Aero enhancements..., What changes work besides huge wings? Options

[mgp4591]

The base of the windshield is a high-pressure area on almost all cars. That's why there are air inlets there.

If you're going to go out the top, you'll want to section the trunk lid like several people on there have. Now I'm completely spacing on the name and BBS ID of the guy who used to live here, went to NC or thereabouts, and has a nice 3.6 in his car. (Blue car, possibly Alaska Blue.) He has the cooler air ducted out of a hole in the front lid.

I believe Sir Andy does as well.

That should be good for lift reduction or even downforce in the front. The rear is a different matter. Smoothing out the underbody with a tray should help air flow smoothly, and may cut lift and/or induce downforce as well.

Most things you can do to change the flow of air over the car will result in more drag.

--DD

Duh.... I'm old enough to remember cowl induction on Chevelles and Camaros- I should have known that, Thanks Dave! There's more than one example of the hood modifications to expel the radiator air in past threads and according to the air pressure build up you pointed out, probably the closer to the front of midway the better the low pressure area would be. However if I don't want to cut holes in the hood (it's just so damn pretty!) a good low pressure area would be under the car as I previously described. Along with an air dam, the low pressure would increase acting more like a vacuum for the hot air venting. Now the question is, how much air is being expelled through those louvers? Would it be enough to negate ALL of the effects of the air dam...?

[SirAndy]

Dumping extra air (and hot air at that) under the car is about the worst you can do if you want high speed stability.


Going from a under the car hot air exit to a shrouded through the hood air exit has dramatically improved the high speed stability of the car.

http://www.914world.com/bbs2/index.php?s=&...t&p=1898832

It also improved the actual cooling to the point where my engine now runs too cool in most street driving conditions.
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[mgp4591]

Dumping extra air (and hot air at that) under the car is about the worst you can do if you want high speed stability.


Going from a under the car hot air exit to a shrouded through the hood air exit has dramatically improved the high speed stability of the car.

http://www.914world.com/bbs2/index.php?s=&...t&p=1898832

It also improved the actual cooling to the point where my engine now runs too cool in most street driving conditions.
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And you're just running an oil cooler I believe, right? So with even more air being pumped through the radiator that would increase the instability. I also see a few exiting through the front wheelwells which if vented correctly should be efficient and not detract from the smooth looks of the hood... Anyone want to comment on their wheelwell vented coolant temps? And I hear what you're saying about improving your stability at higher speeds... maybe I should just design a really sexy looking hood vent. (IMG:style_emoticons/default/drooley.gif)

[Andyrew]

Properly shrouded, venting through the fenders should be almost as effective as venting through the hood. However you wont get the spoiler effect that the hood exit gives you.

I also do not advocate forcing more air under the car. Just a bad thing altogether.

[mgp4591]

Properly shrouded, venting through the fenders should be almost as effective as venting through the hood. However you wont get the spoiler effect that the hood exit gives you.

I also do not advocate forcing more air under the car. Just a bad thing altogether.

I agree but it works pretty well for Ross! I agree that properly ducted the fenderwells will work well and if I had vents in the upper parts of the flares I may still get some downforce- maybe not as much as a hood vent though.

[Chris Pincetich]

You don't really need 2 side mirrors, just one on the driver's side (IMG:style_emoticons/default/shades.gif)
I'd focus on a super clean underbody panel and consider extending the rear diffuser out beyond the rear valence so it is just short of the rear bumper impact zone...maybe add rear tits too?

Have fun and be sure to get us some data and photos! Tough to get the "perfect" MPG measure, but trying to both before and after a suite of mods could actually reveal a difference.

My strategy so far with the cafe racer/commuter 914 I have is light weight all-around, LE spoiler, windows up, top on, and one side-view mirror (IMG:style_emoticons/default/beerchug.gif)

[veekry9]

ThyssenKrupp

http://forums.pelicanparts.com/off-topic-d...tures-1564.html

What compromises should be made to be smoother in the air with your 914?



Well,not much attention was being exerted to make the 914 smooth through the air in '67.
A high powered aircooled engine needs a lot of air,so give it enough to cool it and no more.
A steeply raked windscreen is laid back to reduce the incident angle,like your hand out the window.
The height of the car is reduced to make a smaller hole,bigger is slower.
A more pointy nose,like a diver in the water,palms together,faster.
A big wake makes a big drag,so stop making a wake.
Wide tires look and act like a steamroller,slow,so make the tire look different to the air,pointy.

