# Mk1 TT - vented hood



## funkejay (Jun 18, 2013)

I'm building a track/race car out of my 2001 TT 225 Quattro and I'm told I should vent my hood to avoid cooking my turbo and motor. Has anyone else on the forum attempted this mod and have any advice, or anyone have any suggestions where to source decent aftermarket hood vent(s) that work well and don't look like a dog's breakfast?

There's a lot of cheap looking crap out there, and if anyone has any personal experience with solutions that work, it would be hugely appreciated.

Oh, and if anyone has any photos - please post!


----------



## 20v master (May 7, 2009)

Not necessary. Get a 3 row radiator, low temp thermostat, oil cooler, or combo of those. That will be more effective than cutting the expensive aluminum hood.


----------



## Jayizdaman (Apr 18, 2005)

Of the people on this forum who track their cars, I cannot think of one that has a vented hood; in many cases I would hazard a guess that they aren't designed properly anyways. Also our hoods are aluminum, you have to be pretty ballsy to cut one up.


----------



## Marcus_Aurelius (Mar 1, 2012)

*For a track car, *I don't see why it would not help. Anything that depressurize the bay can be considered a cooling improvement. For example, removing the transverse hood weatherstrip by the firewall, shows some cooling improvement, therefore I'd think that venting the bay would be of the same effect. There are not that many track cars on the board, and the ones that are here may be limited by rule restrictions. Don't go by what has or hasn't been done because not much have attempted! 

BTW, it's been done before (unfortunately, I can't provide any data on the exact effect):


----------



## aircooled56 (Jul 6, 2006)

Though my car is an R32, I used a hood extraction vent from a new GT500. It's pre curved and fits a ton of hood shapes and because its plactic it could be formed as needed with some heat. Placement is VERY important though :thumbup:


----------



## funkejay (Jun 18, 2013)

aircooled56 said:


> Though my car is an R32, I used a hood extraction vent from a new GT500. It's pre curved and fits a ton of hood shapes and because its plactic it could be formed as needed with some heat. Placement is VERY important though :thumbup:


Thanks aircooled - you wouldn't happen to have a pic would you?


----------



## TheDeckMan (Sep 26, 2004)

No problems with overheating here on the original OEM radiator even on the hottest track days. But there is always room for improvement, my big issue is cooked brake rotors. They tend to last about 8 track days before the fronts are cracked. This is doing some heaving braking from 130/135 to 50 and a couple 100/110 to 50 per lap. Things heat up fast, wheel bearings rotors and hubs have been an issue I have been running into. So some cooling to the brakes would always be good. 

I have had some success on a old XK120 with an aluminum hood doing louvers like this (XK120's have aluminum hoods and very little front grille area for cooling)


----------



## funkejay (Jun 18, 2013)

Marcus_Aurelius said:


> *For a track car, *I don't see why it would not help. Anything that depressurize the bay can be considered a cooling improvement. For example, removing the transverse hood weatherstrip by the firewall, shows some cooling improvement, therefore I'd think that venting the bay would be of the same effect. There are not that many track cars on the board, and the ones that are here may be limited by rule restrictions. Don't go by what has or hasn't been done because not much have attempted!
> 
> BTW, it's been done before (unfortunately, I can't provide any data on the exact effect):


Thanks Marcus - I've already replaced my firewall weatherstrip with some low profile trim from Steve at ModShack to help eliminate hot gas from the engine bay, but as this is purely a race car and is going to be tuned very hard, I agree that further venting can only help with heat dissipation. 

I've spoken to the bodyshop that does all my custom work about fabricating extractor vents for the hood and they say they can do it, but thought if there were any decent carbon fiber or fiberglass vents that had been used by other TT runners it might be a less expensive option with the same effect. 

I'll post pictures of the finished hood once it's done, but it's likely going to incorporate vents like the ones in this hood found on a UK based TT forum, but with a more pronounced ridge on the leading edge to create a low pressure area above the vents to help draw the heated air out.


----------



## Tempes_TT (Oct 24, 2010)

In for information and more ideas. Ive tickled the thought of doing something like this much later in my build. I dont see how giving hot gasses more places to be expelled from is a negative thing. Heres an example Ive seen that kind of has me coming back to..


----------



## funkejay (Jun 18, 2013)

Tempes_TT said:


> In for information and more ideas. If tickled the thought of doing something like this much later in my build. I dont see how giving hot gasses more places to be expelled from is a negative thing. Heres an example Ive seen that kind of has me coming back to...


Hey Tempes! That's the same hood that I posted - just from another angle!


