EMWHYR0HEN Posted February 28, 2006 Share Posted February 28, 2006 Ive heard and read time and time again how the aerodynamics of the older Z -cars are just horable. This I can agree with, only from my own personal experience when driving my car over speeds of 120MPH. However, what I would like to know is what exacly is the cause of such poor air flow, and what causes lift (un-downforce) on the front end of a Z? Is it really THAT bad? its just hard for me to comprehend because ive always thought the sporty Z-car had a great shape, along with low wind resistance.... I guess I was wrong.... someone please enlighten me... I just want to know WHY! Also, does anybody have any evidence that the Z car has bad aero design? Pictures? windtunnel results? Just a thought.... From the looks of it, The G-nose (240ZG) front end looks far more aerodynamic than the 240Z's front. Is this in fact true? anybody have any evidence to that? Quote Link to comment Share on other sites More sharing options...
AK-Z Posted February 28, 2006 Share Posted February 28, 2006 Well the first gen Z were designed after the jaguar e-type and the porsche 911. Even though the general shape is much like the jag and the porsche the broad front make alot of resistence and having such a large area for air flow for the radiator to go through doesn't help either. Now looking at the profile you can see that the broadest area (without the bumper) is sloped downward and at 120 m/h+ that can make a big difference. Quote Link to comment Share on other sites More sharing options...
EMWHYR0HEN Posted February 28, 2006 Author Share Posted February 28, 2006 Well the first gen Z were designed after the jaguar e-type and the porsche 911. Even though the general shape is much like the jag and the porsche the broad front make alot of resistence and having such a large area for air flow for the radiator to go through doesn't help either. Now looking at the profile you can see that the broadest area (without the bumper) is sloped downward and at 120 m/h+ that can make a big difference. I see what your saying..... since the G- nose is more 'pointy', would it give a better flow over the front end of the car? I always thought the G-nose looked good, but if it also improves aero, and ultimatly high speed stability, and fuel consumption, maybe even downforce, even more reasons to get one! Quote Link to comment Share on other sites More sharing options...
mom'sZ Posted February 28, 2006 Share Posted February 28, 2006 Is this in fact true? anybody have any evidence to that? There is no doubt that the first gen Zcar is bad aerodynamically. I can't remember the coefficeint (sp) of drag but it's bad even compared to other cars of the same era. It seems the Z is blunt in all the wrong places (front) and smooth in all the wrong places (back). Somewhere on this site is an old thread where somebody (engineer) explains it in extreme detail. (old thread, 2001 I think) The explanation is based on actual wind tunnel testing. I will try to find it later when I'm at work and post a link. I know the headlight covers, the clear ones that cover the ice cream scoop front headlight buckets help a lot. An air dam to stop air from passing under the front of the car helps with the lift issue. Quote Link to comment Share on other sites More sharing options...
johnc Posted February 28, 2006 Share Posted February 28, 2006 Search.... Quote Link to comment Share on other sites More sharing options...
EMWHYR0HEN Posted February 28, 2006 Author Share Posted February 28, 2006 There is no doubt that the first gen Zcar is bad aerodynamically. I can't remember the coefficeint (sp) of drag but it's bad even compared to other cars of the same era. It seems the Z is blunt in all the wrong places (front) and smooth in all the wrong places (back). Somewhere on this site is an old thread where somebody (engineer) explains it in extreme detail. (old thread, 2001 I think) The explanation is based on actual wind tunnel testing. I will try to find it later when I'm at work and post a link. I know the headlight covers, the clear ones that cover the ice cream scoop front headlight buckets help a lot. An air dam to stop air from passing under the front of the car helps with the lift issue. thanks, i'll do a search of my own too. I could imagine that the headlight covers help with drag issues. by the way, the post you were talking about, was it the one about the rear spoiler and the exhaust fumes issue? Quote Link to comment Share on other sites More sharing options...
EMWHYR0HEN Posted February 28, 2006 Author Share Posted February 28, 2006 or was it this? http://www.zccw.org/Tech/Body/early_aero.asp Quote Link to comment Share on other sites More sharing options...
mom'sZ Posted February 28, 2006 Share Posted February 28, 2006 You know it might be, I was looking and found a bunch of really good threads with tons of info on aerodynamics but didn't find that one specifically in the five or ten minutes I spent looking. (boy it's easy to get side tracked using that search function) I remember it was pages and pages long and I think it was from a long time ago. There is a post, toward the end of the thread, where someone describes each 'station' of the car. 'station' being sections of the car, and how each body area and feature (windsheild, trim pieces ect.) reacted and helped or hurt. It was technical but super informative. Also... wanted to mention that as I recall, the Gnose thing really did help the aero a lot. You had asked about that. I have no direct knowledge of this but I do recall it dropped the Cd number a good bit. Quote Link to comment Share on other sites More sharing options...
mom'sZ Posted February 28, 2006 Share Posted February 28, 2006 Here it is, here it is It's a thread started by Jonas240z where he is wanting to buid a 240 mph Zcar. Corzette post #81 (last page) and others as well. http://forums.hybridz.org/showthread.php?t=87322&highlight=aerodynamic Quote Link to comment Share on other sites More sharing options...
mario_82_ZXT Posted February 28, 2006 Share Posted February 28, 2006 One of the problems is the big open front with the flat firewall. The g-noes helps considerably I heard, as well as louvering of the hood or inspection lids and properly placed vents behind the front wheels to help relieve all that pressure in the firewall. I have seen pics of high speed Zs having their hoods bow up front the underhood pressures. Mario Quote Link to comment Share on other sites More sharing options...
