Looking for a few good candidates (And their money)

[Mikelly]

Jon Feel free to start one. I am interested in testing my car with my setup, which is not complete. I just received more supplies for the lower rocker design and I am also looking at another set of strut tubes to cut down for my front end to get it closer to tarmac. From there, I would welcome ideas on what others would be interested in.

 

Mark Icard is another candidate for testing as is Peej. I dont think any of the cars we are testing are going to be a true stock body car, so factor that in.

 

Mike

[JIM73240Z]

Ok folks.  If Matt does not want to "share" his information, that is his prerogative.  We do know that Matt is open with his knowledge and pics and if anyone is wise enough to notice changes in his car from the pics after the wind tunnel test, then he is "Sharing" his results with us in a round about way.  Numbers don't lie and if he puts something there it must be for a reason.  I hope to god Matt goes in on this thing, with or without sharing.  The knowledge gained would be awesome.  My goal is to drive out there this winter and drive on some east coast tracks and try to hook up with some of you and have a little info "sharing".  

 

Jimbo

[cobramatt]

Ok folks.  If Matt does not want to "share" his information, that is his prerogative.  We do know that Matt is open with his knowledge and pics and if anyone is wise enough to notice changes in his car from the pics after the wind tunnel test, then he is "Sharing" his results with us in a round about way.  Numbers don't lie and if he puts something there it must be for a reason.  I hope to god Matt goes in on this thing, with or without sharing.  The knowledge gained would be awesome.  My goal is to drive out there this winter and drive on some east coast tracks and try to hook up with some of you and have a little info "sharing".  

 

Jimbo

Jimbo,

I appreciate your kind words and hope most agree that I try and be as open as I can with anything concerning the car build. I'm in on the wind tunnel and don't mind sharing what we find that works, helps, hurts, etc....... I will say that I apply practical knowledge to my approach to aero. I am fortunate to know some aerodynamicist and fabricators for some pretty elite ALMS and Rolex teams. I asked if one of them I know fairly well and lives here in Georgia, would he come to assist me and the group at the tunnel, He said he would if his schedule permitted and that it would be $1,000 plus expenses for the day. That might sound like an extra expense we dont need but I wanted everyone to know we have that available if we see it is a value worth the $$$. He designed and fabricated the Cadillac LMP cars for ALSM and Le Mans and numerous other teams. In speaking with him, if I ever plan on really making my car aerodynamically slick (as what they consider a high downforce trimmed out race car), I would need to start all over. He likes what I have done to the car and can see how I reached the speeds and times at tracks due to certain items I've fabricated. However he reminds me, the fact still remains that I have a 40 something year old car that was not designed in a wind tunnel, not designed to have 600rwhp and do the things it does. He asks me simply,"What are you trying to do? What are you trying to accomplish? The car wins on track now, isn't that what you were trying to do?". I am interested in seeing the actual data and how the air moves across my car, in person, and be able to maybe generate some new ideas on what may assist me in improving my present set up. In my World Challenge Vette, Its a 2002 C5Z based platform, that was designed in a wind tunnel by GM. It has the baseline for massive improvements in bolt on aero due to the fact that it started its life in a wind tunnel. We will never be able to achieve this with an S30 but we can try and maximize our efforts and improve the cars performance by testing and R&D. I have often envisioned a flat bottom 240Z. If you go and try and smooth it out and add a diffuser it actually works against you. I don't need a wind tunnel to tell me that, I've tried it on the track. To make my car a flat bottom, a functional flat bottom, not a smoother undertray that works around all the crap that is under my car, it would actually require a total redesign of the car. Anyone can add panels under the car to make it look smoother and then a diffuser that looks cool that half the people that have one don't really understand what it really does, I would prefer to leave it alone and not have the extra weight.  I can say from practical experience that I try and understand the pitch sensitivity on my car as best I can, and the tunnel is not going to help with that. If anyone wants to road race their car and experiences the type of braking and acceleration my car generates, then my data might help. If you apply my data to your daily road car its not going to work. 

 

I have some pretty radical ideas as to how to improve my cars aero package. I just cant do it in the middle of a race season because I don't have enough time between races to make the modifications to the body panels and then get adequate testing done. I don't want to share it out loud until I have personally tried it out on my car (if I ever do), but I will say that it hasn't been done yet with one of our cars. 