----------



## aircooled56 (Jul 6, 2006)

funkejay said:


> Thanks aircooled - you wouldn't happen to have a pic would you?


Mine sits a few inches behind the radiator.


----------



## taverncustoms (Feb 18, 2011)

aircooled56 said:


> Mine sits a few inches behind the radiator.


mustang vent.


----------



## funkejay (Jun 18, 2013)

aircooled56 said:


> Mine sits a few inches behind the radiator.


Looks great aircooled! Nice clean installation. I was wondering about the GT500 vent and really wanted to see it installed on a VAG car. 

Thanks for posting.


----------



## Rford71 (Sep 1, 2011)

Here's a vented hood I found one day, I know nothing about it. my TT has a 3.2 turbo so I'm also looking for ways to help keep it cool.










Rob


----------



## Late__Apex (Dec 2, 2007)

The mustang part is a good find. I seriously considered the Evo hood vent a while back. 

The combination of the Valeo 3-row and an oil cooler has solved the engine cooling issues. However, heat generated by the turbo/exhaust mani is another issue. The obvious solution to that was removal of the rear weatherstripping which provides air inflow at speed and outflow when going slow or stopped. A trim or fold of the "shelf" at the top of the firewall and an insulated air guide between the turbo and the brake reservoir was going to be my next step. At speed, air from the cowl area on the engine side would then inflow over turbo and mani. Air on the brake side would inflow over the brake reservoir and booster and on to the intake. The insulation (reflect-a-gold or similar) would reflect IR heat from exhaust mani and turbo away from the brake components.


----------



## 20v master (May 7, 2009)

For the purpose of this discussion, are all engine plastic shields removed, specifically both side pieces under the frame rails?


----------



## funkejay (Jun 18, 2013)

20v master said:


> For the purpose of this discussion, are all engine plastic shields removed, specifically both side pieces under the frame rails?


Excellent question - I'm in the process of fitting a custom front bumper (Rieger RIETT8N-30 (A4)INTK) which comes with some of its own ducting for the lower outside vents, and until I get that fitted I wasn't sure whether the stock shrouds under the frame rails will go back in.

If there's room for those shrouds (even with some modification) I intend to reinstall them along with the OEM undertray.

As for the plastic cosmetic engine covers - those have all been deleted.


----------



## funkejay (Jun 18, 2013)

Rford71 said:


> Here's a vented hood I found one day, I know nothing about it. my TT has a 3.2 turbo so I'm also looking for ways to help keep it cool.
> 
> 
> 
> ...


That looks very clean. Hard to tell from the pic which hood vent they used though...


----------



## rstolz (Jun 16, 2009)

maybe they used the dark band around their fedoras as inspiration

or a saab


----------



## 1fast2liter (Apr 4, 2005)

The hood from the silver tt was for sale. I wish it still was or some one would do a how to with a parts list. That silver one and the aviator roadster are very tastefully done. 

reply typed by trained monkeys


----------



## sciroccohal (May 4, 2005)

*Aerothermodynamics*

Once the poster said *Track car* all other considerations are moot.

Bear in mind that tho' yea verily the turbo being in the extreme rear of the engine compartment and first blush would be to put the vent right over the turbo*.....this is the worst place to put it.

The area just in front of the windshield is a HIGH-PRESSURE ZONE....meaning that should the vent be placed there as an extractor....in fact the OPPOSITE will happen...at high speeds the air will be forced down, not up and out. (the air intakes for the pass compt. are there for a REASON!)

A NACA type duct is recommended about half way up the hood....with a spiral type duct to to turbo area. This will create a top-to bottom flow path....with a low pressure area under the car....hence the belly pan.

*A regular type vent is okay for heat soak...when the car is stopped and engine is off.

good luck.


----------



## funkejay (Jun 18, 2013)

sciroccohal said:


> Once the poster said *Track car* all other considerations are moot.
> 
> Bear in mind that tho' yea verily the turbo being in the extreme rear of the engine compartment and first blush would be to put the vent right over the turbo*.....this is the worst place to put it.
> 
> ...



Couldn't agree more Sciroccohal - I like the execution of the hood vent in the pic I posted, but the location is completely wrong. 

If I go that route, I'd move the vent to the front of the hood (directly above or perhaps even slightly ahead of the intake manifold), with a much more pronounced ridge along the leading edge to create a low pressure area that draws out the hot air passing through the rad and FMIC - similar to the one pictured below (but even further forward). 












I've also considered incorporating a single vent like the one on this Shelby Mustang instead of the louvered vents in my original post.












