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WATCH: Easy and Effective R35 GT-R Aerodynamic Improvements!

Check out how we increased the downforce on our GT-R by 13% and reduced the drag coefficient all the way down to an amazing .25 with just a few simple bolt on parts. All CFD verified. 

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Comments
Darcyy
Darcyylink
Friday, May 25, 2018 3:30 AM
What material in the front diffuser made of? always wondered what the OE's use.
corn
cornlink
Friday, May 25, 2018 10:01 AM
Here we go again .... "cfd verified".... no wind tunnel and cfd data ever match and you should know this mike. How about pre/post coastdown and terminal velocity testing and suspension compression loading data to verify your CD and downforce claims...all i see are shiny parts on your car. I wonder how much you paid for these parts? hmmm. Where is the signal mike?
Mike Kojima
Mike Kojimalink
Friday, May 25, 2018 5:15 PM
@Darcyy, It looks to me like TPO.
Mike Kojima
Mike Kojimalink
Friday, May 25, 2018 5:22 PM
@corn, of course, usually if there budget wind tunnel testing is done and the data is used to adjust the math model for the CFD. If you are an OEM, in aerospace or work for a super well-funded factory works team that is. Let me ask you this, how many affordable aftermarket aero pieces have whole car CDF done on them? I can only think of the stuff by Verus. I did try to do coast down testing but with our traffic around here, I could not get any meaningful data because of interference from other cars. We have pretty heavy traffic, too heavy for clean air coast downs 24/7.
corn
cornlink
Friday, May 25, 2018 6:32 PM
mike, rollback to the original point of this site, to provide truth about what tuning parts provide real measureable function with objective methodology. So looking again at this advert, CFD is claimed but where is it? Why not show it, and there must be baseline OE CFD from an R35 vs the parts shown...right? Affordable has nothing to do with it. Its been claimed, so where is it? Secondly, your excuse for not having done a coastdown of baseline vs these parts is that "theres too much traffic".... not a valid excuse from any engineer. I am not going to argue all this anymore Mike, everything I came here for long ago has been swapped for sellout adverts and a sea of free parts for all the projects here. You have to look in the mirror at your own face. Enjoy schilling for your sponsors,its a good gig.
Mike Kojima
Mike Kojimalink
Friday, May 25, 2018 9:08 PM
@corn, do you see any advertising for Verus here? I would like you to come here to the LA area and try to do a coast down test from 100-60 at any time. Our industrial park roads are not long enough and the freeways always have too much traffic. Believe me, I tried.

Here is the link to the white paper on these parts with baseline to modified results if you wanted to research this yourself.

https://docs.wixstatic.com/ugd/0af162_3b117d0a497f42648c11de18a0e7af12.pdf

I would like to see any aftermarket aero parts company that has this level of engineering in their bolt-on parts. APR does CFD on their wing elements only but no one to my knowledge uses whole car CFD or uses a proper wind tunnel. A tube with a crude diffuser and a fan for smoke testing like what a JDM company used on a couple of their kits is not proper wind tunnel testing.

Conversely, it is very easy for you to say we are selling out and dispute data if you don't like something or chose not to believe it. What to expect me to do, hire an aero guy to do instrumented wind tunnel testing to prove that this product works? Would that satisfy you? That would be our editorial budget probably for the year. If you are willing to pay for it, I would be willing to do it and publish the results. We cannot afford that.

Think about that before you throw stones.
Paul Lucas
Paul Lucaslink
Saturday, May 26, 2018 8:26 AM
I did all the aerodynamic and CFD work on the Verus Engineering components. I can answer any technical questions you would like @corn. But first, let me explain how we engineer our components.

We use ANSYS for all of our analysis work whether it is CFD or FEA. ANSYS is in the top of the field for engineering analysis software and is trusted worldwide by large and small companies. It is also the top for CFD in motorsports along with Star-CCM and OpenFOAM. We use ANSYS Spaceclaim for our geometry preparation and to make the virtual wind tunnel domain. Then that model is opened up in Fluent Meshing where we mesh the model. Fluent Meshing allows us to get very good quality meshes on complex geometry which is critical. This is critical since poor mesh quality can lead to poor results and very poor convergence. The final mesh has around 20-25 prism layers that fully capture the boundary layer including the viscous sublayer. When just sciencing out new designs, I usually only have 1 cell height in the viscous sublayer and the turbulence model will model the velocity profile. However, on final designs, I fully resolve the viscous sublayer. The mesh counts vary from analysis to analysis. This model was meshed before switching to a polyhedral volume mesh and was done with tets. This means the volume mesh was around 40 million cells.

After a quality volume mesh is made, we switch to Fluent solver. This is where we set the physics of the problem like boundary conditions and turbulence model. The wheels are set as rotating walls to capture the wheels and tires. Actually, I am pretty sure the entire setup is in Mike's comment on our white paper. This analysis was still done using the SIMPLE solver however we have since switched to the Coupled solver. It takes longer per iteration but converges much sooner. We post-process both in Fluent and CFD-Post.

Also past that, we have had our analysis checked by one of ANSYS technical partners to make sure everything is good. We have also ran validation runs on different setups including the Ahmed model and the DrivAer model. Both have these have many wind tunnel and CFD comparisons from Universities that we have compared to with great results. Also, we have done coast down testing and strain gauge testing on our components to validate them in the real world as much as we can. As we do not have a shop car GTR, this, however, was not possible on these parts from us.

Also on wind tunnel testing. It has its place in aerodynamic testing just as CFD does. Both have strengths and weaknesses. Trust me, I would love to have a wind tunnel to test ride height sensitivities as this would be way faster in a tunnel. Or test wing angle changes. This is time-consuming to do in CFD. However, for development, CFD is a great tool as it allows visualization of the flow in ways wind tunnels cannot. Plus with the advent of adjoint solvers, optimization can be done in ways that would take engineers much longer to figure out. Both are experiments that hopefully make the vehicles go faster around the track.

Again, if you have any technical questions on what we did, ask away. We are pretty much an open book on how we do things. We just won't always give away the why.

Thanks,
Paul Lucas
i23sonny
i23sonnylink
Sunday, May 27, 2018 7:00 PM
For what it's worth. I'm still very much enjoying MotoIQ's content as I ever was. And I don't think this site is a 'sellout'.

Corn seems to be overly salty...

Cheers MotoIQ team, keep doing you.
Darcyy
Darcyylink
Saturday, June 02, 2018 11:54 PM
@MikeKojima What material would you recommend for a grassroots time attack car?
corn
cornlink
Thursday, June 21, 2018 7:28 AM
Paul - that is a dissertation on how CFD works. I am well aware. I review examples of it every week along with tunnel data, CAE, CSA etc etc. Do not lecture me on the value of any of these tools. Again - where is the proof of the gains mentioned? You dont have a baseline car vs new parts data set to show. So again BS. Stop with the excuses of we dont have enough cars and too much traffic to test etc etc. I am calling out the gains you claim. You cant back it up. This article is a sales advert dressed as engineering. End of story. keep cashing in.
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