 

I have an idea of exactly what I want to learn and test in the wind tunnel on my car. I will share the information gathered. If you decide it can help your project and want to apply it to your own build, I have no problem with any of that. The reason we all share our threads is to help one another. I hope that it helps in some way or another but be aware that we are all different drivers driving different cars with different set ups and in no way will we find a universal application in terms of aero that will apply to everyones individual needs. To say that a g nose helps the air move better across the nose because the wind tunnel data shows that to be the case does not mean that a g nose is a better application for a persons specific needs. 

 

I will say that we, MTI Racing, are presently fabricating a DTM body for a C6 Corvette. This series will be in the US in 2015. If there is any sports car series that can lend us an insight to what actually works and how different it is to what we all have, then this is the series. All the cars are relatively the exact same car under the different outer shells. The driver and outer shell (aero set up) are the only real variables that separate you from the rest of the cars. The downforce and aero packages on these cars are what you will be seeing more and more of as we move forward. If anyone is familiar with time attack here in the states, it also shares the same traits as these DTM cars. I guess now you know what I'm thinking when I say I have some radical ideas about how to change the performance of our cars when it comes to aero.........

 

Sorry for the rant.................

[JMortensen]

If you go and try and smooth it out and add a diffuser it actually works against you. I don't need a wind tunnel to tell me that, I've tried it on the track. To make my car a flat bottom, a functional flat bottom, not a smoother undertray that works around all the crap that is under my car, it would actually require a total redesign of the car. Anyone can add panels under the car to make it look smoother and then a diffuser that looks cool that half the people that have one don't really understand what it really does, I would prefer to leave it alone and not have the extra weight.  I can say from practical experience that I try and understand the pitch sensitivity on my car as best I can, and the tunnel is not going to help with that. If anyone wants to road race their car and experiences the type of braking and acceleration my car generates, then my data might help. If you apply my data to your daily road car its not going to work. 

I'm finding this very hard to believe in light of all the actual racecars that use flat bottoms. I would suggest that if there is a controversy, this would be easily proven one way or the other in the tunnel. I was kind of hoping that you would have a flat bottom since I think you're the most likely person to do it, but since it's just a wind tunnel the bottom doesn't have to actually be attached to the car, or at least not very well. I could see mocking it up with a couple pieces of plywood clamped to the rockers or screwed to nutserts installed on the frame rails or something like that, and if like I said in the other thread, the flat bottom was dropped below whatever hangs down then you could do a nice flat surface all the way back. Once you saw the effect, then maybe you'd know whether it was worth it to do all the mods to your car. I think the big obstacle is exhaust and side pipes is the answer to that. After that it should be relatively easy. 

 

BTW, with regards to the C6, have you seen hemipanter's Vette? Pretty badass: http://www.hemipanter.se/#Corvette Nordic Supercar

Edited June 8, 2013 by JMortensen

[cobramatt]

I'm finding this very hard to believe in light of all the actual racecars that use flat bottoms. I would suggest that if there is a controversy, this would be easily proven one way or the other in the tunnel. I was kind of hoping that you would have a flat bottom since I think you're the most likely person to do it, but since it's just a wind tunnel the bottom doesn't have to actually be attached to the car, or at least not very well. I could see mocking it up with a couple pieces of plywood clamped to the rockers or screwed to nutserts installed on the frame rails or something like that, and if like I said in the other thread, the flat bottom was dropped below whatever hangs down then you could do a nice flat surface all the way back. Once you saw the effect, then maybe you'd know whether it was worth it to do all the mods to your car. I think the big obstacle is exhaust and side pipes is the answer to that. After that it should be relatively easy. 

 

BTW, with regards to the C6, have you seen hemipanter's Vette? Pretty badass: http://www.hemipanter.se/#Corvette Nordic Supercar

John,

 

