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914World.com _ 914World Garage _ Aero enhancements...
Posted by: mgp4591 Jan 21 2016, 04:14 PM
I know top speed isn't the goal with our cars, but I'm wondering what and who has made changes that address the lift issue associated with the negative pressure immediately behind the targa top? Someone once told me these cars lift badly over 100 mph. Any ideas / solutions besides huge aerodynamic add ons?
Posted by: damesandhotrods Jan 21 2016, 04:24 PM
That sounds like a question for the sanctioning bodies rule book…
Posted by: johnhora Jan 21 2016, 04:27 PM
here you go.....
http://www.cassidy-online.com/porsche914/aerodynamic_aids/index.html
Posted by: mgp4591 Jan 21 2016, 04:44 PM
I'm not looking at this from a race perspective- fuel mileage and stability are my goals and focusing on stability. Out west on longer roads we get crosswinds that play havoc with semis and high profile vehicles, but I've also been thrown on the motorcycle a few times with wind. A light car could use some aids in the stability department. Think of it as channeling the air for maximum efficiency... 
Think along the lines of the Ferrari 250 GTO with the cutouts behind the rear wheels.
Posted by: veekry9 Jan 21 2016, 04:52 PM
Virtually identical in every respect,tho a little heavier.
http://www.corvairforum.com/forum/viewtopic.php?f=165&t=766
The air ,it gets under the car,and a huge induced drag penalty in the low pressure volume behind the targa.
The Daytona Cobra worked good and was significantly lower drag,not ploughing like the 427 Roadster.
Take a good look at the behind of the 956/962,an effective method of evacuating the bottom.
I always liked the Hall Chaparrals,vacuuming the car down,brilliant,worked so good they outlawed them.
When I placed the flat fan on the rear decklid of the GT14-12,it was for more than cooling. 
This too is a low drag shape,a four cylinder.
https://www.google.ca/search?q=Hall+Chaparral&espv=2&biw=1280&bih=641&source=lnms&tbm=isch&sa=X&ved=0ahUKEwjL_ZO-r8HKAhXltYMKHcgVB_YQ_AUIBigB
/
Posted by: FastFroggy Jan 21 2016, 04:56 PM
I love this subject.
If I may, I would suggest that you think about your goal. Efficiency will not give you downforce and the downforce is not efficiency.
Efficiency will not necessarily help with crosswind stability. In my book, crosswind stability has more to due with caster unless your making significant aero changes and driving fast(+90mph)
unfortunately you must choose:
a. downforce
b. low drag ( efficiency )
Just my rambling thoughts....
Posted by: Tom_T Jan 21 2016, 05:08 PM
In 10 years & 130k+/- of DD & long trip use 75-85, I never really had any big stability problems with mine on the freeways out west at the 75-100+ mph range, although the chances to do so were few & far between, this included the crosswinds in CA, NV, AZ, UT & with Semi's.
If you're looking for a more stock back-in-the-day type accessory/option, then the small ducktail spoiler on the rear trunk was what most folks used ... probably more for looks. Jeff Bowlsby's classic 914 website has pix of them.
However, that requires drilling the rear decklid to mount it, thereby introducing a new path for the tin worm - so I'd personally prefer to be quick at the wheel for a few gusts/trucks, than opening the rust door!
PS - if mpg is your goal, then stick with the stock 165HR15 (/80) tires at proper cold inflation, since wider & under-inflated tires will rob you of far more mpg, than will any high speed drag which you describe.
BTW, I did 126 mph on I-15 through Virgin River Gorge on a late Friday night run to a weekend Rugby Tournament in Park City Utah in the late 70's on Semperit M601 "Dogbone" 165HR15 tires with no traction/steering-control nor stability problems (doubt you could do it today with the traffic though) - & 75-85 the rest of the run from SoCal/OC. I did so for several years running when we played up there in Sept.
Cheers! 
