Custom Splitter on a CDC Classic Chin Spoiler

[FR500GT]

I don't know how I missed this thread. A lot of good info in here

 

[zquez]

Does the 2010+ styles vented under engine cover fit 05-09s? Part #???

yep. Gmitch's car is a 05-09. Don't know the part number, but if you look up radiator support splash shield on Tousleyfordparts.com you'll find it.

 

[o2sys]

Damn its $130 piece....

 

[Department Of Boost]

Damn its $130 piece....

Which would make it about the least expensive thing I ever put on my car. LOL!

But you need more than just that one section. Check out this thread. This was when I had a GT nose on the car:

http://www.allfordmustangs.com/foru...10-front-diffuser-installed-good-results.html

 

[o2sys]

I'm still baffled of how much of no underpanels exist under my car!

Especially on the front bumper, all cars I've own had to remove at least 2 to 3 panels before even accessing the oil pan!

 

[Department Of Boost]

I'm still baffled of how much of no underpanels exist under my car!

Especially on the front bumper, all cars I've own had to remove at least 2 to 3 panels before even accessing the oil pan!

The 2010+ cars have a panel under the front. It's probably a safe bet there isn't more because of cost. Don't forget the Mustang is a price point car. My friends Aston Martin has panels front to back. It looks like a toy from the bottom. And he paid for them too.

 

[o2sys]

Do you have a full under car shot of your car gmtich? Does the 10+ panel fit to stock mounting locations?

 

[Department Of Boost]

Do you have a full under car shot of your car gmtich?

Below.

Does the 10+ panel fit to stock mounting locations?

Kinda, check out the link I posted above.

And were doing another diffuser (been busy and not driving the car) just like this one which is on 908SSP's car.

 

[o2sys]

I think the part #'s for the front is BR3Z17626B and the Vented is BR3Z6C038A

 

[kona302]

Below.


Kinda, check out the link I posted above.

And were doing another diffuser (been busy and not driving the car) just like this one which is on 908SSP's car.

Needs a repost, This is so beautiful!
It looks like a blown diffuser?

 

[robz]

Nope.

 

[Pentalab]

What's the purpose of the strakes on the rear lower diffuser ??

 

[robz]

To smooth out the airflow.

 

[zquez]

What's the purpose of the strakes on the rear lower diffuser ??

Air entering under the front of the vehicle is low pressure fast moving air. As it passes under the vehicle, it slows down and increases pressure at the same time. A diffuser, and in particular the strakes, not only smooths out the turbulent airflow as it re-enters the ambient air stream but also serves as an expansion chamber. It converts high pressure air to low pressure air that sucks even more air out from under the car, thus producing downforce while also decreasing drag.

 

[frank s]

I can't find Strakes-R-Us in the Yellow Pages.

 

[Pentalab]

Air entering under the front of the vehicle is low pressure fast moving air. As it passes under the vehicle, it slows down and increases pressure at the same time. A diffuser, and in particular the strakes, not only smooths out the turbulent airflow as it re-enters the ambient air stream but also serves as an expansion chamber. It converts high pressure air to low pressure air that sucks even more air out from under the car, thus producing downforce while also decreasing drag.

OK. I take it that various angles have been tried with the main diffuser ?
How many strakes are required ? What is optimum. How much down force can be achieved ? Impact pressure increases to the square of the velocity. If I have it correct, any down force would be quadruple @ 100 mph...VS 50 mph.

How low can you hang any front splitter ? If you had it low enough, you could reduce airflow entering below the car. On paper, that should also increase down force.

 

[Whiskey11]

Air entering under the front of the vehicle is low pressure fast moving air. As it passes under the vehicle, it slows down and increases pressure at the same time. A diffuser, and in particular the strakes, not only smooths out the turbulent airflow as it re-enters the ambient air stream but also serves as an expansion chamber. It converts high pressure air to low pressure air that sucks even more air out from under the car, thus producing downforce while also decreasing drag.

To be more specific, the strakes channel the air and prevent air from entering the channelized air from odd angles (which keeps the air smoother). There are a number of things that make diffusers work better and strake length is one of them. The closer the strakes are to the road surface the more effective they are. The number only matters in the sense that there needs to be enough to keep the air flowing correctly. Something that is almost impossible to really conceptualize without using some form of model and an actual aerodynamics test, either virtually or physically.