AK-Z Posted February 28, 2006 Share Posted February 28, 2006 One of the problems is the big open front with the flat firewall. The g-noes helps considerably I heard' date=' as well as louvering of the hood or inspection lids and properly placed vents behind the front wheels to help relieve all that pressure in the firewall. I have seen pics of high speed Zs having their hoods bow up front the underhood pressures. Mario[/quote'] The vents on the hood were original put there because of heat issues with the L28e engine, I could see how it would hlep with aerodynamics and hood presure. I've seen pics of a guy drill a hole on both sides of the engine compartment through the wheel well and mount some fans on the holes (looked like PC fans), I forgot what his impression was after that. I saw it on some old webpage. just some funny ways I saw on how to releive presure. It was on a Firstgen Z BTW. Now I am considering redesigning the fiberglass fenders that I was going to try to make. Quote Link to comment Share on other sites More sharing options...
EMWHYR0HEN Posted February 28, 2006 Author Share Posted February 28, 2006 Now I am considering redesigning the fiberglass fenders that I was going to try to make. You wanna share some pictures Quote Link to comment Share on other sites More sharing options...
AK-Z Posted March 1, 2006 Share Posted March 1, 2006 You wanna share some pictures I haven't even started yet. All I have are are some drawing and no scanner. And I now there are clearence issues and other thing that determind how it will turn out, might look totally different when I'm done (might not been be able to build a set, I'm just attemping to make one). I can't work on them untill I can get my hands on a set of Yamaha R6 (2003) headlights. Depending on how much of an angle I'm going to have them mounted will dictate the angle of the broad angle of the front. Quote Link to comment Share on other sites More sharing options...
LS1 240Z Posted March 1, 2006 Share Posted March 1, 2006 i think a well designed nose that created downforce and didnt let air go under the car would be the best thing you could do, i can see why the huge *** grille in the car would hinder its movement for sure... as for "reliving" the pressure... skulpt some duckts on the inside of the engine compartment that force the air up through those wierd little hinged doors beside the hood, it would also create downforce... just a thought i think the windshield would be another big aero limiter. from what i understand its as important, or more important to manage the air UNDER the car as oppose to the outer.. Quote Link to comment Share on other sites More sharing options...
AK-Z Posted March 1, 2006 Share Posted March 1, 2006 i think a well designed nose that created downforce and didnt let air go under the car would be the best thing you could do' date=' i can see why the huge *** grille in the car would hinder its movement for sure... as for "reliving" the pressure... skulpt some duckts on the inside of the engine compartment that force the air up through those wierd little hinged doors beside the hood, it would also create downforce... just a thought i think the windshield would be another big aero limiter. from what i understand its as important, or more important to manage the air UNDER the car as oppose to the outer..[/quote'] The windshield actually promotes downforce but hinders aerodynamic coefficient. As for venting the engine compartment, I was thinking of cutting some holes on the firewall attaching the engine compartment with the compartment with the wiper assembily, then cut all those vents out of the panel where the wiper assembily is and flush mount some fine mesh on there. There's all these "little things" I want to change on the car that will help it look and perform better. I'm actually thinking about (just thinking) changing the whole door window design to change it to be more "modernized". Just in thought right now. Quote Link to comment Share on other sites More sharing options...
