2nd gen aero modifications

12095 Views 38 Replies 16 Participants Last post by Aus78Formula, 5 d ago

NOT A TA

Discussion Starter · Sep 1, 2015 (Edited by Moderator)

10

I've been working on some aero mods as part of my rebuild. This is a car I built and raced over 25 years then tore down for a complete frame off rebuild. I figured some of you might be interested even if you'd never do these things to your own cars.

One of the aero changes I wanted to make involves the fender vents. I'm planning on a splitter and pan under the engine compartment. So I need to evacuate the under hood air that comes through the radiator and reduce high pressure air under the hood that causes lift. Many have experienced the effect called "float" at high speeds (over normal highway speed) in regular cars and some models are worse than others. The 2nd gen TA fender vents help reduce that and I want to maximize the benefit.

So I began by doing some tuft testing on the stock vent with the screen removed to see how it performed. Then I made cardboard modifications to the vents and tested again. I spent more than a day on this process testing various configurations and came up with a couple modified vents that should help keep the air pressure lower under the hood.

The stock TA vent has a hole with surface area about 15 sq. in. The screen in the stock vent blocks off about 5 sq.in. reducing it to 10 sq. in. and creates turbulence as the air tries to exit through it. As I went through the testing process I changed the angle of the leading edge, added wicker bills of varying heights and expanded the opening. The modified vents now have openings about 3 times the sq. in. with steeper leading edge and the design of the housings seem to draw a lot more air from under hood. One set will be used for Land Speed racing type events (less drag) and the one with the wicker at the leading edge will be for road course use (more drag but also more evacuation).

As I mentioned it was a long process and lots of variations were tuft tested. Here's a few pics to show a couple of the differences.

Stock vent with screen removed.

Modified vent below with steeper leading angle and stock opening.

Modified vent with wicker and extra slot opening below.

This version seemed to get the best results for evacuation with reduced turbulence. But it wasn't enough "better" to warrant all the extra effort I'd have to put in to incorporate strakes into my design.

Here are the designs I came up with and made. Will tuft test in the real world once the car is back on track. Top pic below is process. Then stock vent, LSR vent, and track vent.

Barefoot%20and%20Track%20Jack%20vents%20

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Mark White

· #21 · Oct 7, 2015 (Edited by Moderator)

I have a Question for the Teacher...

John,

Is it possible with all the heat build up...I mean you thought this through because of it ....

Ok is it possible that the duct connection at the disk (new Cover Fabricated) may have a higher than normal Temperature, and if so, have you wondered if when you are running through the paces on a track.

That the duct hose will melt that close to the actual rotor?

I think what you do is way above ordinary for sure..I hope this all works out for you I know you will tweak it in there.

I was just looking and thought wow, thats gonna be a lot of heat since I warped a set on a Yamaha YZFR 1000 and I got burnt once trying to flick something off a disk, so naturally I thought next I hope the tubes dont melt...

Great news is...Home depot (now I sound like a commercial)..lol Has your Butt ever really itched at Night? if so stand up, and Scratch..lol

Ok Home Depot sells Metal in 3 and 4 and 6 inch sizes maybe a 2" is also available...

Anyhow Best of Luck as I sit in bewilderment...

Mark

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NOT A TA

Discussion Starter · #22 · Oct 8, 2015

Brownie1981 said:
They say it's toughest to lose weight once past 40 yrs old?

Luckily for me I've been the same svelte 134 lbs since high School, well maybe not so svelte anymore...... BUT, I can run almost anybody's car at the drag strip and go faster than they can in their own car! ahahaha

NOT A TA

Discussion Starter · #23 · Oct 8, 2015

Mark White said:
I have a Question for the Teacher...

John,

Is it possible with all the heat build up...I mean you thought this through because of it ....

Ok is it possible that the duct connection at the disk (new Cover Fabricated) may have a higher than normal Temperature, and if so, have you wondered if when you are running through the paces on a track.

That the duct hose will melt that close to the actual rotor?

Yes there's a lot of heat there. My old setup used to get the wheels so hot the Firebird emblems in the canter caps would melt and deform if I left them in place on track. The hoses I'm using are 300 degree duct tubing sold specifically for brake ducts. The backing plates are aluminum so they'll dissipate heat quicker than if they were steel.

I think what you do is way above ordinary for sure..I hope this all works out for you I know you will tweak it in there.

I was just looking and thought wow, thats gonna be a lot of heat since I warped a set on a Yamaha YZFR 1000 and I got burnt once trying to flick something off a disk, so naturally I thought next I hope the tubes dont melt...

Great news is...Home depot (now I sound like a commercial)..lol Has your Butt ever really itched at Night? if so stand up, and Scratch..lol

Ok Home Depot sells Metal in 3 and 4 and 6 inch sizes maybe a 2" is also available...

I did look around at the Depot for HVAC and dryer duct pieces that would be suitable for modificationto use where the hose connects to the backing plates but didn't find anything I liked.

Anyhow Best of Luck as I sit in bewilderment... More coming soon! Next post is going to be either cowl vent block off seal or inner fender seals. Both are done, just need to write them up.

Mark

NOT A TA

Discussion Starter · #24 · Oct 8, 2015

4

Cowl vent write up won out!

