Guest Frank Rich Posted June 28, 2001 Share Posted June 28, 2001 kirkz31, I like your attitude!! We all know that there are mountains of data to be analyzed and applied to this subject, and the variables are endless, BUT (I really use that word a lot, don't I?? if this whole 200 mph thing is approached with common sense and a healthy respect for the forces that can bite you if you give them a chance, then maybe it doesn't have to be quite as complicated as it seems! Just for instance, are you aware that a "streamliner" race car built by Auto Union (German company that went on to become Porsche/Audi, more or less) in the early 1930's went 237 mph! What kind of software did they have to use? Sorry, cheap shot, I really don't mean to be sarcastic - and yes, they did extensive wind tunnel testing, and no, they did not suceed the first time, either. And no, I am not suggesting just using "Kentucky Windage" to try and go that fast - I'm just saying that this wheel has been invented for a long time, with much cruder materials and much less sophisticated techniques than we have to play with. In fact, if memory serves me correctly, there was even a write-up several years ago in a couple of auto mags about a - are you ready for this - Kelmark GT kit car with a full tube frame and a big block V8 that went something like 215 mph! A Kelmark GT!!?? True, its a copy of a very aerodynamic Ferrari body, but 215 in a Kelmark GT, even with a full tube frame? It just shows to go ya, never doubt the determination or ingenuity of a true car nut! "Lead me not into Temptation, I'm getting there just fine on my own" Frank Quote Link to comment Share on other sites More sharing options...
Guest Anonymous Posted June 28, 2001 Share Posted June 28, 2001 I'm just curious if all aspects of the weather are all factored in when calculating the success of a 200mph run. It seems like the salt flats would be windy (never been there)and I wonder if something more closed in like a NASCAR track would smooth the atmosphere any. Plus the high speed banked turns would just HAVE to be worth the extra bucks...Just a thot-. WW∞ Quote Link to comment Share on other sites More sharing options...
clint78z Posted June 29, 2001 Share Posted June 29, 2001 Lots of the older guys did over 200mph in some pretty dodgy setups. The one key factor was testicles the size of hot air balloons. Air flow is a pain in the butt as far as an engineering subject. Basically you start out with a guess, then that guess gives you an answer then you go back and refine your guess and do the equations again. There are so many variables that can change, that would throw your answer way off. Working up to speed slowly, and testing and keeping an accurate log of things is the way to go. Quote Link to comment Share on other sites More sharing options...
Mikelly Posted June 29, 2001 Share Posted June 29, 2001 Man-O-man... I've been to busy to keep up with this thread... I'm located in Fredericksburg, Va. I'm well aware of the airstrip in North Carolina. I've been told by several guys who have run that event that speeds there aren't that high, although it is a good place to start close by. John C and Frank, you both make excellent points. I will not be making my 1st attempt with this car at the unlimited class... You work up to it as John says. My first try will be in the 150mph class. I'd like to shake it out first. Others, I had a sponsor years ago who has connections to a group in Georgia who do weekend track Lap days at both Road Atlanta and Atlanta Motorspeedway. My goal is to go to the Oval at Atlanta and hit some 150MPH+ laps for several laps at a time to shake the car down. As for using the cardboard tunnel, I'd be up for using it when I'm ready as I believe it still would provide valid data for other areas of the car. I'm gonna remove the filler door and smooth it over the winter, and I'm gonna have a chin splitter on the front of the car. Friend of mine in Arizona has put one on his road racer and noticed a huge change in the stability of his car at speeds over 120mph. More so than the belly pans he installed. He claims that he actually felt preasure buffetting under the car at speeds above 140mph. He is in a 2nd generation RX7, which is fairly aerodynamic.. Point to that last paragraph is that some of the more technically gifted guys here are correct. These changes and additions of parts should NOT be taken lightly. I'm not gonna do anything without validating its value, or accepting its detriments, and then only after knowing the max. Thanks guys, and keep this thread going... VERY GOOD DATA FOR ALL OF US HERE!!!! Mike Quote Link to comment Share on other sites More sharing options...