proxlamus© Posted March 1, 2006 Share Posted March 1, 2006 Ok... this might be a long post Two types of drag Parasite Drag and Induced drag Parasite drag = the drag caused by the movement of the car through the air Six types of Parasite drag: Skin friction - caused by the viscous friction w/ in the boundary layer (smooth the surface and file down rough edges) In a Z, hood louvers, sun roof, front bumper, front grill, hatch louvers, side moulding, door handles, mirrors, windshield blades etc Form Drag - drag created or influenced by the form or shape of the car (streamline to help minimize frontal area) Primary source of poor aerodynamics in the Z... Interference Drag - caused by the unterference of airflow patterns around diff car parts (air from the side of the car hitting the air from the roof of the car) Leakage drag - caused by differential pressure inside and outside the car causing air to leak out (repair seals of use tape to elminate leaks around windows and doors) In a Z, bad seals, and especially the high pressure built up under the hood, allows differential pressure to leak out, and air to suck in the car. High pressure always flows to low pressure... the atmosphere always tries to create equality...so the high will always chase the low, and "fill it in" So.. rolling down a window, allows the HIGH pressure outside to flow into a LOW pressure area Profile drag - drag created by moving blades .. which would not apply to us.. helicopters and propeller driven aircraft Wave Form drag - drag associated with shock waves forming around a fast moving car (sometimes considered a seperate or third type of drag) (FYI- a car will not be moving that fast to associate with this type of drag, but it exists) MMM.. I don't know if I can even apply this to a Z, since we don't move fast enough, but baby waves over the roof of the car behind the hatch Induced Drag = the drag created through the production of lift *The front end of a Z and the pointy sloped nose creates a HUGE area of High Pressure, which results in LIFT... Induced drag is a resultant of the lift created Now.. as the air hits the front of the Z, the HUGE grill , causes the air to simply HIT the front end, and slow the car down. The air that flows over the leading edge of the hood, will flow up the hood, and smack into the windshield. The area around the windshield is high pressure, which pushes the moving air over the boundary layer to seperate some. As the air moves over the roof of the Z, the air velocity begins to increase, and slowly breaks off the boundary layer once again, and seperates over the hatch. As the air flows down the hatch, it intersects the air flowing under the car. the air that begins to flow under the front nose/lip of the Z builds up in an area of high pressure... basic flight theory is, high pressure under the wing, and low pressure above the wing creates lift. with an airdam, the air will build up on the front spoiler/dam and creates downforce, but the stock nose creates a "cushion" to float on.. anyway, the air then flows into the front crossmember and axles, and oil pan creating more drag, and then the air hits the firewall.. One weak part in the Z is the firewall, a 90* degree wall, which the air simply collides into, and creates a huge area of high pressure.. if you watch a Z hood at high speeds, you will see it BOW out, Tony D posted pics a long time ago of the hood bowing out... now this high pressure under the hood, creates leakage drag into the airflow over the hood, which then creates interference drag. So all this air flow is disrupted as it hits the engine components, then it hits the transmission, and flows somewhat smoothly along the underbelly.. then the air hits the rear cross member, axels, differential etc, once again disrupting this flow, creating more drag and high pressure.. then the air hits the gas tank, and swirls up behind the gas tank and rear valence or pan. once again, more drag.. A splitter, or rear diffuser will control the air flow, and help it flow smoothly, and quickly... Now all this High Pressure air flows out of the back of the Z and immediatly gets sucked into the LOW pressure area around the tail lights... this is why the Z has terrible exhuast fumes... the low pressure sucks the exhuast fumes up, and leaks through the tail light gaskets, hatch gasket etc. depending on the speeds, but within a few feet from the tail lights, the airflow from under the car, and over the car collide creating more interference drag.. then this wild air flow, equalizes in pressure behind the car.. keep in mind, the headlight scoops, side markers, wheel wells, wheel shape and form, tires, etc also creates drag. Now guys.. I have not over read my post at all... I am not an aerodymicist, so I may not be 100% correct on everything, so feel free to correct me I simply want to give the general idea, why Z's have poor aerodynamics Quote Link to comment Share on other sites More sharing options...
EMWHYR0HEN Posted March 1, 2006 Author Share Posted March 1, 2006 Hey nice writeup, informative. sweet picture too. lol Quote Link to comment Share on other sites More sharing options...
EMWHYR0HEN Posted March 1, 2006 Author Share Posted March 1, 2006 Here's an interesting photo i found while digging through my photo album. It actually looks very funtional, and probably is. The headlight "scoops" are covered and flows with body lines. The front spoiler is fairly low to the ground and masks the bottom of the car from air to flow quikly, which decreases lift. The stock frontal grill area is practically covered completly, stopping the high pressure flowing to the engine bay. but if you look at the picture closely, there are 2 holes on the front grill area. The hole on the passenger side has a pipe directly connected to the manifold, which i think is just awsome. My guess is that the other hole is for air to flow to the radiator, at least I hope so. If you look even closer there is some kind of divider bolted to the core support that looks like it directs air to the radiator. If my assumtion is right about the parts and functions, is this setup efficient enough to cool the radiator and engine cool? Quote Link to comment Share on other sites More sharing options...
EMWHYR0HEN Posted March 1, 2006 Author Share Posted March 1, 2006 Just somthing to look at. IMO It looks like it flows much better than a modded stock front end..... Quote Link to comment Share on other sites More sharing options...
frank280zx Posted March 1, 2006 Share Posted March 1, 2006 The best s30 would be around .38 this is full bellypan gnose all the works... that is where a stock s130 starts!!!! so, to set the title straight ... it is not the 80's z! it is just the s30 that has the same basic aerodynamics as a piece of plywood ( ~.48 for plywood and something like .46 for a split window Microbus..) and the Z is somewhere in between !! I have to look up exact numbers... The s30 is poorly designed in that matter .... if you look at the small lip where the hatch starts on a s130..... it is not there for no reason... those are the secrets that make it so much better than the s30 in this department (not talking looks here) so if you want some good aerodynamics a s30 will not do the trick… that is why TonyD is going to use an s130 on the saltflats! However how many times do you get upto 120 on a windy mountain road or even a track anyway Quote Link to comment Share on other sites More sharing options...
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