Tom
///////
Posted by: damesandhotrods Jan 21 2016, 06:07 PM
Having driven a 914 in storms on Interstates with semi-trucks I can tell you that you can drive it with 1 hand on the wheel with no problem. It is not like the Beetle, or the 911. The 914 is already pretty low drag with the roof on and the windows rolled up. If you are that worried you can add a front air dam which would divert air from going beneath the car and direct it around the car. But the downside is that this can have an adverse effect on engine cooling…
Posted by: SirAndy Jan 21 2016, 06:39 PM
It's not just the low pressure behind the targa top, it's also the large amount of air getting under the car at those speeds.
- Add a front spoiler that directs air around the front instead of under the car
- Add a rear diffuser under the engine and transmission
- Add a rear wing to create more downforce
- Add louvers to the top of your fenders
![popcorn[1].gif](style_emoticons/default/popcorn[1].gif)
Posted by: Andyrew Jan 21 2016, 06:48 PM
My aero plans are as follows in this order
1. Rear diffuser from the cabin back
2. Side skirts that go from the front wheels all the way back
3. Front splitter 8" in front of bumper
Posted by: Andyrew Jan 21 2016, 06:49 PM
And the cars start to lift above 100, but it gets really bad above 150.
Posted by: yeahmag Jan 21 2016, 07:30 PM
One of the things I've read to work is popping the top up at the back to make a slot.
Posted by: JmuRiz Jan 21 2016, 07:41 PM
Never noticed it being bad at 110, but that was in a straight line 
I'd be interested in the diffuser designs, not sure how to route the engine cooling air with a diffuser. Maybe a semi blown diffuser like they banned in F1 would work.
I wonder if Mitsubishi Evo-like shark fins on the rear of the targa would help.
Posted by: cwpeden Jan 21 2016, 08:07 PM
If looks are as important as performance, an LE front spoiler is your best bet in my opinion.
For the limited time my 914 spends at 100 mph or above the stability difference was very noticeable the first time I drove with it.
Posted by: jmill Jan 21 2016, 08:14 PM
I wonder if Mitsubishi Evo-like shark fins on the rear of the targa would help.
I'm sure it would. Add some vortex generators on the rear of the top and add a ducktail and you've got something.
Posted by: Olympic 1.7 Jan 21 2016, 08:33 PM
I wonder if Mitsubishi Evo-like shark fins on the rear of the targa would help.
I'm sure it would. Add some vortex generators on the rear of the top and add a ducktail and you've got something.
Hmmm.... ...........
.
Posted by: r_towle Jan 21 2016, 08:50 PM
here you go.....
http://www.cassidy-online.com/porsche914/aerodynamic_aids/index.html
You can't do better than this report.
Posted by: mgp4591 Jan 21 2016, 09:37 PM
I'm running water cooled Subaru power so the engine cooling isn't an issue. I plan to run a front spoiler with a modest splitter, a pan over the open parts to keep the underflow smooth and modest side splitters for the flow also in addition to a rear lower diffuser. A rear spoiler of sorts, being careful not to create paths for rust worms in the process. I'll be running flares of a different kind and not looking like much else out there but enough to give room for 225s and 245s. I realize the drag/efficiency battle but there's got to be a compromise somewhere that works. I was thinking about cutting channels is the back of the top between the reinforcement ribs at an angle so they would let air from the roof bleed through to the rear deck, filling in the vacuum that way. Still have to look at that. I have other ideas also including fans- and all these ideas and comments are giving me more ideas! Thanks!
Posted by: veekry9 Jan 22 2016, 05:22 AM
The effectiveness of the vertical tailfins on the LMPs can be seen here,separating the helical flows.
Also useful for signage.
Posted by: jd74914 Jan 22 2016, 07:14 AM
http://www.cassidy-online.com/porsche914/aerodynamic_aids/index.html
You can't do better than this report.
Except for CFD with moving wheels. In many cars airflow influenced by wheel movement is a really big deal (especially open wheel, but also closed wheel).
If you're putting a large spoiler of some kind on you absolutely need end plates like Veekry noted. Your downforce vs. drag efficiency is really affected by spillage off the sides of the wing.
Posted by: veekry9 Jan 22 2016, 08:41 AM
https://www.youtube.com/watch?v=FW5HtJ5tou8
Feel the air.
Posted by: mgp4591 Jan 22 2016, 09:43 AM
Looking at their speed and the way the hill flattens at the bottom is giving my legs cramps from the compression!
