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OEM bumber vs airdam


turbogrill

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Hi,

 

1.

What is the difference between "race" aidram and a OEM style bumper on a lowered car and radiator opening closed? The purpose it to make sure air hits the front?

Seems like almost the same thing:

 

ncfront.jpeg.8670be8795f8b419edeb2176a5deed40.jpeg

 

If you close the radiator opening and the fog light opening and lower the car it would be a pretty decent airdam?

 

2.

Ducting before the radiator is no points, so I can cover the meshed radiator opening for free? (I rather  use some plain abs plastic than buy an old dash and start rip pieces from)

 

 

 

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Here is some Cfd on the matter.

 

https://www.verus-engineering.com/blog/cfd-cases-4/air-dam-or-splitter-a-closer-look-12

 

The full air dam reduces drag and significantly increases downforce.

 

It's likely a large number of impacts on the car, The main one I see is that it makes the car seem longer to the air by moving the high pressure zone forward. The longer the profile the better typically. It's also increasing high pressure zone on top of the windshield, make sure you fully tape between the hood and your windshield.

 

 

 

 

 

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1 hour ago, LuckyKid said:

Here is some Cfd on the matter.

 

https://www.verus-engineering.com/blog/cfd-cases-4/air-dam-or-splitter-a-closer-look-12

 

The full air dam reduces drag and significantly increases downforce.

 

It's likely a large number of impacts on the car, The main one I see is that it makes the car seem longer to the air by moving the high pressure zone forward. The longer the profile the better typically. It's also increasing high pressure zone on top of the windshield, make sure you fully tape between the hood and your windshield.

 

 

 

 

 

 

That is a very interesting article! thank you

 

The difference in downforce between Case3 (small airdam, no spliter) and Case5 (large airdam, nosplitter) is huge. Both are 2in from the ground. Why?

From the  center both small and large airdam blocks the same amount? Or is it that the large is completely vertical but the small is angled into the car? At the side the large airdam covers more, is that the difference?

 

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We tested an air dam on my first ChampCar build, a Z32. It didn't do anything to vmax or lap times, so we took it off. That car was very low however. I've been meaning to test some cardboard on our NC.

 

You can absolutely run an air dam without a splitter, but running a splitter without an air dam is a really bad idea since air gets in between the splitter and bumper.

 

I would take all CFD models which haven't been backed up by real-world results with a grain of salt. Most of the random CFD models I see online produce data which is demonstrable false or at least contradicts other models.

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58 minutes ago, turbogrill said:

 

That is a very interesting article! thank you

 

The difference in downforce between Case3 (small airdam, no spliter) and Case5 (large airdam, nosplitter) is huge. Both are 2in from the ground. Why?

From the  center both small and large airdam blocks the same amount? Or is it that the large is completely vertical but the small is angled into the car? At the side the large airdam covers more, is that the difference?

 

As I mentioned, it's likely a lot of things accumulating. But moving the high pressure center forward like they helps as it expands the effective profile of the car. What's more with the normal bumper you're building up high pressure area between the ground and the front bumper that's effective lifting it into the air.

Edited by LuckyKid
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3 hours ago, LuckyKid said:

As I mentioned, it's likely a lot of things accumulating. But moving the high pressure center forward like they helps as it expands the effective profile of the car. What's more with the normal bumper you're building up high pressure area between the ground and the front bumper that's effective lifting it into the air.

 

So if you would move the entire front forward 3ft or something absurd that could potentially help?

 

 

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4 hours ago, Grant said:

We tested an air dam on my first ChampCar build, a Z32. It didn't do anything to vmax or lap times, so we took it off. That car was very low however. I've been meaning to test some cardboard on our NC.

 

You can absolutely run an air dam without a splitter, but running a splitter without an air dam is a really bad idea since air gets in between the splitter and bumper.

 

I would take all CFD models which haven't been backed up by real-world results with a grain of salt. Most of the random CFD models I see online produce data which is demonstrable false or at least contradicts other models.


This is the fastest NC:

image.png.18fa7a5c92ff2043a9bf57d35a9e2d68.png

 

Looks like stock bumper but with just a small airdam between the splitter and the bumper. All the NA/NB airdams are just a complete remake of the front

 

image.png.9243f3f9c7242771379f064f9b92e91a.png

 

https://motoiq.com/nc-hamr-one-extremely-fast-time-attack-miata/

 

Initial build thread, https://www.trackjunkies.org/topic/2987-nc-track-car-build/

 

edit:

@champcar plz don't use this NC to determine VPI. 

 

Edited by turbogrill
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5 hours ago, turbogrill said:

 

So if you would move the entire front forward 3ft or something absurd that could potentially help?

 

 

Or just a couple inches like in this case.

 

The NC seems much flatter from the factory vs. the NA/NB.

Edited by LuckyKid
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57 minutes ago, LuckyKid said:

Or just a couple inches like in this case.

 

The NC seems much flatter from the factory vs. the NA/NB.

 

And in terms of the radiator opening, could the grill just be taped? Just some tape over that plastic mesh. Sounds like 0pts.

For what I understand a smaller radiator opening gives more downforce? (ideally paired with hood vent).

 

thank you

Edited by turbogrill
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Yes, smaller opening is typically good for aero.  Not sure if because of decreased drag or more downforce.

 

However, keep the opening bigger and just cover with tape until the temps are where you want them.  Can always add or take tape off.  

 

Start with no tape and add tape.  It can make a very quick difference to engine temps.  1 piece of tape on our car if great.  2 is no Bueno!

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11 hours ago, wvumtnbkr said:

Yes, smaller opening is typically good for aero.  Not sure if because of decreased drag or more downforce.

 

However, keep the opening bigger and just cover with tape until the temps are where you want them.  Can always add or take tape off.  

 

Start with no tape and add tape.  It can make a very quick difference to engine temps.  1 piece of tape on our car if great.  2 is no Bueno!

 

Thanks!

 

Is that across all temps and tracks?  Or do you have to fine tune?

Sucks if a car needs to pit to remove tape because it got hotter during the day or something.

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2 hours ago, turbogrill said:

 

Thanks!

 

Is that across all temps and tracks?  Or do you have to fine tune?

Sucks if a car needs to pit to remove tape because it got hotter during the day or something.

We will fine tune throughout the day.  Typically, we start with nothing or just one strip.  1 strip if it is cold outside.

 

Add half a strip or overlap strips at the next pit stop if still too cold.

 

Basically, we want to make sure we are between about 170 and 210f in our car.  Colder than 170 and the ecu does funny things with enrichment.

 

Don't go buck wild and cover half the opening on your pit stop.  Just add a bit and see what that does to your temps.  After testing and doing a few races, you will have some idea what you need.

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I would like to point out that this is something we do if we have literally nothing else to do.  If balance of the car is wrong, or we have some quick maintenance to do, we don't touch the grill opening (as long as it's within that 170 to 210 range).

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1 hour ago, wvumtnbkr said:

We will fine tune throughout the day.  Typically, we start with nothing or just one strip.  1 strip if it is cold outside.

 

Add half a strip or overlap strips at the next pit stop if still too cold.

 

Basically, we want to make sure we are between about 170 and 210f in our car.  Colder than 170 and the ecu does funny things with enrichment.

 

Don't go buck wild and cover half the opening on your pit stop.  Just add a bit and see what that does to your temps.  After testing and doing a few races, you will have some idea what you need.

Are you running a thermostat?

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