Guest Frank Rich Posted June 29, 2001 Share Posted June 29, 2001 Speaking of chin splitters, here is the correct url for that site in the UK that sells carbon fibre chin splitters: http://www.xtreme.uk.com They carry quite a few aerodynamic aids, some for specific models and some that are "universal" sizes. Of course, a few of the items they sell fall into the "rice boy dress-up" category, but others look to be quite functional, with good hardware. I've been trying to order from them, but for some reason I'm having a problem with their site encryption - some certificate issue that won't let my order go through ! WHy don't you take a look at the site and see what you think - I'm tryng to get one of the DTM universal chin splitters with the adjustable mounting hardware - looks like a good way to separate air flow before it hits the front airdam, and the bracketry should allow for varying angles of attack... (Oh, BTW - this site is definitely "R-rated", so if there is anyone who's sensitive to such things around, you may not want them looking over your shoulder when you pull it up) "Lead me not into Temptation, I'm getting there just fine on my own" Frank Quote Link to comment Share on other sites More sharing options...
Mikelly Posted July 1, 2001 Share Posted July 1, 2001 Frank, Educate me on this site please.... A: I can't view the products, and B: If you are gonna show me glimpses of naked girls, ateast create a gallory where I can go see the whole image... Mike Quote Link to comment Share on other sites More sharing options...
Guest Anonymous Posted July 1, 2001 Share Posted July 1, 2001 Haha, you know I thought the same thing when I tried it, I thought it was a porn site when I first logged in, I didn't find anything either, although I didn't try real hard. The dancing stripper gif wasn't something I'd put on a commercial internet car parts site... , Lone Quote Link to comment Share on other sites More sharing options...
Guest Anonymous Posted July 2, 2001 Share Posted July 2, 2001 Same here,...uhhh, what's a chin splitter? WW∞ Quote Link to comment Share on other sites More sharing options...
Guest Frank Rich Posted July 2, 2001 Share Posted July 2, 2001 Sorry, Mike, the encryption certification that they're using on that site is one that my version of Windows now shows as "expired" - I'm, looking for a place to download the necessary encryption certificate, and I'll let you know when I find it, or I'll just email it to you... As far as the naked ladies - you used to be ablle to click on the "floating" icons when a female form appeared and it would take you to a ...very different... part of this site. Ah, the Brits do love to throw in little enticements, don't they? Webwalker - a chin splitter is a flat, usually adjustable, extension that protrudes straight out from the bottom of the airdam or front body work rather like a "shelf". It may have tip vortex eliminator plates or end plates, and its purpose is to begin separating the solid mass airflow in front of the car into two streams (one which passes over the car, one which passes under) before the airflow actually reaches the (more) vertical face of the airdam. Chin splitters can be used to help reduce airflow transition turbulence and add downforce by adjusting the angle of attack of the chin splitter in relation to the original direction of the airflow stream. You've seen them before on a variety of different clases of race cars, and just didn't know that was what you were seeing... In fact, F1 cars run splitters of some sort on virtually every leading edge surface on the car! Little aero aids everywhere! Quick! Who knows what a "wickerbill" is? And No, it doesn't come on a playtpus!! "Lead me not into Temptation, I'm getting there just fine on my own!" Frank Quote Link to comment Share on other sites More sharing options...
ZROSSA Posted October 28, 2001 Share Posted October 28, 2001 Well, I know this has been well covered but it late on sunday night and i have had to much coffee. I found this sight and thought i might pass it on. it has some good photos of le mans style spliters and belle pans and a reasonable discription. www.mulsannescorner.com Douglas Quote Link to comment Share on other sites More sharing options...
Mikelly Posted October 29, 2001 Share Posted October 29, 2001 ZROSSA, This site has A TON of data! Good find! I'll be reading this site for a while... Mike Quote Link to comment Share on other sites More sharing options...
