New Product: Rear Aero Undertray
Vishnu guys --
Thats a nice looking piece. It's great that you guys are putting in the time and R&D to develop something like this.
I'm not one to really care how "cool" something like this looks on the car. But I am interested in how well it works and if it lowers lap times. A few questions:
1) Does the undertray extend forward to at least under the rear seats and infront of the rear diff? This would make logical sense that it should, as otherwise, wouldn't the undertray actually increase the amount of "parachute" effect and increase drag as it now created and bigger pocket to catch the air?
2) From my research of aero parts, I understand that a piece like this would be mostly cosmetic unless it is super close to the ground. Looking at the couple of pics, it looks that this piece is pretty far off the ground. In your R&D, how have you realized that there is a increase in aero advantage (instead of disadvantage) from it's mounting position, fin design, etc?
3) I know you guys are involved in a lot of open track activities as Shiv was at OTC while I was there. What kind of track time can someone expect to gain at a high speed track like Willow Springs? It would be great if you guys did wind tunnel testing, but that may be unrealistic for a product like this offered at around $500. So has any body in your test group done some back to back/before and after comparo? For example, some of the Porsche guys did some testing at Willow Springs with the big banana wings, they were getting up to 4 seconds from the wing. What kinda times can EVO owners expect with just the addition of this piece?
I'm been kinda on an involuntary break from racing, but I still try to keep up with the racers and all this stuff as I'm hoping to get back into the EVOs again. You strapping this thing on some of the more serious track cars on the west coast?
Hope you don't mind all the questions, this is quite an exciting part. Just looking for some technical answers beyond just the cosmetics and pricing!
Thats a nice looking piece. It's great that you guys are putting in the time and R&D to develop something like this.
I'm not one to really care how "cool" something like this looks on the car. But I am interested in how well it works and if it lowers lap times. A few questions:
1) Does the undertray extend forward to at least under the rear seats and infront of the rear diff? This would make logical sense that it should, as otherwise, wouldn't the undertray actually increase the amount of "parachute" effect and increase drag as it now created and bigger pocket to catch the air?
2) From my research of aero parts, I understand that a piece like this would be mostly cosmetic unless it is super close to the ground. Looking at the couple of pics, it looks that this piece is pretty far off the ground. In your R&D, how have you realized that there is a increase in aero advantage (instead of disadvantage) from it's mounting position, fin design, etc?
3) I know you guys are involved in a lot of open track activities as Shiv was at OTC while I was there. What kind of track time can someone expect to gain at a high speed track like Willow Springs? It would be great if you guys did wind tunnel testing, but that may be unrealistic for a product like this offered at around $500. So has any body in your test group done some back to back/before and after comparo? For example, some of the Porsche guys did some testing at Willow Springs with the big banana wings, they were getting up to 4 seconds from the wing. What kinda times can EVO owners expect with just the addition of this piece?
I'm been kinda on an involuntary break from racing, but I still try to keep up with the racers and all this stuff as I'm hoping to get back into the EVOs again. You strapping this thing on some of the more serious track cars on the west coast?
Hope you don't mind all the questions, this is quite an exciting part. Just looking for some technical answers beyond just the cosmetics and pricing!
Evolving Member
Joined: Feb 2004
Posts: 464
Likes: 0
From: Livermore, Ca
Ok, so here goes it:
1. I'm working on getting the pictures up of the diffuser from underneath the car. It meets right up behind the rear diff pretty much.
2. You're right, to make a huge increase in aerodynamics, the car itself needs to be really low, and the bottom of the car needs to pretty much be flat(take an indy car for example, or a viper lol). However this was designed, again, to mainly reduce drag(the parachute effect) caused by the rear bumper. Of course it will be more effective at high speeds than at low speeds(driving around down town, etc.) There has been no noticeable disadvantage in its mounting position either.
3. I would LOVE to get our race car in a wind tunnel, that would be freakin awesome. I'd like to see if that vortex generator actually does anything at all. I'll have to get back to you on the times one can expect, as the product will be much more effective at high speeds.
Oh, and we're workin on a few other aero products as well.
Mr. Gerrard will be able to give much more technical answers, he is an aero mastAr.
1. I'm working on getting the pictures up of the diffuser from underneath the car. It meets right up behind the rear diff pretty much.
