And thats even more of a reason not to down shift like that. This even applies for regular street driving....you get a flat...let it coast..

 

Since Bulletproof Automotive represents a number of companies that make rear diffusers and underbody components, Hunter is checking to see what options from among the various companies that, in their opinion, will be best for us to achieve our goals. We may end up using a front undertray from one company, while using a rear diffuser from another. I hope to hear something back from Hunter this week. I have also asked for any windtunnel test data they may be able to get their hands on. He thought TS might have some data from their widebody kit.

Ideally, for testing purposes, we can use a rear diffuser that comes with vanes, but without the vanes already attached, since the TS attachment seems to be permanent without any adjustability. I don't think this would be a stock item. This is an educated guess on my part based on my conversation with Hunter at Bulletproof Automotive, although I have not contacted Intense.

In a perfect scenario, we would be able to attach a standard off the shelf diffuser and have maximum downforce and minimum drag at all vehicle speeds. My SWAG is that this will not be the case, however. Nonetheless, we won't know until we receive test data related to this subject or we perform our own testing.

If the TS rear diffuser (which is made for the TS G35 wide body kit) can be easily modified to fit our stock bodies with the adjustability we would like for testing purposes, that may be the way to go. If the test data shows that the standard vane orientations are adequate for any vehicle speed, and we only need to adjust the mounting angle, that would make things easier and we can all buy off the shelf rear diffusers. Or, maybe, we can use the standard mounting angle and need only adjust the vane orientations. Although neither of these scenarious will be as easy as merely slapping on a stock diffuser, it would make tuning the aerodynamics easier.

In summary, IMO, all options are on the table until we have reliable test data.

 

I agree that it will be easier to modify the widebody diffuser for the standard body than the other way around. And on the same thought.....I do believe that it would be better to order it with the veins because its easier to remove it if it does not work than to add it if we really need it.

 

We will want vanes. For testing purposes, it would be easier to order the diffuser with the vanes, but instruct them to leave the vanes unattached. That way, we can attach them ourselves with suitable fasteners and make their orientation adjustable during testing. Cutting the vanes off of a rear diffuser may not be easy if they are epoxied in place, and we may end up screwing up the vanes and/or the diffuser trying to remove them.

I edited my previous post to try to make my thoughts more clear.

 

During testing I will keep meticulous notes with respect to the affectiveness of various diffuser geometries (angle and vane orientation) at various vehicle speeds. Assuming there are appreciable benefits to be gained from various diffuser geometries, I can generate tables that indicate the downforce and drag for each geometry at various target speeds.

We then would be able to use these tables to tune our diffusers for use at various tracks, depending on the speeds we anticipate we will be running in critical portions of the tracks. In Mike's case, we will try to identify the best geometry for running at 200 mph.

On that note, we should find out what measurement equipment is available at the place where we will be performing testing. Ideally, they will have equipment available to measure both drag and downforce. If not, we may need to rent some equipment. We may be able to rent some scales to measure downforce. If there isn't equipment available to measure drag, we can make measurements of upper and lower air velocities exiting the rear of the vehicle and note which geometries generate the most downforce while keeping the upper and lower air velocities exiting the vehicle appropriately matched.

 

for getting a good picture of aerodynamic properties most people use Computational Fluid Dynamics. if you can get a hold of that and build the model of the car on there you dont need to ever set foot in a wind tunnel and you have a pretty accurate picture of how the car performs aerodynamically. where to get this program though is the question.

 

Precisely, not to mention getting a file that is already setup for the body design of the G35. I would expect that manually creating such a file would take a monumental amount of time. Even if we found someone with the software and hired them to generate an appropriate software model of the G35's body, I expect that the costs will become prohibitively expensive.

Nonetheless, if you know of someone who will do this for around the same amount of money we will be spending on renting the wind tunnel, please let us know and we will contact them.

 

i didnt realize it but solidworks has CFD on it. i think Charles(phunk) mentioned he has used the program solidworks and uses it for making his manifolds.

 

Phunk, what would you charge to model our cars to generate the data we need?

Mike, I'm not sure if Charles is following this thread. If not, would you mind checking with him next time you speak to him about your other project? Again, it may be cost prohibitive, but it is worth asking.

