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  #16  
Old 10-23-2011, 05:37 PM
XT6Wagon XT6Wagon is offline
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Re: Functional Aero Kit

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Originally Posted by smc View Post
The front splitter does indeed extend under the front engine x-member and is designed to smooth out the air under the car.
Smooth is nice, but I'm talking about a front diffuser. Its like the rear diffuser only harder to pull off... and in the front. You couple a splitter with a front diffuser and you get LOTS of front downforce. Ok, well vent the wheelwells and maybe some properly designed canards and you will be there with the other racecars converted from a street car. Not sure how far you want to go to it looking like a DTM. I'll try to find the website that went into the design of the Viper ACR areo package but its some wonderful reading.

as far as the rear spoiler, 8" isn't too high, just recall you can USE the rear spoiler to create clean airflow to itself. This is what the "boyracer" wing on the STi does. It does a good job of sticking the airflow to the rear window where it doesn't on the normal cars. The SVX is.. different than the STi though and I'd hesitate to assume that what works on them will work on the SVX.



I present to you this as another example of how I am thinking to approch balancing your front downforce. Here is some flat sheetmetal with no foil, slope, or whatever. Yet it both produces downforce and reduces drag. More downforce by having a well defined low pressure zone below it and lower drag by smoothing the flow off the car. Now do this with a proper airfoil working with the flow off the top of the trunk lid to increase the downforce to desired levels. Not going to be legal for any road racing class I know of, but I'm thinking that large wings outside the lines of the body have been banned for a reason.
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  #17  
Old 10-23-2011, 07:41 PM
XT6Wagon XT6Wagon is offline
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Re: Functional Aero Kit

Here you go, front diffuser.

http://www.compositesworld.com/artic...peed-stability

btw, don't take my comments personaly. Most SVX owners are not modifing to a rulebook so I view it as a place for much more agressive and "theoretical" areodynamics than if you were setting up a STi for a specific race class. Yet money is allways a limiting factor in how far you go. Just that the SVX needs so much replaced to do a proper areo package one might as well dial it up to 11, where as the STi needs much less to see gains.

Also I'm quite upset about the rash of tuners out there who are making all the same mistakes and misteps that racing cars did in the 60's and early 70's on the way to a solid foundation of knowledge. Google is free and no one is guarding thier top secret areo info from 1978. One not be able to do the insanely complex areo package of a modern F1 car in a small shop enviroment, but we have 40+ years of open wheel, prototype, sedan, hillclimb, rally, etc to pick and choose our well developed areo package from. Even a mostly street car like the Viper shows some really advanced tricks to getting the most downforce for little extra drag.

Course that said I find the trend to generic aftermarket rear wings that are shaped like the vipers very very funny. The viper wing has huge hours being shaped exactly correct to match the airflow off the rear window and bodywork. Which is why the leading edge is higher for the window area and then gets lower at the ends where the bodywork is flat. So a generic curve on a wing won't match whatever car you are using it on thus defeating part if not all of the point of the 3d wing shape.

Last edited by XT6Wagon; 10-23-2011 at 08:26 PM.
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  #18  
Old 10-23-2011, 11:31 PM
Johnybeas Johnybeas is offline
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Re: Functional Aero Kit

My idea of where I want my SVX, it's a modification of the Kstaff Front bumper with adjustable splitter widebody and scoop

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File Type: jpg Blue_Kstaff_widebody_scoop_splitter.jpg (56.3 KB, 1030 views)
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  #19  
Old 10-24-2011, 01:09 AM
smc smc is offline
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Re: Functional Aero Kit

XT6Wagon: No worries, I never take tech questions or suggestions personal. Hell, if there is anything to be learned or added to what Im going for, then by all means, voice your opinion and lay that knowledge on me!
There is ALLOT of aero improvements that I would love to do to this car, however I only have such a budget to create what I can. I would love to have the freedom to make an all out perfect kit for this car. At this stage, and with out a proper wind tunnel, an integrated front diffuser is not in the cards. A rear diffuser will be created however to kick the air up from the back of the car. Wheel arches will not be vented in the front, however rear arch venting may be possible. There will be ducting for brake cooling and NACA ducting for engine bay cooling.


By the by, that was a great article about the viper I love stuff like that! If your ever out and about, pick up a few issues of Race Car Engineering. If you like the viper article, you'll love this mag.

Johnybeas: Im liking that front bumper I also thought about creating a wider stance with a wide body kit. But to do it right, it would involve moving the suspension outward to match the additional width. the VAST majority of people make their cars wider by using more offset on the rims and wider tires. What they dont realize is that they are creating a cornering nightmare. There is something called Scrub Radius when you turn your tires. The further out the edge of the front tires are from the pivot on the steering knuckle, the more it has to rotate to complete the turn. Meaning that your tires have to speed up and rotate quicker than your car is moving in order to complete the movement of the turn. You want that pivot as close to the middle of the wheel as you can to minimize this affect so your not sacrificing traction and speed to corner. Best way to figure this: Draw a straight line from the top center of the strut, past the mounting bolts on the knuckle and continue this to the ground. That line, at the ground should be in the middle of your wheel.


