Dragonfly Posted October 27, 2007 Share Posted October 27, 2007 I was fortunate enough to be able to det a close look at a GT40 up close and personal so I took a few pictures. I know there have been a lot of discussions on diffusers and since none were tested in the wind tunnel on a Z I thought maybe we could learn a little from the design that I am sure Ford tested in a wind tunnel before releasing this car to the general public. Any way here are the pics. I would think that it would not be to hard to adapt something like that to the Z, what do you guys think? Dragonfly Quote Link to comment Share on other sites More sharing options...
thehelix112 Posted October 27, 2007 Share Posted October 27, 2007 The key to a functional diffuser is what you can't see. Ie, all the flow on the underside leading up to the point it becomes visible. If the flow is completely turbulent 10" after the front bar, a lovely neat rear diffuser like that isn't going to do much. At the very least you'd want a flat underside, with attention paid to the front splitter/air dam, and you need to be very careful to ensure the flow in the diffuser remains attached. That means ensuring that the transition where the it goes from flat into diffuser is perfect (not a raggley weld), and that the angle of the diffuser is not too steep. Dave Quote Link to comment Share on other sites More sharing options...
m4xwellmurd3r Posted October 27, 2007 Share Posted October 27, 2007 so basically the underside of the car would need a pretty belly pan specially made for the car? because i don't think the undersides of our cars are smooth enough to fully benifit from a rear diffuser, but i' might be wrong hahaha Quote Link to comment Share on other sites More sharing options...
JMortensen Posted October 27, 2007 Share Posted October 27, 2007 Define "fully benefit". I think a diffuser can make a difference if it's done right. I'll be interested to see some wind tunnel results one way or the other. The Z actually has a fairly flat floor, its the suspension area in the back that is the problem. In the last Race Car Engineering magazine they did some tests on a new Lotus and its factory diffuser. I haven't seen the bottom of the Lotus, but the diffuser itself didn't look that spectacular. With a couple of mods they were able to increase total downforce 20 something percent I think, and FRONT downforce went up 8% (these figures are coming from memory, I'm too lazy to go look it up). They were supposed to continue the story in the latest magazine, but didn't, so hopefully they'll pick it up next month... Quote Link to comment Share on other sites More sharing options...
DrEaM Posted October 27, 2007 Share Posted October 27, 2007 Define "fully benefit". I think a diffuser can make a difference if it's done right. I'll be interested to see some wind tunnel results one way or the other. The Z actually has a fairly flat floor, its the suspension area in the back that is the problem. In the last Race Car Engineering magazine they did some tests on a new Lotus and its factory diffuser. I haven't seen the bottom of the Lotus, but the diffuser itself didn't look that spectacular. With a couple of mods they were able to increase total downforce 20 something percent I think, and FRONT downforce went up 8% (these figures are coming from memory, I'm too lazy to go look it up). They were supposed to continue the story in the latest magazine, but didn't, so hopefully they'll pick it up next month... yeah i've seen the bottom of the lotus and i have to say that yes it is pretty much completely flat under there its amazing the way they did it b/c it looks like one big sheet of metal..BUT infiniti does have ZERO lift kits that they put on their cars,g35/37 m35/45 and i'm sure that neither of those cars are PERFECT on the underside either so i'm thinking with the right soilers and wings or whatever the old s30 could get pretty close to zero lift or at least minimize some of the lift i'm not too sure but i do know from pics and personal experiences with other zcar guys that it seems all we ever do is install the front spoilers just for looks and forget that it is designed for a purpose to guide the air/ or create downforce.. i'm not sure about the american manfactures but many japanese tuners actually windtunnel test their products b4 installing them.. i'm pretty sure with a front spoiler a splitter and a decent diffuser in the back it would make at least a little difference in how the car drives at speed Quote Link to comment Share on other sites More sharing options...
