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  1. #381
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    How effective are the stock rear wraparound spoiler and side skirts from the late-80's Pontiac Trans-Am? I'm planning some high-speed work with my 92 Formula and was thinking of adding those skirts, but would make my own if they are not effective.



    The white car in the photos is mine. Front airdam has since been extended rearward to the wheelwell openings. It's still a bottom-breather so the airdam design is different than most.

    The wraparound spoiler apparently is preferred by LSR guys so may be OK as-is. Any recommendations?
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    70 GTO - 406/200-4R


  2. #382
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    what airflow looks like on a wing with a gurney flap:

  3. #383
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    With new aero kits in Indycar I really looked forward to buying a paddock pass to the Iowa race and as usual wasn't disappointed. I love walking the garage area just seeing what details I notice and what I can figure out. As you look the cars over it becomes obvious just how much effort is put into making the air work for the car at every possible point on the car.

    These are over my head, though. These multi-element front wings don't seem to have much of a "wing" profile to them. Venting air into the turbulent air in front of the wheels doesn't make a lot of sense to me. The curved shape in front view doesn't look like it would generate downforce along much of its length. I don't know what the "tunnels" out on the ends accomplish.

    What's going on here?Name:  2015 Honda wings on racks.jpg
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    Cars are meant to be driven.

    John B

  4. #384
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    I am not sure with the current aero tweaks used on top level formula cars, much any longer can be diluted down to our production cars. I believe we can safely assume every single appendage pictured has a reason, a purpose, and positive advantage, on that car, at that point in space, at that track, for that driver, with that engine package, and in con junction with every other aero device on the car, at that time. It is fun/challenging to ponder, but I also suspect those aero parts that are left in the open, uncovered from being pictured at length, aren't that great of a solution in the first place. To answer your question, I suspect having multiple wing elements, that need under element air flow, has a greater positive effect then the downside of dumping air in the very turbulent area in front of the tire, if I understand your question correctly. I personally don't favor the look of silly little band aid aero devices positioned all over the current cars.They may work very well, but have no sex appeal for me.

  5. #385
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    Quote Originally Posted by j-c-c View Post
    I am not sure with the current aero tweaks used on top level formula cars, much any longer can be diluted down to our production cars. I believe we can safely assume every single appendage pictured has a reason, a purpose, and positive advantage, on that car, at that point in space, at that track, for that driver, with that engine package, and in con junction with every other aero device on the car, at that time. It is fun/challenging to ponder, but I also suspect those aero parts that are left in the open, uncovered from being pictured at length, aren't that great of a solution in the first place. To answer your question, I suspect having multiple wing elements, that need under element air flow, has a greater positive effect then the downside of dumping air in the very turbulent area in front of the tire, if I understand your question correctly. I personally don't favor the look of silly little band aid aero devices positioned all over the current cars.They may work very well, but have no sex appeal for me.
    Couldn't agree more.

    Feel free to chime in or ask technical questions. I am here to help where I can.

    Ron Sutton

    Ron Sutton Race Technology
    Your One Stop, Turn & Go Fast, Car Building Resource Center for Autocross, Track, Road Racing & Triple Duty Pro-Touring Cars

    Check out our 400 Page Car Building Catalog HERE

    Features: Suspension, Chassis, Cages, Brakes, Rear Ends, Engines, Transmisssions, Aero & Much, Much More!

  6. #386
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    Quote Originally Posted by Interceptor5588 View Post
    How effective are the stock rear wraparound spoiler and side skirts from the late-80's Pontiac Trans-Am? I'm planning some high-speed work with my 92 Formula and was thinking of adding those skirts, but would make my own if they are not effective.
    Very effective. What make the whole package work better ... of course ... is lowering the car.

    Feel free to chime in or ask technical questions. I am here to help where I can.

    Ron Sutton

    Ron Sutton Race Technology
    Your One Stop, Turn & Go Fast, Car Building Resource Center for Autocross, Track, Road Racing & Triple Duty Pro-Touring Cars

    Check out our 400 Page Car Building Catalog HERE

    Features: Suspension, Chassis, Cages, Brakes, Rear Ends, Engines, Transmisssions, Aero & Much, Much More!

