DavyZ Posted June 12, 2001 Share Posted June 12, 2001 I'm just wondering if any of us out there in HybridZ land have fabricated a belly pan/engine pan for improved aerodynamics under the car? If so, what materials did you use? I figure that it would be pretty easy to fab one out of fiberglass, but I'm sure that as soon as I run over say, a tin can, it will be trashed. Most new cars use a flexible plastic that lasts a while--then again, most are not 3-4 inches off the ground either. I'm sure that Mike Kelly will be making one of some sort if he is going to break the 200mph barrier with his car. It seems to make complete sense. In practical terms, a lower pan would give the car better aerodynamics and thus better fuel economy on the highway, and it would help keep your engine much cleaner. For those guys that run in areas with nasty snow/slush and mud/rain, this seems like a great idea. Anyone thought about this or has given much attention to it? It's slow here at work, guys, and I have nothing to do but come up with new topics like Owen. David Quote Link to comment Share on other sites More sharing options...
Owen Posted June 13, 2001 Share Posted June 13, 2001 Are you implying that I'm not working??? Just kidding Owen Quote Link to comment Share on other sites More sharing options...
Guest JAMIE T Posted June 13, 2001 Share Posted June 13, 2001 I would build it out of .050" aluminum sheet(maybe polished for that extra low drag effect ) Use dzus fasteners to hold it on. The alum. can be shaped easily with a wooden mallet and a sand bag. If weight(or money) wasn't a concern, you could cover the whole thing with Dynamat too. The Alum. would be lighter than the fiberglass of equal size(length and width, not thickness) Maybe I could make them and sell'em. Jamie Deathstar 250GTO Quote Link to comment Share on other sites More sharing options...
DavyZ Posted June 13, 2001 Author Share Posted June 13, 2001 If they were polished, maybe you could!!! Mike Kelly would be your first sell too! Shaping aluminum would be a first for me,so I think fiberglass would be a better option. Still, I could mock something up using cardboard, and then go to the wrecking yard and look for a plastic one that was similar or at least adaptable, and go from there! Thanks for the idea, Jamie! David Quote Link to comment Share on other sites More sharing options...
Guest Anonymous Posted June 13, 2001 Share Posted June 13, 2001 Not to deflate sails, but if you make the bottom to smooth then does'nt the Z become even a better wing than it already is? "Off we go into the wild blue yonder...", Lone [ June 12, 2001: Message edited by: lonehdrider ] Quote Link to comment Share on other sites More sharing options...
DavyZ Posted June 13, 2001 Author Share Posted June 13, 2001 Heh, you'd think so, but I believe I read someplace that a car becomes unstable by the amount of turbulence under the car (it creates lift under the fron end). A spoiler helps keep turbulent air (and just air for that matter) from under the car. A belly pan helps smooth out what air there is underneath and keeps the air from building up under the car from the engine compartment. That's my take on it anyway. It's all theory.... David Quote Link to comment Share on other sites More sharing options...
Guest Anonymous Posted June 13, 2001 Share Posted June 13, 2001 I know, I was just bustin' your chops... I'm sure anything you can do under the car would be a improvement. I think smoothing the headlight buckets, smoothing the front hoodline and angling the windshield back would probably make quite a bit of difference. (they did the windshield tilt on a convertable hybridz with a ford v8 on a website I saw it was awesome..). I think also it would look cool (although perhaps not help a great deal) would be the center section of the grill to be rounded ala miata. I'd also like to see that with the headlights brought forward even with the front of the grill and using smaller projector beams. Like I say probably would'nt help aerodynamics, but for my tastes would look the business. Regards, Lone Quote Link to comment Share on other sites More sharing options...
Drax240z Posted June 13, 2001 Share Posted June 13, 2001 Uh guys, I hate to burst your bubble. A good belly pan will aid in aerodynamics a whole lot, but a bad one will make it a whole lot worse! Unless you really know your aero you're probably better off NOT making one. There has to be some books out there with some insight into what makes a good one vs a bad one. This is not something that I would attempt to make on a sunday afternoon with no real idea of what I was doing... Or you may find yourself doing backflips at 80mph. Quote Link to comment Share on other sites More sharing options...
pparaska Posted June 13, 2001 Share Posted June 13, 2001 I believe someone posted a good basic design method for bellypans here somewhere...but...I'd be leary of using one on a car unless it's been tested in a wind tunnel, or take up to speed slowly and measure the lift (instrument the suspension?) with and without it. Quote Link to comment Share on other sites More sharing options...
