R.Buffington

Has anyone else seen one for our car or am I the only one doing this? I've designed one in 3dparticular and now progressing to a cardboard test model

R.Buffington

3d software*

alnielsen

iTrader: (4)

I'd like to see what you got. I've seen one for sale, but it is a universal diffuser and not made for our car. The Abflug body kit rear bumper has a small one.

R.Buffington

No mine is a whole underbody in sections, I researched the perfect angle for the rear and such, spent a great deal of time taking multiple measurements. I can post pictures tomorrow when I get back on my computer. This is still in development but support would be appreciated lol

Arca_ex

iTrader: (10)

I'm definitely looking forward to pics. Sounds like a cool concept.

bse50

Nice! Did you go for a 4pcs complete underbody? (front - center L\R - rear) That's what i've done.
We modelled the diffuser with symscape caedium but had some problems finding the right angle\mounting points since the exhaust must be covered or "integrated" in the design. Since the first is cheap and the latter is not we obviously went for the first!

Looking forward to seeing the pics!

R.Buffington

So attached is the first design i came up with, always room for improvement. Criticism is welcome

R.Buffington

It is a 4 pc design, i did not include the front in this because I am not too worried about it now. This design requires that the stock bumper be modified a little bit by removing to lower part where the fake mesh is. The exhaust is covered, atleast mine is lol, and i was able to design around the optimal angle of 9.5 degrees out the rear

bse50

Space is your enemy here...
Think about the exhaust. Will the diffuser be underneath it?
Moreover, transmission and midpipe are on the way. It's better to leave them "Open", hence my 3\4 pieces underbelly comment

EDIT (Just read your comment)
9.5°? We ended up with an optimal angle of 12° but our idea was to use the exhaust itself as a hanger for the diffuser, thus making it "longer".
Very nice design anyway!

alnielsen

iTrader: (4)

With my laymen understanding of aero, it certainly looks like it will work well. Have you looked into how much your going to have to lower the car? Is this a design exercise, a one off for you or are you looking to produce it for purchase?

R.Buffington

All of the full underbody designs I came across had the entire bottom convered, there was a tunnel for the exhaust with a little extra clearance but it wan not "open". Leaving sections open would defeat the purpose of trying to enhance the airflow under the car

alnielsen

iTrader: (4)

My aftermarket catback is only using 2 of the 4 OE exhaust hangers. This leaves the front 2 available for just such a mounting point.

R.Buffington

My car has already been lowered 2.5 inches all around so i sit very low already, And this design was for me to show my skills and produce something I cannot find on the market. I have a few friends with 8's also that would be interested in it. If its successful I would like to market it. I have also toyed with the idea of using it to mold a cf version instead of having to weld all the features. Still, this design is only days old

bse50

That's partially true, the underbody will still be effective with the right sideskirts. The turbulence created does affect the airflow but does not completely kill the benefits.
The fact behind my suggestion is that our exhaust runs extremely hot and already heats up the transmission above a "safe" point when tracking the car. Even a couple of naca ducts and exhaust vents wouldn't be enough! You might even start a fire there.
Yes, welding 2 brackets to the silencers also works, or 2 tie rods bolted to the trunk's sheet metal

Now I see the 9.5° angle anyway, my car is less lowered than yours.

9krpmrx8

iTrader: (46)

Nice work, I wish I could use Solidworks.

Rotr8 is working on something similar and sifu has a rear diffuser already but no rear under body.

It's a nice concept but encasing the exhaust in it is not a good idea. A rotary exhaust runs much hotter than a typical piston engines exhaust.


Edit: bse50 summed it up.

bse50

Sifu's setup is only aesthetic with no benefits and only downsides though, lol!

R.Buffington

If temperature is an issue, additional air ducts can be created and incorporated into the design and the 9.5 degree is just the angle of exit above horozontal, my car doesnt sit at that angle lol

9krpmrx8

iTrader: (46)

True.

R.Buffington

That is true but I dont plan on keeping the rotary after it dies lol, hopefully hinson finalizes their swap design

bse50

The number of ducts necessary would make the setup open anyway! Plus you would have to make exhaust ducts anyway behind the radiator or you will cook your engine pretty fast.