I find it relatively easy, as you put it, to write a paragraph about why don't we just use plywood clamped to the rockers to determine if a flat bottom works. Seriously??? I think that if you are trying to prove to me that a flat bottom car that is designed in a wind tunnel produces more downforce and is preferable over a vintage race car that does not have one is comical. I am fully aware of the advances that have been made in aerodynamics in the last 40 years since our cars were developed. I have raced LMP open cockpit cars at 200mph, I just drove a Crawford Composites DP car at two different tracks assisting a customer of MTI's in setting the car up and clearly understand how the underside of these cars balances the topside of the car and how they work together to keep the car from taking flight. I design and fabricate aero pieces at present for race cars, including my own. I will say this again for the record. Let me paste and copy what I said in my post......... (I have often envisioned a flat bottom 240Z. If you go and try and smooth it out and add a diffuser it actually works against you. I don't need a wind tunnel to tell me that, I've tried it on the track. To make my car a flat bottom, a functional flat bottom, not a smoother under-tray that works around all the crap that is under my car, it would actually require a total redesign of the car. Anyone can add panels under the car to make it look smoother and then a diffuser that looks cool that half the people that have one don't really understand what it really does, I would prefer to leave it alone and not have the extra weight.) Note that I said "MY" car, not just any car. I really am perplexed at your response........... (I'm finding this very hard to believe in light of all the actual racecars that use flat bottoms. I would suggest that if there is a controversy, this would be easily proven one way or the other in the tunnel. I was kind of hoping that you would have a flat bottom since I think you're the most likely person to do it). First I appreciate your thinking that if anyone would have one it would be me, but I don't. I wish I had the money to design an S30 in a wind tunnel from the ground up. Would it have a flat bottom? If the data showed that it was the best way to go then it would have a flat bottom. I assure you there is no controversy, I just don't see any reason to attach plywood to the bottom of my car in a fashion that would not exactly duplicate what I would actually have on my car on the track. Let me assure you that an engineer or aerodynamicist has never in the history of time just attached some plywood to the underside of a modern race car to see the data in a wind tunnel, when they use cad programs to design every piece on the car and simulate the aero in a virtual tunnel before they fabricate exactly the under-tray that is ultimately the best treatment for the car given the data supplied prior to ever even fabricating the first piece on the car.  I want my car to be as slick as I can. I would love to smooth out the bottom of my car and create more downforce, however, in understanding how an actual flat bottom tunneled car works, it would require a total redesign of "MY" car. I also understand clearly the advantage of power to weight ratio's and would prefer my car to be as light as possible. I constructed the front splitter, the side skirts and the wing to help air lay on top of them at speed and through practical, on track application, I have found them to be helpful to me. 

 

John I am the guy who will hire another, much more accomplished, pro driver to drive my car just to hear his feedback and use all his data to improve my track time by 1 second. I want to make my car the fastest and most fun to drive 240GT car on the planet. I never take a position that I have achieved my goal and there is nothing more to learn, as I try and remain teachable and learn new things that might help me in some way. I do not want to be the guy that spent $500K to redesign my car in a wind tunnel. The definition of HybridZ is what each and every one of us has already achieved and the limit will never be reached. When I got my first 240Z in 1978, it was a '72 and only a 5 year old used car, I was hooked and have never looked back. I hope that you do not take my comments to be an attack on you personally but if you want to see the rewards from a total redesign and flat-bottomed "tunneled" z car, I suggest you build one. If you want to pay for it, I'll build it with you. 

 

If we ever wanted to invest in something that would be the most advanced and cost effective way to actually achieving what could be the Ultimate HybridZ then Virtual software would be our answer. There are ways to actually scan your present car in 3D and then run the programs to help answer the questions none of us really have the answers to. I think it might be wise to at least do the due diligence and determine the cost of this approach versus the cost of taking all our cars to the actual wind tunnel. If I had this program I think I would never leave my desk.......... Here is an example of what I'm referring to. 

 

http://www.autospeed.com/cms/A_109131/article.html

 

There is a saying that is as old as motorsports itself and really sums everything up................."How fast can you afford to go". 

[JMortensen]

I assure you there is no controversy, I just don't see any reason to attach plywood to the bottom of my car in a fashion that would not exactly duplicate what I would actually have on my car on the track. Let me assure you that an engineer or aerodynamicist has never in the history of time just attached some plywood to the underside of a modern race car to see the data in a wind tunnel, when they use cad programs to design every piece on the car and simulate the aero in a virtual tunnel before they fabricate exactly the under-tray that is ultimately the best treatment for the car given the data supplied prior to ever even fabricating the first piece on the car.  I want my car to be as slick as I can. I would love to smooth out the bottom of my car and create more downforce, however, in understanding how an actual flat bottom tunneled car works, it would require a total redesign of "MY" car. I also understand clearly the advantage of power to weight ratio's and would prefer my car to be as light as possible. I constructed the front splitter, the side skirts and the wing to help air lay on top of them at speed and through practical, on track application, I have found them to be helpful to me. 

