A Few Dual Exhaust System Questions...

I went into the performance shop the other day to get a feel for the quality of work these guys do on exhaust systems (the speed shops and hot rod buffs all recommend this place). I found that they seem to know what they're doing and do some good work, however, he made a few interesting comments:

1.
He recommended that instead of the typical look where the two tips point straight back, I should have them angled a bit down and also point about 45 degress to the side. His reasoning was that the air stream around the VX will keep some exhaust fumes rolling around the rear tailgate and that there is the possibility that the fumes could be sucked into the car through any gap in the tailgate seal.

Has anyone experienced this or heard of this?? Most new SUVs have rear pointing exhausts (although most vans don't..).

2.
Also, does anyone really feel that smooth bent pipes will noticeably lower performance compared to mandrel bent pipes? (There's no mandrel bender in the City here - special order required)

Thanks for any thoughts...

Ken

http://www.vehicross.info/gallery/da...s/100_1642.JPG

Here's mine at about 45 degree's, but straight out the back. No prob here with fumes...

I think that he means 45 degrees sideways, as in closer the the tires.

I have heard of this and they say that it is a concern for all hatchback like vehicles. The idea is that there is a low air pressure area in the back of the vehicle while you are driving. And the exhaust fumes can be flushed into the passenger compartment if the seals are not working. Cars with trunks have seats and the trunk is more seperated from the passenger compartment.


I really don't think that it would be a major worry. If you smell exhaust open the windows, turn on the air vents and it would be ok untill you could replace the seals.

or drive fast enough to get away from the fumes! ;Db;

... i love the look of duals

my RMS Hooptie van, (extended G20 chevy) has that problem. when i open the rear windows,or when i take the window out completly to haul lumber longer than 14 feet, i get alot of exhaust fumes, so i gotta keep em closed. not saying that my van is as airodynamic as the vx, but the fumes do linger back there, and opening the front windows dosent help that much either, seems to draw them in even more.
seems that the fumes would just blow away, but they dont.......
just makin a point..

duhhh, and my exhaust points out the side , not the rear.....(my most important point) i would think that pointing down would get the exhoust fumes into the air stream running under the vehicle, and away from the back of the mobile.
oh well,
carry on my wayward son.............

The exhaust recirculation is common in pretty much any suv but not really a concern in my book. Since the rear window does not open i would not even worry about it. As for the pipes you will never feel the difference in smooth bent pipes vs. mandrel. You would be really hard pressed to see a diffference on the dyno as well.

There are vents located around the perimeter of the rear door that allow for the exchange of inside air, so it is a legitimate concern. When a significant level of CO builds up you won't smell it, you'll just go unconscious.