Guest Frank Rich Posted October 29, 2001 Share Posted October 29, 2001 Oh Man!! Eureka! Also Holy Sh*T!! Mikelly, did you read the article on that site titled "What is a Diffuser"? It just saved me a TON of work and effort. I've been chasing the idea of a belly pan with partial venturi effect channels running between the chassis features of a Z as the way to kill positive lift and generate negative lift (downforce), and now one little paragraph in that article makes it all a moot point: "Understand that a true flat bottomed car (one without a diffuser) will produce downforce in and of itself when run in rake. Essentially the entire flat bottom becomes one large diffuser. It too has two suction peaks, one upon entrance, the second at the trailing edge of the flat undertray. A diffuser acts to enhance this underside suction, it acts like a pump, encouraging better flow under the car." The article goes on to add some interesting data about the relationship between rear wings and diffusers, but I'm really excited by the idea that a true flat-bottomed configuration, WHEN RUN IN RAKE, generates its own downforce by creating "suction peaks" at two locations! !! This means that a belly pan similar to Scott's will work to generate downforce as long as the optimum angle of rake which is consistent with good handling can be dialed into the cars stance! And the downforce is enhance by adding a rear diffuser, which I had planned on trying in any case!! This GREATLY simplifies the whole project, and shifts the area of tweaking away from complex aerodynamic shapes and functions to one of chassis and suspension tuning, once a "truly" flat belly pan is in place! (A word of EXTREME caution is necessary here, for those who might be caught up in my excitement - trying to go really fast with a full, flat belly pan, WITHOUT somehow dialing in rake will probably have EXACTLY the OPPOSITE effect of that desired, which is generating downforce!Anyone remember the Mercedes prototypes at Le Mans a couple of years ago? Up, up and away!) So now, all I have to do is figure out how much rake is enough to generate the "suction peaks" (does that sound vaguely dirty to anyone else - I think I dated a girl with those in high school!)necessary to make it all work. Of course, there are just a few other variables involved - just a few. Ride height as it effects these forces, balanced against how it will effect handling, day-to-day, real world clearance issues (my office building's parking garage has some really nasty speed bumps on each floor!), how to generate rake without looking like either a lowrider or a hotrodder wannabe all set to cruise the local Sonic - these and about a hundred other questions pop into my mind just for starters! But hey! I've got a new, much more simple place from which to start now! Thanks, Zrossa for pulling my attention to that site - I'd briefly glanced at it once before, but never really dug through all the articles until now! "Lead me not into Temptation, I'm getting there just fine own my own!" Frank Quote Link to comment Share on other sites More sharing options...
pparaska Posted October 29, 2001 Share Posted October 29, 2001 I think we've seen that link before here - great site. One thing I seem to remember is that the flat bottomed , raked approach depends on some pretty low ride heights to get a decent effect - possibly too low for speed bumps, etc. Quote Link to comment Share on other sites More sharing options...
Tim240z Posted October 29, 2001 Share Posted October 29, 2001 Just to add my 2c worth. I know of a Trans Am (knight rider generation) that went 237 MPH without any major aerodynamic additions. Small strip of rubber on the front air dam and a small 'whale tail' on the back and was stable as can be. No belly pans or diffusers or splitters etc. I know that it's not a Z and I am comparing apples and oranges, but Food for Thought. Tim Quote Link to comment Share on other sites More sharing options...
Guest Frank Rich Posted October 29, 2001 Share Posted October 29, 2001 Yeah, Pete - I'm sure that will be the case here - the flat-bottomed w/rake approach will not lend itself to a really streetable, daily driver type of setup - not and be able to generate the type of downforce that will make a real difference in performance - but I may be able to fit a setup that can be used just once or twice a year for "special occaisons" - like, say, in April? "Lead me not into Temptation, I'm getting there just fine on my own!" Frank Quote Link to comment Share on other sites More sharing options...
