scottyMIz Posted February 10, 2003 Share Posted February 10, 2003 hey guys i too have the same prob but not really a suprise huh I found that the tail light seals on my car where gone and then when i looked closer i found that my car had been hit in the drivers side and they replaced the quarter but failed to fix it right so i had huge holes in the side under the back by the exhaust tip.I sealed them all up and the smell was not even as close to as strong as it was but it was still there.I also noticed that when i had my mas kit not on my car i didn't have this prob so the msa kit kinda makes the prob worse.But it looks sooo nice I was thinking i have a rear spoiler on my car that i had to modify to fit, Now what if i put a small lip in the back side of the spoiler forcing air down behind the car?You know a school bus has the same probs. Have you ever seen the dust behind a school bus while it goes down a dirt road?It sworls and just kinda lingers there making the windows in the back very dirty quick.They solved this prob by putting that wing on that directs air down the back.Just thinking maybe for those people who have rear spoilers they could mod theirs to direct air down just enuf to make the exhaust go down and away.well am i way off or what? Quote Link to comment Share on other sites More sharing options...
ZR8ED Posted February 11, 2003 Author Share Posted February 11, 2003 Hey Scott, not you Scott, the other Scott, Its me Scott! Scotty miz You are not off base here at all. notice that older fullsize stationwagons and some mini vans have the spoiler on the top of the roof, pointing down. They do it to keep the back windows cleaner, by forcing air down the window to cancel the vortex created by the original aerodynamics of the vehicle. Form over function..its a catch 22, we want better looks, so we mod the cars rear/exhaust etc... when in effect we are making it worse. So now what.. no one is going to remove their msa body kits, rear wings, or like me expensive performance mufflers. So I guess the challange is to retro fit our cars with something/things, that can help us rid our fumey cars while maintaining our cars looks.. Definately some good ideas are coming out of this. People who are starting to mod their cars should look at this post, and US..well.. we are going to have to work at this a bit. I've been talking with some of my local Z buddies who are suffering as well, and we are thinking of trying some experiments to help ourselves out....though we are about 2-3 months away from our cars coming out... Cardboard is a wonderful material for mocking up wings etc... As far as the yarn on the back of our cars, someone here posted they did this and noticed that many across the middle of the rear of the car (licence plate area) the strings just hung limp at 70mph!.. definately a dead zone there. Sitting here typing and another idea hit me... ever see the belly pans that stick out front under the air dams on race cars?.. kinda stick out a couple of inches parallel with the ground....this helps seperate the air above and below the car before it gets to the car.. Hmm.. they do the same out back...maybe some kind of ground effect with a smooth bottom for the lower rear 1/4 panels of the car. This could help keep the air at the ground level moving faster...thus helping draw the stagnent air behind the car away... not nessesarily a rear belly pan..just on the sides...some of the msa rear bumper kits could be fitted with some aluminum sheeting under them to smooth the air out... I'm just tossing more ideas out guys, maybe one will spark an idea with one of you. This is the way of the inventor...hehe Good discussion going on here!! Quote Link to comment Share on other sites More sharing options...
scottyMIz Posted February 11, 2003 Share Posted February 11, 2003 lots o scotts i am gonna try to put a small but effective lip on my wing to see if it'll help and also i am not too far from toronto so some time we'll have to hook up.How far are you from sarnia?I can get to sarnia in about an hour or two depending on traffic and the boarder guys .Another thing is maybe making a vent that could channel air like down the sides of the hatch and see if that works.Kinda like a small scoop to make the air go down there instead.Just another thought. Quote Link to comment Share on other sites More sharing options...
JoeinCA Posted February 11, 2003 Share Posted February 11, 2003 I seem to remember from working with a miniature windtunnel at my HS. What i saw was that the smoother the bottom of the object, and the better the transition to the bottom, the more lift was created... Of course the object were propped on a 3 inch mast that held them in the center of the tunnel, this doesn't figure for the fact that the gound is so close to the bottom of the car. What i think would provide some downfoce, and decrease exhaust fumes, you could try running a tunnel down the length of the car, angling from the bottom of the front airdam, to .... maybe where the reverse indicator lights are in the rear panel.... Now that would make for an interesting design.(use your imagination, what i just said leaves many things to be considered...) Hmm, now i have to start brainstorming until i get a reasonable design in my head, Joe. Quote Link to comment Share on other sites More sharing options...
Mudge Posted February 11, 2003 Share Posted February 11, 2003 My own twin tip muffler, exits a few inches out of the back of the body, about to the bumper area. I can take a pic and measure if you like, I get fumes. Quote Link to comment Share on other sites More sharing options...
strotter Posted February 15, 2003 Share Posted February 15, 2003 Here's what I'm thinking: we need to take a more "scientific" approach to the problem. We can start with some simple statistics. Some folks get fumes, some don't. Who in particular, then, does and doesn't? Are there variations in the cars that cause variations in the fumes? What variables are involved? Hmm. I'm going to start a Poll, over in the appropriate forum, asking if people do or don't get fumes, and the physical condition of their cars. Perhaps we can isolate the cause(s) a little more accurately. Quote Link to comment Share on other sites More sharing options...