I would argue that a diffuser actually doesn't produce downforce so much as it reduces lift associated with airflow under the car. It's best to think of a car as a really screwed up airplane wing profile. The bottom surface of an aircraft wing is usually flatter than the profile of the top. The idea is that by forcing air to take the "longer" distance over the top, it must also move faster. The faster air produces less pressure and the desire of air to move from high to low pressure creates lift. A car is very much the same only the profile is not an ideal profile for lifting. Air still has to move faster over the top than the bottom so a car will always produce some lift at speed. By speeding up the air under the car you are getting closer to equalizing the pressure above and below the car, so in reality you are reducing lift rather than producing downforce. The end result is the same though, more grip!

I used to have the .pdf files from Racecar-Engineering for the whole "Aero" package for cars and the diffuser section and splitter section was HUGE and extremely enlightening but unfortunately I can't find them anymore.

When it came to design, for most street cars with a diffuser that wasn't humping the ground, I remember reading the angle should be around 7º although that number was also stated to be highly dependent on other variables. Where space allowed, higher numbers with strakes closer to the ground resulted in more downforce so long as the diffuser didn't stall out.

As for how low you can hang a splitter? Well, you can hang it so it is barely off the ground but at that point you are creating an airdamn. An airdamn would make a diffuser largely worthless as an airdamn's sole goal is to remove the underside of the car as a viable place for air to go. A diffuser REQUIRES air flow to work. There is obviously a huge balancing act between splitter height and diffuser size/angle/strakes, etc. While one would think the best thing you could do would be to build an airdamn, keep in mind that there are components under the car that are cooled by airflow. Your exhaust and the rear axle coming to mind. You could certainly pipe a rear axle cooler to some other air source, but airflow over the axle does help keep things cooler without routing that nasty diff fluid through the trunk space or passenger compartment.

The other thing not thought about is the sides of the car. A diffuser works better when there are side airdamns preventing air from coming under the car from the sides.

 

[Department Of Boost]

To be more specific, the strakes channel the air and prevent air from entering the channelized air from odd angles (which keeps the air smoother). There are a number of things that make diffusers work better and strake length is one of them. The closer the strakes are to the road surface the more effective they are. The number only matters in the sense that there needs to be enough to keep the air flowing correctly. Something that is almost impossible to really conceptualize without using some form of model and an actual aerodynamics test, either virtually or physically.

I would argue that a diffuser actually doesn't produce downforce so much as it reduces lift associated with airflow under the car. It's best to think of a car as a really screwed up airplane wing profile. The bottom surface of an aircraft wing is usually flatter than the profile of the top. The idea is that by forcing air to take the "longer" distance over the top, it must also move faster. The faster air produces less pressure and the desire of air to move from high to low pressure creates lift. A car is very much the same only the profile is not an ideal profile for lifting. Air still has to move faster over the top than the bottom so a car will always produce some lift at speed. By speeding up the air under the car you are getting closer to equalizing the pressure above and below the car, so in reality you are reducing lift rather than producing downforce. The end result is the same though, more grip!

I used to have the .pdf files from Racecar-Engineering for the whole "Aero" package for cars and the diffuser section and splitter section was HUGE and extremely enlightening but unfortunately I can't find them anymore.

When it came to design, for most street cars with a diffuser that wasn't humping the ground, I remember reading the angle should be around 7º although that number was also stated to be highly dependent on other variables. Where space allowed, higher numbers with strakes closer to the ground resulted in more downforce so long as the diffuser didn't stall out.

As for how low you can hang a splitter? Well, you can hang it so it is barely off the ground but at that point you are creating an airdamn. An airdamn would make a diffuser largely worthless as an airdamn's sole goal is to remove the underside of the car as a viable place for air to go. A diffuser REQUIRES air flow to work. There is obviously a huge balancing act between splitter height and diffuser size/angle/strakes, etc. While one would think the best thing you could do would be to build an airdamn, keep in mind that there are components under the car that are cooled by airflow. Your exhaust and the rear axle coming to mind. You could certainly pipe a rear axle cooler to some other air source, but airflow over the axle does help keep things cooler without routing that nasty diff fluid through the trunk space or passenger compartment.

The other thing not thought about is the sides of the car. A diffuser works better when there are side airdamns preventing air from coming under the car from the sides.

All this^^^^^^^^^^^^^

The diffuser in the pic above is at 7deg.

 

[2Fass240us]

subscribed

I am going to take my differential pressure gauge to Roebling and get my friend/instructor to take some highway readings for me. The old fashion kind, with pen and paper. Ain't Nobody Got Money Fo a datalogger.

 

[zquez]

subscribed

I am going to take my differential pressure gauge to Roebling and get my friend/instructor to take some highway readings for me. The old fashion kind, with pen and paper. Ain't Nobody Got Money Fo a datalogger.

haha I'm this close to buying an AIM MXL.