Lip spoilers and downforce

[AllBlack]

Would a rear lip spoiler like the Hennessey one provide any real noticeable downforce at speed? How would it compare to a real wing like the ACR one?

I have a front splitter which I got a while ago and I need something to equal out the downforce on the rear end but I'm hesitant to put on a big yet functional wing.

Heres the Hennessey rear lip spoiler:

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Heres the splitter I have:

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Any Ideas?

 

[GTS-R 001]

HEre's a few pics of an ACR Wing on an all black SRT10 Convert

Down low, adjustable




ACR Height, adjustable and functional


down low with Aero endplates

 

[REDSLED]

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[mjorgensen Woodhouse]

A lip spoiler may reduce some lift but it's positioning out of actual clean air flow will prevent it from being anything more than a visual addition. A true splitter compared to a air dam is about that same.

 

[AllBlack]

Hmm, thanks... so would you recommend an actual wing to equal out that splitter?

 

[Boxer12]

I would suggest getting rid of the splitter unless you are using the car as a track car. If you want a track car appearance, then put the Gen IV aero wing (not ACR) on it. Just my 2c.

 

[mjorgensen Woodhouse]

Depending on how functional the splitter you have is, you could h
Get a wing that works with it rather then the ACR equipment. If you want a track car that really works and is balanced then as Boxter states you should get what really works with the Viper from SRT. Keep in mind that you will need a different suspension set up if the aero you choose is really "working".

 

[AllBlack]

Thanks guys

I have a set of Motons on the way, I'm just trying to decide what spring weights to use, and that sorta depends on what I choose to do to with the back and front in terms of splitters and wings

I plan to track the car in the next few years, but for now I love the look the splitter gives, but I notice my rear end is pretty squirrely at speed... not to mention that the front splitter kept lifting off the body until I bolted it down from underneath.... so I'm pretty sure the front splitter is working, I just don't know how much downforce its giving, and what to equal it out with in the back

I guess the ideal thing to do would be to replace it all with OEM aero pieces like Boxer said, but I like the looks of the splitter I have on now, and would rather keep it and add a wing, than spend a load of money on a new aero kit

So I guess the most logical thing to do with what I mentioned above is to try a Gen IV Aero wing, and adjust it to try and make it work? If not replace the whole thing with an aero kit...?

 

[vipzilla]

take into consideration that the front splitter only comes into play at about 150 160mph also rear wing same speed

 

[AllBlack]

I think on the ACR they come into play earlier too, just to a lesser extent... something like 1000lbs @ 150 mph, or 250 lbs @ 75 mph... it's a function of some formula for downforce and speed... I remember reading that here somewhere before

I know they make the most difference and maybe only noticible differences at high speeds, and while I might not be only tracking the car, or only driving at high speeds... I do take her up to 140 mph + on occasion and I bought the car to be able to drive at high speeds, and want to feel comfortable and stable while doing so.

 

[Viperless]

take into consideration that the front splitter only comes into play at about 150 160mph also rear wing same speed

Uh, no. Well before 150mph:

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[vipzilla]

were does 1000lbs of down force begin hmmmm looks like 150mph to me

 

[Viperless]

take into consideration that the front splitter only comes into play at about 150 160mph also rear wing same speed

were does 1000lbs of down force begin hmmmm looks like 150mph to me

So it's no good until it starts making 1000lbs of down force?

 

[vipzilla]

So it's no good until it starts making 1000lbs of down force?

well it takes above 1000.lbs of lift to start getting front end air born dont you guys listen to tanner faust

 

[Nader]

NO wonder why it wont do over 180. 1,400 lbs of downforce.

Uh, no. Well before 150mph:

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[ExpensiveHobby22]

A rear spoiler like the Hennessey one would indeed generate some downforce on the rear, and something like it would probably actually very nicely enhance a base convertible's aero balance, giving it a more rearward bias.

However, with the splitter you have on the car, you'd probably want a wing to be able to balance the downforce it creates in the front as well as the pitching moment it causes, which effectively adds lift to the rear.

