after market diffusers need to look more aggressive

[pixelblue]

been on the fence buying a rear diffuser. honestly as nice as bmw's & icarbons diffuser are they need to look more aggressive and functional. at least the center fins need to extend a bit more to make them semi functional. it would've been really easy to extend those fins if they had thought about it early in their design process. anyway I am posting a photoshop of how one could have looked with extended fins. had to swipe someone pic to get the right angle. hope they don't mind

[BrokenVert]

a "diffuser" is useless without an undertray.


And thats where all of there companies go wrong. APR and Berk seem to be in the midst of solving that problem.

Theyre making a fron end kit, maybe they can be convinced to also make a rear?

[pixelblue]

Hope they come out with one soon. Although you're right about a real diffuser needing an under tray, icarbon could have very easily made their diffuser look better simply by extending those fins

[RaihaX]

Originally Posted by pixelblue

been on the fence buying a rear diffuser. honestly as nice as bmw's & icarbons diffuser are they need to look more aggressive and functional. at least the center fins need to extend a bit more to make them semi functional. it would've been really easy to extend those fins if they had thought about it early in their design process. anyway I am posting a photoshop of how one could have looked with extended fins. had to swipe someone pic to get the right angle. hope they don't mind

All good

[pixelblue]

Thanks man. Btw your car looks very sweet. My second best color combo!

[cooler2442]

Get 10 committed people at 700$ or so each and SleK will make you any kind of Carbon Fiber diffuser you want. That is what they told me when I asked for a new diffuser design.

[RaihaX]

Originally Posted by pixelblue

Thanks man. Btw your car looks very sweet. My second best color combo!

Thanks man appreciate it!

[pixelblue]

Originally Posted by cooler2442

Get 10 committed people at 700$ or so each and SleK will make you any kind of Carbon Fiber diffuser you want. That is what they told me when I asked for a new diffuser design.

Thanks! I have to look into this. I see they have made a nice lip too. I wonder how many people interested in the diffuser if made. Some feedback would be nice

[UsualSuspect]

Originally Posted by pixelblue

been on the fence buying a rear diffuser. honestly as nice as bmw's & icarbons diffuser are they need to look more aggressive and functional. at least the center fins need to extend a bit more to make them semi functional. it would've been really easy to extend those fins if they had thought about it early in their design process. anyway I am posting a photoshop of how one could have looked with extended fins. had to swipe someone pic to get the right angle. hope they don't mind

Yeah I agree. The RevoZport 1M Coupe Raze Kit has a sick functional looking diffuser. We need something like that for our cars.
LOOK, what do you think?

[pixelblue]

^ yup, love that! Going to contact Slek about this. Will update when I get any info

[UsualSuspect]

Originally Posted by pixelblue

^ yup, love that! Going to contact Slek about this. Will update when I get any info

Nice! This company APR makes some nice stuff too. I used to run an APR rear diffuser on my STi. BERK technology uses a modified one from APR, made to fit the 135i.

[BrokenVert]

The best diffuser is the one run by Ebolution Racewerks...have you seen the damned thing? Its awesome!

[pixelblue]

haha, crude but effective.

[135iiiiii]

Originally Posted by UsualSuspect

Yeah I agree. The RevoZport 1M Coupe Raze Kit has a sick functional looking diffuser. We need something like that for our cars.
LOOK, what do you think?

I would be in for this any day. Looks sweet, and functional

[cooler2442]

Once SleK comes out with their front lip / hood / trunk and everyone is confident about the quality and fitment, we can have them make a diffuser. They just need 10 people to be 100% committed so they can recoup the cost of the mold and they will design any type of diffuser you guys want. Only reason they haven't already decided to make one is because of all the ebay 300-400$ diffusers make them worry that people may not want to pay 700$+ for a quality piece and the E82 market is so small. But 10 people would recoup the cost of their mold + production lip to make it worth it for them to make it.

[BrokenVert]

Originally Posted by cooler2442

Once SleK comes out with their front lip / hood / trunk and everyone is confident about the quality and fitment, we can have them make a diffuser. They just need 10 people to be 100% committed so they can recoup the cost of the mold and they will design any type of diffuser you guys want. Only reason they haven't already decided to make one is because of all the ebay 300-400$ diffusers make them worry that people may not want to pay 700$+ for a quality piece and the E82 market is so small. But 10 people would recoup the cost of their mold + production lip to make it worth it for them to make it.

It depends. They need to do something different. All of the ebay diffusers, and all of the legit ones are almost straight copies of the BMW Performance one. Lets get some variety in this community.

If you actually make it functional, and can prove to me that it is, I will gladly pay $700 for one.

And I mean legit math, and if you dont want to do it send me the numbers and ill run the math.

[pixelblue]

Mat,
I am all for something different and new in design. if you have some ideas please share. as far as proving with math the functional impact of a diffuser, I am interested to know how you are planning to calculate the down force effect of a diffuser. what set of numbers did you have in mind to do your calculations?

[BrokenVert]

Originally Posted by pixelblue

Mat,
I am all for something different and new in design. if you have some ideas please share. as far as proving with math the functional impact of a diffuser, I am interested to know how you are planning to calculate the down force effect of a diffuser. what set of numbers did you have in mind to do your calculations?

Im not going to get too detailed, unless you want me too.

