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Andrew Bayley

Can a rear spoiler reduce exhaust fumes?

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denny411    18

Has anyone considered putting stoppers at the outside corners of the hatch to insure that the hatch stays level? One could probably use the same stoppers that are used at the rear of the hood.

This would create five points of contact.

It might also make it easier to keep the hatch seams and gaps aligned for those of us who are interested in those types of nit-picky details.

 

I may do this myself since the whale tail might have a tendancy to make the hatch flutter at speed.

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col    10

Hi just a sugestion for those of us that think fumes are coming from the hatch.To make 100% sure it was or was not a hatch leak I ran tape all round the hatch gap and go for a run. I did and the fumes are gone.looks like new seal and adjustment for me.Just a question for the airflow experts,How big would a spoiler have to be up on the roof in front of the hatch to detach the air from the lid minimising lift and reducing the fume problem?

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josh817    15

Yah uh.. problem. I have a rear spoiler but I have no idea how to install this thing.

hpim1697nm2.jpg

Thats how thick the edge lip is, and the spoiler is hollow so how exactly do you mount it without cracking the fiberglass? I'd hate to say that you just bondo/glass it on...

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Bowtiez    10

Ancient Problem. I had this problem in 1972 with my then new 240Z. It occurred when I had only the driver's side window down and the vents open. That seemed to suck the fumes in. With both windows up or the passenger side window down, there was no problem. The dealer said that was normal????

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jasper    14

I read the entire thread. Very enlightening. However, I saw no mention of the exhaust witness marks......The smoking gun. Discolored drivers side tail lamps. The passenger side is always bright and shiny! The exhaust rolls right back up to the lamp.7829_1.JPG

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cygnusx1    12

There is a clear path for fumes to enter the car. Up the "hatch latch hole" and into the cabin through the vinyl panel under the hatch. The vinyl panel is no where near airtight. Remove the vinyl panel, put a bead of sealant around the opening, seal off the opening with a sheet of plastic, reinstall the vinyl panel. This eliminates one more path.

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There is a clear path for fumes to enter the car. Up the "hatch latch hole" and into the cabin through the vinyl panel under the hatch. The vinyl panel is no where near airtight. Remove the vinyl panel, put a bead of sealant around the opening, seal off the opening with a sheet of plastic, reinstall the vinyl panel. This eliminates one more path.

 

 

-Does someone have a picture of this?

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GeeZ    11

I found that when the previous owner removed the bumper shocks, he did not seal the bolt holes. The exhaust gases were being sucked in thru these holes.

But that has not taken care of all the gas though.

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dennisakon    0
This has been addressed a couple of times..about a yer ago. Was it Mark(?) who said the rear spoiler did in fact reduce the fumes from entering the rear? Must be a common problem. I get sick from the stuff too. My hatch could use some tightening.

JS

 

True. A rear spoiler will reduce the fumes from entering the vehicle.

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rusty72    0

if the rear spoiler is mounted to the hatch and the hatch only i would assume that the bulk of the downforce added would be on the hatch thus sealing it better. that might be why it helps with some and not others it may have very little to do with the spoiler delaying the wake behind the car. people have reported that it helps greatly and also that it doesnt help at all but have not shown how the spoiler was mounted.

 

just a thought.

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chris280z    0

Lots of good info on this thread, I also replaced the seals on my tailight assemblies, the drivers side was jeapordized & definetly allowing fumes to enter. There appears to be several areas of concern back there.....thanks to all for the great info. It's all part of the master plan!

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Edmund    0

Odd question, but it comes to mind. I'm thinking adding something to the gas that will make color fumes, like green, red, or something else(I saw this on a drift video before, but for fancy reason) This way, I can at least visible trace where the fumes is coming to the cabin. Does anyone have any experience what I can add to gas produce color exhaust fume without damaging the car? Thanks.

 

Ed

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cygnusx1    12

Exhaust velocity at the tailpipe might also be at play here.  I find that you get MUCH more stink when driving at part and low throttle.  I think that at high engine loads, the exhaust stream is fast enough to get mostly out past the tail-wake.  When the exhaust is moving slowly, it gets mixed into the tail-wake and swirls around the rear quarter of the car..

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So, for anyone who wants to take a shot at the actual vacuum caused at the back of your car, I learned this by simple experience. I was driving my 78 a few years ago, and apparently didn't catch the latch on my back hatch. It was shut, it just didn't 'click'. When I was going 90-110 (it was a few years ago, so I'm not sure exactly what speed it was at) the hatch popped WIDE OPEN. ALL THE WAY. I even have good working OEM gas struts on it still, and it POPPPED right open. So, if you take a force gauge (or put yourself on a scale, and see how much more you 'weigh' when you're opening the hatch lid, then see at what speed your hatch opens, that will tell you how much 'upforce' you have at a certain speed. Comparatively, with the addition of a spoiler, the force to open the hatch may increase with the weight of the spoiler, but the speed at which it opens should hopefully be MUCH greater than it was before. Any takers for a some high speed test runs?

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One thing I didn't see mentioned was a rear window louvre in terms of the aerodynamics. Would a louvre provide enough edges in the contour to break up the airflow over the hatch? Maybe enough to relieve some of the lift or even eliminate the exhaust fume circulation?

 

My Louvre is currently off because it broke when the car was getting transported. Before that, I never remember having fume issues, but now that it's gone suffer from all the noted symptoms. Once I can source a new louvre that's not a totally ridiculous price, I can post my results.

Edited by Twistedlizard720

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