 

The reason to do it is to see what the results are before you go and redesign your whole car. If the effect is good enough, it might be motivation to go for it and really make that sort of change on your car. Have you ever heard of Simon McBeath? He does the Aerobytes column for Race Car Engineering and wrote Competition Car Aerodynamics and Competition Car Downforce, and he tries stuff on the fly in the tunnel all the time. I've never seen him test a whole floor that was plywood, but he makes parts from cardboard, wood, etc and tapes them to the car to test in the tunnel. Seen articles where he modifies fenders with cardboard, blocks off grill openings and ducts with cardboard, cut holes in fenders with a cutoff wheel, carboard extensions on diffusers, etc. He has done that kind for years, check out some of the old back issues of RCE and you'll see what I'm talking about. He also does CFD and has a company that manufactures wings. I remember Hot Rod Magazine did a LSR car and they had all kinds of crap taped all over it, including the airdam and the hood scoop. After optimizing in the tunnel and then actually mounting the parts, it ended up going 250+ mph and they were able to get the Cd from something like .5 to .22 on their late 60's Camaro. Halfassing it in the wind tunnel makes sense because you can see what works before you put the time and effort into making it permanent. That's the beauty of the wind tunnel.

 

I'm just making suggestions, and it seems like there is a lot of pushback and I'm not understanding why. FWIW though, I've seen flat floors on cars that weren't designed for them and it's not as impossible as you're making it out to be, especially with as much ground clearance as you have. Chris Rado's AWD Scion comes to mind. It had a dropped panel that was probably 4" lower than the floor to avoid all the drivetrain crap underneath the car, and to get the floor down to where it would actually do some good. You or anyone else could fairly easily attach plywood to the bottom of the car to create a flat floor, test it, then take it off and have maybe a few extra nutserts in the chassis or something like that. That's the beauty of the tunnel. It doesn't have to be "right", it just has to be there, and this piece would be easy because it is flat. Anyone could make a flat panel the right shape in 1/2 hour with a jigsaw, then it needs only to be mounted it in the most rudimentary fashion to the car. Do a very simple diffuser, just a 7* angle and see what happens.

 

As to the applicability of this idea to your car, it appears to me that you have plenty of room to drop a floor down to 2 or 3 inches off the ground. If you ran droop limiters you might even have enough clearance to go under all the suspension arms. The windspeed in the tunnel is 80mph as I recall, so I don't think you're likely to be developing huge amounts of downforce. 

[JMortensen]

Here are some pics of the Hot Rod test: http://www.hotrod.com/techarticles/body/113_0703_car_aerodynamics/photo_02.html

 

And the article:

http://www.hotrod.com/techarticles/body/113_0703_car_aerodynamics/viewall.html

Edited June 9, 2013 by JMortensen

[Chris Duncan]

 I have often envisioned a flat bottom 240Z. If you go and try and smooth it out and add a diffuser it actually works against you. I don't need a wind tunnel to tell me that, I've tried it on the track. To make my car a flat bottom, a functional flat bottom, not a smoother undertray that works around all the crap that is under my car, it would actually require a total redesign of the car.

 Nice post, good info

 

 

Why does an undertray and diffuser work against you? What does it do wrong?

 

What would have to be redesigned on a 240Z to make it work?

 

 

I may have something to donate to this cause in the near future.

[cobramatt]

 Nice post, good info

 

 

Why does an undertray and diffuser work against you? What does it do wrong?

 

What would have to be redesigned on a 240Z to make it work?

 

 

I may have something to donate to this cause in the near future.

Chris,

 

I would love to make my car flat bottomed. I would however approach it in a way that the underwing and diffuser actually worked and didn't resemble a flatbottomed car. I see loads of people who attach panels to the underside of a car, I see people buying diffusers all the time and not actually realizing that they are not doing anything but adding weight and drag to the car. The purpose of the diffuser is to allow the air that has been accelerated by the front splitter and undertray and due to that air being accelerated it creates a lower pressure area under the car and causes downforce to occur. The diffuser decelerates the air back to as close to the same speed that existed in front of the car originally. If a diffuser is designed in a wind tunnel or in a CMG virtual program it can then maximize the downforce and create less drag for the underwing. I point out that the undertray or flat bottom is simply much more than a large piece of plywood attached with clamps to the underside of my car. Thats fu@#ing stupid...........Could I redesign the underside of the car and create a functional flat bottomed underwing that had a functional diffuser. Yes I could. Do I have the time and money to undertake such a project, NO. I also contend that I am having a real problem with certain individuals that have all the advise of an armchair quarterback and no real practical sense of what is involved in actual application. I also wonder why does this data actually matter, when no one really has the need for such data. There are maybe a handful of people on the planet that actually would benefit from a functional tunneled undertray and diffuser for a 240. If you take that myself and only a few other individuals actually race these cars in a division that no build rules apply, anyone racing in any vintage division could not do anything with this data or application. At present, if I can get my car to the finish line in a 1 hr sprint race without something breaking I usually have a good chance at winning the race overall. That's really difficult to do and very satisfying when it happens, however if I were to redesign the underside of the car and do all this work and pay for it all, just so we can go to the windtunnel and a few curious people can see the data, well once again I see that as a waste of my time and money. An old saying is that "The juice is not worth the squeeze". If I had an unlimited amount of money and I really thought that this would make a difference worth the investment, I would probably do it. If I had an unlimited amount of money and could do whatever I wanted I probably would be racing at LeMans next week and not on Hybrid Z forum.