Guest Anonymous Posted June 13, 2001 Share Posted June 13, 2001 that is a very good point pete. it can be dangerous to make it then drive it. it should be tested. now then, wind tunnel, VERY expensive. if someone had access to one and was able to test it then they could make them but wouldn't it vary from car to car. different suspension and airdams? just a thought. Quote Link to comment Share on other sites More sharing options...
Scottie-GNZ Posted June 13, 2001 Share Posted June 13, 2001 I used to see the fast Honda drag cars all using a "Fancy" aluminum strip across the rear valance with holes in the strip and valance. Found out that airflow under the car was collecting in the rear valance and acting like a parachute. The stock Z gas tank is wide and close to the valance. Replacing that tank with a fuel cell opens up the possibility of the Z having the same problem as the Honda. I do not have proof or a way to prove it is happening, but it has been on my mind. I will only be in the mid-120s but MikeK, you might want to look into this as a potential aerodynamic trouble spot. Quote Link to comment Share on other sites More sharing options...
johnc Posted June 13, 2001 Share Posted June 13, 2001 My previous post was typed very quickly (as you can tell by the spelling) 'cuz I was late for a meeting. Here's some more information that I've been able to figure out (remember, my thinking was along the lines of downforce for road racing): Front Pan --------- You need to run more of an air dam than a spoiler. Attached to the bottom of that you need a splitter poking forward a minimum of 4". This splitter continues, completely flat, rearward and then curves up behind the radiator, then back down and flat again right at the front wheel center line (the steering rack and the crossmember get in the way here). The intent of the upward curve is to create a low pressure area right in front of the the front wheel center line, creating some front downforce (the splitter does this too). The belly pan continues rearward and mates with the stock floorpan at the firewall. The sides of this front pan need to be sealed from the front wheel wells and the wheels wells need to be vented at the tops of the front fenders just in front of the front wheel cetner line. You also need to figure out where the air exiting the radiator can go (normally it exits down). You'll probably have to cut a big hole in the hood to vent the radiator air up. This can also be tailored to generate downforce. Floor Pan --------- Take a big hammer and pound a concave profile (looking from front to rear) the length of each floor pan making some simple, shallow tunnels. Rear Pan -------- This one will be tough. It will be basically flat from the end of the floor pans but you will have to tuck it above the lower control arms. It will probably have a fairly complex shape. Right after the rear control arms you angle it upwards from 5 to 7 degrees constant (this is is where the fuel tank gets in the way). This rear diffuser would continue past the rear valance and extend about 2" past the rear of the car. Some strakes would need to be added in the diffuser to control flow. Exhaust System -------------- The exhuast should exit into the lower center of the rear diffuser to add some flow velocity. The pipes should be contained within the sealed center tunnel. Heat Management --------------- Haven't figured that out. Ride Height ----------- 1.5" to 2.5" maximum. Spring Rates ------------ You are changing the platform itself from one based on mechanical grip to one based on aero grip. Starting rates would be 500 lb in????? - ultimately determined through aero testing. What you are building here is an aerodynamic platform that must be strictly controlled. Fore-aft pitching and lateral roll upsets the platform and severely reduces downforce (grip). Conclusion ---------- It would turn the 240Z into something that it couldn't be good at. You would save money by buying a GT3R Porsche and end up with a much nicer car. [ June 14, 2001: Message edited by: johnc ] Quote Link to comment Share on other sites More sharing options...
johnc Posted June 14, 2001 Share Posted June 14, 2001 Funny that this topic has come up... I've been half-heartedly designing one for my 240Z but its not for top speed, more for downforce. The floor pans of a 240Z are actually OK from an aerodynamic standpooint, you would just have to seal off the drivshaft tunnel. The diffcult parts are from the spoiler to the firewall and from the rear of the floor pan to the rear bumper. So far I've determined: 1. The front crossmember has to be replaced. 2. The rear fuel tank has to be moved up or forward. In addition, you ahve to some work to help with engine, transmission, and diff cooling. No timeframe on when I'll get this figured out (if ever) but its fun to think about. Quote Link to comment Share on other sites More sharing options...
Mikelly Posted June 14, 2001 Share Posted June 14, 2001 Damn you guys are working me OVERTIME!!!! John is Correct. My current design is to run a loovered pan down the trans tunnel, lookvers allowing excess heat to escape. I also agree that the rear cell area has to be cleaned up, as does the front area... Doing away with the rack I am not so sure of, but may be an issue... John has already looked at this. I checked into time at a wind tunnel in North Carolina... it was rediculous silly pricing per hour, and you better have folks on hand who know what to look for before you venture in to deep. I'm waiting until my little experiement is closer to prime time before I hit up the "Prospective" sponsores for cash to go play in a tunnel. However, the added benefit can be double edged... You can create a wing effect if you aren't carefull. Mike Quote Link to comment Share on other sites More sharing options...