 

WOW great info....They dont teach you this stuff in medical school for sure

I will PM Charles...I guess he is really busy getting my Plenum ready

Its great to have you all involved in this project...and I bet before its all said and done..we will have a few entering the event with me

 

shoot im taking classes that have nothing to do with this and ive learned so much about aerodynamics just on google and from this forum. but i while i was googling about how F1 teams go about setting up their aerodynamics, a car will not actually set foot in a wind tunnel until extensive CFD test have been run on the car. usually they only put the car in the wind tunnel for final testing with relation to how break heat, and other factors affect the air traveling past the car to get that perfect tune. for the most part though its all sorted out with CFD. also another thing to consider is that they use scale models when they put cars in the wind tunnel to do this one test i forgot what its called. but theres a bunch of chemicals involved that is mixed and it can help to reveal some of the patterns of the air flow.

 

Thanks for the info...

 

i dont think i am anywhere near skilled enough to draw a complete car in solidworks, it would take me months!

there is some type of laser scanning that manufacturers use, and thats probably the best way to get the car in CAD. i spoke to a body kit manufacturer who was mentioned that he had the car laser scanned into cad to draw the new stuff on... it was a 350z tho and im not sure if he scanned the entire car or just parts of it. it was the guy that did that Top Gun body kit stuff the forums ate apart when he released it... it wasnt my taste either but the guy was really nice, i met him because he had me supercharge his Z...

i would search around for soemthing up that alley or just getting in a wind tunnel. my boss had his viper wind tunnel tested, but he had an inside connection for that. im pretty sure most wind tunnels are up for rent

sorry i havent been following the thread, we have been so busy its insane... hardly even been logging in to check my PMs the last 2 weeks!

 

Thanks Charles..

I guess we will just go ahead and do the wind tunnel.


Now get back to work on my plenum

 

Have you guys considered five axis to do a 3d modeling of a g35? and possibly having them fabricate the rear diffuser? From their website, past projects, and from what i'ved read they would be able to tackle a project like this. However, i'm not sure they'd be willing to do private projects as they mainly deal with large car manufactures, but its worth a shot.

 

What do you think they would charge?

Also, please post or PM me their contact information. It's worth a call, even though I still think going this route will be prohibitively expensive.

 

You would have to have your car laser scanned and it is $, to make a g35 in Solidworks would take months to get it all 100% to spec.

 

That would definitely put it out of our price range unless we had a whole lot of people who want this and are willing to share the costs.

That said, everyone's input is GREATLY APPRECIATED. Keep the suggestions coming. There are alot of variables in this project and the best solution may still be out there and not yet discussed.

At this point, I think the best cost/benefit ratio will be achieved using as many off the shelf parts as we can and renting a wind tunnel. We have been presented some preliminary options for the front diffuser/undertray, and we need to look at them further.

For the rear diffuser I am leaning toward using TS rear diffuser with vanes, but ordering this with the vanes unattached so that we can make adjustments to their orientation. Of course, I would like to have a concensus from everyone participating in the project before placing the order.

Other than XKR, Alberto, George, RudeG_v2.0 and myself, how may people are seriously interested in going in with us on this project? If we do both 350Z's and G35's, we will probably need to test each body style independently, but hopefully we can use the same components. It just may take more customization for the G35's.

 

Mike I found and official wind-tunnel rendering of the G that may help



Look it even has "wind lines"....or maybe those are reverse speed lines



seriously can't wait for results on this beast....tom

 

Add Sharif to the list.....I am sure Raj also. There were a few others that wanted to join. I agree with you. We may have to start with the windtunnel and the TS diffuser. Sharif can get the info for us on the tunnel....

I also agree on the choice for the front....I spoke to a friend of mine that races fulltime...and is also a crew chief...He also owns a G and has stated that the G was well made and not to discount its high speed ability in its stock form. He feels that YES the car needs a rear and front diffuser....but the center is good to go because everything in the center sits in a tunnel or a groove and not out in the open. He made this statement also after looking at my car at the nissan dealer on the alignment lift that was specially made for the GTR. It gave him a true view of the car up in the air with the wheels sitting flat on the lift.