 

If I were to spend money wisely and do the next step in the evolution of my car and do something I know would make it even more competitive is the suspension and brakes. I am presently working on fitting adjustable shocks and a MTI Racing big brake kit off of one of our Corvette race cars. That would be the wheel hubs and all. Just take the geometry that already works and I am familiar with and make it work under my Z car. The need to stop my car, to take it deeper into turns, to keep the brakes functional for longer periods of time, to make it stronger, smoother, more stable, better balanced, adjustable, etc.... You get the picture. I assure these items are 100% more important and relevant to my build than trying to attach plywood to the bottom of my car in a windtunnel.

 

If anyone disagrees with me, I am no stranger to confrontation or controversy, I support your decision to take your car and your plywood, at your expense ($425 hr) to the windtunnel and supply me with the data.

 

For the record............."I've been told that I'm really a nice guy in person".

Edited June 9, 2013 by cobramatt

[Chris Duncan]

 

 

 

 

 

That's a lot of words for not really answering my questions.  ;>)

 

""I would love to make my car flat bottomed. I would however approach it in a way that..... didn't resemble a flatbottomed car.""

 

this makes no sense to me.

 

""I see loads of people who attach panels to the underside of a car, I see people buying diffusers all the time and not actually realizing that they are not doing anything but adding weight and drag to the car.""

 

I don't see very many people doing this. Of all the build threads I've read in the last 7 years I think there are 2 that did underpanels.

 

Assuming you are talking about aftermarket diffusers, my main question is, you say they don't work, WHY do they not work?

 

I understand the concept of an aftermarket part that has no benefit and in fact may be detrimental. Like a front strut brace with big kinks in it is doing nothing for rigidity. But you haven't explained what makes these bad diffusers and underpanels bad and you haven't explained what makes a good underpanel/diffuser work properly.

 

"" I point out that the undertray or flat bottom is simply much more than a large piece of plywood attached with clamps to the underside of my car. Thats fu@#ing stupid..........""

 

The concept of plywood is just as a mock up. I don't see why plywood if it was done right wouldn't work for the flat areas of the under panelling. I've seen a RUF underpaneled Porsche, it was completely flat to behind the rear axle. The diffuser section after that curves smoothly upwards, I don't really think it's rocket science. Seems to me that was what a Ford GT looks like also, nothing all that complex.

 

"" I also wonder why does this data actually matter, when no one really has the need for such data. There are maybe a handful of people on the planet that actually would benefit from a functional tunneled undertray and diffuser for a 240.""

 

Define benefit. By this definition nobody needs a hybrid Z, it's just being done for the sake of doing it. I want a Z with a flush bottom and a functioning diffuser. I'm never going to race but I just like the idea of having it. Heck I might want to go fast and it would be nice to have solid functioning aerodynamics.

 

I think a lot of people benefited from the last wind tunnel test, don't see why that couldn't happen again.

 

Just an FYI, Solidworks has CFD software embedded, even in the base version, and it's not that hard to use. It would take a while to accurately model a Z but it's probably already been done.

 

 

 

 

 

 

Edited June 10, 2013 by Chris Duncan

[JMortensen]

 I see loads of people who attach panels to the underside of a car, I see people buying diffusers all the time and not actually realizing that they are not doing anything but adding weight and drag to the car.

So am I correct in asserting that the reason you are so virulently opposed to the flat bottom idea is that plain old flat bottoms with plain old diffusers don't work? That seems to be the only line of reasoning to answer Chris's question. 

