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Rear diffuser Ideas

22K views 25 replies 20 participants last post by  Blakbird 
#1 ·
So I'm about to start my repaint project on my supra and after weeks of looking the only rear bumper Ive seen with a nice diffuser is the Trial rear, however I dislike almost everything else about the bumper(the way it bolts on the sides, that random line under the license plate). I was/am still considering it but the thing that aggravates me the most about it is that depending on the picture the whole bumper either looks good or like crap, where as EVERY picture of the stock rear looks good regardless so I'm kinda torn about purchasing one. Does anyone know of a supra /universal diffuser that would fit the supra that doesn't look terrible? I don't really care for the shine one either.
 
#4 ·
^^ haha yours was actually one of the pictures I saw where I liked that bumper, but the two things I don't like are that cut line above the diffuser and how the bumper bolts on through the quarter panel adding an extra line. If I were to get it id wanna mold that line like vicious supra, and that pretty much means theres no going back. Where as I don't dislike a single thing about the stock bumper so I've pretty much talked myself into leaving the rear bumper alone.
 
#6 ·
I just got the Trial bumper myself. It looks more OEM to me, where the TS one looks very track/race inspired. I think you have to have a very aggressive styled car to make that diffuser work.
Orido's car is a good example of what that diffuser would match up properly with style-wise.
 
#7 · (Edited)
TNH the trial bumper is good looking depending on the color and angles sometimes. I dont really want to purchase something im only 50% sure about since I would be molding that bumper to the rear cause of those extra mounting lines I was talking about. And after it gets molded, it will cost alot to go back to oem. I was thinking more of a modern diffuser/insert like most sedans/coupes have. I didnt realize how common they are on modern cars until I wanted one, now every mb/bmw/hyundai/lexus/ etc has a rear diffuser inspired section of the rear bumper thats black and has a few fins or indents in it. That TS diffuser to me might have been useful on a race supra, but for a street driven supra it seems more tacked on then designed to be there. The trial diffuser looks like it belongs, I just have some reservations about the rest of the bumper.

I was thinking something more like :







 
#8 ·
Wow, I have been trying to find someone to do something exactly like this for a while now... something that would just work with the stock rear bumper but be much more streamlined than the current diffuser options (Top Secret or Do Luck... or Trial bumper)
I even referenced those same Evo and STi photos when gauging interest from people to make something, but haven't gotten anyone on board. I would be very interested in something like this if you come up with a solution.
 
#10 ·
Yeah Top Secret in CF gets my vote.
 
#13 ·
Honestly, I think all the supra diffusers look like crap, and they just looked tacked on there. Aside from the original TOPSECRET one which people say were wind tested, I doubt the replica ones have been and so all of the other diffuser designs are aesthetics over function and I dont even think they got that right. Since most of these supra diffusers were designed 10> years ago they dont look very modern or useful. Recent rear bumpers have the diffusers designed as like an add-on piece connected to the bumper, and I think I may end up going that route eventually, I just don't have the time unfortunately to take on another project with my own interior/exterior rebuild happening right now. Ill probably retrofit a simple diffuser on there from another car, temporarily to see if its even worth it. But im suprised not many supra owners have looked in to that, if you type in diffuser DIY alot of other cars(stis,lancer,rx7,subaru,mitsubishi) have a bunch of topics on other people making custom ones, granted there more for show then racing.
 
#14 ·
I will have to agree with you on almost all parts of that except for the wind tunnel testing of the topsecret. The Doluck one has had actual testing performed maybe not wind tunnel, but real world testing at least done so by the manufacturer. The topsecret one is arguable as far as testing goes. Ppl claim it has been real world tested just because Smokey Nagata has done over 200mph with one on his car. That does not tell you if it helped or hindered his performance in any bit. If you have seen a topsecret diffuser installed up close you will wonder how it is supposed to really perform as a functional aero piece. I have not found concrete evidence but from what I have seen there is a possible indication that the topsecret diffuser was never even truly designed for our cars to begin with. It is the exact dimensions of the one made for FD RX7's. On the supra it does not extend all the way to the rear subframe as one would have expected it to, making it a less functional piece. My assumption is that it was designed for the RX7 and then just adapted to the supra either for its looks or hopes of being as functional on our cars. I had talks with my old room mate Andrew Brilliant, a race aero designer and we both concluded that the topsecret diffuser does offer some slight benefits, but is more so a piece for looks rather then actual functionality. In the end you do what you like and for whatever reasons you want but I thought I would share my thoughts and experience with the topsecret diffuser so you could have a little more insight on it. When ppl that are not into cars ask me about the diffuser I still tell them it is for aerodynamics, but I feel like I am full of shit when I respond LOL. I stress that these are just my thoughts and experiences, but you should always confirm your own feelings about things rather then just trust some stranger on a message board like me. LOL
 
#25 ·
I agree with what Brian is saying. The Top Secret diffuser is all about looks. I would dare to say if the diffuser (any of them) isn't covering the whole underside, it's not going to do anything aerodynamically but create drag. With that said, I have a Top Secret diffuser and love it. All aesthetics though, but I don't care. :)
 
#15 ·
Yea I mean im going more for show then race with my own car right now, but I am just intrigued about diffusers because I never cared about one, until I decided on that trial bumper(before backing out of that decision) and then noticing that almost every modern car be it an SUV or a coupe/sedan has some variation or design cue of a diffuser on its back bumper now.
 
#21 ·
My supra has been in storage for a year and I dont think ive logged onto SF for about that long also...

PS: for LOOKS only with no performance benefit, I got a mitsubishi diffuser (I think?!? im shipping my car back to LA so I can actually drive it next month and see) and I had it painted gloss black and centered/attached it to my stock rear bumper. I remember it looking pretty good as a test fit. Whenever I get my car I might take a pic and post here. But thats still like a month and a half way so dont count on one soon.
 
#26 ·
I believe TwinZDesign is working on a Rear Diffuser setup for the MKIV. Their Z32 Rear Diffuser and Bumper with Integrated Diffuser look great blend very well with the car. Based on the stuff they have already made for the MKIV I'm sure a rear diffuser won't disappoint. The question is when will it be available.
 
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