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R Theory V3 Diffuser

 
Old 07-25-2017, 03:44 PM
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Default R Theory V3 Diffuser

RTheory just released a group buy on their new V3 Diffuser what does everyone think. Looks like it should be pretty effective paired with a underbody and front splitter.




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Old 07-25-2017, 10:31 PM
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You planning on running the exhaust out the side like that? That's the only thing I'm worried about doing
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Old 07-26-2017, 03:33 PM
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Originally Posted by Goingnowherefast View Post
You planning on running the exhaust out the side like that? That's the only thing I'm worried about doing
You won't have to run a side exit exhaust like the one in the picture. The V3 will work with the majority of aftermarket exhaust systems that follow the stock exhaust routing.
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Old 07-26-2017, 04:10 PM
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Originally Posted by r_theory View Post
You won't have to run a side exit exhaust like the one in the picture. The V3 will work with the majority of aftermarket exhaust systems that follow the stock exhaust routing.
Do you have a picture of one running a stock location system? If so I'll literally sign up this second.
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Old 07-26-2017, 04:19 PM
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Can you post a pic of the diffuser straight on from the back
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Old 07-26-2017, 05:23 PM
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Originally Posted by Goingnowherefast View Post
Do you have a picture of one running a stock location system? If so I'll literally sign up this second.
Sorry not right now since I only bolted it up to my NA. This weekend I'll be bolting it up to an NB that has a Racing Beat Axle back. The V3 is an identical width to the V1, and the V1 fits between plenty of dual exhaust systems. The V3 will have superior exhaust clearance to the V1 since the V3 curves up around the area where the muffler sits. Versus the V1 which is a straight plane, so you either have to run a low diffuser angle or raise your exhaust if your muffler hangs low. I'll be sure to post pictures of V1's on this thread when I get the straight back pictures for Mat tonight. For the time being feel free to check out my instagram, I uploaded lots of pictures of V1's.
https://www.instagram.com/rtheorymotorsports/

Originally Posted by matrussell122 View Post
Can you post a pic of the diffuser straight on from the back
I'm heading to the car right now. I'll take some pictures when I get there.
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Old 07-26-2017, 11:05 PM
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Originally Posted by matrussell122 View Post
Can you post a pic of the diffuser straight on from the back
This diffuser is the first prototype. I should mention I made some minor changes to make assembly easier and much cleaner. The production version will look the same as this version for the most part. And sorry for the messy garage picture, I'll take more if needed outside when it stops raining!
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Old 07-26-2017, 11:19 PM
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Originally Posted by matrussell122 View Post
Can you post a pic of the diffuser straight on from the back
Originally Posted by Goingnowherefast View Post
Do you have a picture of one running a stock location system? If so I'll literally sign up this second.
As promised, here are some pictures of some customers running V1 diffusers with a stock location exhaust system. V3 fitment will be same at the exit. Under the muffler V3 clearance will be greater than the V1.

Also I'll mention V3 requires a mild bumper cut. Thankfully The Car Passion Channel just uploaded a youtube video on how to do a rear bumper cut!
You can find more details regarding the V3 here-> NA/NB Miata V3 Rear Diffuser Group Buy ? R Theory Motorsports



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Old 07-26-2017, 11:51 PM
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Can you quote some science here on the aerodynamics behind what this will do for my 2000 NB? thank'an you
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Old 07-27-2017, 02:41 AM
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Old 07-27-2017, 09:13 AM
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Originally Posted by Art View Post
I understand it's hard to do for several reasons but I wish places would give something like a lap time bonus or MPH increase when marketing these products. Then again I'm not sure I've ever done a cosmetic mod on one of my cars unless you count painting the wheels or fixing dents. Know your audience and all that.
I would lower the bar even further, how about testing with flow-viz paint to show any aero benefits? Or a video driving through low area with fog? There are so many easy ways to get aero data.

Why is a curved diffuser better than one with abrupt angle changes? It appears to make sense, but I know from my 2-stroke days and building pipes, that those pipes want abrupt angle changes into the expansion chamber and not smooth or curved into the expansion chamber. I have to think that rapidly expanding air, 2-stroke pipes and aero may be quite similar?
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Old 07-27-2017, 09:35 AM
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^Flow separation.

Why don't you guys do your own research instead of trying to dog a modification you don't understand.

If you don't understand how a diffuser lowers drag and increases downforce, you're unlikely to be his target audience.
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Old 07-27-2017, 09:41 AM
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Originally Posted by M2Ken View Post
I would lower the bar even further, how about testing with flow-viz paint to show any aero benefits? Or a video driving through low area with fog? There are so many easy ways to get aero data.

