Aerodynamics discussion

[djliquidsteele]

You had just said to PM you about how to properly cool things when creating a flat bottom on this car. I think the discussion is relevant to this thread.

[plucas]

Originally Posted by djliquidsteele

You had just said to PM you about how to properly cool things when creating a flat bottom on this car. I think the discussion is relevant to this thread.

Gotcha, didn't catch that

[OrbitalEllipses]

Well that settles that...

[ame="http://www.youtube.com/watch?v=T53E3xVQR0M"]Borla R&D - Exhaust Diffuser R&D - 2013 Scion FR-S - YouTube[/ame]
@ayau Check it Aran...

[ayau]

Originally Posted by OrbitalEllipses

Well that settles that...

@ayau Check it Aran...

[Shankenstein]

Let's analyze this. With the diffuser:
- pressure appears to be higher
- turbulence appears to be lower
- flow separation occurs much higher

To me, that says the diffuser is making some real gains.

I'm still confused by the center strip. Above the reverse light, it looks very laminar. Below the reverse light, it's low pressure and lots of turbulence. Is this due to the "tunnel" or reflection off the diffuser vanes? Not sure.

[ayau]

Originally Posted by Shankenstein

Let's analyze this. With the diffuser:
- pressure appears to be higher
- turbulence appears to be lower
- flow separation occurs much higher

To me, that says the diffuser is making some real gains.

I'm still confused by the center strip. Above the reverse light, it looks very laminar. Below the reverse light, it's low pressure and lots of turbulence. Is this due to the "tunnel" or reflection off the diffuser vanes? Not sure.

The test is missing OEM exhaust without diffuser (100% stock). We're not sure how turbulent that Borla exhaust is.

[LeeMaster]

Originally Posted by OrbitalEllipses

Well that settles that...

@ayau Check it Aran...

Wow, I am going to test this method on the factory rear diffuser to see if the papers are still blowing inside or outside.

[Ro_Ja]

Originally Posted by ayau

The test is missing OEM exhaust without diffuser (100% stock). We're not sure how turbulent that Borla exhaust is.

Exactly. There's no baseline.

[OrbitalEllipses]

Originally Posted by Ro_Ja

Exactly. There's no baseline.

Once we establish how much aero we lose it will become apparent whether this is a necessary mod or not. Either way, I'm already speaking to people who can make things happen. It's obvious we lose something by moving to an aftermarket exhaust, you can feel it. If we gain more back by doing this? Well, consider me excite!

[jamal]

Originally Posted by OrbitalEllipses

Well that settles that...

@ayau Check it Aran...

What does it settle? The back of the car is an area of flow separation (even if you had a well designed under body panel, diffuser, and rear wing, which that car does not have). The pieces of paper are going in all sorts of different directions, and if there was downforce to push them up all it would take is a pressure differential of 0.00001 to do it. That is completely worthless.

Without a muffler, if you cut out the entire black section of the rear bumper and then put a flat diffuser in it would help a little. If all you are doing is changing the muffler or putting in a short flat panel, it's not doing jack shit.

[ayau]

Wonder what pressure difference the Griffon 86 makes.

[OrbitalEllipses]

Originally Posted by jamal

What does it settle? The back of the car is an area of flow separation (even if you had a well designed under body panel, diffuser, and rear wing, which that car does not have). The pieces of paper are going in all sorts of different directions, and if there was downforce to push them up all it would take is a pressure differential of 0.00001 to do it. That is completely worthless.

Without a muffler, if you cut out the entire black section of the rear bumper and then put a flat diffuser in it would help a little. If all you are doing is changing the muffler or putting in a short flat panel, it's not doing jack shit.

I understand where you're coming from; what we were shown was super basic and there was definitely science lacking. I consider it POC for those who said the stock muffler AIDED aero is all.

I don't buy pieces that don't have engineering...when a solution comes out with some science behind it, I'll look into it.

Originally Posted by ayau

Wonder what pressure difference the Griffon 86 makes.

[IMG ]http://www.ft86club.com/forums/attachment.php?attachmentid=24057&d=1356969617[/IMG]

The car is probably entirely flat bottomed.

[LeeMaster]

Corny question: Does anyone think poking holes on the fender trim would help remove hot air out of the engine bay faster?

Second question: I know this 'functional' roof spoiler has helped the Lancer Evo IX MR by generating extra downforce to the spoiler. I was wondering, how effective will this thing be on a factory BRZ spoiler or will we have to find a big aftermarket wing like the Tommy Kaira to make this roof spoiler effective?

[serialk11r]

Originally Posted by ayau

Wonder what pressure difference the Griffon 86 makes.

It's curving up WAY too fast at the end, that is very far from an ideal design. Expect little improvement if any.

Originally Posted by LeeMaster

Corny question: Does anyone think poking holes on the fender trim would help remove hot air out of the engine bay faster?

Second question: I know this 'functional' roof spoiler has helped the Lancer Evo IX MR by generating extra downforce to the spoiler. I was wondering, how effective will this thing be on a factory BRZ spoiler or will we have to find a big aftermarket wing like the Tommy Kaira to make this roof spoiler effective?

First of all, learn your terminology, that's not a spoiler, it's a row of vortex generators. It would be useless on this car because the stock spoiler is near the "ideal" position and airflow is mostly attached on the back glass.