  7. #387
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    Quote Originally Posted by Interceptor5588 View Post
    The wraparound spoiler apparently is preferred by LSR guys so may be OK as-is. Any recommendations?
    It provides modest downforce. It's OK for road racing classes requiring factory spoilers/wings.

    Looks like you're going to run some long Bonneville type runs? If that's the case, you'll need to figure out how much down force you need ... and design something with minimal drag to achieve that. That factory spoiler will be horrible for high speed runs. You'll probably pick up several MPH by taking it off.

    Feel free to chime in or ask technical questions. I am here to help where I can.

    Ron Sutton

    Ron Sutton Race Technology
    Your One Stop, Turn & Go Fast, Car Building Resource Center for Autocross, Track, Road Racing & Triple Duty Pro-Touring Cars

    Check out our 400 Page Car Building Catalog HERE

    Features: Suspension, Chassis, Cages, Brakes, Rear Ends, Engines, Transmisssions, Aero & Much, Much More!

  8. #388
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    I'm working on modifying 2nd gen Trans Am front fender air extractors in an effort to reduce lift by lowering underhood pressure. When done I expect to have 3 sets. Stock, Land Speed, and a road course set fox max downforce. GM's had a wind tunnel since the 50's and I suspect the Pontiac engineers used it when designing the 2nd gen TA with it's air dam, rear spoiler, wheel flares, etc. so I'd expect the vents work to at least some degree stock, but how well?

    The factory vents have a screen in them which reduces the area of the opening and probably creates turbulence as air tries to escape from the engine compartment. The stock opening is a little under 15 Sq. In. and the 1/16" ribs of the screen itself reduces that to about 10 Sq. In. according to my crude measurements and math. With modification I can increase the size of the opening to a minimum of 28 Sq. In. increasing the flow capability to roughly triple what the stock screened opening is and about double what the stock flow would be without screen (only considering the size of the opening). What I want to do is modify the vent housing in the hopes of drawing a much larger volume of air through the opening by both the increased size of the opening and by speeding up the air exiting.

    I realize the vents are positioned in very turbulent air with the top of the wheel arch just forward of it and air spilling over the top of the fender from the hood to the side of the car from above. Can I increase the vacuum effect by modifying the size and shape of the housing? Would a small wicker be advisable on the leading edge? Will an increased angle of the leading edge sticking out farther from the body create more vacuum? Would having the top of the housing stick out farther increase downforce as the air spilling over from the hood comes down to it? Any advantage to having the lower edge stick out as far as the top?

    I have two ideas on internal modifications that would possibly increase flow. First is simply a cone shaped piece that would attach to the vent inside the fender that would smoothly flow air into the vent opening kind of along the same idea as port matching heads/intakes. The second would be using a 6" hose that would go from the vent to the area where hot air coming through the radiator fans would blow on it. The front end of the car will be sealed up pretty well so the only air entering the engine compartment will be under the splitter, through the A arm openings, or through the radiator.

    Here's a few pics of what I'm considering (much prettier though) and the stock vent. Any comments or recommendations from anyone appreciated.








  9. #389
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    Check out the vents on the Audi LMP-1 fenders nothing fancy there just a big hole and you know they have the very best aerodynamics engineers

    http://www.racecar-engineering.com/n...943718_RCE+Edi

  10. #390
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    Quote Originally Posted by jaybee View Post
    With new aero kits in Indycar I really looked forward to buying a paddock pass to the Iowa race and as usual wasn't disappointed. I love walking the garage area just seeing what details I notice and what I can figure out. As you look the cars over it becomes obvious just how much effort is put into making the air work for the car at every possible point on the car.

    These are over my head, though. These multi-element front wings don't seem to have much of a "wing" profile to them. Venting air into the turbulent air in front of the wheels doesn't make a lot of sense to me. The curved shape in front view doesn't look like it would generate downforce along much of its length. I don't know what the "tunnels" out on the ends accomplish.

