Guest ScaryFast Posted October 14, 2002 Share Posted October 14, 2002 I was thinking about making a full belly pan for my 240. From the air dam to the rear valance with a diffuser in the rear. It would improve aerodynamics a lot and would cause some down force at speed. I would louver the piece under the motor to let out engine bay heat. This was just a thought and isn't something I will do anytime soon, but I wanted to see if it has been done and get some other opinions. Quote Link to comment Share on other sites More sharing options...
CruxGNZ Posted October 14, 2002 Share Posted October 14, 2002 ScaryFast, if you search the site, you would find this post . Hope this helps you. !M! Quote Link to comment Share on other sites More sharing options...
Guest Anonymous Posted October 14, 2002 Share Posted October 14, 2002 Perhaps I know nothing about aerodynamics, but wouldn't a full belly pan in the front and middle of the car cause a even better wing like surface (unless your difuser counters this) to the already easily airborne Z car? Just curious. Regards, Lone Quote Link to comment Share on other sites More sharing options...
Guest Anonymous Posted October 14, 2002 Share Posted October 14, 2002 I agree with Lone. Those old Z front ends want to join the Airborne at about 100 mph and with a body pan that would put them at the recruiter's office at 70 mph. Just my opinion....correct me if I am wrong. Quote Link to comment Share on other sites More sharing options...
Guest ScaryFast Posted October 14, 2002 Share Posted October 14, 2002 what it is supposed to do is let the air under the car move faster and smoother, creating a partial vacume that sucks the car down. Quote Link to comment Share on other sites More sharing options...
Guest Anonymous Posted October 14, 2002 Share Posted October 14, 2002 As long as you can pinpoint that partial vaccum point and what angle ,vent, etc that creates the downward vaccum.Did any of the old Z race cars have this pan? Quote Link to comment Share on other sites More sharing options...
ZROSSA Posted October 14, 2002 Share Posted October 14, 2002 Couple of things, It seems that you must limit the air into the front end of the z. Once that is done you should vent it through the bonnet(hood). Then the front end of your pan sould be a little lower then the rear before you get to the diffuser part. It seems for a road car that the best thing to do is limit the air under the car. Anything else will only work on the race track. Were do you run the exhuast? I dont mean to be negative. I would like to do the same. Just not sure how yet. Douglas Quote Link to comment Share on other sites More sharing options...
johnc Posted October 14, 2002 Share Posted October 14, 2002 The floor pans of a 240Z are pretty flat to begin with. What causes front end lift on the stock 240Z body is air packing up in a high pressure area under the front of the car. What causes lift on the middle and rear of the 240Z body is the curved upper surface (in comparison to the flat lower surface) creating a low pressure area similar to an airplane wing. Quote Link to comment Share on other sites More sharing options...
gnosez Posted October 16, 2002 Share Posted October 16, 2002 I seem to remember an email I got from Andy Flagg (I hope that's his name), who set a new land speed record in his 78 280 at the Salt Flats last year. He stated that they had to remove the full body pan because of the air foil effect at speeds over 140 mph. Hope this helps... Quote Link to comment Share on other sites More sharing options...
Mudge Posted October 22, 2002 Share Posted October 22, 2002 A guy I know who does the open road races in Nevada etc, said flat out that he would rather not have air under the car in the first place. Since this particular vehicle is an open road car only not street driven, the setup isn't exactly pretty, but he's seen nearly 200 MPH with it just fine. This basically means some steel front and side skirts, with rubber being the last couple inches used. Quote Link to comment Share on other sites More sharing options...
Mikelly Posted October 22, 2002 Share Posted October 22, 2002 Well one other thing to consider is what the air is doing when it is under the car. One member mentioned the reason people use belly pans was to get the air that is under the car to go past as smoothly as possible. This is correct. Turbulance causes lift, by gaining momentum and building presure. What many of the Salt Flats/ Open road racer types have been doing is using black garden edging that you can get at hardware stores to run the last 4-6 inches around the front and sides of their cars. I've seen pics of this stuff on Porsches... Anyway, they use this inexpensive rubber material because it is replacable, adjustable, trimable, and allows you to lower the car to its safest (Without bottoming metal on the road surface) and lowest setting, and then running the rubber "skirt" to within two inches (Or less) of the tarmac. Jon C.s comments about the front end mass are true. The Z has this huge gaping hole up front that splits the wind and forces it to go up or down. That pointy hood and raked grill actially do everything imaginable to HURT aerodynamics. The Zcar looks quite sleek, but in fact carries some pretty pathetic CD numbers. Belly pans are usable, but I'd recommend asking your self honestly if they are worth the work IF you never plan to see the high side of 150mph. I've had several Zs over the 150mph mark and if setup properly, they can be quite stable, as in drive with one hand on the wheel stable (Not that I would recommend it). Using a belly pan up front, a trans tunnel pan in the center, with channels formed into them, and a rear pan/ difuser would be my preference IF I could develope them using a wind tunnel. However, wind tunnels aren't cheap. I was actually trying to get time in one of the local Nascar tunnels in North Carolina and it was going to be hellespensive... Just remember, JUST throwing all these aerodynamic aids on your car without knowing the cause and effect COULD cause your car to take flight... Images of Mercedes at Road Atlanta a few years back pop into my head... And those boys HAD the money and research done, and their gigabuck race cars still took flight... Mike Quote Link to comment Share on other sites More sharing options...
zero Posted October 22, 2002 Share Posted October 22, 2002 well, i say that you do another hybridZ meet, but instead of going to a drag strip, everyone goes to a wind tunnel, and chips in on the cash to get it for a while. And tries to figure out the exhaust problem, and how to make some downforce with these cars. Quote Link to comment Share on other sites More sharing options...
