Open Exhaust on a 617?
 

After doing some other work on my 300D last night, I decided to take the back portion of the exhaust system off to see how it would sound without. Short version: I like. Longer version: I mostly like it except for a bit of very low frequency booming that I get intermittently. I think this is in part due to the fact that my exhaust now terminates under the car approximately under the front passenger seat. Other than that it sounds AWESOME. You can definitely hear what the turbo is doing, and the sound is very pleasant and not too loud. Idle and cruise are only slightly louder than stock.

I'm thinking of getting some straight pipe added to carry the exhaust to the original termination point, but it will probably be a few weeks before I get around to doing that. I'm wondering if there's going to be a problem with having the exhaust like it is during that time. I used to have a '76 Buick with a 350 2bbl that had the exhaust set up the same way and I didn't have any problems with it, but that was a gasser and I think there was a bit more clearance between the exhaust exit and the bottom of the car in that case. Does anyone have experience with this setup in a turbo 617?

Mods: If this goes in Performance Tuning feel free to move.

Based on research I did when I was considering doing a straight-out exhaust on my 300d, you will need to make sure your pipe terminates at least 1" out beyond the rear bumper, to get rid of that boom at higher speeds and on hard acceleration.

To answer your main question, on a previous 300sd that I had, the exhaust rotted and fell off midway under the car and due to my underemployment at the time, I had to drive it that way for about six weeks. The only issue I had was that the insulation and rubber seal were long gone from my shifter opening in the console so when stuck in traffic, or when driving with the sunroof open, I got exhaust coming in the car. The engine on the car was tired so I wasn't the nicest diesel you could imagine.

I put straight pipes in quite awhile ago and haven't regretted it. You can't even hear it when you're cruising. It's also a great way to tell if one of the kids didn't close their door all the way, since it's normally so quiet when everything is closed up.

One of the mufflers had a hole in it anyway, so I had to do something so fumes would quit coming in. The only thing I changed later was to make the exhaust exit out the side, not at all because of noise (didn't change), but because fumes would still come in if just the right combination of windows were open. Now I'm as happy as I could be with it.

-Rog

hmm... would like to hear this....

I tried taking a video with my phone, but it doesn't do it justice. There are examples on youtube.

My exhaust exits thru the right front fender with a total of no more than 18" of pipe. You might want to take a look on my build thread. I'm surprised how quiet it is. We'll see how it acts on the track and at speed - more to come.

Dan