Posted by: Al Meredith Jan 22 2016, 06:53 PM
Google "airtabs" and see vortex generators at work. I don't know if they work on a car but they add to the psych value.
Posted by: Dave_Darling Jan 22 2016, 09:46 PM
I'm sure it would. Add some vortex generators on the rear of the top and add a ducktail and you've got something.
Vortexes are drag. VGs can be useful to energize the boundary layer if you put them in just the right places, but for the most part they just add drag.
AirTabs seem to be one of the worse offenders, as they promise a lot and practically never deliver.
--DD
Posted by: r_towle Jan 22 2016, 10:05 PM
http://www.cassidy-online.com/porsche914/aerodynamic_aids/index.html
You can't do better than this report.
Except for CFD with moving wheels. In many cars airflow influenced by wheel movement is a really big deal (especially open wheel, but also closed wheel).
If you're putting a large spoiler of some kind on you absolutely need end plates like Veekry noted. Your downforce vs. drag efficiency is really affected by spillage off the sides of the wing.
Lots of opinions on.this,topic, but this study has the most factual evidence I have ever seen regarding how the 914 behaves.
We are not talking about other cars here in this question.....
Posted by: mgp4591 Jan 22 2016, 11:02 PM
Wow, you're not kidding. They covered most of my ideas except for venting the wheelwells for the turbulence. They even covered my idea of slots in the rear pillars and got some good results there. The lengthening of the roof came off like I expected with the added length it only creates more drag. I wish they had addressed the rear diffuser possibilities and I have a couple of other ideas that follow along their lines of thinking- I'd love to get these folks in a room for a discussion culminating the sum of thought to arrive with the best compromise of results. A bit hard to get through after finishing my first three documents today- my eyes AND brains are slightly fried... Thank heavens for the weekend! And thanks for the link to those studies! And yeah, pretty damn good for a 45+ year old design...
Posted by: veekry9 Jan 23 2016, 06:37 AM
Well,this is a big topic that needs great study to achieve any significant results.
The design feature of the greatest drag is the boat's prow front end,ploughing through the air and creating a giant pillow of high pressure on which the 914 rides.
Separating the air paths into smooth transitions with little turbulence is the task at hand.
This is a good place to start,and what a satisfying result you could make.
CFD for u.
https://www.google.ca/webhp?sourceid=chrome-instant&ion=1&espv=2&ie=UTF-8#q=linux%20cfd
Design your own ground effects 914.
Go ahead,make your clay.
Posted by: RickS Jan 23 2016, 11:32 AM
Slots in the sides of the targa bar? Who knew? If the one made angled cuts to help channel air to the rear grill and relieving the low pressure zone could be the shizzle. Whose going first?
Posted by: sixnotfour Jan 23 2016, 12:17 PM
Attached image(s)
Posted by: sixnotfour Jan 23 2016, 01:28 PM
ralph did 170mph
Attached image(s)
Posted by: mgp4591 Jan 23 2016, 02:24 PM
ralph did 170mph
True but I'm not a fan of driving on public roads with the Ginther style windscreen- this has to be a road legal DD.... and the vortex generators on GRNMNEE are questionable in their effectiveness if not really cool looking! I've always like the looks of that car!
Posted by: mgp4591 Jan 23 2016, 02:27 PM
Slots in the sides of the targa bar? Who knew? If the one made angled cuts to help channel air to the rear grill and relieving the low pressure zone could be the shizzle. Whose going first?
I don't think they'd have to be as big as the ones in the illustration from their test either. Maybe smaller ones more horizontal than vertical and closer to the body line to take advantage of the airflow line in the stock configuration.
Posted by: jmill Jan 23 2016, 04:24 PM
Vortexes are drag. VGs can be useful to energize the boundary layer if you put them in just the right places, but for the most part they just add drag.
--DD
Very true, but, if you could energize the boundary layer to make the rear spoiler effective you can add a bit of down force on the rear of the car to add stability at speed. It's always a tradeoff. What's more important, limiting drag or down force?
It all depends on how much HP you have and how light your car gets at high speeds.
