stwrangler Posted September 9, 2009 Share Posted September 9, 2009 just finished a 383 for my 78 280Z, 2 1/4" pipe's in to a 3" moroso spiral flow muffler ending with a flowmaster 44. I don't think the outside sound could be better, droning inside is bad. My Q is has anyone had luck with dynamate for droning problems. Quote Link to comment Share on other sites More sharing options...
Pyro Posted September 14, 2009 Share Posted September 14, 2009 just finished a 383 for my 78 280Z, 2 1/4" pipe's in to a 3" moroso spiral flow muffler ending with a flowmaster 44. I don't think the outside sound could be better, droning inside is bad. My Q is has anyone had luck with dynamate for droning problems. I had the same problem. Didn't think sound proofing would be enough to fix it. So, after the transmission I put in a short H-pipe, then two short dynomax bullets before the Y-pipe then to a 16 inch x 5.5 inch case dynomax super turbo. This completely fixed the drone and made the engine very quiet. With only the dynomax on the end, the car was undriveable due to a very very loud drone. Quote Link to comment Share on other sites More sharing options...
stwrangler Posted September 17, 2009 Author Share Posted September 17, 2009 thanks for the info, I'm ready to try about anything right now. Quote Link to comment Share on other sites More sharing options...
rsicard Posted September 17, 2009 Share Posted September 17, 2009 Pyro: Thanks very much for sharing your experience on exhaust systems to reduce interior noise. I will use the same configuration. Just wondering, does the H pipe balance the exhaust pulses as far as you can tell from the sound of the tailpipe? Pictures of your exhaust system would be nice. Please advise. Thanks. Quote Link to comment Share on other sites More sharing options...
Pyro Posted September 18, 2009 Share Posted September 18, 2009 sorry no pictures now. I'll work on getting a few to post. When I first built the exhaust I figured the dynomax super turbo would be quiet and the Y-pipe would balance the exhaust pulses. Boy, was I wrong. I think the inside of the car was louder than the outside. Plus, the outside sounded weird. I was perplexed! So, I pulled all stops and put in a H-pipe after the trans and another set of mufflers before the Y-pipe. I wondered if only one of the fixes would have made it quiet, but since I had the exhaust out I went ahead and did it all. Plus the H-pipe held the pipes in the correct position while I inserted the short bullets. Now the engine sounds almost stock at idle and very quiet during "normal" driving. But sounds good under full power (inside and out of the car). Major difference! I got the idea of putting in the H-pipe before the Y-pipe from 2 other exhaust systems that I built years ago. One on a 73 vette and the other on a true dual V8 240, where two H-pipes were needed to get rid of the drone. One up front by the transmission and the other one in the rear right before the dual mufflers. I got the idea from an aftermarket corvette exhaust system that used a H-pipe in the rear. It worked. Quote Link to comment Share on other sites More sharing options...
rsicard Posted September 18, 2009 Share Posted September 18, 2009 Pyro: Will putting in an "X" crossover in place of the "H" pipe accomplish the same thing as the "H" pipe? Please advise. Thanks. Quote Link to comment Share on other sites More sharing options...
Pyro Posted September 21, 2009 Share Posted September 21, 2009 I would think an X would have the same effect as a H pipe. I like X's better but they are harder to build. Quote Link to comment Share on other sites More sharing options...
stwrangler Posted October 27, 2009 Author Share Posted October 27, 2009 cut the flowmaster open and made a glasspack out of it, I filled it with rockwool. droning was cut at least 75% and noticable increace in power over 4000 rpm's. I'm going to make a 5 1/2" wide version of the muffler with dual 2 1/4" inlets and a single 4" outlet, then change from exaust from a 3" to dual 2 1/4". http://i108.photobucket.com/albums/n14/stwrangler/muffler.jpg Quote Link to comment Share on other sites More sharing options...
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