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Old 08-28-2020   #1
-=Jeff=-
 
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Location: Bartlett, IL
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Default Exhaust question....

Now I have been known to try several different exhaust systems. However there are some I never tried..

So has anyone...

Ever installed muffler eliminators only? (Rest of the system stock)

Ever installed headers with cats to stock exhaust but then added muffler eliminators?


If so, how did it sound? How boomy was it in the car?

No I am not looking to change, just curious
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Late Model IH - Plenum
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Old 08-29-2020   #2
WARP TEN
 
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Default Re: Exhaust question....

Quote:
Originally Posted by -=Jeff=- View Post
Now I have been known to try several different exhaust systems. However there are some I never tried..

So has anyone...

Ever installed muffler eliminators only? (Rest of the system stock)

Ever installed headers with cats to stock exhaust but then added muffler eliminators?


If so, how did it sound? How boomy was it in the car?

No I am not looking to change, just curious
Jeff, this is likely stuff you already know, but the LT5s (and many engines) have two distinct high resonance frequency points, one at about 1,800 rpms (120 Hz) and one at about 3,400 rpms (230 Hz). To reduce or eliminate resonance or "drone" in a stock system, the center resonator addresses one frequency and the rear mufflers handle the other one; I can't remember which frequency is handled by which though. The lower frequency resonance is most noticeable at about 75 mph in sixth gear with a stock rear end, and the upper frequency range is usually run through on each shift. This resonance is most noticeable and annoying under load; if you simply rev the engine in neutral through the resonance points the sound is not nearly as intense as when accelerating. If you remove the mufflers, you will get resonance at one of those frequencies and will likely notice it. While I understand there are aftermarket systems now that can control resonance better than they used to, in the late '90s only the stock and Corsa systems did so. Tested many different systems. My final solution in about 2014 was to reinstall the stock system on my '95 and add electric cutouts just in front of the mufflers. There are several threads on this and on other Corvette forums about this installation and others who have done it. I can tell you that with the cutouts open on the '95, which was similar to having muffler eliminators, it sounded great and could set off car alarms and scare small children if desired. But I never left them fully open long enough to know if they created resonance on the highway. Mostly just for racing although I used to cruise around town with them about one third open for effect. My '95 had headers, no cats and the stock exhaust system. Cats will soften the sound. Mufflers are a horsepower bottleneck--removing them (or adding the cutouts) can add 20-25 HP according to Marc H. Hope that helps --Bob
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Last edited by WARP TEN; 08-29-2020 at 03:20 PM.
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Old 08-29-2020   #3
-=Jeff=-
 
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Join Date: Jul 2007
Location: Bartlett, IL
Posts: 7,146
Default Re: Exhaust question....

Yeah, thanks Bob, I remember that too and forget which is which. But was truly curious on the eliminators. I do know the "stock" or close to stock replacements add a bit of a growl to the sound and don't change the drone or lack of too much. I have the LT4 stock system on my car with headers and cats
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1990 Corvette ZR-1 #1051
Watson Headers (2" Primary) - Borla Catback
Late Model IH - Plenum
Coilovers - 4.10s
Custom Interior
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