Posted by: Andyrew Jan 23 2016, 05:07 PM
I still think the biggest thing we can do for increased rear stability is a proper diffuser and side skirts.
I plan on trying out an airport run when my car is all set and done and I will have the HP and gearing for 200mph, the question is aero, and specifically the rear.
Posted by: mgp4591 Jan 23 2016, 05:35 PM
I still think the biggest thing we can do for increased rear stability is a proper diffuser and side skirts.
I plan on trying out an airport run when my car is all set and done and I will have the HP and gearing for 200mph, the question is aero, and specifically the rear.
That's what I'm thinking also. The engine and gearing I've got is good for 150 plus- not that I'll ever drive it that fast but I want it planted and relieved of the negative pressure that can upset it at speed. It would help with mileage also being easier to move through the air without looking like a Hot Wheels car. I think subtle changes could make a big difference.
Posted by: damesandhotrods Jan 23 2016, 07:20 PM
Vortexes are drag. VGs can be useful to energize the boundary layer if you put them in just the right places, but for the most part they just add drag.
--DD
Very true, but, if you could energize the boundary layer to make the rear spoiler effective you can add a bit of down force on the rear of the car to add stability at speed. It's always a tradeoff. What's more important, limiting drag or down force?
It all depends on how much HP you have and how light your car gets at high speeds.
But you cannot add downforce with a spoiler. It is called a spoiler because it spoils lift; if you are after downforce you need a wing…
Posted by: jmill Jan 23 2016, 08:38 PM
But you cannot add downforce with a spoiler. It is called a spoiler because it spoils lift; if you are after downforce you need a wing…
It's called a spoiler because it "spoils" unfavorable air flow. I'm not going to argue semantics.
Posted by: veekry9 Jan 23 2016, 08:42 PM
https://www.google.ca/search?q=porsche+race+car+aerodynamics&espv=2&biw=1280&bih=641&source=lnms&tbm=isch&sa=X&ved=0ahUKEwiBqISLscHKAhVGlYMKHQ_MCXcQ_AUIBigB#imgrc=W7tGs5e5_vl1SM%3A
Look to father Porsche for your aero ambitions,knowing they got it right.
An online course for the study of the science of fluid dynamics is available for your learning curve.
A faddish '70s applique of 'spoilers' which merely adds weight and trips the flow never did anything for me or the 914.
The IMSA 914 with the plywood looking plank fastened to the front doesn't do it either,never did.
The aero problem with the 914 is how do you make the airflow work like the 917's.
That is your mission ,if you so choose to accept it.
Get ready,get set.
http://racingcardynamics.com/race-car-aerodynamics-air-lap-times/
http://www.tunersgroup.com/engineering/simon_mcbeath.html
UH-OH,this won't end well.Nuts,another wreck on my resume,a LeMans 'flyer'.
/
Posted by: damesandhotrods Jan 23 2016, 11:53 PM
But you cannot add downforce with a spoiler. It is called a spoiler because it spoils lift; if you are after downforce you need a wing…
It's called a spoiler because it "spoils" unfavorable air flow. I'm not going to argue semantics.
These are not semantics, these are engineering principles…
Posted by: veekry9 Jan 24 2016, 04:25 AM
'72 LeMans Class Winner,aero worked great.
It is possible that a 914 could make the transformation,with some cutting and hacking.
Posted by: jmill Jan 24 2016, 09:17 AM
Ok, I'll put it this way. Spoilers reduce up lift at the tail of the vehicle. I suppose an engineer would need to see a positive number on his/her spreadsheet before they would quantify the results as being down force. Although much improved with a spoiler, still being in the negative they would say the vehicle has less up lift.
My feeble mind believes if you have less of one you must have more of the other. What it's called is irrelevant to me when the net result is more weight over the rear of the car.
Posted by: veekry9 Jan 24 2016, 11:04 AM
Smooth as a teardrop.
http://www.wired.com/2014/09/german-aerodynamic/
http://www.thetruthaboutcars.com/2010/02/a-brief-illustrated-history-of-automotive-aerodynamics-part-2/
A brick with a plywood plank up front.