DavyZ Posted June 14, 2001 Author Share Posted June 14, 2001 There is no way I'm going to replace my front crossmember! I can't see that being worth the trouble, for me anyway... The belly pan also works to catch oil dripping from the engine and keeps the driveway clean !!!! (ahem) I don't think I'll launch the car by putting a belly pan under the front of the car, especially when I'll have an airdam and a lowered stance. The amount of air getting under the car relative to stock should be minimal. I will check into it some more just to be sure--you guys scare me My airdam will include a extension that goes from the bottom of the airdam even further to the ground and it's from a Supra--see "Datto's" ride in the Zdriver member's ride; he has that piece. Thanks for the concern guys; I'll research it further when I undertake it. Good luck Mike Kelly in making it all work! David Quote Link to comment Share on other sites More sharing options...
Guest MM_280Z Posted June 15, 2001 Share Posted June 15, 2001 Please do not try to go 200 MPH in a Z! The Z is shaped like a wing. You'd need a BIG ass wing on the back, some MAJOR aeronautical engineering and definately some wind tunnel time to do it without seriously endangering your life. Even the pros sometimes get it wrong. Remember those LeMans Mercedes cars that kept flipping over? Check out this video: .avi]http://www.pubchat.net/rbrx7_215mph[1].avi This rx7 was a well planned, purpose built speeder. It got up to 215 MPH... before flipping over. Quote Link to comment Share on other sites More sharing options...
Drax240z Posted June 15, 2001 Share Posted June 15, 2001 MM_280Z. I appreciate where you are coming from, in that there are a lot of 'silly' people out there that may not prepare themselves properly for 200mph. I would say that Mikelly is one of the opposite, those people that know exactly what they are getting into. If you look around this site, you'll notice Mike is involved in about 1,000 different discussions on what it takes to do 200mph in a Z. As far as engineering goes, I think this site has its fair share of engineers too. At least one aeronautical engineer, 3 or 4 mechanicals, civils, electricals, and at least 4 engineering students. Not to mention that there are MANY non-engineers on this site that know more about engineering that many engineers I've known. Not trying to berate you at all, I've seen so many half-assed attempts at stuff like this (200mph) that I tend to be skeptical at first as well. Quote Link to comment Share on other sites More sharing options...
Mikelly Posted June 15, 2001 Share Posted June 15, 2001 I understand the concern and I appreciate it. However, I'm doing what I'm doing with about 12 years of research, developement, and trials at getting to this point. Quite honestly, If I go up in smoke "TRYING" to attain this goal (I'm VERY goal driven) then so be it, and I hope one of you good souls finds this very post and reminds everyone just that. I'm shooting for 200MPH in a Z car and no one will change my mind. The family and friends gave up long ago. I certainly won't be letting a random post on this board dissuade me. Mike Kelly Quote Link to comment Share on other sites More sharing options...
Guest Thurem Posted June 15, 2001 Share Posted June 15, 2001 You go girl, go. I can just imagine the officer beetred in the face , asking: "Do you know how fast you were just going?" or "Do you know why I pulled you over?" Later Thure Quote Link to comment Share on other sites More sharing options...
Guest MM_280Z Posted June 15, 2001 Share Posted June 15, 2001 Oooooooooooook. If you absolutely MUST go 200 MPH in a Z, then so be it... As long as you understand and are willing to invest the time + energy that it requires, you will succeed. I understand what it means to be goal driven. I am quite difficult to dissuade once I set my mind on something too. Being an Engineer is all about choosing your battles though -- how can you get the best result for the least effort. A personal quest is another story though... I understand. If you are willing to do what it takes to go 200 MPH -- including risking your life -- then more power to you. Having said that, though, theres no reason that it couldn't be done, and reasonably safely. All it takes it time, money, and effort. I haven't read the archives far enough back to know of your qualifications or dedication to this. The tone of this thread, however, was definately leaning toward the "it's EASY, just slap on a smooth belly pan and you can go 200 MPH" line of thinking, however, and that made me nervous. No need to go up in smoke, Mike. Do us all a favor and don't make it a suicide mission, eh? Quote Link to comment Share on other sites More sharing options...
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