Would a rear wing/spoiler help keep exhaust fumes out of my

[Guest bastaad525]

Okay... I know it's pretty common for old Z's to suck exhaust in from the back of the car, due to the shape of the car and it's aerodynamics, and especially if the rear hatch or tail light weatherstripping is worn out. One thing I'm wondering, and wanted to ask since I know a lot of you guys here have put various body-kit parts on your car.... is if putting a rear spoiler or wing on the car will change the aerodynamics enough to stop sucking the fumes back inside??

[Guest Anonymous]

It appears the common thought is no, it won't. Sealing where all the gas hoses are back there and all of the places exhaust can seep in will help enormously. as will replacing all the chassis gaskets around the tail lights etc. (mostly the gaskets, I only mention the hoses because I was blow away when I saw a Z with all of its interior panels off in the back, didn't know there was that many vent houses and what not out there). If you look in the archives there was some in depth discussions about this, but the wing alone won't do it. But then again if you run across a aerodynamic solution that works, several 100 thousand Z people would probably be customers.

 

Regards,

 

Lone

[Guest bastaad525]

Heheh I'm sure they would Well anyways I was just wondering... didn't think it would though but then I guess it would depend on the type of spoiler too. Anyways I ran to MSA today and picked up some tail light gaskets and the rear hatch seal.... $200 for three pieces of rubber !!!! When installing the light gaskets today I found out that not only were the gaskets toast, but each tail light was only held on by 3 screws... 3 out of 8! So I'm betting that was a big contributor to the unbearable smell. I mean it was BAD... caused bad coughing and burning eyes. Well... even if I can't get rid of it 100% I hope that the gaskets and weatherstrip will at least let me drive the thing again!

[GAZRNR]

I'm trying a 3 piece spoiler to create a different air flow over the back of my 78Z. My only problem with exhaust fumes in the car is under deceleration with the window either partly down or all the way down. If this doesn't work I'm going to try some kind of turn down to redirect the exhaust.

[VRJoe]

While my Z is not finished yet I've been reading a number of posts about the exhaust smell. One point that needs to be kept in mind is that the exhaust can only be sucked into the car, i.e., air is being pulled in from the exhaust area into the interior of the car. The best way to solve the problem is to seal the areas that the exhaust can get in, and there are a lot of them in the back of the Z. With the windows open it will actualy create negitve pressure by the rear window (Ever notice how the dust from the back of your car comes up front when you open a window ?) and suck in exhaust if there is an opening. I've seen this in the past on other cars and sealing was always the answer. It may help to think of the problem as a pressure issue, and the the exhaust just gets carried along with the air that gets pulled in.

 

Hope that helps.

 

-VRJoe

[ZR8ED]

I've been fighting the same issue.. I replaced my rear seals.. to no avail.. Only comes in with window down...

 

I'm planing on building some diffusers like on the backs of the lemans cars.. vertical panels underneath the car at the back to give the car side to side stability at highspeeds (I assume)

 

It directs the flow of the air that is traveling under the car.. it smooths out the airflow till it is further past he back of the car. (again i assume that is what the effect is)

 

There is a lot of turbulance at the back of our cars that swirls the exhaust around the back of the car.. then if a low pressure zone appears (ie opening of window) then it simply works its way over and into the car.

 

Don't know it if will work.. might help in the handling department.. not sure either.. worst case senario is it doesn't work, but looks racey! or is that ricey? hehehe not sure.. doubt it will look ricey on my z.

[Guest Thurem]

How about that 2 ft extension on the exhaust, maybe with a folgers can. At the very least you could claim it had a purpose.

Thure

[Guest Thurem]

Maybe you could seal the taillights by covering the whole assembly, from the inside, with plastic attached with double stick tape (cellofane).

Thure

[awd92gsx]

I can honestly tell you, no, it doesn't make the slightest amount of difference.

 

My exhaust smell is there with my spoiler (and I have a tall one =o)

 

Of course....not having any rear hatch seals may have something to do with that...

 

I've found that by adjusting my FPR I can get it a little better. I'm hoping I can tune it even better with my Super AFC and possibly eliminate it altogether.

