XKR Super G... Going for Mach 1
02-05-2009, 07:50 PM
#82
Specifically, I have discussed with Roger and Paul about moving my mufflers to the center of my rear bumper (in fact, I ceramic coated my entire exhaust system except for the rear most section where the exhaust pipes diverge. I will be cutting and re-welding those to get both mufflers and exhaust pipes as close to the centerline as possible, so I figured I would ceramic coat those parts when the modifications are done).
The goal is to form a venturi [EDIT between the middle part of the body pan and the diffuser] channels on both the left and right undersides of the car so that we can benefit from Bernoulli's principle. The idea is to speed up the air flow where you want the down force. As the air flow speeds up, the pressure decreases (in this case between the underpan where the venturi is located and the ground), thus creating downforce. The Enzo is a perfect example of this. Of course, it's structure was designed with this in mind, where our cars weren't. But I have studied the underside of our cars and I beleive we can generate alot of downforce. Maybe not as much as an Enzo, but way more than we are getting now.
EDIT: I just noticed that you were not crazy about moving the mufflers. My concept also involves moving the mufflers too. We could look at trying to create a diffuser channel between the mufflers, and we would get some downforce, but I don't think it would be as much as running two venturis, one on each side of the center section.
EDIT EDIT: I just pulled up a picture of the bottom of an Enzo. It looks to me that the majority of the downforce is happening right smack in the middle of the car. The main venturi is not fromed by the diffuser channels themselves, but the transition from the middle of the underbody to the the diffuser channels (which are raised further from the ground). Although the diffuser runners do appear to have a little bit of a venturi design, and thus may be contributing some down force, their main function appears to be reducing turbulance in the air flow as it slows when it exits from beneath the central portion of the car into the diffuser channels. Ingenious design, and good inspiration.
Last edited by ttg35fort; 02-05-2009 at 09:03 PM.
02-06-2009, 04:16 AM
#88
I am having it done at a shop here in Houston.....Its first going to be done in some form of plastic ( I am sure thats not what its called) then copied in CF.....The problem is the muffler section...
I am going to put it out there because I know you have taken your car above 180...and I was worried about you doing that with out an undertray and getting an air bubble under the car... The muffler will be relocated to the center of the car close to the transmision....The pipes will be routed through the lower part of the rear bumper at both side of the license plate. This will allow the under tray to be flatter. I want them to try to do it with the muffler in the position it is now....but the other way is just a backup.
I am going to put it out there because I know you have taken your car above 180...and I was worried about you doing that with out an undertray and getting an air bubble under the car... The muffler will be relocated to the center of the car close to the transmision....The pipes will be routed through the lower part of the rear bumper at both side of the license plate. This will allow the under tray to be flatter. I want them to try to do it with the muffler in the position it is now....but the other way is just a backup.
02-06-2009, 05:32 AM
#90
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Sick project good luck with it. Now I have a question about the aerodynamics of the car. A while back Nissan designed and produced the long nose Z. My understanding was they did this for sustained high speed runs 180 mph +. Will the stock body design handle those speeds even with the under tray? I understood they had to lengthen the car for the speed you are going for. Have you done any research about this?
02-06-2009, 06:11 AM
#91
Sick project good luck with it. Now I have a question about the aerodynamics of the car. A while back Nissan designed and produced the long nose Z. My understanding was they did this for sustained high speed runs 180 mph +. Will the stock body design handle those speeds even with the under tray? I understood they had to lengthen the car for the speed you are going for. Have you done any research about this?
But the key is to try to keep the air flow accross the underpan of the car moving faster than the airflow moving accross the top of the car. That's how downforce is achieved. You definitely do not want stagnet air under there, that will generate lift.
Now I have seen a couple of ways of doing this. A number of years ago I saw a concept where they had venturies shaped in the body pan itself. When I started my previous post, I was assuming this is what they had done with the Enzo, but it is not. That's why I went back and edited the post.
