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914World.com _ 914World Garage _ Sport Muffler Fab Question
Posted by: tomrev Apr 4 2016, 02:30 PM
Some background: My 914 has gone from a 383Chevy, to a 283, and now Honda 3.5 V-6 engine. A backwards power curve. The Chevy's just didn't sound the way I wanted the car to sound, so the move to the Honda. When it was finished, I re-cut, and re-made a system for the Honda using the twin Dynomax mufflers from the Chevy system, with 2 1/2in main pipes into the mufflers, and 3in. exit pipes. Kind of big for a 3.5, but it was 304 stainless, and I already had it. The car sounded quiet at idle, and glorious at open throttle, a cross between an NSX and a big 911. However, at cruise, and mid revs, ( 2K to 2800) it was pretty boomy, drony, too much so. I took it apart, re-did the pipes, and used a stock early 70's Leitritz banana muffler. Now it is too quiet! My current plan is to convert it to a sport muffler, and not having built one for 25 years, I'm asking those who have if they were able to make them without being too loud, or if a twin in, twin out is inherently going to drone. In my pile of stuff I have some 304 pipe in 2 1/2in. OD. Would this be too big for the exit side? Most sport's seem to have the exit pipes about 12-14in. apart, from the center; are there any inner chambers I can not fuch up by locating the exit pipes in a certain spot? Thanks! (photo of the Chevy system)
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Posted by: mgp4591 Apr 4 2016, 11:28 PM
Someone not too long ago took similar mufflers to your Dynomax and ran 90 degree elbows toward the rear center and welded them to a large diameter long glasspack, then drilled two large outlets for tailpipes exiting center about 6 inches apart. He claims the sound was just right- I wish I could remember the builder but I'm too lazy to look it up and it's past my bedtime... ![yellowsleep[1].gif](style_emoticons/default/yellowsleep[1].gif)
And looked cool as hell.
Posted by: tomrev Apr 5 2016, 05:25 AM
Someone not too long ago took similar mufflers to your Dynomax and ran 90 degree elbows toward the rear center and welded them to a large diameter long glasspack, then drilled two large outlets for tailpipes exiting center about 6 inches apart. He claims the sound was just right- I wish I could remember the builder but I'm too lazy to look it up and it's past my bedtime...
And looked cool as hell.
Would be interesting how he fit all that back there; would be cool to see it from underneath. The big reason I reverted to the Leitritz was packaging, to take advantage of the original design, and weight is pretty light. Thanks!
Posted by: 76-914 Apr 5 2016, 07:37 AM
This? http://www.914world.com/bbs2/index.php?s=&showtopic=201776&view=findpost&p=2295647
Posted by: Mueller Apr 5 2016, 10:53 AM
Some background: My 914 has gone from a 383Chevy, to a 283, and now Honda 3.5 V-6 engine. A backwards power curve. The Chevy's just didn't sound the way I wanted the car to sound, so the move to the Honda. When it was finished, I re-cut, and re-made a system for the Honda using the twin Dynomax mufflers from the Chevy system, with 2 1/2in main pipes into the mufflers, and 3in. exit pipes. Kind of big for a 3.5, but it was 304 stainless, and I already had it. The car sounded quiet at idle, and glorious at open throttle, a cross between an NSX and a big 911. However, at cruise, and mid revs, ( 2K to 2800) it was pretty boomy, drony, too much so. I took it apart, re-did the pipes, and used a stock early 70's Leitritz banana muffler. Now it is too quiet! My current plan is to convert it to a sport muffler, and not having built one for 25 years, I'm asking those who have if they were able to make them without being too loud, or if a twin in, twin out is inherently going to drone. In my pile of stuff I have some 304 pipe in 2 1/2in. OD. Would this be too big for the exit side? Most sport's seem to have the exit pipes about 12-14in. apart, from the center; are there any inner chambers I can not fuch up by locating the exit pipes in a certain spot? Thanks! (photo of the Chevy system)
And a nice video of this glorious sound is where?
Posted by: tomrev Apr 5 2016, 11:19 AM
This? http://www.914world.com/bbs2/index.php?s=&showtopic=201776&view=findpost&p=2295647
Interesting reading; I will stick with the banana, and probably do the usual twin pipe exits. Just hope it doesn't revert to being too loud.
Posted by: rnellums Apr 5 2016, 01:53 PM
If drone in a specific Rev range is your issue look into a Helmholtz pipe. It's a flawless acoustic pipe designed to kill noise of a certain frequency. I'm going to try to implement it on my droney exhaust later this summer.
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