I've already replaced the OEM gasket that runs between the bulkhead and rear of the hood with a much lower profile strip to try and take maximum advantage of the high pressure area at the base of the windshield, and may even utilize some spacers to lift the hood slightly more at the back to allow for better turbo and exhaust manifold cooling. 

It's awfully cold here on the Canadian Prairies in the winter, but it is also brutally hot in the summer (ambient temps are often in the high 90s to low 100s), and our track is short, twisty, and relatively slow, so cooling could be a significant issue.


----------



## drybar (Aug 27, 2011)

Tempes_TT said:


>


Why do I feel dirty for liking this hood?:what:


----------



## Chuckmeister87 (Nov 10, 2009)

funkejay said:


> Couldn't agree more Sciroccohal - I like the execution of the hood vent in the pic I posted, but the location is completely wrong.
> 
> If I go that route, I'd move the vent to the front of the hood (directly above or perhaps even slightly ahead of the intake manifold), with a much more pronounced ridge along the leading edge to create a low pressure area that draws out the hot air passing through the rad and FMIC - similar to the one pictured below (but even further forward).
> 
> ...



I would love to see this :thumbup:


----------



## funkejay (Jun 18, 2013)

1fast2liter said:


> The hood from the silver tt was for sale. I wish it still was or some one would do a how to with a parts list. That silver one and the aviator roadster are very tastefully done.
> 
> reply typed by trained monkeys



I actually emailed the owner of that hood (he and I are both members on another Audi forum) to find out where he sourced the louvers, but so far he hasn't replied. If he ever does, I'll be sure to let everyone know.


----------



## sTT eV6 (Oct 26, 2010)

Tempes_TT said:


> In for information and more ideas. Ive tickled the thought of doing something like this much later in my build. I dont see how giving hot gasses more places to be expelled from is a negative thing. Heres an example Ive seen that kind of has me coming back to..


I have one of these hoods in primer, fitment is good for the brackets and catch but quality of edging needs some work to give perfect look.
I've had it stored for the last 2 years and it maybe time to make a decision on it..sell or fit..
Steve


----------



## taverncustoms (Feb 18, 2011)

http://seiboncarbon.com/store/products.html?product_category=229
http://www.ebay.com/itm/Universal-Hood-Vent-Uras-Style-for-Skyline-Silvia-AE86-RX7-Chaser-Supra-z33-MR2-/131119549862


----------



## funkejay (Jun 18, 2013)

taverncustoms said:


> http://seiboncarbon.com/store/products.html?product_category=229
> http://www.ebay.com/itm/Universal-Hood-Vent-Uras-Style-for-Skyline-Silvia-AE86-RX7-Chaser-Supra-z33-MR2-/131119549862


The Seiben carbon hood for the 2004-2005 Subi looks interesting... I just wonder if it will fit the contours of the TT hood and if the vent is shallow enough to clear the top of the engine once installed.










I've already considered the universal hood and I don't think it will work - it's too long for one thing (at 28" long it would take up almost the entire hood) and aesthetically it would be a disaster. Not that aesthetics should be the first consideration when building a race car, but given all the effort and time put into this build, I also want the car to look good when it's done.

Call me superficial...


----------



## sTT eV6 (Oct 26, 2010)

Fitting hood scoops is going to attract the traffic light racer to wanna play, so only fit these scoops if you've got the go to back up the show..
Steve


----------



## funkejay (Jun 18, 2013)

sTT eV6 said:


> Fitting hood scoops is going to attract the traffic light racer to wanna play, so only fit these scoops if you've got the go to back up the show..
> Steve


lol - no doubt! 

But that's not something I'll need to worry about - this is a pure race car I'm building, and it won't even be road legal.


----------



## sTT eV6 (Oct 26, 2010)

I'm considering removing my wrap and going back to OEM Moro Blue and if I sort the new bonnet to match, it won't stick out like a sore thumb. My TT is street legal, so mods have to conform.
Steve


----------



## funkejay (Jun 18, 2013)

sTT eV6 said:


> I'm considering removing my wrap and going back to OEM Moro Blue and if I sort the new bonnet to match, it won't stick out like a sore thumb. My TT is street legal, so mods have to conform.
> Steve


wow - I just read your blog post for your 3.2 turbo conversion... that's one massive build! 540bhp is impressive to say the least. I'll be happy just to get 400bhp out of my 1.8 when all is said and done!


