Gauging Interest Rear Diffuser

[SunkenFRS]

Alright so i was not impressed by the 2 options out there for rear diffusers for our cars. So i decided to make one. Keep in mind i have a little knowledge with an architectual scale and some artistic talent, thats it. I originally planned to make this out of abs plastic however that turned into just my template as i wanted something more sturdy and will stand up to the exhaust temps as well. I have yet to make one out of aluminum however im talking with a few local iron/steel/aluminum fab shops about getting one made as i have a scaled down drawing of this one. Any criticism is welcome. Thanks


Test Fit

[Kimsey47]

Looks pretty awesome bro! Good work! Def fits the "Because Racecar" meme!

[Maverick22]

I like it, you should also make a panel that can attach to the front and reduce drag between the rear axles and the bumper/ diffuser.

[kALMIGHTY]

I think it would be cool if the diffuser followed the contours of the bottom of the bumper a little more instead of just a slightly curved "underline". It looks really good though.

[womensecks]

Um... yes please.

[boredom.is.me]

You sure that's not actually scooping up air? It doesn't seem to be in the area that actually needs the flat panels.

Otherwise, it looks good. A friend and I were thinking about making some for our cars. (He drives an E36.) I originally thought of using ABS. I'm curious to know if it would hold up.

[RehabJeff86]

Im interested, there r too many sharp angles, if u can smooth them out?

[FRSRAVEN]

It needs to extend farther underneath the car. Also, I think the angles are too sharp. I personally like the understated look of the Borla diffuser, but it only works with their exhaust. Now for a track car, I can see the merits of something a little more aggressive like the Driveway Labs diffuser, but for a street car, there has to be some kind of happy medium.

[SunkenFRS]

Originally Posted by Maverick22

I like it, you should also make a panel that can attach to the front and reduce drag between the rear axles and the bumper/ diffuser.

The one that will be made out of aluminum will have an extension on the passenger side only that goes further under the car and mount up to the rear sway bar similar to the driveway labs diffuser. The reason it can only be on one side is due to the exhaust on the right side. It's hard to try and come up with a solution that will fit most of the exhausts. This extension/mounting point should reduce some of the drag that it probably is creating. Also the whole diffuser will be more pushed in. I don't know if y'all have paid close attention to the under side but behind each wheel on the part that the fender plastics connect to the rear bumper their is a fin of sorts that comes down. I had to make a slit for the diffuser to sit flush. The slit will be longer thus allowing the diffuser to sit further into the car which should help with the subtleness of the diffuser itself. I still wanted something aggressive personally because my car is simple/clean otherwise and wanted to add some flare. Thanks for all the feedback so far

[SunkenFRS]

Originally Posted by boredom.is.me

You sure that's not actually scooping up air? It doesn't seem to be in the area that actually needs the flat panels.

Otherwise, it looks good. A friend and I were thinking about making some for our cars. (He drives an E36.) I originally thought of using ABS. I'm curious to know if it would hold up.

What I found was the ABS was too flimsy for something that is so long. The thickest Plastic sheets I could find locally were an 1/8 inch which is extremely thin for a piece going to be withstanding air turbulence. My friend made a small one for his MS3 for the center similar to the factory sti ones and it hold up but it's small and has a completely flush mounting point.

[Maverick22]

Originally Posted by SunkenFRS

What I found was the ABS was too flimsy for something that is so long. The thickest Plastic sheets I could find locally were an 1/8 inch which is extremely thin for a piece going to be withstanding air turbulence. My friend made a small one for his MS3 for the center similar to the factory sti ones and it hold up but it's small and has a completely flush mounting point.

a 1/8 would work if you made a metal frame for it to attach to, between the bottom of the car and the diffuser itself.

[SunkenFRS]

Originally Posted by Maverick22

a 1/8 would work if you made a metal frame for it to attach to, between the bottom of the car and the diffuser itself.

I thought about this as well however the dilemma you can't get around is that abs is petroleum based and is flammable, that's a problem. I could probably find some plastic that isnt flammable however it would be more expensive and still would require the metal 'backbone.' I literally took some scrap pieces, held a flame near it and it was melting/distorting and when I touched the flame it caught fire. No bueno for something practically touching the exhaust. Even considered having a metal 'heat shield' for the two exhausts port but the heat would still transfer and distort the plastic. When painted with engine enamel it helps a little but the end result is still the same.

[Wonderbar]

Good luck on this. I'm planning on a few more variants of mine. I'm curious to see how you handle a few things on it.

Let me know if you need any help.

[SunkenFRS]

Originally Posted by Wonderbar

Good luck on this. I'm planning on a few more variants of mine. I'm curious to see how you handle a few things on it.

Let me know if you need any help.

Appreciate it. Btw I completely respect the work you did with the driveway labs diffuser. There were just a few things I wanted to change