 

In Competition Car Aero McBeath used CFD on a NASCAR model to simulate a flat pan under the engine and cabin. No diffuser, no wing, not even a splitter. Just flat panels starting at the nose and continuing under the engine and cabin on an otherwise non-optimized car. Panels stop at the rear suspension. Result: 6.5% increase in downforce, 1% reduction in drag. McBeath also said in an email to me that I should panel as much of the underside of my Z car as possible, even if I could only get the engine compartment done. The email is in my splitter/airdam thread if you're interested. 

 

In Race Car Aero Katz examines a 1991 RX7 GTO car with flat floor and simple 6 degree diffuser and says that the published L/D for the car was -.3 to -.4, which is much better than anything that went through the wind tunnel last time. He also says that with a little more attention to detail and room to maneuver with an open ruleset it probably could have generated -1. In looking at this book again, it must be where I got the idea for the diffuser fed with a duct opening in front of the rear tires, as he describes air rolling under the RX7 and increasing the performance of the diffuser. Damn. I really thought I came up with that myself. He didn't describe fences on a flat bottom to make a venturi though. I think that one is an original...

 

I've read other books on aero, but these are the ones I own and can check right now, but so far I'm 2 for 2 in general principle. Obviously I can't make you do anything and I don't want to, but your irritation with my line of reasoning doesn't seem to be an appropriate response to the way I'm approaching the subject and doesn't really fit with anything I've read re: aerodynamics. 

[Mikelly]

So the title of this thread was "Looking for a few good candidates and their money."  I've not started to collect donations for this effort yet, and I'd be just fine with not collecting donations.  Jon, You seem like you're hell bent on dictating what we will and won't test.  For the record, Matt's comments above MIRROR those of the wind tunnel operator during the last test.  Now he didn't write a book on competition car aero, but the guy works in a windtunnel every day with ALL the NASCAR teams located in the region.  His comments were simple.  it's a dirty unibody chassis that was NOT designed for the advances seen in current auto platforms.  likeing a 40 year old platform to a tube chassis nascar platform is a waste of text so lets just stop with the comparisons. 

 

 

Now, Matt and I, and others who are willing to spend the money and time to roll their cars thru the wind tunnel will take ideas and suggestions, but quite honestly, unless you want to get a group together and run your own tests, take the hint and back off on an idea that those conducting the test aren't hot on wasting valuable time to try.  I'm not saying there won't be flat bottom panels associated with my car or a difuser.  I am actively in the process of welding Dzeus fasteners to the chassis this coming week.  I plan to fabricate an NUMBER of aero ideas that I plan to try, just to collect the data.  Give us a chance to come up with our OWN plans since we will be the folks spending OUR OWN MONEY.  Matt Isbell is doing more with this chassis than anyone else I'm aware of.  I'll defer to his judgement any day and twice on Sunday.

 

Chris, to your comments, I believe Matt was referring to what he sees any given weekend on other platforms.  And if you follow any of the aero articles in GRM, you'll see those examples displayed.  You are a smart guy, and you know well that what sometimes seems like a good idea in theory sometimes falls flat.  So the point is that we will have very limited time in the tunnel.  As with last time, we'll need to be practical in our approach.  i'm not certain that we'll be able to pull off a number of verying and difficult tests while collecting data that each of the car owners needs for their specific application as well. 

Edited June 10, 2013 by Mikelly

[JMortensen]

I've got bigger fish to fry today guys, should have a new baby here in a couple hours. Suffice it to say that I'm in no position to demand anything of you, and that you're in position to ignore me if you so choose. I only persist because I think you're wrong, just like I thought the wind tunnel operator was wrong that splitters and rad ducts don't work on Z cars. I will donate if given the opportunity, and I will read through the numbers after the fact like a kid on Christmas morning.

[Mikelly]

^{The wind tunnel operator was the reason my radiator IS ducted and that I have my front end configured the way it is.  I think something was lost in the translation somewhere, but everything he advised I took to heart and am trying to translate onto my own chassis.  I WILL try the front, mid and rear panel closeouts on my car if possible, if for no other reason, than to put this discussion to bed once and for all.}

 

^Mike

Edited June 10, 2013 by Mikelly

[JMortensen]

Wife is on a monitor for a couple hours. Past this point I'm just going to back off and throw some money at you guys. 
 

http://forums.hybridz.org/topic/55913-windtunnel-testing-the-datsun-s-30-z/

 

Me: I know you guys were keen on blocking the open space between the air dam and the rad core support. Was there any attempt on any of the cars to seal the top of the core support to the underside of the hood?

 

You: Jon M., We didn't test any advanced airboxed. We tried to stick mostly with basic stuff.