----------



## Letter K (Jan 8, 2011)

I removed the weather stripping from the wiper shroud/ cowl, and noticed a significant reduction in under hood temps and iat. In traffic you can see the heat bellowing out. Now I don't know about its efficiency in areas of 100+ mph. ... might br something worth a try though.


----------



## racin2redline (Sep 25, 2008)

Idk how functional the placement is on here.. I've had this picture of a TT with hood vents they look pretty good here at least









I know there's a featured build somewhere


----------



## sTT eV6 (Oct 26, 2010)

funkejay said:


> wow - I just read your blog post for your 3.2 turbo conversion... that's one massive build! 540bhp is impressive to say the least. I'll be happy just to get 400bhp out of my 1.8 when all is said and done!


Cheers, but 540bhp at approx 5000rpm and reduced boost indicates the potential at 7250rpm, but slipping clutch on the DSG has forced my hand and I've invested in a way forward which should be complete during April.
My EGTs are high so a vented bonnet may drop them a few degrees.
Sorry to go off topic.
Steve


----------



## 1fast2liter (Apr 4, 2005)

racin2redline said:


> Idk how functional the placement is on here.. I've had this picture of a TT with hood vents they look pretty good here at least
> 
> 
> 
> ...


Any one know what he used for the vents in the hood? I believe this guy was from the uk. 

reply typed by trained monkeys


----------



## 20v master (May 7, 2009)

sTT eV6 said:


> My EGTs are high so a vented bonnet may drop them a few degrees.
> Sorry to go off topic.
> Steve


EGTs aren't going to be affected by a vented hood.


----------



## Krissrock (Sep 10, 2005)

I would love a vented hood. I talked to my fabricator a couple years about doing one and he said it can definitely be done with the aluminum...but you gotta know what your doing to weld aluminum. 

however, I did hear that it would really increase the amount of dirt that would be kept in the engine bay.


----------



## PLAYED TT (Oct 17, 2010)

1fast2liter said:


> Any one know what he used for the vents in the hood? I believe this guy was from the uk.
> 
> reply typed by trained monkeys


He's from PA and it's cut out according to the bracing then filled with mesh. Nothing fancy. If you guys really want to cut up hoods why not just get louvers stamped in?


----------



## sTT eV6 (Oct 26, 2010)

20v master said:


> EGTs aren't going to be affected by a vented hood.


I'm just thinking of excuses to get the hood fitted..
Steve


----------



## 1fast2liter (Apr 4, 2005)

The silver tt anyone know what he used for vents at all? 

reply typed by trained monkeys


----------



## PLAYED TT (Oct 17, 2010)

They're just holes filled with mesh I think. Like I said nothing fancy.


----------



## 1fast2liter (Apr 4, 2005)

If that's the case not worth doing if you can't make it look nice

reply typed by trained monkeys


----------



## Forty-six and 2 (Jan 21, 2007)

I'd imagine you would want to us something quality for the edge, and a good mesh...

Edge material

https://www.pegasusautoracing.com/productselection.asp?Product=4346

You can get sheets of honeycomb mesh as well. It would somewhat match the rest of the grills.

a quick search...

http://pages.ebay.com/motors/link/?nav=item.view&id=321212406072


----------



## G'D60 (Mar 11, 2002)

Forty-six and 2 said:


> I'd imagine you would want to us something quality for the edge, and a good mesh...
> 
> Edge material
> 
> ...


I ended up using something similar. I didn't like the layered honeycomb look, wanted something solid. I went with this instead. 

http://www.ebay.ca/itm/160719312418?ssPageName=STRK:MEWAX:IT&_trksid=p3984.m1423.l2649










Its nice and thick. Can easily be bent and shaped with a little heat. was able to get a perfect curve for the front contour.


----------



## funkejay (Jun 18, 2013)

funkejay said:


> The Seiben carbon hood for the 2004-2005 Subi looks interesting... I just wonder if it will fit the contours of the TT hood and if the vent is shallow enough to clear the top of the engine once installed.
> 
> 
> 
> ...



Talked to my bodyshop yesterday, and they're pretty confident that they can make this vent work, so I've taken the plunge and ordered it. Car goes into the shop in late April for the body work and paint to be completed. 

Thanks to everyone for all the suggestions and advice. I'll post pics as the work progresses...


----------



## taverncustoms (Feb 18, 2011)

funkejay said:


> Talked to my bodyshop yesterday, and they're pretty confident that they can make this vent work, so I've taken the plunge and ordered it. Car goes into the shop in late April for the body work and paint to be completed.
> 
> Thanks to everyone for all the suggestions and advice. I'll post pics as the work progresses...


glad I could help cant wait to see photos


----------

