If there's enough interest ill tape them off next test and tune day. I also have the capability to do thermal imaging but its kind of a hurdle to set it up. Ill get around to it though this winter. Also hopefully wind tunnel time soonish.

I love this idea. Was trying to figure out a good way to vent a top mount oil cooler and this looks like it will work and far more cost effective than a CF alternative. Just need the balls to cut the OEM hood.

Any pics of the underside? Thanks.

I like it. I was also looking to do this at some point and was looking for a manufacturer of such vents.

BTW, is a rain cover available? If it is, it would seal the deal for me. :D I want to leave the rain cover on for street use and take them off for track days.

Those look awesome and saves me some money on buying a vented carbon fiber hood. BTW the s2000 vents are on their websute now.

Doooo iiittt.

Fluid flow around a vehicle is very dependent on the car's design. Just because it works for one, doesn't mean it can be used as a blanket term for all vehicles. You also cannot always trust CFD or wind tunnel testing to have real world results. One big misconceptions of wind tunnels are that they reproduce what the car will see on the road or track. However, this is false. Wind tunnels only simulate the conditions on the road or track. Simulations inherently deviate from reality and it is often hard to quantify all the sources of the error. This is not to say that using wind tunnels or CFD is wrong or isn't helpful. The complete opposite is true. CFD and wind tunnels are very useful in helping design proper parts that work. However, you need to have the experience and know the theory to really understand the reality. You need to have the proper inputs (CFD) or choose the right tunnel for your needs (wind tunnel testing).

We have done CFD testing for the FT86. We do not have the funds for proper wind tunnel testing so results have not been verified by this route. However, on the track, we have seen the real word results. Also I have backed up many CFD cases to other CFD houses and windtunnels. Three examples are the ahmed model, DrivAer models, and the Perrinn LMP1. I will now get off the boring information and get to the CFD of the FT86.

Pressure Plot on the car, specifically the hood
http://i77.photobucket.com/albums/j8...psyhjqr3ep.jpg

Pressure Cut Plot offset from the center line of the car
http://i77.photobucket.com/albums/j8...pscerxxzoh.jpg


Iso Surface around the car showing lower pressure
http://i77.photobucket.com/albums/j8...ps1cuni0wz.jpg

Will they be making a kit specifically for our cars any time soon, or do we just have to buy the s2k kit that's on their website?
Very interested in this significantly lower cost option to a vented hood for my turbo car

I decided to go with a more low key approach, the goal here being vent heat when I come to a stop mostly. My car is a street car and I am seeing heat soak when there is no air coming in the front. I will make some pretty mesh inserts to finish them off.


http://i139.photobucket.com/albums/q...psqshzxdjz.png

http://i139.photobucket.com/albums/q...psn9frmvai.jpg
(edit) Updated photo of mesh insert

Heat soak? What like your IATs that almost instantly drop back down within a few degrees of ambient once you start moving again?

Heat Soak is when everything under the hood rises in temp due to no air moving through the engine bay. Don't even need to look at IAT, just feel by hand. IAT vary to much by daily weather anyway.

My intercooler pipes would continue to rise in temp after coming home from a good drive, this is with the car idling and the hood closed. The temp did seem to plateau but I still saw room for improvement with simple vents.

What do the colours mean? If I remove the small black trim from the corners of the hood near the hinges. I am wondering if hot air will extract.

The colors just represent a scale. It could be any scalar or vector (pressure, velocity, temp, etc.). The colors in the pictures I posted are of pressure. I would not recommend removing the black trim in that area as it is higher pressure.

I see that creating alot of lift at speed. It may also li.jt the amount of air that can pass through the radiator since you're essentially forcing air behind it. We'll see.

Going to have to disagree on that one.

I am also working on a lip for the leading edge, create a low pressure pocket behind it. Reducing lift was never an intent with my vents, they are certainly no large enough.

With the top of the vent higher and no gurney style wicker it might as well be a scoop. Tape some tufts to it. I can almost guarantee at speed that's a scoop and stuffs the bay with air.

To each there own

Does anyone foresee any issues with rain? i wold love to add the vents like the OP did, but living in Florida with all of our rain I don't think its gonna work...

How about just doing mild openings for the fender vents? I've seen a few members take a dremel to the area behind the fake fender vent area and open it up a bit with some decent results.