Also, keep in mind, that on a convertible, regardless of wing or spoiler, the aero effect benefit will be effected significantly by whether the top is up or down. So, if you are tracking it, keep this in mind.

Lastly, in regards to the post about the aero elements not being effective until 150mph, this is simply not true. Their effects are there at much lower speeds as well, as the graph clearly shows.

 

[GTS-R 001]

Given that the front half of a convertible vs a coupe of the same year is pretty much identical, it makes sense that the difference in down force is caused by the lip at the rear of the coupe vs the absence of the lip on the vert. At highway to legal +20mph or so the downforce and its difference is only in the 100 - 200 lb mark, so a 100 lb difference., adding a lip spoiler will probably almost even things out.

To offset the down caused by a functional splitter, one should add a wing

 

[AllBlack]

A rear spoiler like the Hennessey one would indeed generate some downforce on the rear, and something like it would probably actually very nicely enhance a base convertible's aero balance, giving it a more rearward bias.

However, with the splitter you have on the car, you'd probably want a wing to be able to balance the downforce it creates in the front as well as the pitching moment it causes, which effectively adds lift to the rear.

Also, keep in mind, that on a convertible, regardless of wing or spoiler, the aero effect benefit will be effected significantly by whether the top is up or down. So, if you are tracking it, keep this in mind.

Lastly, in regards to the post about the aero elements not being effective until 150mph, this is simply not true. Their effects are there at much lower speeds as well, as the graph clearly shows.

good post, thanks

 

[Newport Viper]

From SRT Chat

The ACR makes significantly more downforce than either aero package. The aero package wings are based on the ACR form but they are twelve inches narrower (cross/car) and do not have the Gurney kick up at the trailing edge.

The roadster aero package makes about the same downforce as a base coupe (roughly 170 lbs at 150 mph). The coupe aero package makes about 600 lbs of down force at 150 mph. The ACR makes 1000 lbs of DF at 150mph.


Originally Posted by Nader
The Roadster areo package makes only 170lbs of downforce? Why bother even offering it then? What on the coupe is creating more downforce then the roadster?
170 lbs of downforce is actually very good considering we did it without adding any drag. The goal roadster aero package was to add moderate downforce without increasing drag. Most sports cars actually make about 100 to 200 lbs of lift at speed. The base roadster is neutral (roughly zero DF).

If you are going to the track, we recommend the ACR. If you've got to have a roadster and still plan on going to the track you'll notice a good improvement in high speed stability and grip with the aero package.

The wing on the coupe aero package is higher in the clean air stream. This makes the wing pick up more downforce.




black08: Obviously, thousands of hours were logged on the track during the development of the ACR. I was wondering if the SRT engineers could give us an idea of how much quicker the ACR was on the track versus the regular '08 model?


We have tested at many tracks and the results vary with them. At a 2.0 mile track (1:30 lap time range) with high speed corners where the aerodynamics can show off, the ACR is typically 3 seconds faster than the 2008 Viper SRT10 and 4.5 seconds faster than the 2006 Viper SRT10.

What have you observed on the standard '08? Any difference between the coupe/convert?
The non-ACR Coupe and Convertible went 202 mph, average in both directions to cancel out wind. The '08 Convertible went 197 with the top down. We had to go to TRC to go that fast. The Chelsea and Arizona proving grounds ovals are too small.

It is "breezy" with the top down though!





I'm bored at work so, random cutting and pasting today.....LOL

 

[ZDigital1]

A rear spoiler like the Hennessey one would indeed generate some downforce on the rear, and something like it would probably actually very nicely enhance a base convertible's aero balance, giving it a more rearward bias.

However, with the splitter you have on the car, you'd probably want a wing to be able to balance the downforce it creates in the front as well as the pitching moment it causes, which effectively adds lift to the rear.

Also, keep in mind, that on a convertible, regardless of wing or spoiler, the aero effect benefit will be effected significantly by whether the top is up or down. So, if you are tracking it, keep this in mind.

Lastly, in regards to the post about the aero elements not being effective until 150mph, this is simply not true. Their effects are there at much lower speeds as well, as the graph clearly shows.

Well stated!