Here is a picture of the Enzo underbody:
http://img84.imageshack.us/img84/907...arienzoyn4.jpg
Instead, it looks like middle under body between the front and rear wheels sits closest to the ground, which reduces the volume (i.e. amount of space) available for the air to pass through, which in turn forces the air to speed up as it passes that section. To acheive dowforce, they are getting the air to flow faster in that section than the air flowing over the top of the car.
The underpan is then gradually raised toward the back of the car on either side of the center section. This provides more volume for the air, thus allowing the air speed to slow down. I suspect that the air speed exiting from underneath the back of the car matches the air speed flowing over the top, which will minimize turbulence; turbulence increases drag, so is not good. I think the diffuser runners are mostly to minimize turbulence in the air as it begins to slow down during the transition.
Also, it looks like they are also trying to divert some of the airflow from going to the rear wheels.
Basically, we should try to get our underbodies to use this same general concept. Without a wind tunnel or aerodynamic modelling software, we are going have to make some SWAGS (scientific wild @ss guestimates) in order to try to match the speed of the airflow exiting the diffusers to the speed of the airflow over the top of the car.
One idea has occured to me, though. I have a MAF sensor housing with a working MAF sensor, and pressure sensors are readily available. Maybe these could be used to estimate the speed of the air flow coming out of the diffuser and coming over the top of the car. If we know the total amount of air flowing through the MAF tube and the pressure in the tube, then we can calculate the speed of the air flow.
To make sure the air speed exiting the diffusers matches the air speed coming off of the top of the car, we can build a fixture to hold the MAF tube at the top rear of the car and then at the exit of the diffusers, and compare the numbers.
If the air flow coming out of the diffusers is slower than the air flow coming off the top of the car, then the diffuser channels wound need to be a little smaller. If the air flow coming out of the diffusers is faster than the air flow comming off the top of the car, then the diffuser channels would need to be a little bigger.
As far as measuring the amount of downforce we are getting, we could use a presure senser to measure the air pressure under the car and measure the air pressure over the top of the car. Alternatively, we can compare the speed of the air flowing under the car to the speed of the air flowing over the top of the car, but I think pressure sensors are probably more readily available.
Last edited by ttg35fort; 02-06-2009 at 06:36 AM.
02-06-2009, 06:15 AM
#92
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I would rather have carbon fiber too, but a one off would be expensive.
Specifically, I have discussed with Roger and Paul about moving my mufflers to the center of my rear bumper (in fact, I ceramic coated my entire exhaust system except for the rear most section where the exhaust pipes diverge. I will be cutting and re-welding those to get both mufflers and exhaust pipes as close to the centerline as possible, so I figured I would ceramic coat those parts when the modifications are done).
The goal is to form a venturi [EDIT between the middle part of the body pan and the diffuser] channels on both the left and right undersides of the car so that we can benefit from Bernoulli's principle. The idea is to speed up the air flow where you want the down force. As the air flow speeds up, the pressure decreases (in this case between the underpan where the venturi is located and the ground), thus creating downforce. The Enzo is a perfect example of this. Of course, it's structure was designed with this in mind, where our cars weren't. But I have studied the underside of our cars and I beleive we can generate alot of downforce. Maybe not as much as an Enzo, but way more than we are getting now.
EDIT: I just noticed that you were not crazy about moving the mufflers. My concept also involves moving the mufflers too. We could look at trying to create a diffuser channel between the mufflers, and we would get some downforce, but I don't think it would be as much as running two venturis, one on each side of the center section.
EDIT EDIT: I just pulled up a picture of the bottom of an Enzo. It looks to me that the majority of the downforce is happening right smack in the middle of the car. The main venturi is not fromed by the diffuser channels themselves, but the transition from the middle of the underbody to the the diffuser channels (which are raised further from the ground). Although the diffuser runners do appear to have a little bit of a venturi design, and thus may be contributing some down force, their main function appears to be reducing turbulance in the air flow as it slows when it exits from beneath the central portion of the car into the diffuser channels. Ingenious design, and good inspiration.