Guest Anonymous Posted February 16, 2003 Share Posted February 16, 2003 We need to determine if rolling the windows down allows the fumes to flow through the windows? Or allows fumes to find hidden entrances into our beloved stinky Z cars? After that is uncovered then a faster fix could be possible! I am going to go do some of the insence testing tonight, Thanks for the clever idea. Quote Link to comment Share on other sites More sharing options...
Guest Anonymous Posted February 16, 2003 Share Posted February 16, 2003 Strotter Which forum is this Quote Link to comment Share on other sites More sharing options...
strotter Posted February 17, 2003 Share Posted February 17, 2003 I posted over in the "Polls" forum. I'm afraid I got a little carried away, though... the question is as long as a tax form, and about as complicated... my bad. I'll boil it down a bit, and repost. Quote Link to comment Share on other sites More sharing options...
ZR8ED Posted February 18, 2003 Author Share Posted February 18, 2003 Well as in much earlier posts, it was noted that my pipes angle up as they exit. But if you look in other pics I have, my muffler tips stick out 3-4" past the body of my car.. I have no bumper, so the muffler clears the entire car. It may be just the angles of my pipes giving me the problems...because they sure clear the car......though....funny thinking about it now... it doesn't stick out as far as it would if it had to clear a bumper as well...hhmmmmm Quote Link to comment Share on other sites More sharing options...
Synlubes Posted February 18, 2003 Share Posted February 18, 2003 my pipe comes out the back at an angle to the left side of car and have never had an issue with exhaust fumes. My rear hatch seal is not in good shape either. Quote Link to comment Share on other sites More sharing options...
ZR8ED Posted March 4, 2003 Author Share Posted March 4, 2003 http://www.hybridz.org/phpBB2/viewtopic.php?p=136637#136637 This linky should work. It takes you to a thread with some photo shop editing of a R33 rear diffuser.. almost looks like a wing UNDER the car.. Anyways.. it just gave me some more ideas.... Have a look. I posted my ideas on that thread while they were still fresh. What do you think? Quote Link to comment Share on other sites More sharing options...
Guest thinkmonkey Posted March 10, 2003 Share Posted March 10, 2003 OK, I didn't have time to read all of the posts so I'm not sure if someone has already come up with this one. Alright, it seems to me that you problem is that the inside of your z is at a slight vacuum when compared to wherever you exhaust leaks is entering the cabin. The solution would be to somehow slightly pressurize the cabin. What I would suggest is using the fender vents that vent into the cabin to let in air, but force more in by tubing the intake for those vents somewhere towards the front of the car where it will have a 'ram air' effect. It's not as if your ears will pop and windows will warp but it may be enough to counteract the effect of the windows being open. It must be loud in there anyway. Shoot, give it a try with some plastic piping if you have some time. Won't fix your downforce problem, obviously. -David Quote Link to comment Share on other sites More sharing options...
ZR8ED Posted March 11, 2003 Author Share Posted March 11, 2003 Ok here is another update/more questions and theories surrounding the issue of exhaust coming into the cars (excluding bad seals) I was talking shop with my mechanic today, and were looking at a 260Z on the hoist. We noticed how the gas tank was flat (parallel to the ground). The rear of the tank had an angle to it..30 degrees maybe. Anyways, the point being is it seems it would have less effect under the car than my 280 tank, which is more rounded and hangs much lower. If I had that 260 tank, it would be much easier to install a rear bellpan. Any idea of a 260 tank will work with a FI 280????? not sure it is suitable for a fi system. Second topic was discussing the lack of holes in the back of my rear valence. At least on my 280, when the stock bumper was on the car, there were oval slots in that rear valence below the bumper.. Nissan did not put those holes in the valence for cost savings. I am quite sure they were there to help let out trapped air... I wonder if this is compounding the issue...I have my whole rear valence smoothed over.. no slots cut out...hmmmm Maybe having some sort of vent on the rear to let out trapped air may help...hmmm topic 2a: There is a gap between the gas tank and the rear valence.. I wonder if air traveling under the car gets sucked up there, as the air passes under my gas tank, then suddenly curves upward..(rear curve is steeper than 7-9 degrees by a long shot) I wonder if I put a panel to block off that gap.... its only 2-3 inches, and as long as the gas tank is wide... I'm starting to wonder if making a partial rear belly pan, may help... something that directs the air normally going under the gas tank, and instead of angleling up sharply... maybe have it come up in that 7-9 degree range, and then make a 90 degree vertical turn and attach it to the rear valence.. (might look kinda like a fuel cell hanging under the car...) Anyone care to try an experiment?.. try putting in a piece of aluminum between the fuel tank and the rear valence.. use duct tape to hold it in place and go for a drive with your window down... does it help .. yes/no.. We got several good ideas in this thread... I'll try them when the car comes out of hibernation, but would anyone else choking on fumes like to try and see if it works for them?.. In case you have not read all the posts, I have good seals on the car, and only get them with the windows partially down... nor do I have any lift problems. This thread has kinda changed its topic more to rear aerodynamics of the z.. for handling..and for exhuast fumes... oh and to help us guy who have styling mods that may be making the situation worse, yet won't remove them.. there is no way I'm removing my $300 muffler.... I kinda like the idea of pressurizing the cabin slightly, but it would most likely make the car way too cold for night cruising...We are talking about street Z's.. Please keep on with the comments and ideas.. its a while till spring up here for me, so if you are in a warm climate and are tired of the fumes in your Z, then try some of these ideas and let us know if they work...It may add years to all of our lives....hehehehe Thanks, Scott. Quote Link to comment Share on other sites More sharing options...