Some racers didn't read the manual,probably not a sharp pencil nor a pilot.
Looking around for the fastest cars and what works,it is a matter of adopting a few features that will integrate with the 914.
The compromises that Porsche were constrained by can be disregarded for the speed/hp you would want.
https://www.google.ca/search?q=solar+racer&espv=2&biw=1280&bih=641&source=lnms&tbm=isch&sa=X&ved=0ahUKEwiTt8Dt9MLKAhXqmIMKHS72BCMQ_AUIBigB
https://www.google.ca/search?q=fuel+efficiency+racer&espv=2&biw=1280&bih=641&source=lnms&tbm=isch&sa=X&ved=0ahUKEwiG_oyb9cLKAhUBx4MKHWyBB7MQ_AUIBigB#tbm=isch&q=streamliner+racer
Posted by: damesandhotrods Jan 24 2016, 01:35 PM
Smooth as a teardrop.
http://www.wired.com/2014/09/german-aerodynamic/
http://www.thetruthaboutcars.com/2010/02/a-brief-illustrated-history-of-automotive-aerodynamics-part-2/
A brick with a plywood plank up front.
Some racers didn't read the manual,probably not a sharp pencil or a pilot.
Looking around for the fastest cars and what works it is a matter of adopting a few features that will integrate with the 914.
The compromises that Porsche were constrained by can be disregarded for the speed/hp you would want.
https://www.google.ca/search?q=solar+racer&espv=2&biw=1280&bih=641&source=lnms&tbm=isch&sa=X&ved=0ahUKEwiTt8Dt9MLKAhXqmIMKHS72BCMQ_AUIBigB
https://www.google.ca/search?q=fuel+efficiency+racer&espv=2&biw=1280&bih=641&source=lnms&tbm=isch&sa=X&ved=0ahUKEwiG_oyb9cLKAhUBx4MKHWyBB7MQ_AUIBigB#tbm=isch&q=streamliner+racer
You do realize your “Smooth as a teardrop” example is a perfect wing cross section. You now have designed in lift.
The “plywood plank up front” diverts air around the car. That is what you want. Until you are able to add tunnels under the car to speed up the under car air you are always going to have the air over car traveling faster than the air under the car. Air above the car moving faster than air beneath is lift, air above the car moving slower than air beneath the car is downforce…
Posted by: veekry9 Jan 24 2016, 01:39 PM
Is this the fastest Porsche 914 hybrid/GT1?I like what they did,tho I believe it is too heavy.
https://books.google.ca/books?id=yMJFvrORtzAC&pg=PA171&lpg=PA171&dq=porsche+914+center+of+gravity&source=bl&ots=OgYpJX_Mrl&sig=Jn9bKeNBn4GNrf932541IMNGIOw&hl=en&sa=X&ved=0ahUKEwivnLTvpLrKAhWrxIMKHVRGDcAQ6AEIOjAF#v=onepage&q=porsche%20914%20center%20of%20gravity&f=false
Kicking a few ideas around,working with cadcam,cnc in many fields for four decades plus.
Robotics for manufacturing,aerospace hardware from the StearmanPT-17 and T-33,to contemporary.
Gonna build a clean fourteen machine in a way untried and I hope effective,we'll see.
The suspension for sure is due for an update,to exploit the new rubber of today.
http://www.914world.com/bbs2/index.php?showtopic=222522
/
Posted by: veekry9 Jan 24 2016, 01:56 PM
The drawing states the name of the designer,the date and the city.
Really,any person who has studied hydrodynamics has studied this drawing.
The beginning of aero theories as applied to automotive applications.
https://www.youtube.com/watch?v=OcnQuzpBkWQ
https://www.youtube.com/watch?v=fkZwGa50eqM
https://www.youtube.com/watch?v=PfcII0AIW0c
https://www.youtube.com/watch?v=myxMudtFX6g
As a personal test might I suggest you stand up in the passenger seat of your 914 holding a plank of similar size.
Have you wife or girlfriend drive up the Cabrillo hwy at a speed you think you can handle.
Good luck.
Posted by: veekry9 Jan 24 2016, 02:50 PM
Nicki Lauda 3 time F1 Champ
Someone has scanned the R+T article from '79 or thereafter.