I wanted to seal off the openings on the top of the cowl where fresh air enters. This will increase air pressure on the top of the cowl so I'll get more down force in conjunction with a new hood to cowl seal which will be installed after final paint. I decided to use a reproduction screen I already had and modify it to seal off the openings. I used 3/32 EPDM rubber sheet and it's held in place with # 10 - 5/8"Phillips pan head screws and nylock nuts with 3/16" body washers to spread out the clamping force. The higher the air pressure, the tighter the seal will be. The car very rarely ever gets wet so I'm not concerned too much with drainage but if I'm on a trip and it rains I'll just pop the screen out.

Here's the pics!

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pauls428

· #25 · Oct 8, 2015

Should have looked at this before I posted a separate topic awesome work

NOT A TA

Discussion Starter · #26 · Oct 8, 2015

pauls428 said:
Should have looked at this before I posted a separate topic awesome work

Thanks Paul ! You have a PM

Josh77TA

· #27 · Oct 12, 2015 (Edited by Moderator)

Hi john , impressive work , you have got me worried about my complete aero setup on my 77 ta race car , in regards to front end airflow !
Look forward to seeing more of your work

NOT A TA

Discussion Starter · #28 · Oct 12, 2015

5

Josh77TA said:
Hi john , impressive work , you have got me worried about my complete aero setup on my 77 ta race car , in regards to front end airflow !
Look forward to seeing more of your work

Thanks Josh! I'd like to see more of what you're building there. Looks very cool!

Continuing my efforts to manage under hood airflow and pressure I wanted to seal off the inner fender wells above the frame. The stock inner fenders have a factory installed "splash shield" which helps separate the air in the inner fender from the engine compartment. I wanted to take that a step farther. So I made up some patterns and used 1/8" EPDM rubber sheet to more effective seals. I'm going to be running the modified stock upper control arms for a while after reassembly but plan on eventually switching to upper and lower arms that will allow more positive castor and negative camber so I'll need to reconfigure the seals. With that inn mind I'll be using threaded hardware to hold the seals during assembly after paint now but may use pop rivets to save a little weight when the tubular arms are installed.

Stock splash guard in pic below. Note the gaps to the inner fender well not only around the control arm but also where there was no stock shield between frame and inner fender.

Pics below show pattern making and the new seals in place.

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Josh77TA

· #29 · Oct 12, 2015

Great work ! I feel I have over looked this effect on my 77 ever post I read , very impressive John , I'm defiantly into your extended guard vents !
Great work

cajun

· #30 · Oct 13, 2015

Looking good John.

NOT A TA

Discussion Starter · #31 · Oct 17, 2015 (Edited by Moderator)

7

I finished up mounting the core support seals.

The core support of the early 2nd gens had a lot of gaps on the sides and top as well as large openings for the bumper supports to pass through it. I wanted to seal these areas off to keep the air out which should reduce under hood air pressure and increase the difference in pressure in front/back of the radiator which will help the radiator be most efficient.

Now those of you with early 2nd's might go look at the car and think pffft there's only an inch gap here and there and the holes for the bumper supports. However even though they're not directly open to the front of the car the cavity between the core support and the bumper/splash pan is one of (if not the) highest air pressure areas on the car. So the air is trying to get past the core support through the gaps as fast as it can. This is the same principal of why the brake cooling duct openings are placed in the core support rather than on the splash pan.

So how big are the gaps really? I added them all up, then recalculated thinking I must be wrong but no.... Imagine a hole this big in the core support letting air in!

The bottom of the core support is bolted tight to the lower edge of the splash pan sealing it. So the sides, top, and bumper openings are where I needed seals. To seal the sides and bumper holes I used 3/32 EPDM rubber sheet and pop riveted it in place. 3/16" aluminum rivets with 3/16" body washers.

To seal the top of the core support I used the same rubber but with plastic push pin fasteners for a more finished factory look. All of the seals will become tighter as air pressure increases forward of the core support with speed.

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Poncho400

· #32 · 8 mo ago

The fender vents were one offs? Never planned to market?

tommy vercetti

· #33 · 8 mo ago

this is one cool thread, rereading this again. thanks for sharing

mob_seven

· #34 · 6 d ago

So is there a thread where I can see all of your cool aero stuff done. Super cool thread and rad engineering work!

Aus78Formula

· #35 · 5 d ago

Look up Not a TA threads on many forums. John passed away.

mob_seven

· #36 · 5 d ago

Boy

Aus78Formula said:
Look up Not a TA threads on many forums. John passed away.

boy am I sorry to hear that. Was this recent? I feel like I’ve followed so many of his threads before I joined this last year.

Aus78Formula

· #37 · 5 d ago

RIP John Paige (NOT A TA)

Hello, I know this will be some news for the long-time car forum community. I searched some forums I frequent and see that no one has posted this. I just went to tag my friend John Paige on a Facebook post and ended up finding out he passed away in December. Where do I start with...

www.pro-touring.com

sleepyhollowtaman

· #38 · 5 d ago

sea dog said:
Can't wait to see the real world driving tests.

I second that!

Aus78Formula

· #39 · 5 d ago

And clearly not going to occur.

21 - 39 of 39 Posts