Specifically, I have discussed with Roger and Paul about moving my mufflers to the center of my rear bumper (in fact, I ceramic coated my entire exhaust system except for the rear most section where the exhaust pipes diverge. I will be cutting and re-welding those to get both mufflers and exhaust pipes as close to the centerline as possible, so I figured I would ceramic coat those parts when the modifications are done).
The goal is to form a venturi [EDIT between the middle part of the body pan and the diffuser] channels on both the left and right undersides of the car so that we can benefit from Bernoulli's principle. The idea is to speed up the air flow where you want the down force. As the air flow speeds up, the pressure decreases (in this case between the underpan where the venturi is located and the ground), thus creating downforce. The Enzo is a perfect example of this. Of course, it's structure was designed with this in mind, where our cars weren't. But I have studied the underside of our cars and I beleive we can generate alot of downforce. Maybe not as much as an Enzo, but way more than we are getting now.
EDIT: I just noticed that you were not crazy about moving the mufflers. My concept also involves moving the mufflers too. We could look at trying to create a diffuser channel between the mufflers, and we would get some downforce, but I don't think it would be as much as running two venturis, one on each side of the center section.
EDIT EDIT: I just pulled up a picture of the bottom of an Enzo. It looks to me that the majority of the downforce is happening right smack in the middle of the car. The main venturi is not fromed by the diffuser channels themselves, but the transition from the middle of the underbody to the the diffuser channels (which are raised further from the ground). Although the diffuser runners do appear to have a little bit of a venturi design, and thus may be contributing some down force, their main function appears to be reducing turbulance in the air flow as it slows when it exits from beneath the central portion of the car into the diffuser channels. Ingenious design, and good inspiration.
Well said....You are on the same mind set as me.....I am not TOTALLY against aluminum.....especially now that there seems to be members that would want this setup....I was told by to shops out here that the Muffler part HAS to be relocated to get the perfect effect. The CF version of a one off will cost over $6000 if I want to keep the muffler that way it is...but cheaper if I relocate it.
Lets see what we all can come up with.
(XKR removes Romey from Hit-List)
Well I think the twin oil cooler that I am running should help things....the water temps will be fine....you let up a little and they will drop.
Good info-thanks man. This is a great project, very different from what we are used to seeing. At high speeds with only a Top Secret diffuser I have yet to feel anything that would question my fortitude to stay on the gas lol. But, I have not tried going around even highway like smoother curves past 165mph-past that is only done in a straight line. Ive thought about making something for under the car in the past, but havent looked into it yet since falling away from the car some.
Sick project good luck with it. Now I have a question about the aerodynamics of the car. A while back Nissan designed and produced the long nose Z. My understanding was they did this for sustained high speed runs 180 mph +. Will the stock body design handle those speeds even with the under tray? I understood they had to lengthen the car for the speed you are going for. Have you done any research about this?
Last edited by XKR; 02-06-2009 at 06:47 AM.
02-06-2009, 06:51 AM
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Raj
I am sure that most that know me on here knew that this was coming....it was just a matter of time for the drugs to wear off
Last edited by XKR; 02-06-2009 at 07:26 AM.
02-06-2009, 07:24 AM
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Look at the video that Cass posted on this thead....look at the back of that 350Z....that is what my setup MUST look like...exhaust through the bumper and air directed down the center.
Looks like Alberto and the Z guys may be in luck....It looks like its already been made for the Z
There are only a few spots where you will be able to hit those speeds....So the car should be able to handle it....There is nothing I can think of that would be worst than some noob in a Lamo looking in his/her rearview and seeing a G catching up
Looks like Alberto and the Z guys may be in luck....It looks like its already been made for the Z
Last edited by XKR; 02-06-2009 at 07:30 AM.