 

You again: Well lets backtrack to the other comment you made for a second... You're worried about an extravigant sheetmetal box for the radiator, but you missed the whole section on how the radiator only needs 2X4 inches of space to stay cool... That sheetmetal "box" is probably effective at doing that, but probably isn't as big of an aerodynamic aid as you might think, so you have to think in different terms there.

 

Me: I'm not sure you're getting the point of the box. It isn't only there to limit the amount of air coming into the radiator. That is it's less important purpose. It's more important purpose is to eliminate the pressure from the underside of the hood. And this ties in with the other question as well, about sealing the core support to the hood.

If you have positive pressure inside the nose of the car and have not sealed the core support to the hood, then presumably just as the air can go down underneath the airdam under the car, the air can also go OVER the rad core support and through the holes in the core support as well. This will increase the amount of pressure under the hood.

If one were to do the box structure and seal the hood to the grill area so that all the air that went into the box went through the radiator, then you'd get a couple of benefits. You guys already showed that cutting down the amount of air is beneficial. In addition though, you'd cut down the size of the pressurized area in the front of the car. In fact, you could probably get negative pressure in the front hood area above the box. Negative pressure under the hood, coupled with the pressure of the air being diverted over the hood = more downforce, and that's why you see so many race cars using that type of radiator duct. If memory serves I think preith has this type of setup on his car, with a sealed box and a much smaller inlet hole for the radiator.

Here is a link that describes what I'm talking about from a circle track magazine: http://www.circletra...ch_definitions/

The magazine article has some flaws, but the article estimates a 180 lb downforce gain from this type of box. It also talks about using a wide airdam to suck air out of the fenderwells.

 

You: Jon, No. Not according to Bob Smith. His comments were that you're going to get air packed in under the hood... There's no getting around it. Sealing off the nose of the car in general, like Roddy Sugg's car does, is an effective way to deal with the area at the mouth of the car. Look at the test data for #28, along with the other data for closing off the grill in other tests...

Also, remember, air is exiting the radiator/fan assembly at 15mph. You're travelling a lot faster than that (we hope) and what does that create? An area for air to pack up and create lift. Forego the whole "Aerodynamic downforce" theory of yours for a moment and think about just closing off that gaping hole in the front of the Zcar, known affectionately as the "grill". Do that, provide minimal feeding for air, and then funnel that air to your radiator however you wish, via ducts, tuning, sheetmetal/plastic radiator box, or whatever. Just remember that the air isn't travelling any faster than that, which means the larger that opening, the more air is getting caught there... and remember the first lesson we passed on from our friend Bob Smith. What happens at the very front of the car will impact everything else along the way... Total package, JM. Total Package!

 

Me: I think I'll have to disagree with Bob on that point then. I don't think you'd see so many race cars from so many different classes doing the same thing if there were no point. The opening to the box I'm suggesting could be whatever size you want to get a very small frontal opening. 

This is very similar to the point you guys proved about sealing the air dam to the core support. That prevents air from spilling out UNDER the radiator. The box prevents air from spilling out OVER the radiator and through the holes in the core support. And if you have a LOT less air in the engine compartment you might just make a low(er) pressure area under the hood, which translates to more downforce.

 

You: I won't debate "IF" a box would have worked, since it wasn't tried. But Bob Smith has tested hundreds of cars, and his insite was amazing. All these boxes on these cars could very well be tested, or could very well be something people "Think" is a good idea. Until we test them, I'm listening to the man that does this stuff for a living. he wasn't wrong pretty much every recommendation he made... choice is yours to trust a pro. I am.

Edited June 10, 2013 by JMortensen

[JMortensen]

d/p

Edited June 10, 2013 by JMortensen

[Mikelly]

Right... MY radiator doesn't HAVE the core support that MOST Zcars have.  THAT is the point in all of this.  My car is vastly different from a stock chassis and that will alter everything in my tests.  Bob Smith told me exactly what you posted.  He also told me that i would require a box based on all the sheetmetal I was MISSING from my chassis.  He was very specific in his point that you WILL pack in tons of air under the hood and at a point, it fills to capacity and you won't be able to extract it.  It's the same exact effect as having the windows rolled down inside the car.

 

Goodluck with the impending stork visit.

Edited June 10, 2013 by Mikelly

[Mikelly]

Guess your fish aren't that big since you posted all that back and forth, which clearly took lots of time... Here's a tip.  We all know you have to be the smartest guy in the room all day, every day.  Every thread you're in... we got it.

 

Go have your baby.  I think your water just broke. 

