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hood vents: ideas...


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With regards to the S flaps and the verticals on the splitter, seems like you can't really do both in the same spot. It would be possible to put the fences in a ways, maybe a foot or so from the edge to "capture" the air on the splitter, and then use the S flap to evacuate air from the engine compartment. I think it makes a lot more sense to use the S flap if you have a path for air to get out of the engine compartment as well. If you have a full fenderwell, you can only pull from under the frame rail. If that area is removed there is a better path for air to get out from under the car.

 

FWIW I agree with Cary that the calcs on the Bimmer should have some value. I don't think it's "shoot blindly in the dark or pay for a wind tunnel session" and in fact, I question the usefulness of the wind tunnel sometimes. You can get a good idea of the overall effect, but if you have limited time in the tunnel you might make more than one change at a time and then you lose the capacity to figure out which change had what effect. This manometer testing gives the chance to test and test and test at comparatively low cost. I think cfd would be another really good way to go. Seems to make more sense to get things fairly well optimized with the cheap repeatable methods, then go in and fine tune the thing with the tunnel.

Edited by JMortensen
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Thanks for the pic. I was trying to figure out if I could get away with mounts like that in SCCA XP where the wing would be reverse swan neck mounted.  The rules specify the wing location but don't really talk about the mounts at all.

 

For those interested here's a thread about the aero development of the red Z we're talking about.

 

http://www.viczcar.com/forum/index.php/topic,9059.0.html

 

Cary

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For those interested here's a thread about the aero development of the red Z we're talking about.

 

http://www.viczcar.com/forum/index.php/topic,9059.0.html

Thanks for the link, I've been planning a rear diffuser similar to this, and I'm glad to see one already in use on an S30. I'm thinking mine will extend out slightly more, and I'll notch the rear panel to allow it to come up a little higher as well; something like this, hanging off the rear bumper:

 

Audi-Quattro-S2-James-Dorey-PMcG-27-680x

 

Anyhow, considering this is a hood vent discussion, I'll redirect that way. I'm planning on cutting some holes in the hood for venting, and installing some almost flush louvers (I will rarely track the car, despite it's many 'race car' features, so I'm not opposed to making some successions for aesthetics). Has anyone here made custom louvers in this fashion? I've seen it more and more often in the OEMs, and despite their fascination with non-functional fashion vents in the 90's I'm inclined to think that they do serve their purpose. Here are a few examples to illustrate.

 

Ford Raptor:

Raptor-hood-vent-thumb-717x537_zps56505c

 

Aston Martin V12 Vantage:

30-2011-aston-martin-v12-vantage_zpsc5ee

 

I'm planning on something closer to the Aston's in terms of design and shape, but much simpler in construction. A basic riveted aluminum design, powder coated to match the exterior trim work. This is the closest thing I found on the web:

 

IMG_4404_zpsf944c447.jpg

 

I'm also planning a set of matching fender vents, situated right behind the ZG flares. My hopes are that the flare will act like the small spoiler before the vent that has been discussed earlier in this thread...

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It has bigger brakes than standard, no problems that I know of. In my experience with big brakes all that is needed is to remove the backing plates, after all brakes are meant to run fairly hot and so too much cooling can reduce their efficiency. 

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Test results at ~60 mph:

 

image_zps1728fd29.jpg

 

I was a bit shocked at +0.75 " water

 

image_zpsb2a3ba7e.jpg

 

I was equally shocked at -1" water

 

Net 1.75" water of lift

Looking back at pics I took at the Indy Grand Am race and came across this Porsche. Its used to vent air from some cooler ( oil?) but tells me maybe there is something to venting near the front of the hood to at least take advantage of low pressure on top to reduce lift?

 

image_zps47aeb9f7.jpg

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Might be a bit too far forward to be in the low pressure zone but I guess that has been looked at prior to deciding to locate a vent there? There will be some disturbed air behind the vent so that would tend to negate any lift tendency in that area.

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  • 3 weeks later...

If you were local I'd introduce you to 'the louver guy' who punches the louvers in the inspection lids I have available, here and he could punch as many you'd like!

Where can i get louvers put in my hood? or you guys just welding on little louvered strips?

Edited by 1 tuff z
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  • 1 year later...

I like it!

 

Me to.  I'm in the middle of the same type of problem solving with my extreme under hood temps. I have twice the turbo/ exhaust plumbing heat to extract out from under my hood...

 

I wish I could go with the hood ZT-R is. It's going to look menacing...   :twisted:  

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