Guest Anonymous Posted October 29, 2001 Share Posted October 29, 2001 One thing I haven't seen discussed yet is employing suction fan(s) on the underbody to lower the coefficient of pressure under the car thereby increasing downforce. This isn't as crazy as it sounds, in 1976, Gordon Murray Used that very same principle for the BT46b, which won its very first Formula 1 race before being outlawed. For pics and more info on that, check out http://www.f1mech.co.uk/bt46.htm Murray later used the same principle on the McLaren F1, but instead of using a rearward facing engine-driven fan he used an electric underbody fan (not terribly big either) to impart the stability the car needed at 240mph without the aid of spoilers... Jim Hall did the same thing with his Chaparral race cars too, can't remember which ones though Quote Link to comment Share on other sites More sharing options...
Brad-ManQ45 Posted October 30, 2001 Share Posted October 30, 2001 One place to look at what has been done on a production vehicle, if I remember correctly is the Ferarri 360 Modena. If I remember correctly (again) there was a small raised area in the center of the front air dam tunneling back to an enlarged area (providing a low pressure area under the front for downforce there), then making its way back to the rear diffuser (pproviding downforce in the rear. I believe I saw all of this in a Road & Track magazine a cople of years ago. This would tend to modify somewhat the flat bottom theory, which addmittedly is better than nothing if rake is provided, but then the windshield is at a higher angle of attack, providing more drag, and possibly leading to buckling/collapsing. Anyone else recall seeing the design I'm talking about? I of course have eliminated a lot of stuff that they did on the Modena, but another trick was to have oval/elliptical susension arms that had to go through the tunnels to get to the wheels etc. It was interesting reading at the time - maybe I can scare the article up - if I can get past the scary thought of searching through all the boxes from the move..... Brad Quote Link to comment Share on other sites More sharing options...
Guest hgray14 Posted October 31, 2001 Share Posted October 31, 2001 Hey guys, I am new to this site but love this string. I have been thinking about this stuff for quite a while because I too want to see a Z-car go 200 mph. I just watched the footage of that RX7 going over at 215 mph and three things struck me. 1. Holy crap...I didn't realize that a car could go over so easily. Of course it is easier at 215 than at 60 but I tend to be closer to the 215 end. I am running a lite-weight '72 240z with a 280z engine/tranny with some suspension mods and an aerokit. I have pushed it as high as 145 mph and from the looks of the tach (I could only glance down for a second...if that) it had a little more to give. I only run in the early morning out in the desert when there is no wind but holy crap I didn't realize how much danger I was putting myself in by not having a roll cage. 2. Damn if that roll cage didn't hold up well!!!! I didnt read anything about it but I assume the driver lived. He looked fine just hanging there at the end of the clip. I found a low cost/high protection roll cage for my Z and am going to have it installed before I do any more desert runs over 100 mph. 3. How many times out of 10 do you think that gust of wind will be there like the one that caught that car? Maybe 1 out of 10 times? If so, that sounds like a reasonable risk to me. MiKelly, I would love to watch you do 200 in a Z. If you need a test driver just let me know. ...Has anyone thought about or looked into those roof flaps that the cars in NASCAR have that help them from flipping over? thanks for the great tread. Quote Link to comment Share on other sites More sharing options...
DavyZ Posted October 31, 2001 Author Share Posted October 31, 2001 Houston, Mike is one of the most gung-ho guys I have ever met about Z-cars, I seriously doubt he'll let anyone else behind the steering wheel, even his wife! Davy Quote Link to comment Share on other sites More sharing options...
Guest Anonymous Posted October 31, 2001 Share Posted October 31, 2001 What if under the car was not a flat belly pan, but one that either smoothly curves up and then down (like a string of whoop dee doo's). Reason I ask, if you can break up the air going under the car, and the air flow over the car is = to the air going underneath wouldn't there be no lift? Or would it cause to much wind resistance and slow the car to much? Just curious. Perhaps like a under the car spoiler back by the fuel tank? Might be a stupid idea, but thought I'd through it out there anyway. Regards, Lone Quote Link to comment Share on other sites More sharing options...
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