2. You're right, to make a huge increase in aerodynamics, the car itself needs to be really low, and the bottom of the car needs to pretty much be flat(take an indy car for example, or a viper lol). However this was designed, again, to mainly reduce drag(the parachute effect) caused by the rear bumper. Of course it will be more effective at high speeds than at low speeds(driving around down town, etc.) There has been no noticeable disadvantage in its mounting position either.
3. I would LOVE to get our race car in a wind tunnel, that would be freakin awesome. I'd like to see if that vortex generator actually does anything at all. I'll have to get back to you on the times one can expect, as the product will be much more effective at high speeds.
Oh, and we're workin on a few other aero products as well.
Mr. Gerrard will be able to give much more technical answers, he is an aero mastAr.
Newbie
Joined: Jun 2004
Posts: 73
Likes: 0
Originally Posted by lambtron@vishnu
Ok, so here goes it:
1. I'm working on getting the pictures up of the diffuser from underneath the car. It meets right up behind the rear diff pretty much.
2. You're right, to make a huge increase in aerodynamics, the car itself needs to be really low, and the bottom of the car needs to pretty much be flat(take an indy car for example, or a viper lol). However this was designed, again, to mainly reduce drag(the parachute effect) caused by the rear bumper. Of course it will be more effective at high speeds than at low speeds(driving around down town, etc.) There has been no noticeable disadvantage in its mounting position either.
3. I would LOVE to get our race car in a wind tunnel, that would be freakin awesome. I'd like to see if that vortex generator actually does anything at all. I'll have to get back to you on the times one can expect, as the product will be much more effective at high speeds.
Oh, and we're workin on a few other aero products as well.
Mr. Gerrard will be able to give much more technical answers, he is an aero mastAr.
1. I'm working on getting the pictures up of the diffuser from underneath the car. It meets right up behind the rear diff pretty much.
2. You're right, to make a huge increase in aerodynamics, the car itself needs to be really low, and the bottom of the car needs to pretty much be flat(take an indy car for example, or a viper lol). However this was designed, again, to mainly reduce drag(the parachute effect) caused by the rear bumper. Of course it will be more effective at high speeds than at low speeds(driving around down town, etc.) There has been no noticeable disadvantage in its mounting position either.
3. I would LOVE to get our race car in a wind tunnel, that would be freakin awesome. I'd like to see if that vortex generator actually does anything at all. I'll have to get back to you on the times one can expect, as the product will be much more effective at high speeds.
Oh, and we're workin on a few other aero products as well.
Mr. Gerrard will be able to give much more technical answers, he is an aero mastAr.
Also, one more question, how hard is it to take off?
I have a special brand of hatred strictly reserved for the front undertray and hope that the mounting points for the rear facilitate quick removal...at least quicker than the front stock one.
I have a special brand of hatred strictly reserved for the front undertray and hope that the mounting points for the rear facilitate quick removal...at least quicker than the front stock one.
Newbie
Joined: Mar 2003
Posts: 47
Likes: 0
Guys, guys, guys:
Cost is a relative thing.
The Varis rear diffuser at Gruppe-S will set you back $1150.
Yes, it is carbon fiber, but fella's its all in what you persieve the value to be.
For me, I'll go for the Vishnu diffuser.
Cheers,
JS
Cost is a relative thing.
The Varis rear diffuser at Gruppe-S will set you back $1150.
Yes, it is carbon fiber, but fella's its all in what you persieve the value to be.
For me, I'll go for the Vishnu diffuser.
Cheers,
JS
Evolving Member
Joined: Feb 2004
Posts: 464
Likes: 0
From: Livermore, Ca
Originally Posted by 4G63>OOOO
Also, one more question, how hard is it to take off?
I have a special brand of hatred strictly reserved for the front undertray and hope that the mounting points for the rear facilitate quick removal...at least quicker than the front stock one.
I have a special brand of hatred strictly reserved for the front undertray and hope that the mounting points for the rear facilitate quick removal...at least quicker than the front stock one.
So is it a flat piece starting from behind the diff? Or does it actually completely close off the area between the rear diff and the rear bumper? I would imagine that to swing the parachute effect either to a-lot-more (undesired) or a-lot-less (desired). An unmounted pic of pic of the car in the air would be cool.
Now given it does reduce the parachute effect, the next question would be -- Does it reduce lift, increase lift, or actually create downforce? Reducing the parachute effect would be nice, but definately not at the expense of increased lift. It would sort of be like -.5 sec on a track from reduced parachute, but +3 seconds now that the back of the car is wiggling around at speed. Especially since the car is already a nightmare when it comes to drag and aerodynamics.
