Does anyone know if the MR trunk lip adds as much downforce as the high gsr wing?

I want to go wingless, but want to keep the downforce. if the lip actually does something, This seems like my best option...

 

If you aren't going to track your car at high speeds it really won't make a difference.

 

^true.

What little down force actually generated would only come from the high wing. The lip does (nearly) nothing from an aero stand point.

To prove it - measure fuel economy with and without the high wing. If there is NO difference - then it is not generating drag (which is 'downforce')...

Or do a computational flow dynamic modeling run to prove my point...

But - as pointed out - you won't miss it - so make it look like you want!

 

Some people have claimed to be getting 3-4MPG more which IMO is completely unrealistic from taking off a wing. But then again... if you are concentrating on MPG then you will drive differently. But yeah, pretty much everything else is true.

 

huh! I would not have expected that much - which does indicate an effective down force generator...

[scratches head and mumbles to oneself]

 

I read it on this thread on the first page

https://www.evolutionm.net/forums/ev...ces-ideas.html

Granted the guy said it was on the VIII...not sure if there is a difference?

 

^yeah, read that thread next... i saw the claim. Enough people going wingless stated an instability at high speeds and if the 3 MPG difference is true - then the high wing is effective.

Now, somewhere in there was a post saying 'so i can increase downforce and improve MPG...' uh... no.

 

With how fast you would need to be going...you wont be getting better MPG anyways.

 

Oh, my, No. If the relation between downforce and drag were a fixed, constant value, then there would be no research on wing design, no patents on such, and no reason to keep your new design secret until the first race of the season. But you're wrong; the relation is not some fixed, constant value, which is why there is research, there are patents, and people do keep their wings secret as long as they can.

Even more, when deciding what to put on a given car (i.e., when deciding what aero to add to a given body), the first question is: "what are you after?" Do you want more rear downforce, less drag, or some particular mixture of the two? A wing is for when you want downforce. Things like turbulators are for less drag. Lips are a weird mix of the two, although they often end up more like wings in that they aren't very good and disturbing the air behind the trunk.

I think about all this every time I see an Evo X with turbulators on the back edge of the roof. Then I usually giggle, because the flow down the rear window is almost perfect on the body without the turbulators, so these are worse than nothing. Yes, they helped Evo 8s and 9s, since the flow down the rear window was a mess on those, but the Evo X doesn't need and probably doesn't want them.

 

so, after 4 years, our community is still in disagreement on whether our ginormous wing actually does anything?

Somewhere on this forum, someone actually had the facts of how many lbs downforce the wing produces vs. the MR lip; i can't find that now, but i remember that the numbers were pretty close in comparison.

So we are in consensus that it does have a significant affect when tracking.
I will be tracking the car, and don't want to deal with putting it back on every time i go to the track (and those funny looking lowe's hole plugs).
when i do decide to take it out on the streets during weekends, I don't want the wing.. it's a little obnoxious IMO, and just str8up cop bait.

 

/thread

Nothing else needs to be said

 

^Everything you said is true. It is not a constant for caclulating downforce from drag, but a way of saying 'my driveway is wet - it indicates it rained last night.'

Yes, you would 'tune' the rear wing for either reduced aero drag OR down force by changing the angle of attack and/or shape.

But i stand by the statement: 'you don't get something for nothing' (i.e. downforce is proportional to drag for a rear wing design)

I 'believe' the lip is near useless for downforce due to the placement aft of the boundary layer separation. I would need to see CFD analysys to disprove it.





(my belief is based on my MS in Engineering and 18+yrs fighter aircraft design experience )

 

My brain is hurting from all this technical stuff...

But i get the jist of it. High wing > MR lip.

 

@Veronica

It is absolutely the case that you cannot get something for nothing. The simplest way to "prove" this to yourself is by noting that even a newly-washed car that has been treated with uber-expensive Grandmother's Own raised-on-purified-rose-attar honey-bee wax will have some surface drag, so adding more surface area (by adding a wing) will always add drag, even if the wing is flat, infinitely thin, with a zero angle of attack.

As I used to say every time I had to change the clutch in my DSM: "there is no such thing as a free launch." [sic]