The BB was the Buchmann+Buchmann brothers,German hotrodders.
https://www.google.ca/search?q=isdera+commendatore&espv=2&biw=1280&bih=641&source=lnms&tbm=isch&sa=X&ved=0ahUKEwjI-PaDqMPKAhUklYMKHU2OA5AQ_AUIBigB#imgrc=v4StQkcRfBgozM%3A
http://isdera.de/
Some 32 yrs ago.Very nice designs.
/
Here's an example of a "blogger" who hasn't done the simplest search and in the absence of effort and facts
made shit up,a blatant obfuscation,a lie.
http://blog.iso50.com/17004/1978-mercedes-benz-study-cw311/
Claiming to have designed a Pininfarina Ferrrari would have him prosecuted,as has happened before,not long ago.
Intellectual copyright laws exist to protect those rights,so you can't just attribute someone's work as another's.
All very cute,took photos that someone else took,and typed bullshit for some unknown motivation.
Here's another,without regard for the actual designer,labelling it with his own.
http://humster3d.com/2016/01/15/mercedes-benz-cw311-1979/
Fairly easy to hit a sitting duck,clean out of the water.
They might be morons.
/
--
Posted by: r_towle Jan 24 2016, 04:11 PM
I wonder, has anyone ever taken a 914 to the salt flats for speed week?
What did they do for aerodynamics?
Posted by: Dave_Darling Jan 24 2016, 04:16 PM
But very little drag. The teardrop shape (with a particular length-to-width ratio!) produces the lowest drag.
So the question is, what are you aiming for? Maximum downforce? Minimum drag? Some compromise between the two?
BTW, the stock-type engines really do need the forward air-flow along the rear deck; that is how cooling air get to the engine!
--DD
Posted by: veekry9 Jan 24 2016, 05:42 PM
http://jnkdesignworks.blogspot.ca/
A lifting body has drag.The effective wing section in 1937 was..10mm wide,still is today.
A cd of 0.15 is why the fuel efficiency was so great,the largest significant factors were the R# and the wetted area.
The vehicle was light,an aircraft monocoque of aluminum.
Easy to test,make a 3' scale model in foam and epoxy glass and drive it the same way on the PCH.
Try to duplicate the conditions as closely as you can holding it up like the plywood.
https://www.google.ca/search?q=aerodynamic+testing+by+car&espv=2&biw=1280&bih=641&source=lnms&tbm=isch&sa=X&ved=0ahUKEwim5pDEzcPKAhUHuYMKHbvBAC4Q_AUIBigB#tbm=isch&q=using+a+914+as+a+wind+tunnel
Posted by: sixnotfour Jan 24 2016, 08:00 PM
Attached image(s)
Posted by: mgp4591 Jan 24 2016, 08:01 PM
But very little drag. The teardrop shape (with a particular length-to-width ratio!) produces the lowest drag.
So the question is, what are you aiming for? Maximum downforce? Minimum drag? Some compromise between the two?
BTW, the stock-type engines really do need the forward air-flow along the rear deck; that is how cooling air get to the engine!
--DD
I understand Dave, but I'm running a Subaru setup. I'd like to run a Porsche 6 cyl. but the dollar sign is way too high for my budget. It's cool if you can do it - it doesn't make dollars/sense to me but I admire those who make it work. Very cool!
And speaking of cool and aero, presently I have the radiator designed to flow out the bottom of the car but rethinking a cleaner topside exit to, again, clean up the airflow as to minimize drag. Directing the air to negate lift is the object of this exercise- if we achieve that, we don't need much downforce to keep the car planted. I'm not trying to have the tires bite so hard that they'll out corner a gazelle, just keep the car cruising smoothly with as little upset from angry air as possible. And no Veeks, I'm not gonna design a teardrop no matter what the cD says!
Posted by: JmuRiz Jan 24 2016, 08:47 PM
I wonder, has anyone ever taken a 914 to the salt flats for speed week?
What did they do for aerodynamics?
