mounting RE rear CF diffusor w/o OEM gas tank?
08-10-04, 04:40 PM
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mounting RE rear CF diffusor w/o OEM gas tank?
Im running a full race fuel system in my car so i have eliminated the stock tank and have a 10 gal fuel cell in the trunk. I also have a Rotary Extreme CF rear diffusor. Now i havnt mounted this thing up to the stock configuration or with the fuel cell setup.
Ive seen some pictures and it looks like to me that the diffusor mounts to some brackets that come off the stock tank. Since my tank is gone, i think it would just act as a giant wing underneath the car. Resulting in less than desirable handling characteristics. I think the tank acts as a belly pan in which the diffusor mounts flush with it. With the OEM tank not in the picture, its going to be a great open hole. even if i could still make the diffusor mount up to the proper brackets... This worries me if i were to travel at any speeds above 45. lol.
To anyone that has some insight on this... Do you think i should get some aluminum sheet metal and make a custom belly pan and have it mount flush to the bottom of the diffusor? -Or- leave that gaping hole there where the tank used to be? Any other suggestions would be greatly appreciated!!! thanks
-james
Ive seen some pictures and it looks like to me that the diffusor mounts to some brackets that come off the stock tank. Since my tank is gone, i think it would just act as a giant wing underneath the car. Resulting in less than desirable handling characteristics. I think the tank acts as a belly pan in which the diffusor mounts flush with it. With the OEM tank not in the picture, its going to be a great open hole. even if i could still make the diffusor mount up to the proper brackets... This worries me if i were to travel at any speeds above 45. lol.
To anyone that has some insight on this... Do you think i should get some aluminum sheet metal and make a custom belly pan and have it mount flush to the bottom of the diffusor? -Or- leave that gaping hole there where the tank used to be? Any other suggestions would be greatly appreciated!!! thanks
-james
08-10-04, 05:04 PM
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screwed by chad hall
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well i would suggest you jack your car up and try it out...just hold the diffuser with your hands and match up the mounting holes and look to see if you are missing any mounting holes on that specific part of the diffuser...good luck and peace out
08-10-04, 05:17 PM
#3
Hooray For Boobies!!!
Black Magic: So do you really have 550 @ 0psi? Explain Please.
I am looking into picking up a diffusor sooner or later and would like to know if I need an aftermarket fuel tank. Just caught my eye and I will watch this thread.
I am looking into picking up a diffusor sooner or later and would like to know if I need an aftermarket fuel tank. Just caught my eye and I will watch this thread.
Last edited by x605p747R1; 08-10-04 at 05:19 PM.
08-10-04, 05:52 PM
#4
The concept of a diffuser is twofold: the upwards sloping angle is an attempt to minimize both drag and lift by matching the airflow above the car and below the car. The vertical slats are to prevent turbulence.
Here's more info, in case my explanation's not the best: from http://aerodyn.org/Annexes/Racing/hlifts.html:
Venturi Channels
Simple fluid dynamics says that flow that accelerates looses pressure. This is in fact the nozzle effect (or Venturi effect), when flow in a convergent nozzle accelerates and looses pressure. Pressure is then recovered in the diffuser.
By shaping the underbody as an inverted wing, or with appropriate channels, or even with a simple scant angle that work with the Venturi effect, the overall pressure between the underbody and the ground decreases.
from http://wings.avkids.com/Book/Sports/...ce_car-01.html
The ban on side skirts lead to the development of underbody channels. These channels are a type of diffuser and are sometimes referred to as venturi channels. As the flow accelerates under the car, the pressure decreases as dictated by Bernoulli's relation. This low pressure air then slows down through the channels. At the same time, air enters the channels from the side of the car. If the outer walls are close to vertical, a strong vortex will form in the channel. This vortex will keep the flow attached within the channel while helping to stabilize the flow beneath the entire vehicle. Therefore, these channels increase the downforce and decrease the drag of the vehicle.
