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So I've been trying to read up as much as possible on aerodynamics for the C5. I know a common mod is to run the trackspec louvers on the hoods in the center and over the wheel arches.
My question is, does the number of fins make a significant difference or could you potentially run a smaller number and still see similar improvements?
Anything, no matter how small that you ad to the hood will increase drag. The louvers in my opinion look horrible. As a side note, look at the bowtie on the front of a ZL1 camaro.......it's hollowed out to reduce wind resistance..
What goal you're trying to accomplish? The hood vents decreases from end lift.
have you ever drove with your hood unlatches or had one side unlatch? if so you'll see how much the hood wants to come up, from all the air that getting trapped in the bay with nowhere to go. without vent the air is still trapped pushing up on the underside of your hood, causing the front end to lift and drag.
But I don't think anyone here has the direct to answer what you're asking, trackspec has a small and large hood vent option, if someone has the answer its probably them.
Anything, no matter how small that you ad to the hood will increase drag. The louvers in my opinion look horrible. As a side note, look at the bowtie on the front of a ZL1 camaro.......it's hollowed out to reduce wind resistance..
you're thinking of it one sided, the drag is already there. the vents relieves more drag than the vents can add to the car.
Anything, no matter how small that you ad to the hood will increase drag. The louvers in my opinion look horrible. As a side note, look at the bowtie on the front of a ZL1 camaro.......it's hollowed out to reduce wind resistance..
I get that it'll increase drag that's what basically any aero does. I'm not so much worried about that as I am getting effective aero.
Originally Posted by FourG63 97GST
What goal you're trying to accomplish? The hood vents decreases from end lift.
have you ever drove with your hood unlatches or had one side unlatch? if so you'll see how much the hood wants to come up, from all the air that getting trapped in the bay with nowhere to go. without vent the air is still trapped pushing up on the underside of your hood, causing the front end to lift and drag.
But I don't think anyone here has the direct to answer what you're asking, trackspec has a small and large hood vent option, if someone has the answer its probably them.
My plan is to make a carbon fiber hood for my C5 with the vents molded into it, as opposed to it being an add-on. Obviously the more vanes there are, the more complex and difficult the mold will be to make. So I was trying to see if running a small number of vanes would still have the same effect of reducing front end lift, or if the higher vane count helped evacuate the underhood air more effectively.
I'm going to go out on a limb and say no/little ACTUAL research has been done (or is available to us) to be able to answer your question. We can theorize and speculate, but unless anybody here has the data to back it up, that's all we're doing. The location and size are important and Trackspec tells you exactly where to put their vents. If you do a search, you'll find at least one old post where a member actually did conduct research on location, size, etc. That post has some good info. The fact that Trackspec subsequently developed wickers to add to their louvers to improve their effectiveness tells me there's definitely some wiggle room in what you're looking for.
Actually, there was a significant amount of aerodynamic research done on the C-5 platform.
First and foremost, thanks for sharing that pdf, I saved a copy to my C5 folder
I think most of us are very aware that there has been extensive testing done on a 20+ yr old championship winning platform. It would be impossible for there not to have been lol. My answer was specifically pertaining to the question he asked which was about amount of louvers in hood vents having a significant impact. The pdf you shared doesn't seem to address anything hood related that I can find, maybe I missed it somewhere? There is definitely some great info in that document otherwise!
First and foremost, thanks for sharing that pdf, I saved a copy to my C5 folder
I think most of us are very aware that there has been extensive testing done on a 20+ yr old championship winning platform. It would be impossible for there not to have been lol. My answer was specifically pertaining to the question he asked which was about amount of louvers in hood vents having a significant impact. The pdf you shared doesn't seem to address anything hood related that I can find, maybe I missed it somewhere? There is definitely some great info in that document otherwise!
Perhaps the individuals conducting the research knew that the hood louvers are unnecessary boy racer bits.
Unless the louvers are so closely spaced so as to create a meaningful flow restriction, I would expect that the overall area of the vent and its placement would be much more influential than whether the vent has seven louvers, or nine. That said, the aerodynamic drag induced by the exhausted radiator air being trapped under the hood, would likely far outweigh just about any aerodynamic mischief that you could cause by adding an exhaust vent in the hood.
I don't believe the number of louvers will have much significance if we're talking say 7 instead of 9. The placement of the vents on the other hand is of major significance. They need to be in a low pressure zone to ensure the vents are flowing air out vs. if they are placed too high up on the hood and instead allow air to come in. Placed correctly they will let more air flow pass through the radiator and release the hot air out of the vents keeping engine temps down. And at high speeds you won't experience hood lift anymore.
But if you're doing them for front end aero purposes the increase in down force is minor at best. And nothing compared to a splitter as far as impact.
I purchased an extra paint matched hood with Trackspec vents for my car to keep temps down after adding the Novi. I think the black vents look good on a black car. More so than other colors. But I'm biased.
Vents form a low pressure zone. Will suck air from the compartment. Minimum effect on engine temp. I installed these vents for a different look on the C5.
Vents form a low pressure zone. Will suck air from the compartment. Minimum effect on engine temp. I installed these vents for a different look on the C5.
Those are dangerously close to a high pressure zone aka where a cowl induction hood would bring air IN to the hood.
Like the other fellas said, placement is key. Up front right behind the radiator (where Trackspec puts them and even though the C5R is far from stock, where they put it as well) is ideal.
Those are dangerously close to a high pressure zone aka where a cowl induction hood would bring air IN to the hood.
Like the other fellas said, placement is key. Up front right behind the radiator (where Trackspec puts them and even though the C5R is far from stock, where they put it as well) is ideal.
the above louver placement couldn't be worse for functionality. But he states he did it for looks. Which I personally don't see the point. Especially when it has an adverse effect and he had to cut up a nice hood.
I reviewed a dozen or more windtunnel test videos years back before sourcing my Trackspec hood. There was a wind tunnel test performed on a C7 that showed (if memory serves) a 10% reduction in heat (reason I opted for it) when the center vent louvers were installed over stock hood, 70lbs of added down force at 80mph, and 100lbs of DF at 120mph over the stock hood. Placement was at least 24 inches from the windshield cowel and just behind the radiator. Exactly where the center vent is on my hood.
So yes, when using a large center vent correctly placed, they do reduce heat and they increase down force.
My plan is to make a carbon fiber hood for my C5 with the vents molded into it, as opposed to it being an add-on. Obviously the more vanes there are, the more complex and difficult the mold will be to make. So I was trying to see if running a small number of vanes would still have the same effect of reducing front end lift, or if the higher vane count helped evacuate the underhood air more effectively.
I find this three part series incredibly accurate at depicting the work involved in making a carbon fiber hood -- a fun watch whether one wants to go this way or not:
I find this three part series incredibly accurate at depicting the work involved in making a carbon fiber hood -- a fun watch whether one wants to go this way or not
I think I've watched that video series (and the rest of the stuff easy composites has posted) about a dozen times. I used to work in a composute shop so im fairly well versed in the "how to" aspect of it, I just don't have the background in engineering/aerodynamics to properly do the "why" aspect.
Hood louvers question
the above louver placement couldn't be worse for functionality. But he states he did it for looks. Which I personally don't see the point. Especially when it has an adverse effect and he had to cut up a nice hood. 