    What's going on here?
    Multi-Element wings allow one to push a wing harder without penalty.


    The air on the backside actually stays attached and still gets directed up and over the tire.

    IndyCar made Honda get rid of their end plates because the drivers are driving like it's NASCAR and it makes for a metric **** ton of debris.
    Name:  attachment.php.jpg
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    The reason the wings have the shape it does is to direct air around and over the front tires. Interestingly, it looks like they have a gurney flap that runs the width of the wing.

    http://mccabism.blogspot.co.uk/2015/...irca-2003.html

    The little humps on the underside of the wing create vorticies which help seal off the sides of the wheels and actually act as side skirts which prevent air from getting under the car.

  11. #391
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    Quote Originally Posted by Cobra 498 View Post
    Check out the vents on the Audi LMP-1 fenders nothing fancy there just a big hole and you know they have the very best aerodynamics engineers

    http://www.racecar-engineering.com/n...943718_RCE+Edi
    Those holes exist because of the rules. Before the rules were instituted, Audi used a nice louver setup.

  12. #392
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    Quote Originally Posted by NOT A TA View Post
    I'm working on modifying 2nd gen Trans Am front fender air extractors in an effort to reduce lift by lowering underhood pressure. When done I expect to have 3 sets. Stock, Land Speed, and a road course set fox max downforce. GM's had a wind tunnel since the 50's and I suspect the Pontiac engineers used it when designing the 2nd gen TA with it's air dam, rear spoiler, wheel flares, etc. so I'd expect the vents work to at least some degree stock, but how well?

    The factory vents have a screen in them which reduces the area of the opening and probably creates turbulence as air tries to escape from the engine compartment. The stock opening is a little under 15 Sq. In. and the 1/16" ribs of the screen itself reduces that to about 10 Sq. In. according to my crude measurements and math. With modification I can increase the size of the opening to a minimum of 28 Sq. In. increasing the flow capability to roughly triple what the stock screened opening is and about double what the stock flow would be without screen (only considering the size of the opening). What I want to do is modify the vent housing in the hopes of drawing a much larger volume of air through the opening by both the increased size of the opening and by speeding up the air exiting.

    I realize the vents are positioned in very turbulent air with the top of the wheel arch just forward of it and air spilling over the top of the fender from the hood to the side of the car from above. Can I increase the vacuum effect by modifying the size and shape of the housing? Would a small wicker be advisable on the leading edge? Will an increased angle of the leading edge sticking out farther from the body create more vacuum? Would having the top of the housing stick out farther increase downforce as the air spilling over from the hood comes down to it? Any advantage to having the lower edge stick out as far as the top?

    I have two ideas on internal modifications that would possibly increase flow. First is simply a cone shaped piece that would attach to the vent inside the fender that would smoothly flow air into the vent opening kind of along the same idea as port matching heads/intakes. The second would be using a 6" hose that would go from the vent to the area where hot air coming through the radiator fans would blow on it. The front end of the car will be sealed up pretty well so the only air entering the engine compartment will be under the splitter, through the A arm openings, or through the radiator.

    Here's a few pics of what I'm considering (much prettier though) and the stock vent. Any comments or recommendations from anyone appreciated.
    <snip>
    Test, test, test.

    tape a ton of small lengths of string on the hood and fender around that area and go for a drive at varying speeds. run a road course like that even. set up a go pro or something to record it and go from there.

    if there is a lot of turbulent air spilling off the hood, you will need to keep it from disturbing the airflow out of the fender wells. the string and drive method, youll be able to get a good look at it.

    a wicker could cause some nasty side effects there:


    concerning shapes to use... perhaps a revers naca duct that is shielded from the top down airflow? if you can get a hold of it.. get a manometer. you can use it to measure the pressure differentials in and out of the wheel well at that spot.