Guest Anonymous Posted April 6, 2003 Share Posted April 6, 2003 Here's a great link for whoever's interested in reducing lift, increacing downforce, or just genrally reducing their drag coeficiant: http://www.eng.ed.ac.uk/~jchick/Y5/thesis/FormulaStudent/public_html/aero2.htm Quote Link to comment Share on other sites More sharing options...
Synlubes Posted June 2, 2003 Share Posted June 2, 2003 Hey folks, I saw this pic of member Ozoners car and had a thought. Notice the tabs along the flame rails Now, with some tabs mounted along the rails use a sheet of *something* to close in the center under belly. ? ? ? Quote Link to comment Share on other sites More sharing options...
ZR8ED Posted June 2, 2003 Author Share Posted June 2, 2003 Yea it does look like mounts for an under tray.. except they hang lower than the rails.. I wonder if it is for clearing the exhaust? I looked at my exhaust, and I will most likely have to redo mine to be able to fit a belly pan under the trany tunnel... certainly not out of the question! Girls hate poisonous gas! Quote Link to comment Share on other sites More sharing options...
Nismo280zEd Posted August 16, 2003 Share Posted August 16, 2003 Don't know if this helps... My father has an 89 Porsche 911 Carrera, when i was painting my car 2 years ago, i added some custom flairs in the back. I love porsches, so i copied the entrance to the flair and exit. They are EXACTLY the same as the 89... it only changes at the top of the flair due to the Z design. Anyhow... i also put on an after market flow through muffler to loose the weight of the "Turbo" muffler and the 8" long tip it had. My tip is about 1" past the rear body... 3-4" from the bumper and i have no problems w/ exhaust w/ the windows down. However... if you open the hatch while driving.. it sucks the fumes in like a vacumn. I suspect you have a leak around the rear of your car, silicon works wonders -Ed Quote Link to comment Share on other sites More sharing options...
Guest penguin Posted November 14, 2003 Share Posted November 14, 2003 yeah i know everyone got off the rear diffuser idea and have moved on to a REAL solution, but i wanted to through my two cents in; if you want to suck the exhaust out in a vortex, get a very low front clip. get some side skirts, and lower your car. you dont really have to worry about the actual diffuser if you arent looking for downforce. as your car pushes forward through the air, hardly any will be allowed under it, creating a slight vacuum under your car. the result should be a rather fast, rather turbulent stream coming out the back pretty low. the reason racing cars use the diffuser is to calm the stream and mix it with the one coming over the car. one more point. the 360 Modena most certianly does NOT have a flat bottom. it is a very unpredictable, very deadly thing to drive on the road. lets all think back to i think the 99 le mans and the mercedes clk-gtr flying through the air. that was because it crested a hill, the wind caught the underbody, and the very stable, very fast car became and very short lived excuse for an airplane. also, if you really want to fix the problem, just go for a side pipe. no fumes at speed, and at stop lights, it will give you a slight headache and a really light happy feeling. Quote Link to comment Share on other sites More sharing options...
ZR8ED Posted November 15, 2003 Author Share Posted November 15, 2003 Penguin: I don't think anyone else's street Z has a lower air dam than me... Mine is about 1.75" off the ground...pretty low.... As for the rear bellpan. Mine is complete...I just need to install it now...I got held up with bigger probs this summer and it got left on the sidelines. This thread is pretty old, and was meant to deal with inherent issues of installing aerodynamic equipment on our car, that makes any exhuast issue more severe... No one here is going to remove spoilers, wings etc.. to solve the exhaust problem...I know I won't...and a straight pipe out the side is not an option after some of us have spent big money on large exhaust and mufflers. I had thought about what can be done with out changing these things...My reasons are for exhaust fumes, and I just love the "Geewizz" factor of a rear bellypan (I already have a large front pan) Its all about keeping the air under the car moving faster than the air on top and beside...AND keeping the exhuast low to the ground to try and get a scavaging effect... But in the name of performance I think reducing that vortex behind the car may be of other benifit as well... I know with my wide body styling, I've made it worse..but I'm not going to change it back...so I've been studying other answers...which have created more questions of course. I hope more people will look at this thread and post what has worked/ not worked for them for reducing fumes in the car.....If you read all the posts, there doesn't seem to be one sure fire solution... Always looking for options and ideas..... Thanks, Quote Link to comment Share on other sites More sharing options...
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