ZDrifter Posted October 27, 2007 Share Posted October 27, 2007 I have had the pleasure of being around one of these so I will put in my input. I have been under one on the lift and there is a belly pan the runs the full length of the car. To service anything from the bottom it has to be removed. I even got to drive one for about 20 feet into the shop I dont think I have been that scared tryin not to hit anything lol. Anyways for these to work on a Z a belly pan would have to be fabbed. Like we all know the faster we get that air sliding under the car the more downforce we can take advantage of. Quote Link to comment Share on other sites More sharing options...
Mikelly Posted October 27, 2007 Share Posted October 27, 2007 As the windtunnel operator told us, our money and time is best spent elsewhere... Take a look under that Ford GT and you'll see a flat bottom car, very similar to the C5-C6 Corvettes and very similar to my 996TT. They're flat for a reason... No frame rails, or exsposed trans tunnels, no open engine compartment... It's all sealed off or as flat as can be in the corvettes case. You guys are trying to come up with things that simply won't add benefit, unless you plan to do the whole bottom of the car... Remember, TOTAL PACKAGE is what works... anything else is only addressing one end of the car, and making a significant negative impact on the "other" end. Mike Quote Link to comment Share on other sites More sharing options...
buZy Posted October 27, 2007 Share Posted October 27, 2007 How about making some that just look cool. Who cares if they actually work or not. Quote Link to comment Share on other sites More sharing options...
MaTTSuN Posted October 27, 2007 Share Posted October 27, 2007 if it does not work i would not want to put it on my car if it didnt work it would be very rice Quote Link to comment Share on other sites More sharing options...
aziza z Posted October 28, 2007 Share Posted October 28, 2007 How about making some that just look cool. Who cares if they actually work or not. i think it would look good functional or not too. Quote Link to comment Share on other sites More sharing options...
Mikelly Posted October 28, 2007 Share Posted October 28, 2007 OK, let me try the OTHER approach... What if it made your car handle worse? Putting that device on the rear without the added benefit of the rest of the package would seriously hinder its ability to function. Sometimes looking cool hurts the performance of a car... This is the WINDTUNNEL category... You want looks, go over to the Body and Paint section. I'd like to keep this category focused on what works, what doesn't and why. Mike Quote Link to comment Share on other sites More sharing options...
JMortensen Posted October 28, 2007 Share Posted October 28, 2007 I'm going to have to see some windtunnel test results in order to prove that a diffuser won't work on a Z. The wind tunnel guy said some other things that I thought were wrong too. I know, he's a wind tunnel operator and I'm a pet door salesman, but that doesn't mean that he is right and I am wrong. As I said before, I think some of his statements may have been made based on the cars he was looking at, none of which were very close to the ground. Since we are talking about "ground effects" I think that may have colored a lot of his comments. Call me a hardheaded dumbass if you want, but I think that a lot of what we see in the racing world can be made to function on our cars. Air is air, and pressure is pressure. Quote Link to comment Share on other sites More sharing options...
DrEaM Posted October 28, 2007 Share Posted October 28, 2007 yeah i think this whole mindset "its impossible or impractical" on a z thing is holding us back.. thats probably why noone has designed a decent front airdam that doesn't look like it was designed in the 80's.. think about it as popular as our old z's are has there been any really nice new parts to come out for our cars in the past ten years? yeah this year the engine damper did come back out and yes there are companies like technotoytuning paving the way for us classic car guys but it doesn't really seem like anyone it taking any of the new tech today and applying it to any of the old aero and body parts that have been out for YEARS.. maybe if we get away from the thought that something can't be done we can start figuring out what can be done with our cars.. and besides the exhaust and framerails i think that we could smooth the bottom of our cars out fairly well and for a decent price.. a big enough front splitter and a decent rear defuser i think would go a little ways in improving aero, especially coupled with a nice wing and some vortex generators.. Quote Link to comment Share on other sites More sharing options...
