Jump to content
HybridZ

louvers & aero?


Recommended Posts

I've been skimming through these threads and have been real impressed with all the detail of testing of particular parts. my 76 has the famous rear window louvers and other than being a funky and rad 70's-80's mod do they offer any aero advantages or disadvantages?:hs:

Link to comment
Share on other sites

  • 4 weeks later...

I can't give any kind of 'real' answer about the aero advantages or disadvantages of the louvers but I can give my opinion... so I will. Any air that is traveling over the car is going to be seperated from the car when it reaches the louvers since the air is going to see a bunch of steps and it won't be able to stay on all of them, so my thoughts are that they have a negative effect on aerodynamics (personal opinion).

 

As far as I know the louvers were created to provide protection from the sun and some security, the only reason they are stepped is so the occupants can see out the back. I do not think any aerodynamic effects were taken into consideration when these things were dreamed up and hit the market. BTW zwilliams thats a nice looking Z.

 

Dragonfly

Link to comment
Share on other sites

I have never looked at the louvers as a style thing, they were always functional to me.

 

This car is a greenhouse, and putting a set of louvers on the back blocks (by MY estimate) about 60% of the radiant heat from the sunlight that gets in the car. My uncle runs with the louvers and always uses a sunshade, and his car is ten to fifteen degrees cooler than mine ever was when parked in full sunlight.

 

fortunately, to my eyes, on a Z, they just look right.. but it WOULD be interesting to discover what impact they have. To my thinking, installing vortex generators on the roof ahead of them may lessen any spoiling of laminar flow.. and for all I know the louvers may even aid in this endeavor by pushing the boundary layer further from the car...

 

 

..but then again, for all *I* know, I am talking way over my head and mis-using terms and concepts left and right. So I will shut up now :)

Link to comment
Share on other sites

Louvers are used to EXTRACT air. When they're put on a fender, they extract air from the fenderwell. On a hood, they extract air from the engine compartment. When you put them on the decklid, they can't actually extract air out of the hatch, so they just create turbulence and a low pressure area over the louvers. I don't know for sure, but I'm thinking that will increase drag and perform no useful function whatsoever.

Link to comment
Share on other sites

Louvers are used to EXTRACT air.

 

Well, if you ask me, the louvers put on the hatch of a Z are designed to do nothing with air; they are there to block the sunlight. :D

 

But you would probably know better than I what the aerodynamic characteristics would be like. Personally, I wouldn't imagine that a well installed, flush mounted set would cause much difference in either direction.

Link to comment
Share on other sites

Well, if you ask me, the louvers put on the hatch of a Z are designed to do nothing with air; they are there to block the sunlight. :D

Exactly. They aren't used for aero purposes on a Z, they're used to protect the interior from sun damage or as a styling addition.

 

As an aero device they're used to extract air. Since there is no air to be extracted, they should only be able to do what they do to the top layer of air, which is to cause turbulence. This turbulence causes low pressure as the air crosses the louver vent, and that's what makes them extract the air in that situation. So now you'd have the low pressure doing nothing useful, but the turbulence causing drag.

But you would probably know better than I what the aerodynamic characteristics would be like. Personally, I wouldn't imagine that a well installed, flush mounted set would cause much difference in either direction.

I'm not an engineer and have no special qualification to say what they'll do. I can say with some degree of assuredness that these are not flush mounted by definition. A flush mounted louver would have the bent part inside the hatch with only the hole at the hatch level.

Link to comment
Share on other sites

I can't give any kind of 'real' answer about the aero advantages or disadvantages of the louvers but I can give my opinion... so I will. Any air that is traveling over the car is going to be seperated from the car when it reaches the louvers since the air is going to see a bunch of steps and it won't be able to stay on all of them, so my thoughts are that they have a negative effect on aerodynamics (personal opinion).

 

...

 

Dragonfly

 

 

Isn't that section of the car the part that creates lift in the rear? The laminar air flowing over the downward slope of the car is what causes lift, right?

 

So, if one were to interrupt this laminar flow, with louvers of course, the effect would be to minimize rear lift. (although probably at the expense of an increased drag coefficient.)

Link to comment
Share on other sites

I don't know much, but I do know this. I have the louvers on my car and my rear carpet stays in great shape compared to the other Z's I have owned without them. Also, If I don't get my hatch latched, it will open fully at almost exactly 80mph-lift! Don't know if that happens without the louvers though.

Mike

Link to comment
Share on other sites

I had a louver on my car way back when I first got it 8+ years ago. I was doing a "high speed" run aka 100mph+ down a nice open country road when all of a sudden I hear this horrible racket coming from the back....by the time I turned around to see what it was my louver was gone! I looked in the side view mirror only to see my louver going end over end about 30 feet into the air! LOL It was the funniest thing I've ever seen! I have to assume just from that experience that they create lift. I'm just glad there weren't any other cars around!

 

Guy

Link to comment
Share on other sites

I think I can bring up a better point that's worth mentioning. :D

 

If louvers are going to seperate air from surface of the car (which we can be pretty certain it will) then it's going to FORCE you to have a higher spoiler/wing to get the same downforce than you would otherwise.

 

You'll also be creating turbulence wich will probably make your spoiler less efficiant.

 

It also might be worth noting that many tracks won't let you race with louvers on because it's deemed a hazard, thus removing the point of the topic from that one particular area of vehicle use.

 

 

On the front and sides I can't imagine it'd have a terrible effect, but on the back of the car it's lying right in the path of all the air comming down off the roof of the car. Though if you get the air to start separating from the car sooner than the effect of the louvers might be held to a minimum.

 

Though I feel like I have to give the same warning as daeron in my post and say "hey, what do I know?". These are just my opinions about what I've learned on my own about aero, doesn't really mean much.

Link to comment
Share on other sites

well here's a pic of mine with side and rear louvers.

Took forever to find abs rears.

 

The whale tail puts alot of force down so I got used to it over the years. I just got the rear louvers and I can feel that the rear down force has been lightened now.

I have only driven if a couple times since and seems that there is no noticable change till speeds exceed 100. around 135^ the change seems more drastic. I know too fast for public roads but whatever.

 

I also have a brand new set of these for a 280zx if anyone wants to treat theirselves.

uknowntattoos003.jpg

Link to comment
Share on other sites

Join the conversation

You can post now and register later. If you have an account, sign in now to post with your account.

Guest
Reply to this topic...

×   Pasted as rich text.   Paste as plain text instead

  Only 75 emoji are allowed.

×   Your link has been automatically embedded.   Display as a link instead

×   Your previous content has been restored.   Clear editor

×   You cannot paste images directly. Upload or insert images from URL.

×
×
  • Create New...