  13. #393
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    OK, I'm going to have to come clean and expose my shade tree aero tricks. I recently attended Ron Sutton's seminar in Columbus, which is how I know he is a sharp guy. I dovetailed that stop into a visit to a car show at Carlisle, PA. Decided before leaving, if I took my PU, I could actually buy some items, but had no way to secure/protect anything in the bed. The trip was approx 3200 miles a lot thru the Smokies. I have over 300K on the truck, I'm religious about check mileage, and surprisingly it hasn't changed since new. So I built what I thought was a temporary wooden sloped hatched cover. Even with the added weight (125?lbs) running typical 62-70 mph, thru the mountains, mainly highway driving, I picked up 2.1 mpg. The only other change I made was whatever fuel was available vs So Fla fuel, and an oil change and a K&N filter service before departing. In 300+K miles, I've cleaned the filter many times, and it wasn't dirty to begin with. Upon return, I taped on numerous yarn tuffs on the drivers side bed cover to see what was happening. The shade tree aspect, I had a slim buddy pf mine sit on pass door, while I drove at speed ( back road) to see all the tuffs on the sloping side. I was amazed how his partial body on the pass side effected the drivers side tuffs. A lot of attached flow it seemed. I have run a few more tanks thru the truck in Flat Fla, results slightly better. No pics, I'm waiting on my patent attorney to call back. Test, test, test.

  14. #394
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    Thanks Hellphish, it makes a lot more sense now. Yes, some of the teams ran the Gurney flaps, some didn't. Some of the teams ran "stall strips" on the sides of the rear "bumpers", some didn't. A lot of the fun was seeing which parts of the aero kits each team decided to use.

    For those who might not realize, there's no reason for any of the team owners to hide those parts. It's IRL, not F1, so the aero kits on all the Honda's and all the Chevy's are the same. The teams select the specific bits to suit their needs, but everyone gets the same selection of bits.
    Cars are meant to be driven.

    John B

  15. #395
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    Quote Originally Posted by HellPhish89 View Post
    Test, test, test.

    tape a ton of small lengths of string on the hood and fender around that area and go for a drive at varying speeds. run a road course like that even. set up a go pro or something to record it and go from there.

    if there is a lot of turbulent air spilling off the hood, you will need to keep it from disturbing the airflow out of the fender wells. the string and drive method, youll be able to get a good look at it.

    a wicker could cause some nasty side effects there:

    concerning shapes to use... perhaps a revers naca duct that is shielded from the top down airflow? if you can get a hold of it.. get a manometer. you can use it to measure the pressure differentials in and out of the wheel well at that spot.
    I planned on doing yarn tuft testing using a fan on just the fender since the car will not be moving for a while to test at speed. There's a lot of aero things I'm doing while rebuilding the car, some things like these vents will get painted when I paint the car. If they work as planned great, if not I'll use the stock piece.

  16. #396
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    Quote Originally Posted by NOT A TA View Post
    I planned on doing yarn tuft testing using a fan on just the fender since the car will not be moving for a while to test at speed. There's a lot of aero things I'm doing while rebuilding the car, some things like these vents will get painted when I paint the car. If they work as planned great, if not I'll use the stock piece.
    time for a shade tree wind tunnel lol

    actually, if you have a scale model you can use and modify to be like the car youre building... you can reliably create a scale model wind tunnel to test on..

  17. #397
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    Quote Originally Posted by HellPhish89 View Post
    time for a shade tree wind tunnel lol

    actually, if you have a scale model you can use and modify to be like the car youre building... you can reliably create a scale model wind tunnel to test on..
    I'm on it! Not sure how revealing the testing will be though with the fender vents being so small.


  18. #398
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    Quote Originally Posted by NOT A TA View Post
    I'm on it! Not sure how revealing the testing will be though with the fender vents being so small.

    this should get interesting..

    http://makezine.com/projects/model-wind-tunnel/#

  19. #399
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    you will need to figure out how you want to visualize the airflow whether by smoke or with fine string.

  20. #400
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    It was a joke dude, there will not be a Corona scale model wind tunnel. I can learn more with fans and a leaf blower on the actual pieces in less time.

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