Why is a curved diffuser better than one with abrupt angle changes? It appears to make sense, but I know from my 2-stroke days and building pipes, that those pipes want abrupt angle changes into the expansion chamber and not smooth or curved into the expansion chamber. I have to think that rapidly expanding air, 2-stroke pipes and aero may be quite similar?
Smooth curved transitions keep the flow attached and keep drag low. An abrupt transition would likely produce more downforce, but at the expense of much more drag. The main attractiveness of a diffuser is a high L/D, so keeping it smooth makes sense.
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Old 07-27-2017, 09:55 AM
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Originally Posted by z31maniac View Post
^Flow separation.

Why don't you guys do your own research instead of trying to dog a modification you don't understand.

If you don't understand how a diffuser lowers drag and increases downforce, you're unlikely to be his target audience.
Diffusers | Engineering basics | Aerodynamics - Racecar Engineering

Just to get this thread back on track. The above are great links for aero. Kyle Drives has many good videos explaning aero that everyone exploring aero should watch. Race care engineering just buy the book its worth it.

I understand aero and the purpose and concept of this diffuser (I have been waiting for this release and will buy one) The intent of this threat were to discus the ascetics, shortcomings and where it excels. Its pretty obvious this is functionally better than the v1 and v2. I think it looks good especially for a bolt on part. As far as downfalls what concerns me is that without a full underbody air will still follow on the topside of the diffuser and get stuck in our parachute rear bumpers. Im hoping RTheory can chime in on this part even though i know he has underbody plans in the works. The one other thing that could be a concern to me is ground clearance for loading on the trailer or a steep hill.
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Old 07-27-2017, 10:22 AM
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I would like to point out that you participant ranges on the group buy site have a gap between 15 and 20 participants. I was also curious how many deposits have already been received. I am right on the fence so if we are looking at sub $300 I will most likely jump in.
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Old 07-27-2017, 01:59 PM
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Originally Posted by acedeuce802 View Post
Smooth curved transitions keep the flow attached and keep drag low. An abrupt transition would likely produce more downforce, but at the expense of much more drag. The main attractiveness of a diffuser is a high L/D, so keeping it smooth makes sense.
I deal a lot with incompressible fluids and venturi devices, and a diffuser appears to be nothing more than the diverging cone of a Venturi. Every Venturi has a straight slope with an abrupt change; you will never see a venturi with a curved cone. It isn't because they can't be fabricated. So while I agree a smooth transition makes sense, data doesn't always agree with what I think it should show. Or perhaps it works better, but simply isn't worth the effort?

I also know with 2-stroke pipes, the diffuser also needs to be an abrupt change. However temperature most likely is a factor here (related to compressibility).

I could purchase one and do some low-tech testing. However I have to think the market would be higher if the manufacturer did some low-tech testing as they have the product in hand. Unless of course it is simply an aesthetic device; but if that were the situation this site would suffer the same fate as clubroadster...
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Old 07-27-2017, 04:02 PM
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Old 07-27-2017, 04:42 PM
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Old 07-28-2017, 05:50 PM
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You guys ask great questions.
For the people asking if the V3 is designed for function or for aesthetics, we designed it with function and form in mind. We are limited to what tools we have to test the diffuser but I do have access to CFD software. With my software we can't give you values such as how much downforce is created at what speed. Although we can illustrate how fluids would flow around a certain object(s). Admittedly our software is somewhat elementary in its CFD features since we only own the entry level of this particular 3D CAD/CFD software, but it does a good job of representing how the air should flow.

I did some CFD testing on the older V2 and this is what I came up with. Take it with a grain of salt, in our software we're limited to 50 plot lines. So I had to lower the ceiling of the test area to an unrealistic height just to increase the density of the plot lines under the car. So the curve of the air from under the car will be a little milder in real life, but either way it does show that the diffuser is creating a low pressure region under the car. I'll post some similar CFD analysis of the V3 once I get some bugs sorted in my software!


I also did a CFD analysis on the V1 and wrote a blog entry about it on the website. You can check it out here. September 19th, 2015 - Miata Rear Diffuser CFD Analysis ? R Theory Motorsports

And someone asked why run a diffuser with a curved profile instead of a flat inclined plane. Both styles work but curved profiles work much better. With a curved profile you get a more gradual change in flow and the air stays attached to the diffuser's surface much more effectively. With a flat inclined plane it's much easier for the air to stall. When I was playing around with different angles on the V1 with our CFD software the air started to stall around 11 degrees; and this was with a flat undertray under the rear subframe. Without the flat undertray it seemed to be only effective up to around 7 degrees. With the curved rear diffuser we can run more aggressive angles without the air stalling. Despite this we will still be offering the V1 since not everyone is after max downforce. This way we'll have a diffuser for different needs.
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Old 07-28-2017, 05:51 PM
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Originally Posted by Ryan_G View Post
I would like to point out that you participant ranges on the group buy site have a gap between 15 and 20 participants. I was also curious how many deposits have already been received. I am right on the fence so if we are looking at sub $300 I will most likely jump in.
Fixed the gap

We're currently at 8 and we have a few more weeks to go. I would be surprised if we didn't hit 10 people/sub $300.
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