Very radical car, that's for sure.
http://www.914world.com/bbs2/index.php?showtopic=247827
Posted by: veekry9 Jan 24 2016, 08:56 PM
Hey,with a derelict 914 chassis anything is possible.
I've seen stretch limos,pickups,station wagons,chopped racers and any number of neato contraptions.
This one blows my kilt up,for a refreshing breeze.
A Sean S,from Coos Bay,on board,gone quiet.
I really like what the skin guy did,tho as always,there are some details I would have done differently.
Overall,an outstanding effort and result.
Note how the doorskins have been reshaped to the new width,to make a smooth transition to the rear fenders.This is CanAm big,and could have a use for the wing thingy handlebar.The wing itself seems to have a measure of curvature on the bottom and might be totally functional.
The color selections were done with a measure of subtlety,not the usual blazing high contrast of bright primaries.
Looks like he's done a slight top chop and a vinyl topping in a medium tan to complement the interior.
I'd like to see more pix of this one.
Posted by: veekry9 Jan 24 2016, 09:47 PM
Appears to have been riveted on to the trunk's topskin.
I like it,not only because I too went down that path,the 944's snowshovel spoiler,but because it would in fact be quite effective.
The nose job however,looks like too much anteater and not enough pointy wedge.Might be cleaner than I think.
Scale models in a concrete form tube,with a leaf blower or two,a test section with the sensing by modern piezoelectrics.
https://www.google.ca/search?q=miniature+wind+tunnels&espv=2&biw=1280&bih=641&source=lnms&tbm=isch&sa=X&ved=0ahUKEwjRosbohMTKAhVKs4MKHVZICOMQ_AUIBigB
Build your own,make a test run of your latest winged Mulsanne Masher and smile at the results.
We are not dealing with some unknown effects,this is all straightforward.The shape is the nexus.
https://www.google.ca/webhp?sourceid=chrome-instant&ion=1&espv=2&ie=UTF-8#q=online%20hydrodynamic%20lessons
/
Posted by: mgp4591 Jan 24 2016, 10:00 PM
Hey,with a derelict 914 chassis anything is possible.
I've seen stretch limos,pickups,station wagons,chopped racers and any number of neato contraptions.
This one blows my kilt up,for a refreshing breeze.
A Sean S,from Coos Bay,on board,gone quiet.
I really like what the skin guy did,tho as always,there are some details I would have done differently.
Overall,an outstanding effort and result.
Note how the doorskins have been reshaped to the new width,to make a smooth transition to the rear fenders.This is CanAm big,and could have a use for the wing thingy handlebar.The wing itself seems to have a measure of curvature on the bottom and might be totally functional.
The color selections were done with a measure of subtlety,not the usual blazing high contrast of bright primaries.
Looks like he's done a slight top chop and a vinyl topping in a medium tan to complement the interior.
I'd like to see more pix of this one.
Blown up way too big! I'd like the end result to look like a 914, not some cut up mid 80s Corvette. Not to be insulting, it just ain't my cup o' tea. I think my solution is small changes that make a positive difference to what has already been proved to be a fairly efficient design, kind of like intake/exhaust/c.chamber modifications- small improvements can go a long way unless you're out to breathe heavy at 9 grand. Same with these cars. Even the studied results favored small changes and resulted in positive gains for a well balance approach to my goals.
Posted by: RickS Jan 24 2016, 10:51 PM
What a fantastic project. It's 914 meets GT40, meets, Carrera GT, meets F40. Would love to see a butt shot.
I wouldn't own it but I admire anyone with the vision and talent to make it a reality.
What bums me about the professor's findings is that a front splitter and/or rear spoiler actually add drag.
Posted by: veekry9 Jan 24 2016, 11:48 PM
This is the link to the past:
http://www.914world.com/bbs2/index.php?showtopic=19030&st=80
The looks are deceiving,it is no wider than the average IMSA,hauling large rubber.
The proportion of the targa height to width of the new doorskins is what changes the perspective from what you usually expect with unmodified doors.Omg,omg he made the doors ..thicker!
More info on the car other than what I can see here would be nice,like how much does it weigh?
