Hard top and Soft top owners, exhaust question

[matt s]

Currently my dual exhaust runs straight out the back on my blazer, and I am having problems with fumes in the cab. I have plugged and sealed everything in the rear, but it's a gas and it finds a way in. It's not a leak in the system somewhere up front, I have checked that. On to the question

Does turning the exhaust 90 degrees to go out behind the rear wheels make a significant difference with this issue?

Just trying to limit the hoops I jump through while chasing this one down.

Thanks in advance.

 

[dsw4x4]

Moving your exhaust to the side will make all the difference in the world I have two box style broncos and a cj7 and every time I ran duals straight out the back it smelled in the cab. Just a little angle on the tail pipes so they dump between the taillights and the rear of the wheel is all it takes to get rid of the fumes.
Derek

 

[ntsqd]

The rear of vehicles with this type of shape will have a huge vacuum pocket right behind them when at speed. Dumping the exhaust into that pocket does what you're experiencing.

The pocket is easy to see. Have someone drive the vehicle down a dusty but smooth road while you watch off to the side from a little distance. The faster that they can go, the easier it is to see the size & shape of the pocket.

If you're curious you might try one of those old roof top spoilers that deflects air down the rear window. It may or may not make the bubble go away. I've wanted one for my Sub to keep the rear windows cleaner.

 

[matt s]

The rear of vehicles with this type of shape will have a huge vacuum pocket right behind them when at speed. Dumping the exhaust into that pocket does what you're experiencing.

The pocket is easy to see. Have someone drive the vehicle down a dusty but smooth road while you watch off to the side from a little distance. The faster that they can go, the easier it is to see the size & shape of the pocket.

If you're curious you might try one of those old roof top spoilers that deflects air down the rear window. It may or may not make the bubble go away. I've wanted one for my Sub to keep the rear windows cleaner.

Thanks, I am all too aware of the pocket, and the dirty windows to go with it! I knew that it was the source of the problem, I just wasn't sure if going out the side behind the rear wheel would get the exhaust far enough out of that pocket to make a difference. From what I read here, and others I have talked to, it ought to make a big difference. I will keep the spoiler in mind, although I have never cared for the looks of them too much, but clean air trumps looks anytime.

Thank you both for the responses!

 

[computeruser]

A slight turn-down on the pipe seems to help, too. Look at any OEM setup on a Jeep TJ Wrangler as an example.

 

[matt s]

A slight turn-down on the pipe seems to help, too. Look at any OEM setup on a Jeep TJ Wrangler as an example.

I wondered about that, there was a set of turn down tips I almost bought for that reason.

I am thinking I will take them out the side, it will make doing anything near the rear of the vehicle (while running) more pleasant anyway. Hooking up a trailer "real quick" with those blowing in your face is a particularly lovely experience.

 

[ntsqd]

Could always, gasp!, install a catalytic converter or two.

I know, I know, now I'm talking crazy......

:sombrero:

 

[JIMBO]

:sombrero: I've had 9 off-road vehicles ALWAYS with duals and ALWAYS with turned down tips or down-angle cutoffs

Never had gas fumes in the back

I had one Dodge pwr wagon with the side (behind wheels) exhaust and that lasted one week--FUMES

:costumed-smiley-007:safari-rig::safari-rig: JIMBO

 

[matt s]

Thanks everyone, the change has been made. My hats off to Midas who did it for no charge 6 months after the initial job without any questions. In the end we cut the exhaust back by the rear tires and ran it from there at a 45 to the outside corners. This was for two reasons, going 90 and out by the tire put my rear shackles in the way, and bringing it farther back before going 90 was just going to look funny as it would be parallel to, and right below my bumper. The 45 was a good solution, required no new hangers, is less restrictive, and looks better too.

The drive home was without exhaust so I am hopeful that it worked. Another little bonus is I swear it sounds better, a bit quieter and smoother. I guess a little more length and another turn in the pipe can do that. If it takes a little fine tuning from here I imagine I can experiment with some different tips as they are cheap and easy to install.