Obviously w/o the use of a wind tunnel, track times would be the next best thing. Besides just seat of the pants reviews (which I'd really be amazed someone can tell the difference in the parachute affect), what other data points are you collecting in your R&D from the racers you've been testing with?
Now given it does reduce the parachute effect, the next question would be -- Does it reduce lift, increase lift, or actually create downforce? Reducing the parachute effect would be nice, but definately not at the expense of increased lift. It would sort of be like -.5 sec on a track from reduced parachute, but +3 seconds now that the back of the car is wiggling around at speed. Especially since the car is already a nightmare when it comes to drag and aerodynamics.
Obviously w/o the use of a wind tunnel, track times would be the next best thing. Besides just seat of the pants reviews (which I'd really be amazed someone can tell the difference in the parachute affect), what other data points are you collecting in your R&D from the racers you've been testing with?
Evolved Member
Joined: May 2003
Posts: 2,136
Likes: 0
From: Arlington, TX
Lift effects aside, In our own testing we have been doing on our own rear undertray panel (not this one) showed significant and very easily noticed improvements in 80-140mph times. We have also noticed improved rear grip, but it would be comparing apples to tangerines in our case with a lot of lightening, coilovers, full slicks, much lower, etc compared to most rides that are quite near stock setups.
Newbie
Joined: Jun 2004
Posts: 73
Likes: 0
Originally Posted by Derekw
So is it a flat piece starting from behind the diff? Or does it actually completely close off the area between the rear diff and the rear bumper? I would imagine that to swing the parachute effect either to a-lot-more (undesired) or a-lot-less (desired). An unmounted pic of pic of the car in the air would be cool.
Now given it does reduce the parachute effect, the next question would be -- Does it reduce lift, increase lift, or actually create downforce? Reducing the parachute effect would be nice, but definately not at the expense of increased lift. It would sort of be like -.5 sec on a track from reduced parachute, but +3 seconds now that the back of the car is wiggling around at speed. Especially since the car is already a nightmare when it comes to drag and aerodynamics.
Obviously w/o the use of a wind tunnel, track times would be the next best thing. Besides just seat of the pants reviews (which I'd really be amazed someone can tell the difference in the parachute affect), what other data points are you collecting in your R&D from the racers you've been testing with?
Now given it does reduce the parachute effect, the next question would be -- Does it reduce lift, increase lift, or actually create downforce? Reducing the parachute effect would be nice, but definately not at the expense of increased lift. It would sort of be like -.5 sec on a track from reduced parachute, but +3 seconds now that the back of the car is wiggling around at speed. Especially since the car is already a nightmare when it comes to drag and aerodynamics.
Obviously w/o the use of a wind tunnel, track times would be the next best thing. Besides just seat of the pants reviews (which I'd really be amazed someone can tell the difference in the parachute affect), what other data points are you collecting in your R&D from the racers you've been testing with?
On a related note, it seems that the Vishnu team at One Lap noticed that the Evo needed more downforce in the rear. I think that Mitsubishi should have made the wing on the Evo adjustable. Has Vishnu experimented with changing the angle of attack on the stock spoiler or putting in a better airfoil.
Last edited by Yargk; Jul 28, 2004 at 06:56 PM.
Originally Posted by Yargk
...On a related note, it seems that the Vishnu team at One Lap noticed that the Evo needed more downforce in the rear. I think that Mitsubishi should have made the wing on the Evo adjustable. Has Vishnu experimented with changing the angle of attack on the stock spoiler or putting in a better airfoil.
l8r)
Evolving Member
Joined: Feb 2004
Posts: 123
Likes: 0
From: Solano County, CA
I've always thought that it would be marketable to simply develop adjustable side plates for the stock wing like the ones that were originally supposed to come on the Evo. Come on, I'll bet the Japanese or European version Evos already have it. Just need to copy it.
You can already get an adjustable splitter (https://www.evolutionm.net/forums/sh...ad.php?t=90022) and (http://www.autovation.net/groupbuy/M.../splitter.html). IMHO it's the best looking splitter so far, and I will be getting it to complement the Vishnu rear undertray. I don't really care for the APR splitter, since it replaces the existing front undertray, and besides, I want to paint it, so aluminum works better for me.
l8r)
l8r)