Wow.. That made perfect sense in my head but in text its a hard read..
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  #20  
Old 10-24-2011, 03:29 AM
XT6Wagon XT6Wagon is offline
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Re: Functional Aero Kit

well, you can get some free wheel well venting by... making the front bumper/fender slightly wider across the front 1/2 than it is in the back 1/2 of the opening. This is how Nascar pulls out the air since they are not allowed to run vents. The larger front creates negative pressure across the wheel and pulls out the air preventing lift. I wouldn't have thought of this, and apparently its rarely talked about. It was some offhand comment on some site that was the first I'd heard of it. Its subtle but you can see it on the Nascar cup cars once you are looking for it.
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  #21  
Old 10-24-2011, 11:58 PM
smc smc is offline
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Re: Functional Aero Kit

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Originally Posted by XT6Wagon View Post
well, you can get some free wheel well venting by... making the front bumper/fender slightly wider across the front 1/2 than it is in the back 1/2 of the opening.

True. But that deals mostly with additional drag. Our cars dont have much of a problem with drag. Its just downforce im searching for.
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  #22  
Old 10-25-2011, 12:38 AM
Johnybeas Johnybeas is offline
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Re: Functional Aero Kit

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Originally Posted by smc View Post
Johnybeas: Im liking that front bumper I also thought about creating a wider stance with a wide body kit. But to do it right, it would involve moving the suspension outward to match the additional width. the VAST majority of people make their cars wider by using more offset on the rims and wider tires. What they dont realize is that they are creating a cornering nightmare. There is something called Scrub Radius when you turn your tires. The further out the edge of the front tires are from the pivot on the steering knuckle, the more it has to rotate to complete the turn. Meaning that your tires have to speed up and rotate quicker than your car is moving in order to complete the movement of the turn. You want that pivot as close to the middle of the wheel as you can to minimize this affect so your not sacrificing traction and speed to corner. Best way to figure this: Draw a straight line from the top center of the strut, past the mounting bolts on the knuckle and continue this to the ground. That line, at the ground should be in the middle of your wheel.


Wow.. That made perfect sense in my head but in text its a hard read..
I'd be interested to read the book this is pulled from. As an ASE certified steering and suspension tech who owns a shop and is purchasing the latest and greatest in Hunter alignment rack with their tuner add on, I'd love to understand more on the aftermarket end. However correct me if I'm wrong but wouldn't camber caster plates and adjustable lca's help with the change in offset?
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  #23  
Old 10-25-2011, 01:58 AM
XT6Wagon XT6Wagon is offline
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Re: Functional Aero Kit

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Originally Posted by smc View Post
True. But that deals mostly with additional drag. Our cars dont have much of a problem with drag. Its just downforce im searching for.
Its actualy for lift reduction. What normaly happens on a street car is pressure builds up in the front wheel wells and this then creates lift. Think of air as lots of foam blocks. If you keep shoving them in there faster than they leave they start to jack the front of the car up as the tire can not move down.

Its why if they allow it, all race cars run the top of the fenders vented.


The old "car of tomorrow" shows the wider front clearly, while I can't really see it in the latest photos.


Just a thought as its cheap to tweak the fender and bumpercover, likely no real custom work past careful pulling and maybe a couple new innerbraces to the chassis to hold the new profile.
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  #24  
Old 11-01-2011, 07:58 PM
smc smc is offline
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Re: Functional Aero Kit

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Originally Posted by Johnybeas View Post
However correct me if I'm wrong but wouldn't camber caster plates and adjustable lca's help with the change in offset?
Not really. Not on a McPherson strut design anyway. On a double wishbone suspension this can be played with. However on a mac. design, the axis of the strut is the steering pivot, and its also a stressed member of the suspension. No matter how you play with the camber, the pivot will always be in the same relation to the wheel.

You want the wheel to pivot in the center of the tires contact patch when you turn. Extremes off offset/backspacing on the wheels will either make you pivot on the outside of the contact patch, or the inside. Neither is good when your looking for that last bit of grip. camber plates just shift the contact patch left or right. However having to get extremes on the camber to do this is only a bandaid on other chassis flaws.
On tarmac events in rally, we tend to run zero camber front and rear to get the most grip we can. But then again, weeks are spent on suspension tuning and you can only truly get away with this in AWD classes of cars. FWD or RWD need additional camber to aid with chassis stability and steering. In AWD, we just gun it and the car tends to bring itself around
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  #25  
Old 11-01-2011, 08:01 PM
smc smc is offline
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Re: Functional Aero Kit

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Originally Posted by XT6Wagon View Post
Just a thought as its cheap to tweak the fender and bumpercover, likely no real custom work past careful pulling and maybe a couple new innerbraces to the chassis to hold the new profile.
I hate to say it, but there will not be enough of a benefit in drag redution to make it worth making the SVX ugly with oddball fenders
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  #26  
Old 12-19-2011, 05:27 PM
Johnybeas Johnybeas is offline
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Re: Functional Aero Kit

bump, any progress?
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  #27  
Old 12-28-2011, 09:48 PM
smc smc is offline
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Re: Functional Aero Kit

Nada as of yet. Im still waiting for the funding to become available. The deal I was working for nearly 35k fell apart at the table. So here I sit for a little bit. Im still on track with the rest of the mods for racing. But the aero kit may be a few months down the line. It will happen. Just not a quickly as I had hoped.
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