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Aero mods??


petawawarace
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So we got our new to us Champcar (07 Cobalt SS) out for its first test.  Things went pretty well and we are happy with it.  It’s decently quick and ran 95C on a 38C day.    Now we are looking to make some improvements.  Our stint length may be shorter than hoped, but adding a fuel cell and surge tank should get us close to 1:45 at Calabogie.  
 

Im going to start looking at aero mods to help it get through the air a bit better as it’s a decently large car.  Looking for some opinions on weather these things are a good place to start, and if there’s anything else we should do.  
 

1. ducting to the rad.  There’s nothing there now.  About 10” of open space between the grill and rad.   
 

2. remove fan shroud.  It blocks about 1/2 the rad. I’m thinking just a fan mounted to the rad.  
 

3. ventilate the hood to help get the air out from the engine compartment. 
 

4. “tuck”,  cut,  fold etc to the fenders behind the front wheels to help get air out of the engine compartment.  
 

5. Lexan at the front of the side windows. The Cobalt has really big doors and windows.  
 

any other ideas for making it more slippery?   The balance of the car is fairly good, so for now just looking to make it faster.  

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Just remember less drag does not reduce fuel use if you are still driving 100% throttle to the brake zones, just a faster speed and lap times.  

For the rad, make sure any air into the bumper grill is efficiently routed though the rad then fully ducted out the the hood. 
Folding the back side of fenders is a good as the low pressure zone behind the tire will help pull air out from under the car.

Additional things to consider,
Diffuser and flat floor
Side skirts with front air dam.
The lower 3-9 o-clock frontal area of the tires if they are wider then factory might be causing large amounts of tire squirt and drag. 
 

Edited by dwendel
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We are low power(relative to Cd) but aero creating downforce/reducing lift makes us faster overall. 

How many points do you have?

Points:
1. Splitter/Airdam(Cover front wheel) & Wing  - The splitter/airdam will reduce drag as well.
2. Flat Floor - Downforce and drag reduction.  (Managing heat is a mo-fo)

Free:
1. Vent Hood (Reduces Lift, find low pressure areas)
2. Make sure OEM under-trays are in place if relevant.
3. Vent front fenders
4. Add Side Wing Windows
5. Remove mirrors
6. Remove Wipers
7. Tape Cowl
8. Radiator Ducting (In not out)

Depending on goals you hit a point where its "not worth it".  We've been continuously making modifications to our package because we want to win every single race, but aero can be a big PITA.  When balancing the "fun" of the weekend, keep in mind how much more work you can be creating for yourself.  Our experience with the floor floor is minimal but it completely changed the way the car handled.  We had to add negative rake to get the car back into balance at Road Atlanta.  We scheduled a test day before the Gingerman test day just to get more time to dial in the balance from with this one aero change.  Most other races we spend the bulk of the test-day to dial in the aero balance.  Its a lot of work.
 

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Biggest thing that I have heard (and did) is to "hide" the tires.

 

Make sure air doesn't hit a spinning tire.  Very draggy.

 

Also, get spot mirrors and move them onboard as far as you can.

 

Only let air in the front of the car where you want it.  Block off, divert, etc any other passageways (including under the car)

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Thanks guys.  
 

We don’t currently have any points to play with.  So the free ones are the only ones we will do for now.  
 

The car does have a small splitter from the factory but there’s nothing behind it connecting the splitter to the lower rad support. I think there may be a factory piece that goes in there, but I’ll need to investigate.  
 

One of you mentioned taping the cowl. I’ve removed the plastic and rubber pieces where the hood meets the windshield and there is now a good 2” gap there.  Would this not help get some air out from under the hood? Am I missing something here? 
 

I do have to roll the fenders out as we have spacers installed and the tires do stick out.  I hadn’t thought of the tires sticking out creating that much drag, but they will for sure. That’s easy enough to correct.  
 

 

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7 hours ago, LuckyKid said:

We are low power(relative to Cd) but aero creating downforce/reducing lift makes us faster overall. 

How many points do you have?

Points:
1. Splitter/Airdam(Cover front wheel) & Wing  - The splitter/airdam will reduce drag as well.   30 points
2. Flat Floor - Downforce and drag reduction.  (Managing heat is a mo-fo)

Free:
1. Vent Hood (Reduces Lift, find low pressure areas)   not free it you use bought vents


 

 

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Just some advice on aero (we don't run any). Be very careful who you listen to and probably spend some time looking at race-winning cars in the paddock. 

I suspect a TON of teams are wasting money and points on stuff that doesn't work because they don't know what they're doing. Others have done quite well and make cars that seemingly work very well. There were a few well set up Miatas at COTA and PB definitely does a ton of testing and data collection. GWR and Huggy have done well with E30's. 

Good luck, welcome to the series. 

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16 minutes ago, Snorman said:

Just some advice on aero (we don't run any). Be very careful who you listen to and probably spend some time looking at race-winning cars in the paddock. 

I suspect a TON of teams are wasting money and points on stuff that doesn't work because they don't know what they're doing. Others have done quite well and make cars that seemingly work very well. There were a few well set up Miatas at COTA and PB definitely does a ton of testing and data collection. GWR and Huggy have done well with E30's. 

Good luck, welcome to the series. 

Thanks for the advice.  I have a full data system in the car, so I will be able to test and see any changes.   We are looking to have fun and try to be as competitive as we can.  We got this car (caged and lots of good parts on it) for a steal.  Plus replacement parts are dirt cheap.  Just bought a 35k motor for $350CAD.   That’s like $200USD.  
 

The 13 Gal fuel tank will likely be our weak point, but it is what it is.  

Edited by petawawarace
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