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Why does the NSX-R not have a trunk underspoiler?

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I just installed an NSX-R spoiler for some added downforce (and style :smile: ). I also noticed that in 2002+ Honda added a trunk underspoiler lip, which supposedly reduced drag (and added downforce - not sure about this).

My question is this, why do you think the NSX-R did not have this same improvement? Would having both be a good or bad things... your thoughts?
 
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Maybe I'm not understanding your question but the NSX-R has an entirely different, more aggressive diffuser/underspoiler assy (see pic).
 

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Maybe I'm not understanding your question but the NSX-R has an entirely different, more aggressive diffuser/underspoiler assy (see pic).

detailopt.jpg


I believe he's talking about this.
 

Osiris_x11

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'02'-'05 trunk-lid spoiler...

Maybe I'm not understanding your question but the NSX-R has an entirely different, more aggressive diffuser/underspoiler assy (see pic).
I believe SaberX is referring to the OEM trunk-lid piece that is found on '02-'05 models (above the trunk deck-lid and below the actual spoiler-wing).

'02+ NSX-R (no such 'mini' trunk-lid spoiler):



vs.

'02-'05 NSX (notice 'mini' trunk-lid spoiler):



vs.

'91-'01 NSX (no such 'mini' trunk-lid spoiler):





(all thumbnails clickable)



Nota Bena: KSXNSX beat me to it (showing the aftermarket CF trunk-lid spoiler)... :cool:
 
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I do not think that this part has an aerodynamic effect… :rolleyes: or then very little of normal use on road, it is certainly an aesthetic addition! but… I make can be an error? :rolleyes: :smile:
 
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the type r didnt have that piece becaus of the intesity of the type r vtec coupled with the lightness of the flashy lightweight type r recaros it would have made the type r nsx pop a wheelie,

its safe with the non type r model though(less vtec crazyness)
 
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Re: '02'-'05 trunk-lid spoiler...

I believe SaberX is referring to the OEM trunk-lid piece that is found on '02-'05 models (above the trunk deck-lid and below the actual spoiler-wing).

'02+ NSX-R (no such 'mini' trunk-lid spoiler):



vs.

'02-'05 NSX (notice 'mini' trunk-lid spoiler):



vs.

'91-'01 NSX (no such 'mini' trunk-lid spoiler):





(all thumbnails clickable)



Nota Bena: KSXNSX beat me to it (showing the aftermarket CF trunk-lid spoiler)... :cool:

Osiris - you hit the nail on the head... that is exactly what I want to know. Anyone know the answer?
 
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I recall reading that the small lip spoiler on the '02+ increased the top speed from 168 to 175mph....this was a factory claim.
 
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I recall reading that the small lip spoiler on the '02+ increased the top speed from 168 to 175mph....this was a factory claim.

The increase in top speed came from the reshaping of the front bumper, the smoothed out contours of the side skirts, and to a small extent, the lip spoiler may have helped. Not the lip spoiler alone.
 
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to me the 02-05 piece is more like a pad for you to close the trunk ;) Anything that small and resides under the spoiler really have no measurable performance downforce or drag wise...

However I would think of it being directing rain drops and dirt accumulating or something like that... Anyone have first hand experience on that??

That makes a lot of sense the R losing it then, cuz the R needs to be lighter(yes, even couple lbs.) And who cares that little nuisance about water spots and dirt on a track car?
 
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It's likely the small trunk lid spoiler only worked in conjunction with the original OEM wing. It's possible that it's use yielded zero (or negligible) benefit when used with the higher profile NSX-R wing.
 
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I have both (lip + R spoiler) I really like it. Placebo or not, when adding the lip to the R spoiler which was already on + the hood duct & front bumper undertray, I felt the difference, especially during an on-ramp acceleration in the rain at higher, more stable speeds than in the past...

The other variables make it difficult to judge the individual impact, but I think it is all goodness. :smile:

Also - remember that a bunch of cars have such a lip stock - the Mercedes, BMWs etc... and that along with an undertray make those cars very stable at high speed with a low CD (I've seen .27 on some Mercedes) - that is much better than an NSX and more stable than some would say with the NSX.

I think the question should be not whether it works - but whether it would work against the R spoiler.
 
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It's likely the small trunk lid spoiler only worked in conjunction with the original OEM wing. It's possible that it's use yielded zero (or negligible) benefit when used with the higher profile NSX-R wing.

+1 .. But I still have both now. lol
 
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I'm trying to find a response I recieved to the same original question and will post if I find it.

However, it was told to me that the ommision from the NSX-R, of the later lip spoiler from the stock 02+ models was for balance.

Honda spent a lot of time and money to develop the NSX-R aero package in such a way that it a) increased the downforce efficiency b) reduced lift and c) retained the front to rear balance + feel of the stock NSX when at speed.

I have the full aero package :cool: and would say that high speed stability is improved with enhanced steering feel.

IMHO, if I choose at a later date to 'infil' the space under the high spoiler with the lip spoiler, I doubt I could notice any difference that maybe the Honda R&D guys could in testing.

HTH, Paul
 
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Greetings

I have a friend with a 99. The rear end of mine does not get as dirty when we go on drives as his does. We both noticed this a while back. It did not seem to matter which car drove first up Bear Creek Road. He would have more dust on the tail light lenses when we returned. I don't know how measurable this effect is.