A simple Bernoulli and Ventouri correlation should be sufficient for this application, Ill make some assumptions based on shapes and assume the cross sectional area to be a square occupied by the top, blades, and fictional 4th wall more or less to simplify the math and to keep a roughly rectangular control volume. I can run it at a few different velocities too. Again, just rough numbers with this, but they should be good enough for now. Its not like were designing a racecar here.

If somebody wants me too I can run some Navi-Stokes calculations, but those are a lot more complicated and time consuming as I would have to modify my matlab code a lot (because its only good on wing sections currently).



Actually, its all a bit of a farce honestly, unless you redesign the entire bottom of the car it wont do so much.At that point on the car the flow is highly turbulent, as the unoptimised airflow is interacting with control arms, wheels, the exhaust pipes, etc.
That turbulent air is too uncontrolled to properly interact with the viscous layer of air on the diffuser section and undertray...basically the air is so rough that its essentially stalled once it reaches the rear of the car, thus providing no lift at all (aka no downforce).



Cliffs: Its all useless without a purpose built undertray and aero kit from the front bumper to the rear bumper. But it does look cool

Ive also wanted somebody to do a type of blown diffuser for a while honestly, I think it would be fun. Do it similar to F1 style, instead of routing the DV air back into the intake stream set up a BOV into the undercar free stream mix it with the exhaust under the car...seems like it would be fun.

[Satalite]

Originally Posted by BrokenVert

Im not going to get too detailed, unless you want me too.

A simple Bernoulli and Ventouri correlation should be sufficient for this application, Ill make some assumptions based on shapes and assume the cross sectional area to be a square occupied by the top, blades, and fictional 4th wall more or less to simplify the math and to keep a roughly rectangular control volume. I can run it at a few different velocities too. Again, just rough numbers with this, but they should be good enough for now. Its not like were designing a racecar here.

If somebody wants me too I can run some Navi-Stokes calculations, but those are a lot more complicated and time consuming as I would have to modify my matlab code a lot (because its only good on wing sections currently).

[pixelblue]

Originally Posted by BrokenVert

Im not going to get too detailed, unless you want me too.

A simple Bernoulli and Ventouri correlation should be sufficient for this application, Ill make some assumptions based on shapes and assume the cross sectional area to be a square occupied by the top, blades, and fictional 4th wall more or less to simplify the math and to keep a roughly rectangular control volume. I can run it at a few different velocities too. Again, just rough numbers with this, but they should be good enough for now. Its not like were designing a racecar here.

If somebody wants me too I can run some Navi-Stokes calculations, but those are a lot more complicated and time consuming as I would have to modify my matlab code a lot (because its only good on wing sections currently).



Actually, its all a bit of a farce honestly, unless you redesign the entire bottom of the car it wont do so much.At that point on the car the flow is highly turbulent, as the unoptimised airflow is interacting with control arms, wheels, the exhaust pipes, etc.
That turbulent air is too uncontrolled to properly interact with the viscous layer of air on the diffuser section and undertray...basically the air is so rough that its essentially stalled once it reaches the rear of the car, thus providing no lift at all (aka no downforce).



Cliffs: Its all useless without a purpose built undertray and aero kit from the front bumper to the rear bumper. But it does look cool

Ive also wanted somebody to do a type of blown diffuser for a while honestly, I think it would be fun. Do it similar to F1 style, instead of routing the DV air back into the intake stream set up a BOV into the undercar free stream mix it with the exhaust under the car...seems like it would be fun.

dayum, you gots all physics on my ass I totally agree in order to do it right you would need a whole new under tray design. I would have loved to see adjustable aero for the front and back. I can picture a rear tray possibly adjustable that extends across the bottom from say the diff to the exhaust tips with vertical fins running up to and connecting to a new valance. of course it would have been cool to design venturi's into the whole under tray from the nose to the tail but lets not carried away with this since we are working with limited budgets

btw, how do you know all this stuff? is it hobby or were you schooled in it?

[BrokenVert]

Originally Posted by pixelblue

dayum, you gots all physics on my ass I totally agree in order to do it right you would need a whole new under tray design. I would have loved to see adjustable aero for the front and back. I can picture a rear tray possibly adjustable that extends across the bottom from say the diff to the exhaust tips with vertical fins running up to and connecting to a new valance. of course it would have been cool to design venturi's into the whole under tray from the nose to the tail but lets not carried away with this since we are working with limited budgets

btw, how do you know all this stuff? is it hobby or were you schooled in it?

Ventouri ducts arent hard to design so long as you do it from the get go, those verticle fins are supposed to be part of a ventouri/ ground effects package on racecars.

Its about controlling the airflow, without a full undertay package nothing except a rear wing will give you a noticeable improvement in downforce. Although they might be better for bulk air evacuation, which would reduce the high pressure system that develops under the rear of the car at speed (I feel it bad when I go above 140ish.



And I know it because its my job. Im an aero engineer, haha. Well im almost there. Im almost done with my education, but this is easy stuff to do if you properly simplify the calculations...actually anything under about 250 knots is easy to design for, everything behaves well and predictably and you dont get localized supersonic flow like you do in transonic jets.

[pixelblue]

oh wow, had no idea you are an aero engineer. very cool. let's put some of the talent to use then what industry do you work for if you don't mind me asking?

I am going to photoshop my rear tray idea. let's see how it turns out