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Old 12-08-2019, 07:47 PM
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Originally Posted by slowbird View Post
I'd insulate the kids room for noise before touching the car. But that's me lol
that actually gives me an idea. i always open the shop doors, then start the car, so it starts on high idle and i have to rev it briefly to step it dow. i bet if i start the car first and drop it off fast idle before i open the doors that will help a bunch, especially if i switch from manifold to ported advance and cut the idle rpm down some.

  #22  
Old 12-08-2019, 07:48 PM
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Jim Hand runs 2-1/2” mufflers with a 3” X-crossover reduced right before the mufflers and 2-1/2” tailpipes on his 11-second Le Mans wagon if I’m not mistaken.

I know one of his favorites was the 2-1/2” Dynomax Super Turbo 17749 20” case muffler, quiet and free flowing. I use those mufflers on both of my Pontiacs and they’re great mufflers for quiet street performance.

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  #23  
Old 12-08-2019, 07:49 PM
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Originally Posted by b-man View Post
Jim Hand runs 2-1/2” mufflers with a 3” X-crossover reduced right before the mufflers and 2-1/2” tailpipes.

I know one of his favorites was the Dynomax Super Turbo 17749 20” case muffler, quiet and free flowing. I use those mufflers on both of my Pontiacs and they’re great mufflers for quiet street performance.
i literally have an old jim hand post open in my browser right now that gave me this idea!

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Old 12-08-2019, 08:43 PM
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Originally Posted by i82much View Post
i grew up in the 90’s. the word “flowmaster” immediately conjures up images of some vanilla ice looking dude pulling up next to my gto in his five point oh mustang and revvkng his engine while cranking the rap music and fixing his hair.

you don’t have to worry about me running flowmasters!!!!
X 5.0!

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  #25  
Old 12-08-2019, 09:19 PM
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Did you say if you have a “X” pipe or a “H” crossover pipe on it now?

I’ve read here about going from a X pipe. To a H crossover making a difference.l

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  #26  
Old 12-08-2019, 09:24 PM
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Originally Posted by 77 TRASHCAN View Post
Did you say if you have a “X” pipe or a “H” crossover pipe on it now?

I’ve read here about going from a X pipe. To a H crossover making a difference.l
x pipe on mine. i miss straight duals, easier to work on!

  #27  
Old 12-09-2019, 03:09 AM
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Originally Posted by TCSGTO View Post
Try putting a Dynomax bullet muffler in each tailpipe. It would be quieter and no power loss...
Basically a resonator at the very end of the tailpipe. Worked for Cadillac and Buick, etc...

Farther to the rear, the cooler the exhaust and the less impact a muffler or resonator has on power output. A resonator should have much less impact than more restrictive mufflers. I was considering something like this for the Bonneville 505 build since I thought it would be cool to have a much quieter exhaust and still blow the doors off the competition on the street.

It would be very interesting to know the db drop with resonators and also how much they actually restrict horsepower.

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  #28  
Old 12-09-2019, 12:25 PM
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Originally Posted by TCSGTO View Post
Try putting a Dynomax bullet muffler in each tailpipe. It would be quieter and no power loss.
https://www.summitracing.com/parts/wlk-24215/
^^^ This is what I did to quiet down the complete 3" 70.

  #29  
Old 12-09-2019, 12:32 PM
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Originally Posted by lust4speed View Post
Basically a resonator at the very end of the tailpipe. Worked for Cadillac and Buick, etc...

Farther to the rear, the cooler the exhaust and the less impact a muffler or resonator has on power output. A resonator should have much less impact than more restrictive mufflers. I was considering something like this for the Bonneville 505 build since I thought it would be cool to have a much quieter exhaust and still blow the doors off the competition on the street.

It would be very interesting to know the db drop with resonators and also how much they actually restrict horsepower.
Dad's 69 GTO had factory resonators in the tailpipes right at the exit behind the bumper. That was the first thing he removed when he bought the car new, lol.

What I've done in the past is run the system I want on the car, what ever that might be, and if it's a touch too loud, I reduce the tailpipe size after the muffler or mufflers. It's surprising how much difference a little change like this makes in sound. It's also shown to have very little if any impact on performance in a mild application.

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Old 12-09-2019, 01:28 PM
jerry455 jerry455 is offline
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I used to work with a friend of my dads who used to race his 1961 Ventura back in the 60's. He always stepped down in pipe size the farther back he went. His theory was , as the exhaust cooled, he could reduce pipe size to maintain gas velocity. He was not making as much power as many here are talking but the theory is interesting.

  #31  
Old 12-09-2019, 02:18 PM
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It's a real theory, hence the reason you see stepped headers.

The exhaust gasses cool as they move through the system, and they lose velocity, which is why a smaller pipe towards the end of the exhaust system doesn't have as much affect.

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Old 12-09-2019, 02:25 PM
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"Generally, the X-pipe will deliver a more high-pitched exhaust note, making a car sound more exotic, whereas an H-pipe gives a deeper tone with more of a traditional hot rod sound"

Like different muffler sounds and levels of sound some will dislike one mid-pipe type over the other.

X-pipe here:
https://www.youtube.com/watch?v=c90Jnw8hqbk


“As for the difference in power gain between the two, it is very minimal"

http://www.superchevy.com/how-to/exh...-for-your-ride

Just Google "X-crossover vs H-pipe" and you will get a dozen or more comparisons. Some with actual dyno testing.


.

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  #33  
Old 12-09-2019, 02:43 PM
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Quote:
Originally Posted by Steve C. View Post
"Generally, the X-pipe will deliver a more high-pitched exhaust note, making a car sound more exotic, whereas an H-pipe gives a deeper tone with more of a traditional hot rod sound"

Like different muffler sounds and levels of sound some will dislike one mid-pipe type over the other.

X-pipe here:
https://www.youtube.com/watch?v=c90Jnw8hqbk


“As for the difference in power gain between the two, it is very minimal"

http://www.superchevy.com/how-to/exh...-for-your-ride

Just Google "X-crossover vs H-pipe" and you will get a dozen or more comparisons. Some with actual dyno testing.


.
I've been through that myself. Tried a couple of "H" systems on my bird and switched to an "X" and got absolutely nothing from it. LOL Car still runs identical ET and MPH. As far as sound I don't notice much if any difference there. We switched my sons Mustang from an "H" to an "X" and it did nothing for sound at all on his car.
2 cars have the more expensive Dr. Gas "X" in the system custom made, and one necks down from 3 1/2" to 3" at the "X" and continues 3" for the rest of the system.
Still a couple cars here with an "H" and they'll likely stay that way since I can't find any measurable difference between the two, I'm going to spend money in other places.

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