Martin
 
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At the risk of getting shot by the Physics/Aerodynamic gurus, the rear trunk spoiler certaintly does have a positive effect! It adds downforce because it's slightly tilted (greater stability) some drag for the same reason. With that said, it may reduce rear turbulence and thus the overalldrag and maybe having a positive effect.

A simple illustration: When you put your hand out the window at 60 MPH, you probably notice that the flatter it is, the less resistance, obviously but also the easier for it to change direction erratically if you change it just a litlte bit.

However, if you can manage to, as you slowly tilt your hand, you will feel the resistance towards the top of your hand, addiwng downforce + drag and the closer you get it to 0 (? eg, TDC) degrees, the greater resistance and drag on the entire hand...

The trunk spoiler in discussion does exactly that. Adds downforce with minimal drag.

Note that however, generally speaking, the lower the CD the less high-speed stability, but easier to get there.... This is why race cars and big wings have a lot of drag (.3x+) and the Lexus LS400 as an expample, has a CD of .26sh while F1 cars have .7-1.1 :EEK: The Lexus at 140 MPH is very floaty while the F1 car has thousands of lbs of downforce that would allow it to race upside down in a tunnel! :EEK:

A balanced aero design looks to get a good bit of downforce while minimizing drag. The NSX-R attained .32 (more drag than the .30 on the 2002 wich gained a few mph (172 or 175 vs 168?) in top speed and I think it large part of the R-wing. It mitigates it by having flatter undertray, the duct etc to get air to flow as smooth as possible over and under the car. Without those components, the drag would probably be much more, maybe .37+. This is why I have allured a number of times that the copy-cat R wings, unless they are absolutely perfect, may do more damage in drag than good. Each milimiter makes a difference imho (think hand illustration)

The post above me provides an excellent observation. One of the ways to test aerodynamic efficiency is to see how dirty the car gets at the rear (or anywhere. The smoother the air exits the vehicle, the less air and thus dirt will be pushing it.

The real question is still what SaberX stated - why didn't the NSX-R have it? I'm not sure still. Hopefully it's not because it's counterproductive but instead weight management. I would think/hope that if both produce downforce 1 + 1 downforce unit results in increased downforce, however, I haven't seen too many other cars do this :cool:

And again - the BMWs and especially the Mercedes (in the .26 range) use these in conjunction with flat undertray and small(er) frontal area to minimize drag while producing enough downforce for high speed stability.

A few couple of good links:
http://www.camaro-untoldsecrets.com/articles/rpo_d80.htm (don't diss the old school Camaros! :) )
http://autospeed.com/cms/A_107773/article.html (they even mention the NSX as a "very aero-sophisticated car!"

That's all for now.. gotta run to a meeting.:biggrin:
 
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Well, the top of the R wing isn't flat like the stock wing...probably designed to incorporate the job of both wings into one.
 
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I think I found out the answer to my own question... What do you think?
nsxrdf.jpg

Maybe. But if it does have a downforce as I suspect, I don't think 61/62 to 38/39 balance should make a difference.

If I would venture to guess it would be that the negligeble difference isn't worth the additional weight where every ounce (literally) counted...
 
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It adds downforce because it's slightly tilted (greater stability) some drag for the same reason. With that said, it may reduce rear turbulence and thus the overalldrag and maybe having a positive effect.

I've wondered myself whether the lip on the trunk lid adds or cuts drag. As slownsxt stated, it will increase downforce (decrease lift) at the rear of the car but I haven't found a clear answer as to whether it reduces drag.

On this web page, Honda lists the aerodynamic specifications of the 2002 NSX and 2002 NSX-R. As SaberX posted, the NSX-R has a coefficient of lift of -0.040 in the front and -0.060 in the rear. It has more downforce at the rear than at the front so the faster the car travels, the better the rear will stay planted to the road. Maybe Honda got the downforce they were looking for with the big wing and didn't need an additional trunk lip spoiler.

The standard 2002 NSX has a similar distribution of aerodynamic forces. The rear stays better planted than the front at high speeds. It has a coefficient of lift of +0.055 in the front and only +0.020 in the rear. In 1997, the German magazine Sport Auto tested an NSX in Mercedes' wind tunnel. They found that the pop-up headlight NSX had a lift of 8.02 kg at the front and 13.66 kg at the rear at 200 km/h. So the early NSX without a trunk lip spoiler had more lift at the rear than at the front. Maybe it's the trunk lip spoiler on fixed-headlight NSXs that cuts lift at the back to below the levels found at the front.

Now as to whether it reduces drag - I'd love to know. From all I've read, it probably increases drag a bit. But it might decrease it.

What's also interesting on that Honda web page are the drag coefficients for the 2002 NSX and NSX-R. For the regular NSX it's listed as 0.30 and for the NSX-R it's listed as 0.32. So in total, the aerodynamic changes made to the NSX-R give it more downforce but at the cost of higher drag. The front undertray, vented hood, and rear diffuser should all decrease drag. So the big rear wing probably increases drag noticeably.
 

BD

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NSX-R GT has both!!!
13449NSX_R_GT_Page_3.jpg
 
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