/

[Dave_Darling]

The nose is less important than the wake. Far less. Blunt noses and pointy noses give the same results at any speeds that we care about. Unless you're getting high subsonic, or transsonic, which I don't think is happening in a 914... (IMG:style_emoticons/default/wink.gif)

--DD

[mgp4591]

We're keeping it subsonic...
Any positive or negative ideas about a front splitter? I read Andyrew is planning for a larger one than I want, but then again I'll have to see it and get feedback from him about its functionality. I'm getting the idea that small improvement will work the best which really keeps the look of the car relatively stock compared to the race cars we see. The racers need the downforce for those high speed sweepers where I just want it to move around the car as smooth as possible. I also want air to move through the car to help anchor it as well as I can. Think the Ferraris that don't have the big aero wingdings clogging up the good looks- just making it work with the design.

[Chris914n6]

If this is too racy for you, click the linky About air dams, splitters, air curtains and diffusers (IMG:style_emoticons/default/idea.gif)

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[veekry9]

Aerodynamics 101
https://www.google.ca/search?q=aerodynamics...N4s2WGEqWZIM%3A

As we ski down a hill,like the speed skier above,we can `feel` the wind and the drag as we pass through the air.
Assuming the crouch,into the `tuck`,we can go faster by presenting a pointy shape to the air volume,wedging our way through it.
As a test,drive your 914 up the 101 with your hand out the window at 40 mph,it should be easy enough to hold it in place with your left thumb up and palm open.
You can experiment with the difference in drag when you splay your fingers or cup your palm.
The second part of the test involves a sheet of material,plywood will do fine,12"square.
Strap that plate to your hand and do the speed which exerts the same force on your arm,noting the speedometer,careful,you won`t be able to do 40.
This is called`flat plate area`,next build an apparatus to hold a 5 square foot flat plate into the wind above your 914.
Before you mount this test rig,drive out to the hwy and map out the test track,a measured distance of say,10 miles.
Take a few passes up and down the highway,an average 40mph will do fine,noting fuel consumption by a test tube arrangement,with markings in cc`s,to set a baseline number.
Maintain a constant steady state,within reason,to derive actual fuel consumption over the 20 mile test track.
Mount the test apparatus and repeat the test,duplicating the test parameters,measure the actual fuel consumption and compare the difference to the baseline.
5 square feet of flat plate area will reduce the fuel efficiency by :-->your results.
This is to prove to yourself the facts of aero,already a known quantity through such experimentation,done 80 yrs ago.
Now,I don't expect you would actually go out and do such an experiment,because it would be too hard to do and take too much money and time.
Perhaps a google,or looking at fast Porsches,you could come up with a round estimate of the work done to be smooth in the air,or water.
A look around at the average lakes speedster,a good amount of effort is made to be clean,to reduce drag,that work can't be discounted.

https://www.google.ca/search?q=studebaker+l...HB8b0GeFa_sM%3A

[sixnotfour]

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[mgp4591]

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That's the most radical 914 I've ever seen! (IMG:style_emoticons/default/w00t.gif)
Most of the ideas I've had come from successful designs I've seen on race cars. They have different needs for their purpose but there's a lot to be learned from their designs without the race car look. From the comments it seems that the rear of the car needs the most attention and very little done to the front - an air dam and a small splitter will probably do the trick.
I'll read up more and see what works... (IMG:style_emoticons/default/idea.gif)

[sixnotfour]

1967 alfa romeo tipo 33 stradale

[Andyrew]

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My thoughts for a rear diffuser.

[veekry9]

The 956/962 was,is a proven design by the wind guys,in a wind tunnel and on the track.
Huge difference,between what they built and an ineffective adornment,like pretend spoilers and wings,useless.
The 944 above is the only example that I've seen that would be a performer,with the turbo six power to use it.
Going fast enough to accelerate the airflow under the 956 is the objective,setting the Nurburgring lap record was the result.
(956 6:37 Derek Bell)
The venturi has to start far ahead,under the cockpit,bringing slightly pressurized air from under the front ducts,then exiting to the low pressure turbulence behind the car,unobstructed by suspension hardware.
The competitive field is huge,a great deal of effort is being exerted to win.

Buy this book for the latest techniques by a successful competitor.
http://www.mulsannescorner.com/newsnov15.html

How much of that can be applied to a 914's unique top hat is up for debate.
First,move the transmission to the center of the car,getting it out of the path of the airflow!
Second,replace the flat engine with a V type,opening up a duct on either side of the engine.
And on and on,compromises disregarded.

[veekry9]

https://www.youtube.com/watch?v=w_QazJD9nyI


A new production,some ideas of aero application.
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