489 exhaust system - Chevelle Tech
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post #1 of 46 (permalink) Old Feb 11th, 20, 3:58 AM Thread Starter
 
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489 exhaust system

Hi all,

I'm going to be putting in a 602hp 600ftlb 489 BBC into my car and wanna know your opinions on what exhaust system I should go for.

2 1/8" headers into a 3" system. Should I go for H pipe or X pipe and why?

Also, to quieten the car down my exhaust guy has recommended I go down to 2.5" after the mufflers (magnaflows). What are ya'll thoughts on this?
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post #2 of 46 (permalink) Old Feb 11th, 20, 4:25 AM
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Darren
 
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Re: 489 exhaust system

2 1/8 inch headers are too large for your setup, 2 inch max. A 3 inch exhaust system with an x pipe and good straight thru type mufflers (Ultraflos or Magnaflows) is what I'd run.
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post #3 of 46 (permalink) Old Feb 11th, 20, 4:48 AM Thread Starter
 
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Re: 489 exhaust system

Quote:
Originally Posted by 71454Chevelle View Post
2 1/8 inch headers are too large for your setup, 2 inch max. A 3 inch exhaust system with an x pipe and good straight thru type mufflers (Ultraflos or Magnaflows) is what I'd run.
Thanks for your input! I dyno tested 2" vs 2 1/8" and picked up on average 5-10hp and tq throughput the rev range.

What do you think of going down to 2.5" after the mufflers?
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post #4 of 46 (permalink) Old Feb 11th, 20, 6:53 AM
 
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Re: 489 exhaust system

Quote:
Originally Posted by moncam View Post
Thanks for your input! I dyno tested 2" vs 2 1/8" and picked up on average 5-10hp and tq throughput the rev range.

What do you think of going down to 2.5" after the mufflers?
2.5 after mufflers is - just like you said - an often used method to bring sound volume a little bit down without sacrifizing flow too much..

check these infos out:

Auto Exhaust Science

https://www.hotrod.com/articles/engi...-inch-exhaust/

https://www.hotrod.com/articles/ccrp...-inch-exhaust/
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post #5 of 46 (permalink) Old Feb 11th, 20, 9:24 AM
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Re: 489 exhaust system

I like x pipe ,Its possible H pipe can become ineffective at rpm.

Did a test one night ran 9.82 then pulled of the 3inch magnaflow system with x pipe this took 35Lb off of the car and it ran 9.85 next pass
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post #6 of 46 (permalink) Old Feb 11th, 20, 9:28 AM
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Lew
 
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Re: 489 exhaust system

Run a 3 inch muffler if you can. It will be a little louder but with your engine size and HP a 3 inch all the way back is the way to go.
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post #7 of 46 (permalink) Old Feb 11th, 20, 10:31 AM
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Rick
 
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Re: 489 exhaust system

What year chevelle?
On my 69' 467/400th I am using 2" primaries with 3.5 collector. I wanted 3" all the way. I wanted it tucked up so it was not visable from the sides. The problem was the collectors extended further back than expected and the factory trans cross member was not going to work. I bought an aftermarket which gave me plenty of room. The muffler guy had several types to choose from and we tried 4. Ended up with a Dynomax spin off which is straight through. Used it for 2 years now and still sounds the same. About 1/2 the cost. What state ?
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post #8 of 46 (permalink) Old Feb 11th, 20, 10:39 AM
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Re: 489 exhaust system

I'm running a 3" system with an X pipe all the way out on my 67. It's got a 575HP 468 with a stick.

I love the way it sounds. I like my Musclecar to sound like a Musclecar and since it's a weekend cruiser that only sees about 500-700 miles a year, I'm not overly concerned if it's too loud.

My current muffler set up is 3" Flowmasters but I'm not a huge fan anymore. It just seems like everyone at the cruise night has Flowmasters. When I did a custom exhaust set up on my old car (a BB 69 Camaro) I went with Spintech mufflers. I love the sound and how they're different than most everyone else. Once the weather warms up a bit, I'll be swapping my Flowmaster's for Spintech's.
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post #9 of 46 (permalink) Old Feb 11th, 20, 2:37 PM
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Re: 489 exhaust system

3 pipes all the way. X or H.... (I prefer X on my cars to quiet them more). Good muffs like Ultra Flows or Magnaflows.

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post #10 of 46 (permalink) Old Feb 11th, 20, 2:41 PM
 
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Re: 489 exhaust system

I have a similar engine setup and running 2" primary to 3.5 collectors with 3" x pipe and race pro Pypes mufflers with 3" tails.
I would do this again when building another car.
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post #11 of 46 (permalink) Old Feb 11th, 20, 4:08 PM
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Re: 489 exhaust system

Quote:
Originally Posted by moncam View Post
Thanks for your input! I dyno tested 2" vs 2 1/8" and picked up on average 5-10hp and tq throughput the rev range.

What do you think of going down to 2.5" after the mufflers?
Im really surprised by that. Typically on a 600 hp 489 BB the 2 headers are better for torque output.
I run a three inch exhaust on my 489.
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post #12 of 46 (permalink) Old Feb 12th, 20, 12:01 PM
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Re: 489 exhaust system

Quote:
Originally Posted by bradley67 View Post
Im really surprised by that. Typically on a 600 hp 489 BB the 2 headers are better for torque output.
I run a three inch exhaust on my 489.
What size primary tube do you run?
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post #13 of 46 (permalink) Old Feb 12th, 20, 12:38 PM
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Re: 489 exhaust system

I would put the smallest header I could get away with. I would say a 2" out of the box header fits better than a 2 1/8" header. If you are going to go custom made that's a little different. But my 565 made 980 hp on the dyno through a 2 1/8" header. So if that pipe can handle making that power, a 2" pipe can handle a 600hp engine without issue. So figure out what header is needed to fit your exhaust ports and go with that.
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post #14 of 46 (permalink) Old Feb 12th, 20, 2:43 PM
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Re: 489 exhaust system

running a 467 with almost exactly identical output. Engineers ( flOW) have told me same, size of tails after mufflers is irrelevant to performance. Pressure /heat has dissipated much by then is why. If you go 2.5" tails, ensure they are mandrel bent.

2.125" is large for your app. Peak TQ in a 467 is around 4000 with a 2" pipe, which is exactly where my 467 peaks. The 4.25" arm may bring that own to 3700 rpms in your application. 2.125" likely close to 5000 rpm, peak header torque. The cal'cs use an area squared so if it appears non-linear, it is slightly exponential is why. EG, in brackets 565, that same 2.125" primary may show it's peak at 3700, not 5000.

Will it see 5000-7000 often? If not, then 2.125" are academic in this app and may hurt short times if you race. But if you have them , run'em. Peak header torque is additive , not critical to the system.

PS to brackets point, my oem heads are HEAVILY massaged by a pro and I had to open up the 2" pipes so as to uncover the modified exhaust port completely. Didnt have that problem with my old oem heads! So do check!

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post #15 of 46 (permalink) Old Feb 12th, 20, 3:45 PM
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Re: 489 exhaust system

Do you care about how low to the ground the exhaust is?

I like X pipes, but (in my case at least) the X pipe is hanging much lower than an H pipe would due to the way the pipes bend to go into the X pipe in and where the X pipe has to sit, and in order for it to have adequate driveshaft clearance it is low.

With an H pipe, I can route it right under the tailshaft/yoke of the driveshaft and have it sit much higher than where I can put an X pipe.

I currently have an X pipe, and might switch back to an H pipe to raise the exhaust back up.

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