[denny411]

I think that a spoiler could actually make it worse. The air flowing over the spoiler could cause low pressure behind the car, causing the fumes to be pulled forward and through any open areas around the tailights,and through the bottom edge of the hatch. Maybe

[Guest Anonymous]

There is concern that the vents under the insignias on the side sail panels on the the fast back roof line may pull in fumes. Block these round vents off under the insignias.

[VRJoe]

The vents in the sail should actually help draw pressure from the rear of the car, it gives the air a path to escape from the hatch area. I'm planning on putting a cover over them, like a reverse scoop, to help draw air from the interior (and change the lines a little bit )

 

When sealing the back be sure to seal the overflow tank lines from the fuel tank.

 

I suspect that exhaust is getting pulled under the car, then pulled from under the car in to the rear hatch area. Check the complete rear area for any leaks. There are a lot of places in the rear area for air to get sucked in. Did you remove the bumper mounts? If you did make sure you sealed those holes.

 

-VRJoe

[Guest Anonymous]

VR Joe, members have posted that the sail panel vents "pull" in fumes and plugging the holes have significantly reduced the fumes. I would suggest a simple experimental test of stuffing a suitable material in the vent hole and replacing the insignia and see if there is an improvement.

[denny411]

I`m planning to weld patches into the sail panels.

[Guest Dan0myte]

I know this is resurecting an old thread, but I thought I would just post this finding.

 

http://www.mulsannescorner.com/Lola-PM7.jpg

 

Professional race teams have this same problem, with the low pressure zone right behind the car. Their solution for it was quite simple. Ducts were placed on either side of the car, right infront of the rear tires. As air passed around the car, the vent draws air into itself and spits it out behind the rear tire to fill in the low pressure zone created by both the tire and trailing edges on the sides of the rear diffusers. Also you can see that sharp box like thing there behind the wheel on the body work...thats a vortex generator used to further aid base area fill.

 

I'm not sure if you'd make a hole that drastic in a Z car, but something similar and on a smaller scale may be able to be worked out?

[Guest zfan]

I own a 1971 240Z and have welded all vent holes and hatch vents closed. Also have replaced every piece of weatherstrip known to man on the Z and with the windows down I get fumes with them up I am pretty much fume free.

 

I have no rear spoiler/wing or rear bumper. Everything is sealed. I also extended dual exhaust out another three inches from old placement and that helped I think.

 

Man the fumes will KILL YOU if your not careful

 

Mike

[flibuoy]

I am quite short in height, and have adjusted to that fact. In a like manner, after years of stock and hybrids, I adapted to exhaust fumes with one window down at some speeds. If you start the car then I think you will have some fumes at some speeds. The best to hope for is good sealing minimizing it to point that you can see through it to drive. john

[fl327]

280 guys, do you guys get fumes?

most of my weatherstripping is probably original

i run a 3" exhaust, and have no fumes, at any speeds, and i love it, i wonder if its a 280 thing. i had a 240v8 and it was a smoking me out, and i tried a million and one tricks to seal it out, to no avail.

[S30Z Bushido]

my 280z definetly has the fumes problem, always have to keep the windows down.

[Guest Anonymous]

All the fumes come in because of an extreme negative pressure directly behind the license plate. Sure, you could put a wing in place, but lo and behold, the fumes still come in. that is because there is much turbulence that forms behind the car when the high pressure air comes out from underneath the car and fills in all that low pressure space, and continues to flow in through all the low pressure areas, such as in through all the rear seals. (i'm trying my best to explain this) sure, you could go the racecar method and create a duct to route the air to the back from the sides, BUT it is useless unless the air pressure is enough to balance the air pressure coming from above and beneath the car, otherwise you negate the effects and create only more turbulence.

 

A more common (well, maybe not common, but easier) solution is to add a diffuser to the underside of the rear. You typically want it as long as possible under the car, but near the rear of the car. I believe it is supposed to have an upslope of 7 degrees EXACT. fins are used on these usually to decrease as much vortexing air as possible, thus also decreasing turbulence. if you decrease turbulence, you create downforce, thus sucking your ass to the ground at high speeds.

 

Well, I know i'm forgetting to say something, but i guess it's my 2 cents or so.

 

-Jimmy