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Working on some hybrid cutouts for my FRC

Old 04-24-2018, 09:23 AM
  #41  
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Originally Posted by nsogiba View Post
I didn't have a chance to complete the hybrid mufflers yet, been busy wrapping up an LS3 swap in the car.

I'm not sure why you'd want to put a cutout in the H-pipe. It's there to balance exhaust pulses, so with the cutout open, it's basically identical to the stock setup. With it closed, it's a true dual setup with no merge. Since actuating the cutout in that location doesn't actually remove any muffling devices out of the system, you won't have a change in volume.
Sorry, I wasn't clear on my intention. I am talking about adding a cutout to the cross pipe that exhausts to the outside, not blocking off the cross pipe. This should increase sound level with half the work of two cutouts and it keeps me further away from the plastic rear spring with hot exhaust gasses than most set ups installed farther back than the cross pipe. I'm not doing it for increased performance just for a louder exhaust when wanted.
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Old 04-24-2018, 09:26 AM
  #42  
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Cross pipe that exhausts to the outside? I'm still not following. Sketch a diagram of what you want to do.
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Old 04-24-2018, 09:33 AM
  #43  
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Originally Posted by nsogiba View Post
Cross pipe that exhausts to the outside? I'm still not following. Sketch a diagram of what you want to do.
I am not sure how to post a sketch. Just picture a stock H pipe then look at the little short horizontal cross pipe that connects the two sides. Drill a 2" hole into the center of the cross pipe and weld on a cut out that exhausts to the outside when the cutout is opened.
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Old 04-24-2018, 09:35 AM
  #44  
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Ah, I see. That's worth a shot, it would probably increase the noise, but might sound funny with all those sound waves from each side crashing into each other. I say give it a try!

I did a ton of research when starting this project and never ran across anyone that tried that.
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Old 04-24-2018, 09:39 AM
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Originally Posted by nsogiba View Post
Ah, I see. That's worth a shot, it would probably increase the noise, but might sound funny with all those sound waves from each side crashing into each other. I say give it a try!

I did a ton of research when starting this project and never ran across anyone that tried that.
Yeah I agree but was hoping to find someone else that has already tried it so as not to waste my time doing something that has already been identified as something that didn't work for one reason or another.

I guess I'll try it and see for myself. Thanks for the input.
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Old 04-24-2018, 09:41 AM
  #46  
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In order to test it out, you could always use a hole saw to just cut a hole in that cross over pipe and drive it around like that to see the "open" effect. If it doesn't sound good, weld it back up with the slug you cut out. If it's fine, install the cutout
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Old 04-24-2018, 09:50 AM
  #47  
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Originally Posted by nsogiba View Post
In order to test it out, you could always use a hole saw to just cut a hole in that cross over pipe and drive it around like that to see the "open" effect. If it doesn't sound good, weld it back up with the slug you cut out. If it's fine, install the cutout
Yes, that's a good idea. Thanks. Everybody says the holes are way small where that cross pipe connects to each side pipe and I expect I will need to open those up as well but your suggestion should give me a good indication before committing to the whole job. Again thanks.
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Old 06-12-2018, 10:10 PM
  #48  
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Default Single Vacuum Exhaust Cutout for more noise not more performance

Well I drilled the hole in the H Pipe short cross pipe and it sounded like crap, only slightly louder with a high frequency sound. Just for the heck of it I ground one of the 5/8" diameter holes in the driver's side main pipe to about 1.75" diameter and tried it again and it sounded good. Much louder and a lower frequency. So decided to charge ahead. Ground the 5/8" diameter hole in the passenger side main pipe to 1.75" and am taking the H pipe to a guy that has a tig welder Friday. In the mean time am working out vacuum line plumbing. I am optimistic.
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Old 10-12-2018, 08:01 AM
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Completed my single vacuum operated cut out on the cross section of the H-Pipe and love it. It is not super loud but loud enough that the wife does not like it open so that is about perfect. Could only fit a 2" cut out in the space. Tapped into the HVAC tank for vacuum and used a $14 vac switch from a 2010 Ford Focus that controls the intake manifold tumblers/runners Everything else came from Ebay/China. I love the instant on and off of vacuum over electric, which I've had on other cars. No leaks at all. When its' of it's off completely and does not rattle open over time. I used a normally closed valve so it will fail closed and needs vacuum to open. Cost was under $130 Including $60 for welding and I did all the labor. It sounds way better after grinding the 5/8" holes out on both ends of the cross pipe to match the pipe ID. No noticeable heating of the rear leaf spring on long drives or track days.




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Old 10-12-2018, 10:57 AM
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Nice work, would be interested in hearing a before and after.
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Old 10-12-2018, 12:05 PM
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Originally Posted by nsogiba View Post
Nice work, would be interested in hearing a before and after.
Sorry but I don't have the right equipment to record exhaust sounds. Everything sounds the same and very tinny when I use my phone.
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