 

I've got bigger fish to fry today guys, should have a new baby here in a couple hours. Suffice it to say that I'm in no position to demand anything of you, and that you're in position to ignore me if you so choose. I only persist because I think you're wrong, just like I thought the wind tunnel operator was wrong that splitters and rad ducts don't work on Z cars. I will donate if given the opportunity, and I will read through the numbers after the fact like a kid on Christmas morning.

[cobramatt]

Guess your fish aren't that big since you posted all that back and forth, which clearly took lots of time... Here's a tip.  We all know you have to be the smartest guy in the room all day, every day.  Every thread you're in... we got it.

 

Go have your baby.  I think your water just broke. 

I'M HERE TO TELL YA, THAT'S DAMN FUNNY RIGHT THERE..............

 

 I don't want to be all long winded like Chris pointed out so I'll be brief.............

 

Chris Duncan: You don't have the slightest idea of who you are talking to or what you are talking about. Your quote ( I want a Z with a flush bottom and a functioning diffuser. I'm never going to race but I just like the idea of having it. Heck I might want to go fast and it would be nice to have solid functioning aerodynamics.) I'm glad that "Heck" you might want to go fast one day. You sound like a teenager who has gotten his first car and wants to make it look cool. I don't have any flat bottom on my car and its probably one of the fastest 240Z race cars on the planet, so what would I know about going fast or winning races or NASA and SCCA Championships. For the record I've won 6 in a Z car. So like I said, what would I know??? The reason you don't understand my comments is you don't understand the questions you are asking. 

 

Jon:  I would love for my car to have a functional underwing and diffuser. I do not have the money nor the time to pursue that fabrication right now. Do I think it would work, yes. Do I think it would be worth the time and money to design properly, fabricate and install, NO. Do I feel there are other items I can address on my car presently that could give me more bang for my buck, without question, YES. It is just not a priority for me right now. 

 

Items that will reap larger returns: 

1. larger calipers (hence bigger pads / more surface area) possibly adding ABS

2. better and bigger rotors

3. stronger / larger wheel hubs

4. adjustable coil overs

5. tube frame chassis

6. more and more weight reduction

7. better rear end (9inch ford or curry)

 

These are the items that I feel are of more importance to me.

 

Lastly...........I think it is interesting that you know I have all this practical knowledge and hands on experience and I find out tonight after reading Mike Kelly's post that the gentleman who runs the wind tunnel, the guy that certainly knows more than any of us, said the same thing that I did about the underside. I don't mind being questioned or challenged but knowing what I said and what a guy who runs the wind tunnel said about the under-tray are identical yet you still push your agenda. 

 

Lets please return to the topic of this thread and organize and mobilize the crew that will make this event happen. 

[Chris Duncan]

Chris Duncan: You don't have the slightest idea of who you are talking to or what you are talking about. Your quote ( I want a Z with a flush bottom and a functioning diffuser. I'm never going to race but I just like the idea of having it. Heck I might want to go fast and it would be nice to have solid functioning aerodynamics.) I'm glad that "Heck" you might want to go fast one day. You sound like a teenager who has gotten his first car and wants to make it look cool. I don't have any flat bottom on my car and its probably one of the fastest 240Z race cars on the planet, so what would I know about going fast or winning races or NASA and SCCA Championships. For the record I've won 6 in a Z car. So like I said, what would I know??? The reason you don't understand my comments is you don't understand the questions you are asking. 

 

  I didn't mean for this to be a hostile exchange.    And it's pretty easy to see who you are, after all you made a video of a race day. A lot easier for me to see who you are than you to see who I am.

 

You described what a diffuser does, I already know that. You've asserted that the ones you've seen (at the track) don't work.

 

My questions, that you haven't answered, are, why do they not work, and what would it take to make them work?

 

I just love it though, and it really feeds my drive to succeed at something, when someone says something won't work or I don't know what I'm talking about. So keep it up, it has positive effects.

 

I've been building cars from scratch for 25 years. I was wrenching on Z's before you had a drivers license. I don't know why these aftermarket or scratch pans and diffusers don't work and I was asking someone I thought might know. But even race car drivers don't know everything I guess. That's disappointing, I thought they were omnipotent.

 

That's okay though, I'll figure it out one way or another.

 

I invested in Solidworks (with CFD) a long time ago. Pretty sure I can dig up a s30 solids file. I'll spend some time with the Z aero and get back with you guys.

Edited June 11, 2013 by Chris Duncan