Mudge Posted October 22, 2002 Share Posted October 22, 2002 Good post by Mike. The edging isn't pretty, again its for the serious guys who usually only race the car, and it does hug the ground so sure, its not all that ready for the street, although it is flexible and if it were to break off in chunks no loss. That was the whole point that was made to me when I inquired about it for another car, dont let the air under the car in the first place. One thing you could do is at least use a little rake in front, meaning lower the front end in relation to the rear to try and produce some downforce, but am new to Z cars somewhat so am not sure what is optimal either. I do plan to road race this but not neccessarily open road, so will probably never see above 150 (except maybe at Buttonwillow). Quote Link to comment Share on other sites More sharing options...
blueovalz Posted October 22, 2002 Share Posted October 22, 2002 We should also consider the effect of blocking off all this air in front, and on the sides, but leave the rear of the car as open as possible (a spoiler here may help even more) to allow this low pressure generated behind the car to be expressed forward and under the car. Quote Link to comment Share on other sites More sharing options...
Mudge Posted October 23, 2002 Share Posted October 23, 2002 Part of the idea of an open rear end is actually creating a small vacuum in that area, as well as not trapping air underneath the car and simply causing resistance/lift. That seems to be the basic setup, block the front, sideskirts, and open rear, and whatever wing(s) and slanted nose setups that might get used. Quote Link to comment Share on other sites More sharing options...
Mikelly Posted October 23, 2002 Share Posted October 23, 2002 Actually, No. You don't want to NOT address the rear of the car... The rear also has issues with lift... IF you install a rear spoiler, you will aid in keeping the back of the car more planted. IF you install a rear pan you ALSO aid in helping that air to exit the back of the car more smoothly, and racers have reported picking up several miles per hour on the top end out at the salt flats. You really want to think this through... there is a reason that those channels are made into the rear facsia panels... One thing I was looking at was carrying the whole underbelly out to the rear valance, in essence, covering the exhaust and fuel cell... Getting the car as low as possible would help with minimizing the ariflow under the car. The wing on the rear deck would aid in getting the presure over the rear deck... The Gnose and an adjustable chin splitter would kep the nose in check.... However, at 180mph things change... At 155mph in the white Z I had, the car was VERY stable. However, presure built up along the rear deck and cracked the seem between the whale tail and the hatch...What would have happened over say 5 miles? At 168 mph in an MSA body kit equipped yellow Z (With the MSA Design Whale tail), including side skirts and molded front and rear facsia, the car was a little lighter, as it had an L6 motor in it at the time. The car was stable, but hit a defenite "Aero BRick wall" that wouldn't allow me to go any faster. At that speed the car actually saw the MSA body panels start to pull away from the sheet metal. I also noticed that the windows started to loosen from their seals and the windshield started to leak water a little bit in the drivers upper corner after that experiment. One mirror had started to loosen up, and the door gaskets did NOT hold their seal very well. The runs in the yellow Z were verified via a radar gun. The white Z was using an electronic speedo, which has fairly good accuracy. In the White Z, I felt more stable, and the car was only pushing 3800 RPMs in 6th gear... That was with a 383 stroker... there was MUCH more on tap, but running out of space to top it off, I chose to abort any further high speed exploration. With fewer places to safely test this kinda thing, it gets less and less likely that I'll ever see 200mph in the car. Now on the motorcycle... that is another story... Mike Quote Link to comment Share on other sites More sharing options...
blueovalz Posted October 23, 2002 Share Posted October 23, 2002 I agree that any spoiler or whale tail on the Z rear end is an advantage. Case in point: I had to carry an 8' piece of 3/4" steel conduit years ago in my Z. The conduit was inserted into the car from the hatch up between the seats, and the front rested on the floorboard under the passenger side dash. Unfortunately the rear of the pipe end still stuck out past the hatch, so I simply allowed the hatch to sit down on the pipe, unlatched. Thus, the outside lip of the hatch rested on the pipe, the pipe then rested on the interior edge of the interior trim (roughly 4" inward of where the hatch lip rested on the pipe. This then created somewhat a lever in which about 7' of pipe was on one side of a fulcrum, and about .3' of pipe was on the other, with a small amount of force from the hatch pushing down on this short end (sorry for all the long description). Anyway (now to the interesting part), I got onto the highway, and as my speed increased I notice the end of the pipe that was resting on the floorboard under the dash started lifting off the floor. So I push the rational limits of highway speed, and very easily was able to see enough down force from the hatch (with a 4" high spoiler) to lift the long end of the pipe all the way up to the bottom of the dash. This by no means gave me any hard numbers (I regret not investigating this further), but was very useful in verifying the efficacy of a spoiler on the rear of these cars. Quote Link to comment Share on other sites More sharing options...
Mudge Posted October 23, 2002 Share Posted October 23, 2002 So are we saying the rear of these cars 'gets light' at high speed? The C5 Vette is the same way, and I imagine many cars are. Is anyone using software to try and analyze this info? Quote Link to comment Share on other sites More sharing options...
cameraobsess Posted October 23, 2002 Share Posted October 23, 2002 hey Terry what dose that hood you have do to your downforce? i would think it would put some presure on the front of the car but i am not sure. Quote Link to comment Share on other sites More sharing options...
blueovalz Posted October 23, 2002 Share Posted October 23, 2002 I wished I could give a good answer, but it's like a lingering headache that finally goes away. You alway know when you have it (light front end at high speed), but when it went away, you don't even realize it. The car drives great, but only recently have I started pushing it into the triple digits. It's as stable there as it is at 55. Quote Link to comment Share on other sites More sharing options...
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