aziza z Posted October 28, 2007 Share Posted October 28, 2007 for my case i don't think a rear diffuser would make the car handle worst. Heres my reasoning. i just did a ls1 gas tank swap and i cut my spare wheel well out so it places the tank higher. but it left a giant gap between the back of the gas tank and the rear of the car. The stock gas tank had covered this area before. Now it looks to me like a giant area where air could get stuck against the rear of the car (shaved bumper area). The rear diffuser would block of this area and carry the air all the way from under the car. hope i described that well:hs:. ill see if i can get pics if anyone wants to see what im talking about. maybe a rear diffuser would benefit people who have done a ls1 gas tank swap. just my opinion anyway. Quote Link to comment Share on other sites More sharing options...
DrEaM Posted October 28, 2007 Share Posted October 28, 2007 and no i don't think "just because it looks cool, put it on my car" thats dumb to me.. thats where the term RICE comes from Quote Link to comment Share on other sites More sharing options...
Mikelly Posted October 28, 2007 Share Posted October 28, 2007 There will be another round of testing, and hopefully Mayolives RedBird will be in the tunnel. His car does have a rear difuser and will be able to answer some of the speculation. Mike Quote Link to comment Share on other sites More sharing options...
Mikelly Posted October 28, 2007 Share Posted October 28, 2007 for my case i don't think a rear diffuser would make the car handle worst. Heres my reasoning. i just did a ls1 gas tank swap and i cut my spare wheel well out so it places the tank higher. but it left a giant gap between the back of the gas tank and the rear of the car. The stock gas tank had covered this area before. Now it looks to me like a giant area where air could get stuck against the rear of the car (shaved bumper area). The rear diffuser would block of this area and carry the air all the way from under the car. hope i described that well:hs:. ill see if i can get pics if anyone wants to see what im talking about. maybe a rear diffuser would benefit people who have done a ls1 gas tank swap. just my opinion anyway. So how are you going to compensate for that big valley in the tranny tunnel that runs back to the rear diff and control arms/axles/swaybar? There's a lot of pockets under the car that cause problems long before getting back to the area where a rear valance would start. It's really not hard to understand the whole "total package" that Bob Smith described... Look at the Spook/Whaletail combo... It's the same kinda deal as that, except "under" the car. I'd bet large sums of money that you'd cause more harm than good... And I've got the same exact problem as you. I removed the rear spare tirewell and installed a flat bottomed fuel cell. I'd love to make the underside much more flat and integrate a difuser. But I know that it would take a lot more work than might be useful. However, I'm smart enough to know when I'm getting good advice. Bob Smith doesn't do brain surgery, he does windtunnel testing. I'll go to someone else for brain issues. But when it comes to things aerodynamic, He's a true authority in my book and the only person I know who sees aerodynamic devices tested on a daily basis. But hey, what does he know? Mike Quote Link to comment Share on other sites More sharing options...
buZy Posted October 28, 2007 Share Posted October 28, 2007 Sorry guys. I didnt mean to down play the seriousness of this subject. I just thought these parts have might have some curb appeal too. Quote Link to comment Share on other sites More sharing options...
Dragonfly Posted October 29, 2007 Author Share Posted October 29, 2007 There will be another round of testing, and hopefully Mayolives RedBird will be in the tunnel. His car does have a rear difuser and will be able to answer some of the speculation. Mike That would be great, Red Bird is one of my insperations. Here is the diffuser on Red Bird. This pic came from Hybridz. Dragonfly Quote Link to comment Share on other sites More sharing options...
260DET Posted October 29, 2007 Share Posted October 29, 2007 My S130 is going to get one, at the very least it will help tidy up the airflow around the rear and reduce drag around the rear panel area and bumper bar. Plus it should work in conjunction with a whale tail to exert negative pressure under that. I'd be interested to hear why this should not be done, far as I'm concerned if something is based on valid principles and well designed and executed its a plus. Just a reminder about the S30 in this video, something is working there for it to outrun the competition spec Viper. Quote Link to comment Share on other sites More sharing options...
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