I know that your car doesn't sit at 9°, i just stated that my car sits higher than yours so i had to use a different angle (around 12°) to make the diffuser effective.

9krpmrx8

iTrader: (46)

Yeah, you are about the 500th noob to make that statement and never back it up. Besides Hinson is allegedly a bunch of crooks (busted for having stolen cars in their shop), I doubt that kit will ever be finalized.

R.Buffington

EDIT I'm not a noob, if they dont have a design I can go elsewhere, with an engineering background im sure i could figure things out if i had enought time. I do plan on putting a piston enigine in my car for multiple reason just like i do plan on having a fully functional diffuser shortly. I shouldnt have to defend myself haha

9krpmrx8

iTrader: (46)

Don't take noob as a negative insult, it's just what you are for now. Everyone was a noob at one point and for now you are still a noob despite your educational/work background.

I am sure you could figure things out but I doubt you will. It's just one of those things, people come in all the time saying they are going to do this and that and 99.9% of them never do ****. The piston engine into the RX-8 is nothing new but I have yet to see a streetable RX8 with a proper piston engine and I highly doubt you will be the first person to do so. The guys from Pakistan (why I don't know) have done some swaps but they are seriously lacking in power, and fit an finish.

Take a look at all the threads started about doing LS swaps and then show me one that is actually running and being driven. The only one I know of that was even close, was trashed.

Highway8

iTrader: (11)

My post came in after others said some similar things related to heat.

Any and all underpaneling will help, it doesnt have to be perfect. Obviously the more you can cover and the smoother the air flow, the less drag and more downforce you will produce. But at what cost? If you cover the entire exhaust, you will be in for a world of hurt.

Heat sensitive components.
1- Engine. You need to get hot air out of the engine way. This is usually done out the bottom. You can and should panel under the engine with a louvered panel. This will smooth out the airflow and help evacuate the air past the engine, into the transmission tunnel area. Beat rush makes a nice piece. A little pricey and a little heavy, but a good design. Notice the S2 rX8's have a under engine panel. Adding a vented hood also helps get heat out.

2- Transmission. As long as you get some air passing by the transmission, you will be ok. But if you panel from the engine straight back accrossed the trans and dont let it breath, it will get hotter and could suffer. I suggest Naca Ducts to bring in fresh air at the bell housing, louvers under the trans and naca ducts post trans.

3- Differential. Even without underpaneling the diff will suffer from excessive heat if driven hard in excess of 30-40 minutes straight. This is largly due to the close prximity to the exhaust pipes. My suggestion and plan for my similar project is to leave the exhaust pipes open. This will create a tunnel for the air to flow through and keep the exhaust from cooking the diff and the underside of the car. I might even suggest going one step further and where possible actualy creating a half tunnel around the exhaust to smooth out the airflow. When the exhaust moves to the center of the vehicle, under the driveshaft, you could leave it open or cover it and use naca ducts to let air in and louvers or naca ducts to get air out. As the exhaust passes near the diff, I might had a heat shield to protect the diff. Not sure how much room will be in there, but its an idea worth looking into. You could also panel around the diff but not directlty under it. Again, need to physicaly get in there and see what space is available.

4-Lastly, the mufflers. The issue I have here is that if you panel below it you will trap in the heat and cook your trunk and bumper. I have 2 ideas both envolve the existing heat shield above the mufflers. You can either leave everything open under the mufflers and connect the paneling the one side of the heat shield and the otherside to the diffuser, or you add additional heat shielding to protect you bumper and panel under the mufflers using louvers to help heat/air escape. I like idea #2.

I plan to use a small guage aluminum. Only needs to be thick enough that I can wield in naca ducts and louvers.

For my diffuser, I have just gone with the mazdaspeed rear. It might not be the perfect diffuser but it is an improvement. Additionaly, is rounds off and raises the bottom of the rear bumper. Something adding a diffuser to a stock bumper wont do.

I look forward to see progress on thse projects.

9krpmrx8

iTrader: (46)

Talk about under body paneling



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