Diffuser and Drag

[92StockMx3]

I was taking a look around my car to try and get some ideas of what i can do and couldnt help but notice the rear bumper and how it looks like it would cause a lot drag. Also remember someone putting signs of some sort underneath their car to help with that.

Did some searching around on here to see if from a near stock height if there would be a great deal of air potentionally getting trapped there. Went on reading people having different thoughts on if it would be worth it to make/invest in a type of diffuser. Some were saying unless your an inch or so away from the ground that would be where a noticeable effect would occur.

So looking at many peoples worklogs and what they have done, plus i've noticed some people with hondas would cut holes in their bumpers i tried to put some ideas together. Honda having a much bigger aftermarket/ following then MX-3's, that maybe theres been more research into that particular area, maybe not we've all seen the horrible ideas Honda guys come up with .

I'm not about to go drilling holes everywhere and what not but i was looking at the Euro front bumper and the holes for the foglights and thought what if i took either ports from a sub box, cut out the holes and insert the ports for a cleaner look. Thinking it might not work with the ports and the curve on the bumper to use a type of weatherstripping to clean it up.

Took a quick look on ebay and found http://www.ebay.com/itm/Universal-Rear- ... c6&vxp=mtr maybe that would work for what i have in mind. I'm probably just overthinking things like i always do. But since without a windtunnel test for any of the ideas its basically just trying and take a similar idea and convert it over. Now that i've rambled on for a while i'd like to hear some ideas on if the holes in the bumper would make a difference and if a diffuser would be a good way around the irreversible holes, or if thats more cosmetic that anything. Thanks for the input!

[Daninski]

Aircraft use vortec generators to create a vortec of air spilling off of the wing instead of air just spilling off the rear buffetting causing drag. that item on Ebay looks a little like what I'm talking about however one side of the fin has to have more area than the other side in order to create the vortex.
http://www.sigmaautomotive.com/performa ... ortekz.php

[Sleeper6]

I still plan on doing rear cutouts for my car and borrowing the fins from the evo mr (vortex generators) too

http://www.goldeneaglemfg.com/index.php ... Path=79_92

[fowljesse]

I am going to make an underbody piece like the one on my front. I have a side exhaust, so I can smooth it over completely back there. I believe it will make a difference for gas mileage, and for serious drag racers, it could shave off tenths. However, I think holes in the bumper on a street car are silly, especially if you have the core support, which would be stupid to take out. I don't know, but I think the holes would have no effect at all, with the support in. Unless it's tested, I think the Ebay diffuser wouldn't work any better than a flat sheet.

[wytbishop]

There is some gain to be found under the car I think. Based on the shape of the car I don't think we could ever generate any significant downforce but you could definitely improve flow under the car.

Cutouts in the bumper is not a completely terrible idea. Releasing internal flow into and area of low pressure is an excellent way of reducing drag. On properly optimized cars (racing, exotic, etc..) designers first determine the areas of low pressure and high pressure on the surface and that's where they put the inlets and outlets.

[Ryan]

Why do these threads keep coming up? This is number 3.

[Josh]

Why do these threads keep coming up? This is number 3.

+1


on another note I think I am going to put one of those diffusers on my roof.... It might give me the down force i am looking for under the hard cornering I do on the freeway on ramps...

[Mooneggs]

on another note I think I am going to put one of those diffusers on my roof.... It might give me the down force i am looking for under the hard cornering I do on the freeway on ramps...

How would you measure the gain? It's the same problem with the R+D on the bottom diffuser. Also the ones on the top of the car are vortex generators, not diffusers.

I think you will lose the clean lines of the mx-3 and have no gains whatsoever.

Yeah and why all the diffuser threads all the sudden? we might have to start laying down the SEARCH hammer again since we have alot of n00bs trolling about recently.

[Ryan]

Don't even bother with the search cry.


A diffuser won't work, barring all but a s--- ton of money or experience.

[Josh]

on another note I think I am going to put one of those diffusers on my roof.... It might give me the down force i am looking for under the hard cornering I do on the freeway on ramps...

How would you measure the gain? It's the same problem with the R+D on the bottom diffuser. Also the ones on the top of the car are vortex generators, not diffusers.

I would measure it with the G-sensor in my HTC EVO and my GPS tracking.... duh

Mark, I am completely kidding. There was supposed to be some sarcasm in there... I really wanted to keep it going but after the A pillar incident I cannot afford to look even dumber haha. what's really funny is that its true!..

But really guys quit with the diffuser threads there are several new enough to tack onto the end of. If you do it it is more for looks over function by like 90% looks 10% or less function and what ever is left over for hype to say that you have one on a FWD car.