Posted by: Chris914n6 Jan 25 2016, 01:15 AM
Aerodynamics for the water pumper is going to be different than for a stock air-cooled. Aircooled has top and bottom airflow with air being mechanically moved from above to below. The open engine bay of a water pumper makes for a really odd shape, plus the rad outlets.
My first rear float fix attempt is a solid engine lid.
That body kit was called the F-Zero.
Posted by: mgp4591 Jan 25 2016, 09:38 AM
Aerodynamics for the water pumper is going to be different than for a stock air-cooled. Aircooled has top and bottom airflow with air being mechanically moved from above to below. The open engine bay of a water pumper makes for a really odd shape, plus the rad outlets.
My first rear float fix attempt is a solid engine lid.
That body kit was called the F-Zero.
Not sure what you mean by solid engine bay Chris. And I'm planning on flush panels around and under the engine and trans so that air doesn't get trapped in that compartment. Then transistion to a simple diffuser to direct the airflow from underneath. Currently, my radiator setup is planned for large louvers in the area where the A/C outlet would be - 4 large louvers will be at least 2X the inlet for the radiator and should cool fine, leaving me some frunk space. That will have hot air exiting out the bottom which isn't ideal for eliminating lift but I'm wondering if it's really enough to be concerned with. My other idea is to duct it up similar to others but have it exit close to the base of the windshield where there's already enough airflow to suck it out through an opening. More efficiency and some airflow resulting in downforce with minimal drag.
Posted by: Dave_Darling Jan 25 2016, 03:51 PM
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
Posted by: mgp4591 Jan 25 2016, 05:34 PM
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...?
Posted by: SirAndy Jan 25 2016, 06:21 PM
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=&showtopic=44700&view=findpost&p=1898832
It also improved the actual cooling to the point where my engine now runs too cool in most street driving conditions.
Posted by: mgp4591 Jan 25 2016, 07:06 PM
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=&showtopic=44700&view=findpost&p=1898832
It also improved the actual cooling to the point where my engine now runs too cool in most street driving conditions.
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.
Posted by: Andyrew Jan 25 2016, 08:01 PM
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.
Posted by: mgp4591 Jan 25 2016, 08:06 PM
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.
Posted by: Chris Pincetich Jan 25 2016, 08:24 PM
You don't really need 2 side mirrors, just one on the driver's side
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
Posted by: veekry9 Jan 26 2016, 09:12 AM
ThyssenKrupp
http://forums.pelicanparts.com/off-topic-discussions/391522-random-transportation-pictures-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.
/
Posted by: Dave_Darling Jan 26 2016, 10:10 PM
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... 
--DD
Posted by: mgp4591 Jan 26 2016, 11:00 PM
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.
Posted by: Chris914n6 Jan 26 2016, 11:33 PM
If this is too racy for you, click the linky http://www.1addicts.com/forums/showthread.php?t=795049 
Posted by: veekry9 Jan 27 2016, 12:47 AM
Aerodynamics 101
https://www.google.ca/search?q=aerodynamics+101&espv=2&biw=1280&bih=641&source=lnms&tbm=isch&sa=X&ved=0ahUKEwi5pKDjnsnKAhWFsYMKHWH5DIsQ_AUIBigB#imgrc=l7N4s2WGEqWZIM%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+lakes+racer&espv=2&biw=1280&bih=641&source=lnms&tbm=isch&sa=X&ved=0ahUKEwiT0rj5scnKAhWjvIMKHbIKCicQ_AUIBigB#imgrc=uhHB8b0GeFa_sM%3A
Posted by: sixnotfour Jan 31 2016, 01:43 PM
Attached thumbnail(s)
Posted by: mgp4591 Jan 31 2016, 03:51 PM
That's the most radical 914 I've ever seen!
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...
Posted by: sixnotfour Feb 1 2016, 10:22 AM
1967 alfa romeo tipo 33 stradale
Posted by: Andyrew Feb 1 2016, 10:59 AM
My thoughts for a rear diffuser.
Posted by: veekry9 Feb 1 2016, 01:27 PM
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.
Posted by: veekry9 Feb 1 2016, 06:41 PM
https://www.youtube.com/watch?v=w_QazJD9nyI
A new production,some ideas of aero application.
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