As long as your diffuser is securely fastened, and is sealed so that air only flows on the underside of it (and not up into the area where the fuel tank used to be), it should be fine. If the Rotary Extreme diffuser is relying on the fuel tank to guide the air flow, then it sounds like you need a different diffuser setup (which would work better anyway, since it would have more length to work with). They're really simple devices, you should be able to fabricate one using aluminum. For a lot more info, check out Competiton Car Downforce , by Simon McBeath. My college library had it, it's a great read with lots of helpful illustrations. http://www.amazon.com/exec/obidos/tg...71163?v=glance
-s-
Here's more info, in case my explanation's not the best: from http://aerodyn.org/Annexes/Racing/hlifts.html:
Venturi Channels
Simple fluid dynamics says that flow that accelerates looses pressure. This is in fact the nozzle effect (or Venturi effect), when flow in a convergent nozzle accelerates and looses pressure. Pressure is then recovered in the diffuser.
By shaping the underbody as an inverted wing, or with appropriate channels, or even with a simple scant angle that work with the Venturi effect, the overall pressure between the underbody and the ground decreases.
from http://wings.avkids.com/Book/Sports/...ce_car-01.html
The ban on side skirts lead to the development of underbody channels. These channels are a type of diffuser and are sometimes referred to as venturi channels. As the flow accelerates under the car, the pressure decreases as dictated by Bernoulli's relation. This low pressure air then slows down through the channels. At the same time, air enters the channels from the side of the car. If the outer walls are close to vertical, a strong vortex will form in the channel. This vortex will keep the flow attached within the channel while helping to stabilize the flow beneath the entire vehicle. Therefore, these channels increase the downforce and decrease the drag of the vehicle.
As long as your diffuser is securely fastened, and is sealed so that air only flows on the underside of it (and not up into the area where the fuel tank used to be), it should be fine. If the Rotary Extreme diffuser is relying on the fuel tank to guide the air flow, then it sounds like you need a different diffuser setup (which would work better anyway, since it would have more length to work with). They're really simple devices, you should be able to fabricate one using aluminum. For a lot more info, check out Competiton Car Downforce , by Simon McBeath. My college library had it, it's a great read with lots of helpful illustrations. http://www.amazon.com/exec/obidos/tg...71163?v=glance
-s-
Last edited by scotty305; 08-10-04 at 05:55 PM.
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08-11-04, 12:04 AM
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:quote: Black Magic: So do you really have 550 @ 0psi? Explain Please. :quote:
--See ijneb's reply :-) The RE diffusor is meant to mount up to the stock gas tank. I have a fuel cell style gas tank (mounts in trunk instead of underneath the vehicle) because i found it more appropiate for my setup. basically my fuel system is good to 800Rwhp hands down.
:quote: As long as your diffuser is securely fastened, and is sealed so that air only flows on the underside of it (and not up into the area where the fuel tank used to be), it should be fine. :quote:
--that was exactly my thinking. If i get aluminum sheets, custom fab up a belly pan, mount it flush to the diffusor with added bracing, it should work perfect, if not better. Ive also saw a few pics where you can see it doesnt quite mount flush by any means to the gas tank. Looks like it would actually scoop air from underneath the car, which is not what i want. This is what had me kinda iffy as to how to mount it properly. Simply because i was on the thinking that maybe that person knew what the hell they were doing... guess not. thanks for the good links and info!
:quote:You forgot the nitrous bottle...:quote:
---yes he did ;-)
--See ijneb's reply :-) The RE diffusor is meant to mount up to the stock gas tank. I have a fuel cell style gas tank (mounts in trunk instead of underneath the vehicle) because i found it more appropiate for my setup. basically my fuel system is good to 800Rwhp hands down.
:quote: As long as your diffuser is securely fastened, and is sealed so that air only flows on the underside of it (and not up into the area where the fuel tank used to be), it should be fine. :quote:
--that was exactly my thinking. If i get aluminum sheets, custom fab up a belly pan, mount it flush to the diffusor with added bracing, it should work perfect, if not better. Ive also saw a few pics where you can see it doesnt quite mount flush by any means to the gas tank. Looks like it would actually scoop air from underneath the car, which is not what i want. This is what had me kinda iffy as to how to mount it properly. Simply because i was on the thinking that maybe that person knew what the hell they were doing... guess not. thanks for the good links and info!
:quote:You forgot the nitrous bottle...:quote:
---yes he did ;-)
