Dansk dual in/out question

J-Mac · J-Mac's Garage

My '75 Carrera setup is an '86 3.2 with SSIs. Can you baffle or cap just one of the out pipes? In other words do they both exit the same chamber? If I was baffling one I want to make sure I wasn't choking one bank of cylinders. I was thinking of experimenting with baffling or capping to see if it made any discernible difference to mid-range torque. Good or bad idea? Thanks all.

Reiver · 01-15-2015, 03:53 PM

What muffler is it? RSR? I've been messing with a Dansk RSR 50mm/ 2 in two out. I've an '83 SC euro 3.0 with 220 HP and SSI's.
I've tried baffling (2" long sleeves 1/8th in thick) 5" deep into each outlet. I think this was too aggressive so went to baffling just the driver side and leaving the opposite open. This more clearly replicates the 4" total area of the stock muffler it was tuned for.
My butt dyno tells me this works best for mid and top end torque.
The banana muffler has open chambers in that it is not halved and one bank of cylinders feed 1/2 the muffler.
Try it and take if for a spirited drive.
It takes some fiddling to get an open flow muffler to work in mid range (where street driving is) and still keep a hot top end.
Race mufflers were designed for wot regardless of the gear selected...hard to do that on the street.
I think I have a handle on it as it's snappy at 3600 rpm now.

J-Mac · J-Mac's Garage

Thanks Reiver. Yes this is the RSR 50mm banana muffler. Great info. I will try your baffle specs and see what I notice in torque changes.

911pcars · 01-15-2015, 04:36 PM

Is your Dansk a 2in/2out sport muffler? If so, I've been unable to get any data on the internal structure of this particular muffler (via internet search and Dansk inquiries). If it's the same as a 2in/1out version, then the exhaust chambers are connected and thus you can go ahead and cap one tailpipe and see how that works.

Here's one cutaway illustration of a 2in/1out Dansk muffler and suggested mods to convert to 2 out "cowhorn" pipes. Notice the number of bulkheads in the muffler shell? You should be able to observe their number and location by the telltale signs of spot welds on the outside and compare with yours. Even then, the internals may not be the same.

If correct, both inlets share the same chamber. Capping one side will probably reduce the exhaust level. As for torque, one could measure the difference accurately on a chassis dyno.

Sherwood

J-Mac · J-Mac's Garage

Thanks Sherwood, I had found that diagram earlier and hoped the dual out was similar in construct. I agree on the chassis dyno, though I'll probably use my butt one first

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DanielDudley · 01:01 AM

SSIs already help with the mid range. That is not a particularly great flowing muffler even with two outlets. Plugging one would really drop your top end power. A Flowmaster or Dynamax with the internal crossover would flow better and help with scavenging, but they are LOUD.

Re gearing your transmission would put your power band where you want it.

IROC · IROC's Garage

Quote:

Originally Posted by DanielDudley

...That is not a particularly great flowing muffler even with two outlets...

I have the same muffler and would agree. There doesn't seem to be anything "sport" about this sport muffler.

Why are you wanting to cap one outlet? I don't find this muffler loud at all (relatively speaking).

Reiver · 01-16-2015, 08:21 AM

Don't think he wants to cap it just get a snappier mid range. The stock muffler that the stock motor is tuned for has a total exit area of 4"....the RSR is 5.5".
A sleeve/restrictor in one pipe gets it closer to the stock flow and does make mid range back in the sweet spot without affecting top end much if at all.
If you have a modified motor none of that applies.