Super Quiet Exhaust!
11-11-04, 11:39 PM
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Super Quiet Exhaust!
Heeding the advice of some board members and my engine builder, I might add, yesterday I replaced the busted out Edelbrock muffler on my street-port 85. Yes, the Edelbrock experiment is officially over; (at least for the EXHAUST side; the 600 carb lives on!!) once a year replacement is a little too much for ole Sanspistons. Not to mention the noise...
Specs; Pacesetter header, Edelbrock RPM Nitrous Race muffler and thin-wall pipe crimped down onto short piece of original center pipe feeding into junkyard ($30!) RacingBeat PrimaFlow. Replaced Edelbrock with a 2 1/2 Dynomax "bullet" and used RB thick-wall 2" pipe to connect to stub of center piece. The guy was almost able to run the pipe straight back from the bullet to the stub with a little judicious bending of heat shielding. Forget bending this stuff unless you have two torches and a BIG bender.
He also had to nest different sizes of pipe in the bullet to adapt to the RB pipe; not the most efficient flow-wise but it worked. Wish Dynomax made these things in 2" sizes...
Anyhow started it up and we both laughted!! -the car came in sounding like a ProDragster, went out sounding like a stocker! Almost can't hear the engine running at all! You CAN hear the wind noise from the worn out door seals (hey, she just made 20 yrs old!), transmission noise, (hmm..) axle noise, (HMMM...) brakes squeaking, suspension thumping etc... not to mention the Carter humming like a hive of bees under the floor boards. Yes, Virginia; there IS a radio in the car and now I can prove it!
Sounds a little ricy, actually, with the usual PrimaFlow pop-pop at idle; not a bad sound at all. Over 4000 it starts to scream, with a sound like ripping silk that gets louder up to 8000 but never TOO loud. Seems to have added some low end torque; it's easier to launch cleanly from a start but with no sign of top end power loss. I have to re-learn to drive this thing again; before I could shift by ear, now I look down and I'm doing 5000+ in third!!
So my advice for members thinking about custom exhaust is: 1. Always use thick-wall pipe, rotary racket goes right through the normal stuff and you can hear it UNDER the car instead of BEHIND like it should, and it's the only stuff to stand up to the Wankel Waster. 2. The Dynomax Bullet makes a cheap (but not perfect) pre-silencer replacement. 3. The RacingBeat stuff is pricy but not as pricy as 4 years of failed exhaust experiments (and some hearing loss, I think...)
Thanks again!!
Sanspistons for (quiet!!) performance
Specs; Pacesetter header, Edelbrock RPM Nitrous Race muffler and thin-wall pipe crimped down onto short piece of original center pipe feeding into junkyard ($30!) RacingBeat PrimaFlow. Replaced Edelbrock with a 2 1/2 Dynomax "bullet" and used RB thick-wall 2" pipe to connect to stub of center piece. The guy was almost able to run the pipe straight back from the bullet to the stub with a little judicious bending of heat shielding. Forget bending this stuff unless you have two torches and a BIG bender.
He also had to nest different sizes of pipe in the bullet to adapt to the RB pipe; not the most efficient flow-wise but it worked. Wish Dynomax made these things in 2" sizes...
Anyhow started it up and we both laughted!! -the car came in sounding like a ProDragster, went out sounding like a stocker! Almost can't hear the engine running at all! You CAN hear the wind noise from the worn out door seals (hey, she just made 20 yrs old!), transmission noise, (hmm..) axle noise, (HMMM...) brakes squeaking, suspension thumping etc... not to mention the Carter humming like a hive of bees under the floor boards. Yes, Virginia; there IS a radio in the car and now I can prove it!
Sounds a little ricy, actually, with the usual PrimaFlow pop-pop at idle; not a bad sound at all. Over 4000 it starts to scream, with a sound like ripping silk that gets louder up to 8000 but never TOO loud. Seems to have added some low end torque; it's easier to launch cleanly from a start but with no sign of top end power loss. I have to re-learn to drive this thing again; before I could shift by ear, now I look down and I'm doing 5000+ in third!!
So my advice for members thinking about custom exhaust is: 1. Always use thick-wall pipe, rotary racket goes right through the normal stuff and you can hear it UNDER the car instead of BEHIND like it should, and it's the only stuff to stand up to the Wankel Waster. 2. The Dynomax Bullet makes a cheap (but not perfect) pre-silencer replacement. 3. The RacingBeat stuff is pricy but not as pricy as 4 years of failed exhaust experiments (and some hearing loss, I think...)
Thanks again!!
Sanspistons for (quiet!!) performance
Last edited by Sanspistons; 11-11-04 at 11:54 PM.
11-12-04, 12:01 AM
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Don't think so; it runs BETTER than the almost straight-through Edelbrock setup and is a whole lot quieter. Besides, everytime I detune the exhaust size (from it's original dual Edelbrock 2 1/2 from the collector out the rear) it GAINS in power. Seems this engine just likes ~ 2" pipe sizes, at least for the midrange. Since I mostly drive on the street and autocross, a midrange power increase is worth any loss I might have around the usually unreached 8000rpm.
Sanspistons for midrange flow velocity
Sanspistons for midrange flow velocity
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